z os iis * ee EE et, en ll ——ees “ “ Digitized by the Internet Archive in 2010 with funding from University of Toronto htto://www.archive.org/details/reportsofsurveyb03geol * ) Minnesota Plant Life. aia 3. races — ' at L chy J _ le > Be % sni7st A (.s99iqemorT) .1 ATAIT { .omod tied? odem etnsiq » ay a Veolemss . WEIN Nola Oo 7 eb ae I Po by Conway MacMillan HE PIONEE n PRESS =SAINT PAU keport— of the Survey Botanical Series BY ees Saint Paul, Minnesota October 30, 18909 PUBLISHED BY AUTHORITY OF THE BOARD OF REGENTS OF THE UNIVERSITY FOR THE PEOPLE OF MINNESOTA Edition, 10,000 copies Preface. i T has been well said that the main difficulties with the book on popular science are that, if popular, it will not be scientific, and, if scientific, it will not be popular. Yet, notwithstanding the truth thus epigrammatically expressed, I am venturing to put forth Minnesota Plant Life as a book certainly meriting the designation of popular, in so far as it is addressed to an audience not composed of botanists, and at the same time scientific, to the extent at least of choosing for its field one of the two great realms of living things — the king- dom of flants. While to be out of fashion is to be out of the world, I have, nevertheless, resisted the impulse to designate this volume as a suitable text-book for the “secondary schools.” On the contrary, such a use of it would be, in my opinion, ‘distinctly un- fortunate. It is not written in pedagogical vein, nor does it pre-suppose an acquaint- ance with teachers and laboratories. It would, however, be disingenuous to deny that the author has a definite educational purpose in view. Since this volume is to be distributed in every county and perhaps in every school district in Minnesota, it should, especially among the young, stimulate an interest in the study of plants. With a minimum of technicalities, sentimentalities, unavoidable inaccuracies or cum- bersome details, it seeks to accomplish the following ends: J. The plant world is presented as an assemblage of living things. 2. The different kinds of plants in Minnesota, from the lowest to the highest, are briefly reviewed in their natural order. 3. Some plant structures and behaviors are elementarily explained, as adapta- tions to surrounding nature. 4, Certain plant individuals and societies are brought before the reader as hav- ing life problems of their own, not as mere material for economic, anatomical or classificatory industry. In short, I have recognized that there are in Minnesota a number of intelligent men and women, boys and girls, who wish to know more about plants, and in the pages of this book I have sought to bring together what, from my own experience as a student of plants, and as an instructor of the young, seems to me a sufficiently adequate and compact presentation of the subject. Errors of judgment and of fact no doubt exist, as in many works of mere human construction. I hope that they will not prove harmful. In some matters, indeed, the point of view has shifted since cer- tain chapters were in type. For example, experiments recently completed by the United States Department of Agriculture tend to modify the German and Danish ex- vl Minnesota Plant Life. planations of bacterial relation to dairy industries and to the curing of tobacco, Other new facts have keen elicited by investigators studying the red and purple coloring substances in plants, so that, if prepared to-day, various chapters would undergo slight alteration. In a subject developing so rapidly as is modern botany, it is diffi- cult to be always aksolutely abreast of the current. A large number of the illustrations in the volume are from photographs of Min- nesota vegetation, some of them made by myself, or under my direction, others selected from the collections of friends, acquaintances and dealers. Many figures, too, have been obtained in other ways. I have particularly to thank Dr. N. L. Britton, of the New York Botanic Garden, for the cuts from his splendid J/lustrated Flora of North America, here credited to Britton and Brown. I am also much in- debted to Professor G. F, Atkinson, of Cornell University, for permission to use nu- merous engravings from his excellent text--ook, Elementary Botany, and likewise express my thanks to the United States Department of Agriculture, to Professor Francis Ramaley, of the University of Colorado, Mr. C. G. Lloyd, of Cincinnati, the Botanical Gazette, Meehan’s Monthly, Professor L. H. Bailey, of Cornell Univer- sity, Professor B. D. Halsted, of Rutgers College, Professors Hall and Appleby and Instructors Mackintosh, Mills and Wheeler, of the University of Minnesota, Professor Bruce Fink, of Fayette College, the late Warren W. Pendergast, and several others, all of whom have assisted me in collecting illustrations. Iam also greatly obliged to my father, Dr. Geo. McMillan, for much valuable assistance with the proofs, and to Miss Josephine E. Tilden for the preparation of the index. I am particularly indebted to President Cyrus Northrop for suggestions and assistance, without which, in all probability, this volume would have been neither prepared nor published. Among many books that I had occasion to consult during the preparation of manuscript the Illustrated Flora of Britton and Brown, Sargent’s magnificent Silva, Kerner’s Plant Life, Warming’s Ecology, Schimper’s Plant Geography, Lafar’s Technical Mycology and Upham’s Catalogue of the Minnesota Flora, deserve especial mention. Yet I should not give the impression that Minnesota Plant Life is wholly a product of the study; it is much more the offspring of the woods, the prairies, the rivers and the lakes. In every part of the state, during the past twelve years, I have visited them, and this book, with whatever merits and demerits it may have, received an inspiration from such excursions among the plants themselves, If, by the distribution of this volume a broader knowledge, a deeper interest, a truer appreciation and a better understanding comes to those in whose hands its pages open, the writer will feel well repaid for the labor of preparation. An intelligent study of nature is one of the foundation stones of useful citizenship. The University of Minnesota, October 2, 1899. PREFACE (CEES) eee CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER } CHAPTER CHAPTER Table of Contents. Plant Wanderings and Migrations............. Slime-moulds and Blue-green Algae........... eat t Brighii= cree Al Gaey sane eae aoe ena cee Browne loader: andehedi@Nllo-a cas ane enge see Hooton ‘Bhe Wower Sorts ‘of Punded.-o').ec%. ics ake SialitcerantiG WeLNUStS ree ee eee tc eee es Sees ee Sete Trembling Fungi, Club-fungi, Shelf-fungi and > > > > intr Siiig@ @ rinse et epee o rescore hie ean 8 oly ee Carnion-tunedande eit balsa. see sss sess ae Yeasts, Morels, Cup-fungi and Truffles........ Cee ee Blights, Black-fungi and Root-fungi......... iichens) and Beetle=tungines se 5.0 47-60 sean \WEiROUIS 1Ghavls ot IDRC, a5 oe ceo dees eee Mosses and Liverworts as Links between the AMipdevandeiicher elantsee re eae kee ee ee IEE WOLS TOL s\linnesOtdaw. ae ee ee INMGSSESHOIs MLInneSOtalenet ante eee eee aK, 5 Christmas-green Plants or Club-mosses....... Beer te. Hernscand VV aterstennss ae aoe se Sree Scouring-rushes and Horse-tails............... What Seeds Are and how they are Produced... Ground-hemlocks and Various Pines.......... Brom Cat-tails to Eel-grassés...... food. sss. (SC CASSeGeA TIE OCURES a aes he ach cacararsers (fit ees 122 107 204 Vill CHAPTER X} CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER Minnesota Plant Life. From Callas to) Water-stai-grasses. ..........- 627 Rushes, Lilies, Blue Flags and Orchids........ 224 Poplarsearnids WillOwsStarce acc oe aoe eree 233 From Bayberries to Oaks, Elms and Nettles... 243 From Sandalwoods to Buttercups:............ 256 From Barberries to Witch-hazels.............. 274 lkoses, “Peas andsthe Relatives... eee 286 From Geraniums to Maples and Touch-me-nots 305 From Buckthorns to Prickly Pears...........: 319 From Leatherwoods to Dogwoods............ 332 High Types and Low Types of Flowers....... 343 From Wintergreens to Chaffweeds............ 350 From Ash, Trees to Verbenas. .:..-\-2--oseeee 360 From Peppermints to Plantains....--2-2-2--5-375 From Bedstraws to: Lobelias. & .... 2. a2eeeeeee 388 Dandelions, Ragweeds and Thistles............ 309 Adaptations of Plants to their Surroundings... 417 Elydrophytie: Plants): ace 045-6 eee 442 Merophytic “Plants....0. 55.2 sea.) ee eee 463 Ealophytessand Mesophytes!=). -- ease 473 Maintenance of the Plant Individual........... 483 Maintenance of the Plant Species.............. 509 Prare I: Peart — 11. Brat ltl Piate IV. List of Plates. se A ravine near St. Paul, where shade-loving plants make their home. From a photograph by Dr. Francis | PRES Ty GIGS A Se rl foe oy Ory RP naa Sener pa a Frontispiece. In the black oak country. Near the Chisago lakes. From a photograph by Dr. Hrancis: Ramaley:...5.:¢.2-5:-4:7- 248 Pond with lilies. Ramsey county. Around it are growing oaks, willows, sumacs and blue flags, milkweeds and smartweeds. From a photograph by Williams.......... 312 Roadside vegetation near St. Paul. The most conspicu- ous plants are hemp, wormwood, squirrel-tail grass and daisies. From a photegraph by Dr. Francis Ramaley... 456 lRKeS Fic. Fic. Fic. Fic. Fic. Fic. Fic. to Index to Iflustrations. SF In the forest district. Growth of white pines and spruces upon a rocky island. Steamboat channel, Lake of the Woods. Miter photocraph Dysthe author. 2-G..c..2 2.626 nes eee eres ae Prairie scene on the Coteau. Sunflowers line the roadway on either side. After photograph by Mr. R. S. Mackintosh..... Roadside vegetation. Grasses and pulses. An elm tree in background. Cedar lake. After photograph by Williams... Spruces forming a zone around a peat-bog. Farther back are tamaracks and pines. The shrub in the foreground is the bog-willow, while the flowers are those of an orchid,—Pogo- nia. Near Grand Rapids. After photograph by Mr. Warren RENO ERO ASIA As oan en SPE CPR ee ie ost hes oi cis eueeichae aie ee Zones of aquatic vegetation. In the center pond-lilies; at the edge smartweed; farther back cat-tails, blue flags, sweet flags and sedges; still farther back soft turf with grass, moss, sedge and milkweed. After photograph by Williams........ Island in the Mississippi above St. Paul. The center is occu- pied by elms while the rim is fringed with willows. An ex- ample of a “minor tension.” After photograph by Professor Pare OPED i ce eA noe Sec OR en he tae a: Lake border vegetation of cat-tails, grasses, reeds and sedges. Lake of the Isles. After photograph by Williams........... Portion of a board which had been standing in the tank shown in Fig. 10. It is encrusted with limestone deposited by a colony of blue-green algae. After photograph by Miss Jos- ephine E. Tilden. From the Botanical Gazette............... 10 II 12 18 Xl Minnesota Plant Life. Fic. 9. Portion of a pond-scum thread, showing how it is made up of Fic. Fic. Fic. Joie: laine. Fic. Fic. Fic. Fie. Fic. Fic. Fic. Io. 12. 14. 16. ee 18. 19. 20. 21. transparent-walled cells with a coiled green ribbon in each, much magnified. After Atkinson Patches of pond-scum floating in a tank. A lime-encrusting alga grows on the boards up to high-water mark. Near Minneapolis. After photograph by Mr. R. W. Squires Patches of wheat-rust, natural size and enlarged. The red rust stage. After Atkinson 0.0) Co. 0! ele 8 0116, 0 8)(6, @ e);e ve, 0:0) 0,0), « .e.0)J0,\e,0 nelesetelsiameiemelle Patches of wheat-rust, natural size and enlarged. The black rust stage. After Atkinson Wheat-rust in its barberry-leaf stage; to the left a barberry leaf with diseased spots; in the middle, a single spot with cups; to the right, two of the cups, in top view slightly mag- nified. After Atkinson Magnified section through a cluster-cup of the wheat-rust in its barberry-leaf stage. Shows chains of spore-cells. The large cells at the sides are those of the barberry leaf much magni- fied. After Atkinson Growth of club-fungi on decaying wood. After Lloyd........ Shelf-fungus growing on dead stump of oak tree. After pho- tograph by Hibbard Upper and under sides of mushroom-like pore-fungus. After Lloyd A pore-fungus lying flat upon a decaying branch. After Lloyd Deadly variety of mushroom. After Atkinson. Bulletin 138, Cornell Ag. Exp. Station. This is sometimes known as the “poison cup”’ © Slee © 0 0 0, ¢ 6 0) © 0.6 (0 10 }¢) 0) Jvloue, © ele 06) ¢ « 9) elleueens! ©) alelehe inl oelemsgans Under side of two mushroom-fruits. After Atkinson. Bulletin £38, CornellvAg. Exp: (Station. 2. ceeicee es «te ee Common edible mushroom. After Atkinson. Bulletin 138, Cornell’ Ap. Exp..Statiom. . 4. 00re = oe: eee 34 35 51 51 52 53 56 57 59 60 61 62 Minnesota Plant Life. bie. 22: Fic. Fic. Fic. Fic. Fic. Fic. Fic. Ere: Fic. Fic. Fic. Fic. Fic. Fic. Fic. 23. 24. By. 26. 27. 28. 20. 30. ay. 32: 33: 34. 36. 37. Development of mushroom-fruits on their underground vege- tative tract. After Atkinson. Bulletin 138, Cornell Ag. Exp. SUEITIGNT: Bega beatae Caiets OF Somer ane ae ee ey aera ENS a Mandya iit pall ooAt cers tO ss Sec trans ocd 5s Sickie coe Singsio See mies Miteaapiiit—palle Atter-IglOyd. «. sscetng snc osc = a+ ae ha elebsiaie)= Pocket-fungus on sand-cherry. After Bailey. Bulletin 70, Slayer ys ea Bg reese Sey chn Rate nee MORIbe ae OIC Deen oon Aamorclinutpody. Aiter Vly i... ton Gins2 ane Sele me Sarees Cup-fungi growing on decaying twig. After Lloyd........... Leaf-spot disease caused by fungus. After Halsted.......... Leaf-spot fungus growing on pear leaves. After Duggar. Bul- letin- 145, Cornell Ags. Exp! Stations. .. 24202-2322 seen en Fungus spot-disease of strawberry leaf. After Bailey. Bulletin 7o) Cornell Univ, Aes Exp, Station. a... 2)... 22 -)oos ee en Fungus spot-disease on leaf of false Solomon’s seal. After TE Ipilgiatch a eee eoianoe oc AGae aoe comanG anime as aEmmacoer Fungus spot-disease on pear. Aiter Duggar. Bulletin 145, Sten aN Bae: StALOMs . 2. i ee le eee Ae tants ws ere ier Fungus spot-disease of bean pods. After Haisted............ Twig-fungus on currant canes. After Durand. Bulletin 125, Connellepacn Stations cnt ee eo ee ne aio eee Rock-lichens growing profusely in a glacial pot-hole. Near Taylor's Falls. After photograph by Mr. E. C. Mills........ “Old man’s beard.”’ A lichen growing attached to the twigs of tamarack. Lake Superior, north shore. Natural size, six inches in length. After photograph by Professor Bruce Fink A lichen growing upon a rock, and covered with the charac- teristic saucer-shaped fruits of its fungus component. After TANS A Ferho EO) 9 PM PaO itg SOR Catach Rn, SUE ne JME ecu ae eee eae hs near em x1 64 82 83 84 85 86 87 88 92 93 XIV Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. IES. Fic. 40. 4l. 43. 44. 40. 47. Minnesota Plant Life. A tuft of “reindeer moss.’’ Natural size, 2% feet in diameter. Age, probably over one hundred years. North shore of Lake Superior. After photograph by Professor Bruce Fink....... A male moss plant. The spermaries are produced in clusters at the end of the stem. After Atkinson............-..-+-++. A female moss plant. The egg-organs are inclosed in the tuft of leaves at the tip of the stem. After Atkinson...........-- The club-shaped spermary of a moss, much magnified, and two spermatozoids, very highly magnified. After Atkinson...... Tip of a leafy moss plant, sectioned lengthwise and magnified. The flask-shaped egg-organs, one with an egg in place, are shown. These bodies are barely visible to the naked eye. Adter AtkansSo ive \. ac-cie Senn aciee oe teneinl lores onetotiat a eee Mud-flat liverwort, showing method of growth and branch- ine: -Attéer Atkinsonee:s cn, sccne sce psn ene oe ae eee The umbrella-liverwort; showing the prostrate vegetative pody, and the upright branches on which the egg-organs are borne, and where later the capsular plants will be found perchinge, After Atkinson: 2.255.25-0 255-39 ceo eee Stem of the umbrella-liverwort, showing the little cups with bodies inside, which are employed by the plant for purposes of propagation. Aiter Atkinson. 2.5. ...seeee ae Road across a peat-bog; tamaracks and birches in background. Near Grand Rapids. After photograph by Mr. Warren Pen- dereast sis tip en sian Oe ae sie ee eee Peat-moss leafy-plants with capsular-plants imbedded at the tips of short leafless erect branches. After Atkinson......... A moss leafy-plant, with prostrate propagative branch and erect female reproductive branch. On the latter two egg- organs have developed their eggs into capsular plants, one of which is ejecting spores. The two round bodies are spores much magnified) After Atkinson one secs eect ee 97 127 132 136 138 145 147 Minnesota Plant Life. Fic. 49. Fic. Fic. Fic. lene. Fic. Fic. Fic. Fic. Fic. Fic. 61. . 62. Branch of a club-moss plant, bearing two canes; with a single leaf of the cone, showing the spore case and one of the spores, the latter much magnified. After Atkinson.......... Flat-branched club-moss. After Britton and Brown.......... Smaller club-moss. To the left a plant with three cones, next a single cone dissected to show the spore cases, next a single large-spore-case with four spores revealed, and on the right a small-spore-case with the small spores sifting out. After NTH FeTTo Yo 0 ete Sc er eee Rene oer ee eon ILE MIO cleo eet ap oe Adder’s-tongue fern. After E. N. Williams, in Meehan’s DOTTETULM a ey oc poe WAN ae pey -tisee key eee Tako ae tegen Sea RTM aoe rel cick Virginia grape-fern. After Britton and Brown............... NX Gheilihorejeyoes wavitiemwatshanlorls bas Sue eeacacmes dacckoudoct Clayton’s, or interrupted fern. After Britton and Brown..... Bed of ferns. Sensitive fern in middle of foreground. After PhHotorraph bya VWoalliannsweeces aleve ase cvfoie Sees ele take = Chi-brakes. After Britton/and Brown... 20.4. .a 22605 see nse The interrupted fern (in background) and shield-ferns (in fore- Sround).Aiter photograph by, Walliams... > eee ee oe Four-leaved water-fern. After Britton and Brown............ A sexual fern-plant somewhat magnified. Its natural size is about a quarter of an inch across. The round bodies are spermaries, the chimney-shaped ones are egg-organs, seen Pept WDELOW, = AULOT CALKINS OMS, :,\. 08h 2 eiete oiler Gea wee ie sete, ee A fern-plant embryo imbedded in the enlarged egg-organ, where it arose by segmentation of an egg. S, tip of rudi- mentary stem; L, tip of first leaf; R, tip of primitive rootlet; F, nursing foot. Much magnified. After Atkinson......... Portion of maiden-hair fern leaf, showing marginal pockets, which serve to protect the clusters of spore-cases under each SEIN BECRITGT: MMINSONT. sh at ang Gd sn etn rs pe tatiahn s a oieet & 159 168 Fic. Fic. Fic. Fic. IDG, Fic. Fic. Fic. Fic, Fic. . 63. 64. SOS 66. 67. 68. 73- Minnesota Plant Life. A patch of spore-cases on the back of a common polypody- fern-leat. “Magnifieds “AiteryAtkinsom . 2 lita. 1 keer Spore-cases of the common fern, much magnified, showing how the spring back reverts and then snaps shut again, throwing the spores as from a sling. After Atkinson........ A walking-fern climbing down a hillside. Buds form at the very tips of the slender leaves and grow into new plants. After AtkinsOn's .<..)..0<% nv ocs © ole cree gotecs wien cee aloe ee eee Maiden-hair ferns and lady ferns. After photograph by Wil- liam)... 0530s oe Ses eae oie Se ee EG Oe Se eee A fruiting stem of the horse-tail. The shield-shaped spore- bearing leaves are aggregated in a cone. After Atkinson... . Scouring-rush spores; to the left a spore with appendages curled up, in moist air; to the right a spore with appendages extended) in-dnyoains, Attter Atikinisone + .)-sei eis eee Diagram of an ovary, with one seed-rudiment, in a higher seed-plant. s, the stigma, where two pollen-spores have germinated; o, wall of ovary; i, stalk of ovule; ai and ii, rudimentary seed-coats; n, spore-case, with single large spore, which has germinated to produce the reduced female plant; k, the egg; e, the body which forms the albumen; b, other cells of the female. The male plant is shown as a tubu- lar thread growing towards the egg. After Atkinson........ White pines on the rocks at Taylor’s Falls. After photograph by: Wallianiss..2..\o8nc.d see o ten coon eae COR eee jJack/pine:- After Brittonvand- Brown....4-5 602 220 eee Rock-vegetation near Duluth. White pines, white cedars and junipers, — Atte photography bya Walliams: sere eee Tamarack swamp with sedge border. After photograph by Walliamigos sacs nitecaton crak eae hee de CE ee Red cedars on the banks of a Minnesota lake. After photo- graph by: Walliams. .). big-t on oe ee 170 17I 172 173 176 177 181 187 188 189 IQI Minnesota Plant Life. Fic. ETc: Fic. Fic. Dies Fic. Fic. Fic. Fic. Fic. Fic. BiG. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. 75: 76. 77- 79. 8o. go. gl. 94. Rock on the St. Croix river, near Taylor’s Falls. Shows zonal distribution of trees. White pines stand on top of the rock, -and birches and poplars on the sides. After photograph by Mr. H. C.. Cutler Bur-reed. After Britton and Brown Lakeside vegetation. Just off shore is a growth of the floating pondweed, then of arrowheads, while farther out are reeds and rushes. After photograph by Williams Clasping-leaved pondweed. After Britton and Brown Evening scene in Minnesota. Arrowheads, bulrushes and wil- lows in foreground. After photograph by Williams Arrowhead. After Britton and Brown Eel-grass. After Britton and Brown Wild rice and pond lilies. After photograph by Williams Beard-grass. After Britton and Brown Barnyard grass. After Britton and Brown Minnesota Muhlenberg grass. Aiter Britton and Brown Beckman grass. After Britton and Brown Indian corn in the shock. After photograph by Williams Wild rice in a Minnesota lake. After photograph by Williams A cluster of sedge-flowers (Carex-type), a single pistillate flower with one fruit rudiment. and a staminate flower with three stamens. After Atkinson Cyperus-sedge. After Britton and Brown......... Cotton-grasses growing in a bed of peat-moss. ‘Near Grand Rapids. After photograph by Mr. Warren Pendergast...... Lake border vegetation. Bulrushes and reed-grasses. After GCS MACE U OO VV LLIRARNY Sits iscaidve'syg ate Te ai viule& iis iin 's Wig 8 salvia eee XVIl 195 198 199 200 201 202 202 204 205 205 206 206 207 208 209 209 Fic. Bes Fic. IR. Fic. Fic. Fic. Fic. LOO? Len ; LQ2: . 103. 106. 107. 108. 100. 110. Minnesota Plant Life. Bulrush-sedge. After Britton and Brown...............-.... Carex-sedge. After Britton and Brown....................:. A skunk-cabbage in early spring, before the leaves have un- folded. The purple hood covering the flower cluster is shown on one side. Attter-Atkinsontia. «5-6 1- oa) Sedges and rushes. After photograph by Williams........... Dog’s-tooth violet in flower. After Atkinson..............-. Clintonia. Atiter Britton ands EB rowiteereer iste Blue flags. After photograph by Williams................... Stream-side vegetation. Blue flags in foreground. After pho- oyesezhoam lone \NAUUNehINSS gon guceeasoodsodsoe don dodolsoscoc soo Hs Yellow lady-slipper. After photograph by Mr. R. S$. Mackin- S Waldorchis:. -Atter binittoneand dione scisene retain . Cottonwoods on the Minnesota. After photograph by Wil- DATING Ha Gaps a eo Seb euler oh cava gape FRLmiaL OACRS a1 ORIG eee Poplar vegetation of burnt district. Near Rat Portage, Ont. Miter photograph ibys the authors ee eee eens eee ene Cottonwood) Atte, Brittonsand Birowileees ee ete ener Peach-leafed willows on shore of stream. After photograph by Walliams... pei oc bh 4 Sb gpad cede owt Gisen a cere Clusters of willow flowers; on the left the pistillate flowers and on the right the staminate. Each pistillate flower con- sists principally ofa single fruit-rudiment, and each staminate flower of two, or sometimes a larger number of stamens. After Atkinsoire ate 2s hee asitcrsdcociuenis adie tenia kee eee Beach vegetation, Garden Island, Lake of the Woods. The long-leafed willow forms the outer zone, and the black willow the inner. After photograph by the author.......-.....se.. . Hickory trees. Lake Minnetonka. After photograph by Wil- IGE: y 0c kc eee eA RD Mie RM RNS MI NUN, i a copa c 229 230 235 237 238 239 240 241 Minnesota Plant Life. Fic. 112. Ironwoods and oaks. The smaller trees are ironwoods and hop-hornbeams. Lake Calhoun. After photograph by Hib- Fic. 113. The paper or canoe birch. After photograph by Williams... . Fic. 114. An Indian encampment, Lake of the Woods. The vegetation is principally the canoe birch, and the canoes and tepees illus- trate the uses to which birch-bark is put by the aborigines. After photograph by Wright. From Minnesota Botanical SEE LNE SMES eer ee er spray PAR Ue a lk ta nee he Racers = Sanaa re Sr Fic. 115. An oak twig with leaves and both sorts of flowers. The one with three prongs is the pistillate flower; the other, with five stamens, is the staminate. The staminate flowers grow in drooping clusters, Aten AtkinSonis. sass. cree oe alee Fic. 116. Oaks and blue flags. A marshy place in the oak-woods. After PHotosraplie bys Will tammis Meera eee eis sass ove oie ten ieveneten ot atovors Fic. 117. American elm. After Britton and Brown.................... Fic. 118. American elm. Lake Minnetonka. After photograph by Wil- Fic. 119. Roadside vegetation of nettles and vines. Winter aspect. After photograph by Williams Fic. 120. Glasswort. After Britton and Brown Fic. 121..Pokeweed. After Chesnut. F. B. 86, U. S. Dept. Ag........ Hieer22 scarpetweed. After Britton and Brown... 2.26 oa. -s ose.es cess Pic, 123. Spring-beauty in flower. After Atkinson.............5.....- Pre. 124, VVater-shield. After Britton and Brown..::..<.......0...2..- Fic. 125. Water-lilies. After photograph by Williams................. Fic. 126. Marsh-marigold or cowslip. After Britton and Brown....... Fic. 127. False rue-anemone growing in pots. University plant house. After photograph by Dr. D. T. MacDougal. From Minne- ROLMISLIOLUAG ELMS TUL S OR vest Sid eR taco SR as Dee Fic. 128. White water-buttercup. After Britton and Brown............ X1X 248 Fic. FIG. Fic. Fic. Fic. Fic. Fic. Fic. Fie. Fic. Fic. Minnesota Plant Life. 129. Early meadow-rue. After Britton and Brown................ 272 130. May-apple, or mandrake, in flower. After Atkinson.......... 275 131. Clammy-weed. After Britton and Brown..............:....- 276 132; Blood-root. After*Britton and Brown =. >. 22.0) -6.8e eee 276 133. \Water-cress. Attter Britton and=Browi-.-s-.20-.4-e meee 277 134. Pitcher-plant. Atte Britton ands Browne. 24s eee 278 135: pundew. Aiter Britton and Brownh--- 9-4 -- eee ree eee 280 136. River-weed. .Atter Brittonvand Browne. e eee 281 137. American alum-root. After Britton and Brown.............. 282 138. Marsh Parnassia. After Britten and Brown..-.-o2-.9-eeeee 283 139; Hawthorn) Atter Brittonjand | Brownees-).5: sae eee 287 140. Apple-blossoms. After photograph by Williams.............. 288 141. Marshifivehnser Atte: Brittonyand) Brow) 4seee soe eee 289 142) Roses» Atter photograph py. Wallianishess eae see eee 291 143. Sand-cherry in fruit. After Bailey. Bulletin 70, Cornell Ag. | Dp. OPM SLE: 1819) 1 eee een eee Hera AAR ROP Ss So dood ose 292 144. A cluster of choke-cherry flowers and a single flower dis- sected. « Atfter Atkinson: .. 657 ciclacs sonnet ate ce 203 145. Kentucky coffee-tree. After Britton and Brown............. 206 146, Wald lupines- Atter Brittonvand Browtles...544. eee 298 147. Sweet-clover bushes. After photograph by Williams......... 299 148. White clover. After photograph by Williams:........... Rats casio) 149. Hick-trefoil. After Britton! and) Browitees- sen ose eee 303 150. Sumac bushes, with golden-rods in foreground and maples in background. After photograph by Williams......:......... 300 151; Poison-sumac.- After Chesnut. F.9B 86, U.S! Dep Aaa 310 152. Poison-ivy. After Chesnut. F. B. 86, U. S/ Dept. Ag... ca:-. 311 153. Leaves and flowers of the sugar-maple. After Atkinson...... 314 154. A grove of sugar-maples. Near Lake Minnetonka. After photograph bys Mire Bee ©. Mallises es hes ote ee 315 Minnesota Plant Life. XX1 Fic. 1Eaites Bas FIc. Fic. Fic. 155. Moosewood maple. After Britton and Brown.............-.. 316 156. Touch-me-not. After Britton and Brown.............---.+-- 317 157. Tree covered by grape-vine. After photograph by Williams.. 320 158. Virginia creeper on tree trunks. After Schneck in Meehan’s Mito yutiila eric ce te sre eee ate ae Se ees aisle recto ee ea raeie 322 159. Basswood trees. Shore of Lake Calhoun. After photograph Pla DARC coos See targets eee a et a Ae GANa aout cued ca Sars aeons 324 moo. Beach heather. Aiter Britton and) Brown. ..... 2. <.0 2 oa: S505 327 161. Sweet white violet. After Britton and Brown................ 328 162. Western prickly-pear cactus. After Britton and Brown....... 330 nossa Ginseno. Atte brittom and. BrOwlle sce seas eee «ery el 337 TOA Wiater parsnip: Aiter Britton, and Browtes-s2>cee-es soo ee 338 165. Wild parsley. After photograph by Williams................ 339 166. Water-hemlock. After Chesnut. F. B. 86, U. S. Dept. Ag... 340 io7aOwarn come Attem Brittom and Brown. .-.a205ss00. ase eee 341 168. Wintergreen plant in flower. After Atkinson................ 351 ieaetcaltmia tiowers. After Atkinson: . . 020.2. tice. os eet ek sie 354 170. Moss-plant. After Britton and Brown............... 355 171. Small cranberry. After Britton and Browny—...-............ 357 172. Yellow gentian. After Britton and Brown................... 362 173. Swamp milkweed. After Britton and Brown................. 305 174. Brookside vegetation. Milkweeds in foreground. After pho- Peers Oe WO AIBIGN. ccs, aloe son ote inte sioe ee oi chars R 366 175. Dodder in flower; the parasite is seen to be clutching tightly the stem of its host plant. After Atkinson.................. 368 >. 176. Virginia water-leaf. After Britton and Brown............... 370 .177. Blue verbena. After Britton and Brown.................... 373 178. Wild mint. After Britton and Brown...............++eeeeee: 375 179. Clump of horse-mint (in middle of picture). After photo- graph by Williams. ...........ccecee secre erent enereneeeeaes 376 XX11 Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. 180. 181. 194. 195. 196. IG . 198. . 199. - 200. Zor: Eee. Minnesota Plant Life. Horse-mint. After Britton and Brown............ Sacre: View in Minnesota lake district. Shows in center two mullein plants in characteristic positions. After photograph by Wil- TATUS! eh ccdic chia Soon AS raed oo eta, Soe ee ine ne eee . Monkey flower. After Britton and Brown................... - Lousewort., Aitter Britton and Browne «4.2109 2 eee . Bladderwort Atter Britton and Browns. -- 444.46 eeeeeee . Cancerroot. After Jellett in Meehan’s Monthly................ » Rugel’s plantain. Aiter Brittonland Browinl...5--5- eee » Bedstraw: Atte Brittonvand) Browne... see ; Partridgeberry, Aiter Britton and Browns...) eee . High bush cranberry. After Britton and Brown............. . snowberry. After Britton and) Brown...>...... 20) see ’ Biue=bells) Aiter Britton and Brown...) os. » Blue dobelias Atter Britton andebrowte.-. oe eeee eee . Chrysanthemum in flower. After Miller. Bulletin 147, Cor- nell Ag Exp: Station: . occ 4t2th wee oe eee ¥i Dandelions in flower. Lake Calhoun. After photograph by Hibbard oi: yncks ous je teresa Oe ere eh ee Dandelions in fruit. After photograph by Williams. .-22eeee Wild iettuce, a compass-plant; the fruits stand in heads, and each fruit is provided with a parachute of bristles. After Atlanson . ».c.cgsecnos re kote onio See ana aoe eee eee Rattlesnake-root. After Britton and Brown............... Hee Cocklebur: After Britton and Browns.:....-.-- 2s: see Ragweed. Aiter Britton) and) Brownies alee eee Autumnal vegetation of marsh border. Thoroughwort or joe- pye weed. After photograph by Williams.................. Boneset or thoroughwort. After Britton and Brown......... Blazing-star,— After Britton ands Browne: ee eee 400 Minnesota Plant Life. Fic. ic: Fic. [Brite Fic. Tene’ Fic. Fic. Hie.2 Fic. Fic. Fic. Fic. Fic. 203. 204. 205. 206. 207. 208. 209. Pha Autumnal composite vegetation. In foreground golden-rods, sunflowers and asters; in background, on brow of cliff, wormwood or sage-brush. Aiter photograph by Williams... Early golden-rod. After Britton and Brown................. Asters and golden-rod. Banks of the Mississippi. After pho- tagraphoby Walliatns rc. ds os cercek sels sre mee ook nnn te ® Rosinweed compass-plant. After Britton and Brown......... Cone-flowers. After photograph by Williams................ Prairie cone-flower. After Britton and Brown............... Water bur-marigold. After Britton and Brown.............. . Connie: ANiter IBiatinorn aymcl BRON Al. oso accbnoeeuecaoonose . Bur oak and bracken fern. Illustrates relation between strength of stem and the weight to be borne. After photograph by (ESTini Wp ait, cl eager sycnsencectey Aes aso seese eee ee strc here iets ieee ae . Willows and bulrushes. The latter are typical surf-plants. Miter apHotootaph aby: WWalhia tis ot : ¢-e<20 9-2) eee 441 447 448 449 452 454 455 456 458 461 466 468 Minnesota Plant Life. Fic. 232. The valley of the Minnesota river in the prairie district. Abun- Fic. Fic. Fic. Fic. Fic. Fic. Fic. 233 234 235 236. 2377. 238. 230. 240. dant grass vegetation. After photograph by Professor R. D. Cottonwood trees on the Minnesota river. After photograph love WGI PEb a ae eet eo Acasis coca ono aneao oo OCOD oo Oct e mcrae A Minnesota meadow bordered by shrubbery and deciduous forest. After photograph by Mr. W. A. Wheeler............ Roadside vegetation in summer. After photograph by Wil- Roadside vegetation in winter, St. Anthony Park. Oaks, sun- flowers and goldenrods. After photograph by Williams..... Autumnal underbrush, Mississippi river, between Minneapolis and St. Paul. Golden rods, asters and sumac. After photo- eige idle lenge Gl Ube vans ae San a SriginC On HOC 6 6 Op oo aoe aapercanigo cus Neglected corner in the Minneapolis manufacturing district. Weeds and shrubbery. After photograph by Williams...... Modern hardwood forest of the St. Croix valley, near Osceola. After photograph by Professor W. R. Appleby.............. View of Fort Snelling, showing midsummer vegetation. After PLHotoetaplmabys VV WAMISH ee sw cc. ene x agers ie oe eee alee cines XXV 471 474 475 477 477 478 479 480 ae be + . ,; 2 a) 4 n eu ) ‘ i. a - = ] * . i. i i bs 2 2 r ig A a j ‘ 7 - 4 > 7: = ~ e ~ Chaprersle Plants in their Societies. SF Purpose of this book. In the pages of this book I hope to give the reader an idea of the diversified plant life which occupies the air, the soil and the waters of Minnesota. First of all, it must be remembered that plants, although passive creatures, are quite as truly living beings as are the more active animals. Just as men and women, either themselves or their ancestors, have entered the state from some other region, so also have plants, according to the nature of each, found their way and selected their abodes. It is no easy problem to de- termine why some family has chosen one village rather than another. This may have been from causes which are too subtle or too remote for analysis, but it is recognized that people have not come to make their homes without some reason which seemed sufficient to them or to their forefathers. So, too, there is always some reason for the appearance at a particular spot of one kind of plant rather than another, and it is possible in a general way to explain the vegetation of the hills and meadows of the state. Minnesota geography. A glance at the map will show that the State of Minnesota lies between the 43rd and 4gth paral- lels of north latitude and between the 89th and 97th meri- dians west, and that it is centrally located in the North Ameri- can continent. Within its domain rises the Mississippi and by this great river the surplus rain-fall of the state is in large measure carried away to the Gulf of Mexico. The northwest- ern portion by the Red river and its tributaries, is drained through Lake Winnipeg into Hudson bay, while a few streams flow in the valley of the St. Lawrence to the Atlantic ocean. Minnesota, therefore, is not only geographically, but hydro- graphically central. Hence it might be supposed that its plants 2 2 Minnesota Plant Life. would have immigrated equally from all directions. Such, how- ever, is by no means the fact and it is needful to inquire further into the conditions which regulate plant distribution before the true situation can be understood. Minnesota climate. Connected with the geographical posi- tion of the state, and to a very great degree dependent upon it, is that combination of average winds, average temperature, average precipitation of moisture, and average illumination by the sun to which is given the general name of climate. Min- nesota enjoys what is known as a mid-continental climate, characterized by warmth in the summer and cold in the winter. There are no prevailing winds from year’s end to year’s end as there are at some places by the sea. ‘The sun never shines with equatorial directness, nor are there ever weeks or months of twilight, or of darkness, as in the regions of the poles. There are no great mountain ranges to cool the clouds as they move across the sky and to force them to yield their moisture in the eternal snows; and during the year there may always be ex- pected an average rain-fall of about twenty-five inches. Through the spring and summer there is always a rise in temperature to stimulate growth, but there is never that fervent, damp heat which favors the rank and luxuriant vegetation of the tropics. Consequently there are to be found in Minnesota plants adapted to the rhythm of the seasons, to the oblique illumination of the sun, to the average moisture of the air and of the soil, and to the winds which sometimes sweep over the prairies with an almost resistless force. As an illustration of the adaptation of plants to seasonal rhythm may be mentioned the autumnal habit of most trees in Minnesota of shedding their leaves. Indeed, this is so common a fact of experience that it is scarcely realized to be a definite reaction of the plant to its environment. Yet leaves do not fall merely because the nights are growing cold, but because there is formed at the base of each leaf-stalk a little layer of cork which, when complete, cuts the leaf from the twig as if by a pair of shears. Certainly such is not everywhere a necessary habit, for it is known that in the tropics many trees do not lose their leaves each year, but retain them for varying periods of time until their usefulness is past—a character shared also by some Minnesota Plant Life. 3 trees of temperate regions. Apparently, then, the habit of rejecting leaves that would be killed by the winter’s cold and would become burdensome another summer may be directly connected with the geographical position of the state. Again, trees with enormous, delicate leaves like those of many palms or bananas, are not found upon the prairies of the Red river, because, clearly, if trees with such thin, large leaves were exposed to the wind they would be blown to pieces and their life would be destroyed. Large delicate-leaved forms are more characteristic of regions where the wind is slight or where it is broken by masses of surrounding vegetation. Furthermore, in a state so well watered as Minnesota there is no development of those curious desert types which are seen in Arizona, in the Sahara, or in the arid regions of South Africa and Australia; for where it is arid those plants only can grow that by structure and habits are fitted to utilize the relatively small quantities of moisture. The strange columnar cacti of the Gila, standing leafless and rigid—vegetable pillars of the desert—would be out of place wherever the rain-fall permits the production of ordinary leaves and branches. Thus in survey- ing the vegetation of the world one is impressed with the influ- ence of climate upon the plant population oi every district. The physical history of Minnesota. A knowledge of its geography and climate does not, however, afford all the data for comprehending the vegetation of any region, since it is not alone the climate of to-day, but even more strongly the climate and other conditions of the past, that are reflected in the forms and structures of the plants. Therefore, a knowledge also of the geological history of the state and of its various soils is essential to an understanding of its vegetation. There is strong reason to suppose that about ten thousand years ago much of the surface of North America was covered by a thick sheet of ice which advanced slowly from the north and later as slowly retreated. The period of ice-advance is known to geologists as the glacial period, and throughout Minnesota are to be found the traces of glacial action. The clays, pebbles and bowlders so abundant throughout the state are believed to have been depos- ited either upon the front of a glacial mass, or underneath, or from the waters caused by its melting. When such a move- 4 Minnesota Plant Life. ment of ice took place there must have been a great modifica- tion of drainage conditions over all the invaded district. Streams were dammed, hills were levelled, valleys were filled, lake bot- toms were hollowed out or covered with confused masses of rocks and clay—ground into powder by the powerful action of the ice, continuing, as it did, through more than a thousand years. It is clear, too, that the ancient vegetation must have been almost wholly swept away by this invasion from the Arctic zone. It is true that plants are sometimes found growing close to the edge of glaciers in the Alps, in Greenland and in Alaska. Sometimes even masses of soil are so borne upon the surface of the glacier that plants of hardy habit may continue their exist- ence there. Yet, with a due regard to these well-known facts, it is not conceivable that for so long a period of rigorous cold the old pre-glacial plant-population of the state could have held its ground. It must be supposed, rather, that as the glacier steadily advanced from the north, year after year plants flung their seeds into air-currents moving southward or attached them to the fur of animals seeking a warmer clime and thus gradu- ally season by season themselves migrated toward the south. Evidently those plants provided with seeds, buoyant, winged, barbed or hooked were best fitted by such contrivances to leave the snows and ice of a thousand years, while the plants with smooth and heavy seeds either migrated more leisurely and more sparingly or were quite extinguished by the cold. When the glacial period came finally to an end and the ice- sheet moved north beyond the confines of the state, there opened to the immigrants from the south a new Minnesota. Great lakes formed by the waters of the melting ice now lay where before there was land. Rivers were flowing in new direc- tions and were carving for themselves new gorges through the rocks. A fertile soil was deposited upon the hill-sides—not, indeed, a rich leaf-mould, but capable of supporting many kinds of plants. Into this land of promise the southern plants began to come. Winds from the south, animals ranging toward the north and water-fowl in their annual migrations, brought back in some instances no doubt the very same varieties which hun- dreds of years earlier had fled before the ice, and in others, new kinds born and bred in the south and seeking new homes where Minnesota Plant Life. 5 they might obtain a foothold for themselves and their descend- ants. When one contemplates for a moment this epitome of plant-wanderings he is impressed by its similarity to the history of his own race. It is known how peoples have moved from one country to another, not usually em masse but individually, quite as did the plants and under very much the same impelling forces. For it is those plants which were able to leave the region of increasing cold that later continued their kind under more favorable circumstances, as it is also the hardy race of men who migrate from the worn out farm, or congested city to some new. country in which they may find prosperity and happiness for themselves and for their children. Laws of plant distribution. There are, then, three paths along which to seek the general laws of plant distribution. First, as regards an area, one must inquire what is its geographical position? second, what is its climate? third, what is its soil and physical history? ‘The answers to these three questions ex- plain in large degree what must be the plant population of that area. With respect to the vegetation of Minnesota the most impressive fact is that it is an immigrant vegetation. It mani- fests the characters of a new community quite as truly as does the American Republic, in its social and political organization, the characters of anew country. This can be illustrated clearly if one compare the Minnesota forest with the ancient forest of the tropics in India, in Venezuela, or about the sources of the Nile. When one enters the dark solitudes of an equatorial for- est his first thought is, from the sounds that reach his ears, that the life of the forest must be above his head. Few animals are seen, almost no insects and scarcely a green leaf or plant upon the forest-floor, but there, rather, are dead and decaying trunks of trees which have fallen and massive columns of trees that are standing, while arching overhead are interlaced branches that intercept the light and make the scene like that in some dim cathedral. But if froma balloon one could look down upon the immemorial crowns he would see spread out beneath him a world alive with birds and insects, brilliant with flowers and rich with the verdure of vines and air-plants. It would be much as if the tree-tops had taken the place of the turf and shrubbery of more northern climes. Many orchids and other plants of that 6 Minnesota Plant Life. nature would be seen perched upon the branches, dangling their roots into the damp air below; climbing and twining plants would be abundant and especially would there be observed a much greater variety over a particular area than could be expected in temperate regions. This peculiarity of the tropical forest, this exuberant development of tree-top life is a natural result of age. It is because the forest has been standing for countless centuries, unmodified by changes of climate, unin- vaded by glacial sheets, that it includes so many different kinds of individuals. For the same reason there have arisen depen- dencies between different varieties of plants, and some have learned to perch themselves upon the branches of others or have entwined themselves around the stems of their neighbors. Just so, in an old society like that of India or wherever there is not the democracy and equality which exists under a newer social order, is caste developed. People are born to be dependent and it is fore-ordained in the social system that they and their de- scendants shall not rise above this position. In the forests of Minnesota all is very different. When one enters the pine-woods of the north, or the elm and maple-woods of the south, he is not impressed with the silence and solitude of the forest-floor, nor does he discover that the tree-tops have become a special soil for the development of peculiar plants. Perching plants are rare; vines and lianas do not form so large a proportion of the total population. ‘There is nearly always a well-developed underbrush, and many sorts of little heatis, asters, gentians and golden-rods display their flowers and ripen their fruits under the shadow of the trees. ‘They are not com- pelled by the umbrageous growth of larger plants to climb the trunks or hang themselves upon the topmost branches in order to obtain their share of sunlight and of rain. Nor is the number of kinds in an acre nearly so great as in the tropics, for there has not yet ensued that long period of competition which, in the tropical forest, has reduced what might once have been social clumps of trees to the lone survivors of to-day. Forest and prairie. There are two principal vegetation- regions in Minnesota, the forest and the prairie. ‘The forest occupies the northern portion of the state, extending south to Minnesota Plant Life. 7 the valley of the Minnesota river. The prairie comprises the southern portion of the state and a strip along the western boundary in the valley of the Red river of the North. These two regions, so different in their appearance, are inhabited by plants which are not altogether dissimilar to each other. Most of the plants at home on the prairie are not entirely absent from the forest, while the greater number of forest plants may be encountered, possibly not so abundantly, but at least casually, on the prairie. The difference between the two regions does Fic..1.—In the forest district. Growth of white pines and spruces upon a rocky island Steamboat channel, Lake of the Woods. After photograph by the author. not lie in differences in the kinds of plants so much as it does in the different character of the dominant plants. Among the pines and spruces of the forest occur many of the grasses, vetches and asters of the prairie. Along the borders of prairie sloughs and streams there will be growing the same varieties of arrow- heads, milkweeds and willow-herbs that form a characteristic vegetation in similar places in the forest. But the dominant plants of the forest are trees, lifting up their erect, perennial stems, struggling with each other for light and air and giving to the whole formation an upright effect, while the prairies are 8 Minnesota Plant Life. dominated by grasses with prostrate underground stems woven together into a solid and matted turf, thrusting into the air only their side-branches and thus giving to the whole a flat and level character. It is not very well known precisely why the prairie type of vegetation has established itself over such large areas of the world. Some have attributed it to fires, others have thought that climate and soil are responsible for the difference between prairie and forest. Perhaps all that need be said is that there are these two principal methods of developing plant-stems. When the dominant plants of an area are such as have acquired the habit of trying to avoid each other’s shade by elongation of their stems, that region is a forest. When, on the other hand, an area is occupied by plants that have learned to elbow each other beneath the surface of the soil, that region is a prairie. It is a mistake to suppose that the lofty tree is in every sense stronger than the modest grass, for the two have simply devised different means of accomplishing the same result. A prime necessity of most plants is sunlight, since without it they are unable to construct their food from the gases of the atmosphere and the water of their sap. Therefore, they must have light, and to obtain it they adopt instinctively the methods of growth which will enable them to do their own life-work regardless of their neighbors. The pine tree may be described as a plant which for ages has been solving the problem of better illumina- tion by a progressive increase in height. The grass, by copious ramification of a protected underground stem upon which lat- eral leaf-bearing branches are produced, in its way strives to obtain illumination, nutriment and persistence. Another difference which exists between the forest and prairie of Minnesota is in the direction from which the plants have come. ‘The forest is, in large part, composed, so far as its domi- nant plants are concerned, of northern forms, while the prairie is inhabited rather by immigrants from the south. So ona map illustrating plant distribution in the northern hemisphere it will be found that the prairies in Europe, in Asia and in America lie south of a forest belt. It is true that in the tropics around the world a forest region exists, broken only by deserts like those of the Sahara, or northern Australia; but in regions beyond the tropics it would seem that in both hemispheres there Minnesota Plant Life. 9 are intermediate forest zones between the prairies of temperate regions and the tundras about the poles. Minnesota is situated between the forest and prairie regions of the North American continent and includes a representation of each. A careful study of the populations in these regions will show that each is striving to extend itself; thus wherever a stream flows from the forests of the north down through the prairies of the south, forest plants advance along the banks and reach more southern latitudes. In Minnesota the pine trees that in the north form so characteristic a growth are found in isolated patches, fewer in numbers, down the Mississippi—even Fic. 2.—Prairie scene on the Coteau. Sunflowers line the roadway on either side. After photograph by Mr. R. S. MacIntosh. beyond the confines of the state, for the white pine exists upon the Mississippi bluffs in Iowa. Similarly, along the open which a river produces, there is chance for southern winds to distribute the seeds of prairie plants, and characteristic vegetation of the prairie, such as sunflowers and golden-rods, has pushed its way up into the forest, leaving the larger streams along their tribu- taries, and finding a path even into depths of the pine-woods where the soil is favorable. It would be a great mistake to count plants quiet, unenterprising creatures, not alert to make use of every opportunity for growth and development. The forest must rather be regarded as composed of plants eager to compete with those of the prairie upon their own ground, and equally must the prairie plants be regarded as ambitious on their 10 Minnesota Plant Life. part to try conclusions with those of the forest, if they obtain an opportunity to penetrate between the interstices of the more northern erect formation. Plant populations, then, in the two great vegetation regions of the state, are in a state of tension, and the line between them is necessarily slowly shifting and irregular. Some little change in the topography, some slight modification of the drainage, the drying up of a lake or the erosion of a deeper gorge by a stream, may give an opportunity for one formation or the other to extend its limits at the expense of its neighbor. This gen- eral state of tension exists not only between the forest and the Fic. 3.—Roadside vegetation. Grasses and pulses. An elm tree in background. Cedar lake. After photograph by Williams. prairie, but also between plants on the tops of hills and those at the base, between plants in the center of swamps and those at the circumference, or between plants at the edge of a lake or stream and those farther inland. Plant zones. ‘The result of such competition is seen in the pretty general appearance of plant zones wherever the topog- raphy permits them to be developed. A simple and well-known example of this tendency of plants to grow in zones or lines may be seen along any road, path, ditch or trail in the state. It is well known that certain kinds of plants particularly select the road-side as a favorite place for growth. Such are usually Minnesota Plant Life. II robust, enterprising plants of modern structure, and the pick ot the whole world for growing ability—for nowhere is there so great a proportion of what are called weeds and introduced plants as beside a road. ‘There one finds the knot-grasses, rag- weeds, thistles, coxcomb-grasses and other imported species, many of them belonging to types which by sheer vegetable enterprise and ability have found their way with man around the whole northern hemisphere, and some of them are common even to Australia and Africa as well. As might be expected Fic. 4.—Spruces forming a zone around a peat-bog. Farther back are tamaracks and pines. The shrub in the foreground is the bog-willow, while the flowers are those of an orchid,— Pogonia. Near Grand Rapids. After photograph by Mr. Warren Pendergast. from their distribution along paths or other works made by man, they have been assisted in their wanderings by human agencies rather than by the ministrations of the winds, the water-fowl or the beasts of the field. Such plants appear also in door-yards, in neglected meadows, in pastures, along railway lines and in short wherever man has gone. Another kind of zonal distribution, not influenced by human agencies, may be seen around the lakes of the state, especially where beaches have been formed. Here special beach-rows of te Minnesota Plant Life. plants will be found, consisting among others of certain sand- loving grasses, cockleburrs, pinks and fumiutories, and clearly distinct from the plants farther back upon the shore. Nor will these plants develop so vigorously under any other conditions. Again in the swamp region of the north, where a peat-bog is slowly filling with moss and encroaching upon the forest, beau- tiful illustrations of this zonal arrangement can be observed with the tamarack and spruce trees becoming gradually smaller and smaller toward the center of the bog. In meadows, too, Fic. 5.—Zones of aquatic vegetation. Inthe center pond-lilies; at the edge smartweed; far- ther back cat-tails, blue flags, sweet flags, and sedges; still farther back soft turf with grass, moss, sedge and milkweed. After photograph by Williams. formed by the drying-up of lakes, are sometimes found en- croachments of the meadow plants upon such knolls as were originally islands surrounded by water. ‘The meadow, as it were, washes up upon the knoll and upon the banks of the old lake, so that mingled with the dogwoods, willows and other shrubs of the knoll or bank one will observe the grasses and sedges of the meadow. Zonal distribution is a characteristic arrangement not only of land, but also of water plants, and as one pushes his canoe trom the shore of a Minnesota lake he will doubtless find that he Minnesota Plant Life. 13 passes over distinct zones of aquatic vegetation. First, there will be the sedges at the water’s edge, then the reed-grasses, or wild rice in a little deeper water, then the bulrushes with their cylindrical, leafless stems rising from submerged rootstocks below, and exposing as small a surface as possible to the action of the surf. Next will come the pond-lilies and water-lilies, the water-shields, and sometimes the lotus with its circular leaves rising from or floating upon the water and presenting every- where their arched margins to the waves. Then come the pond- weeds and milfoils with their stems and submerged leaves as- cending through the water but not reaching the surface, and finally the bass-weeds with their lime-encrusted stems and leaves lying upon the bottom at a depth of from ten to fifteen feet. Whether one climbs a hill, rows out into a lake, walks from the margin of a stream back to the prairie or the woods; whether one steps from his house and across the road into a field, or strolls from a meadow up to a wooded bank, he will find that he is traversing zones of vegetation. The occasion for such a distribution of plants in zones is to be sought generally in the topography of the region, and where there is great irregu- larity in the topography there is irregularity in the zones, while sometimes over a level no zones appear. Sometimes, also, where the topography is favorable to the development of plant zones special conditions of distribution serve to obliterate them or prevent their occurrence. The same general causes which tend to separate the forest from the prairie, defining their limits, are seen to mark also the boundary between one portion of the forest and another. Just as the great prairie group of plants strives as a whole to en- croach upon the forest, so the plants at the base of a knoll strive to climb it and establish themselves over its surface, and mean- while quite as vigorously the plants on the knoll attempt to make their way into the gullies and sloughs. The plant on drier soil may be regarded as always endeavoring to accommo- date itself to moister soil, and that on moist soil as always strug- gling to gain a foothold where the moisture is not so great. So there are often seen at the margin of ponds the pond-lilies emerging as far as they are able upon the mud, exerting them- selves to the full limit of their structural qualities to maintain 14 Minnesota Plant Life. a terrestrial life, and in the same pond may be found land-piants pushing down to the very water’s edge or beyond it until they can go no farther because of the limitations of their structure. The tension between the forest and prairie, because it extends so widely, may be called a continental tension. ‘The other ten- sions, between knolls and ravines, between banks and meadows, between beaches and pond edges, may be called minor tensions, but the law of the two cannot be very different. Indeed, there may be gained a fair idea of the fundamental difference between prairie and forest by observation of an area so limited as a road- 4 Ee ee i, Fic. 6.—Island in the Mississippi above St. Paul. The center is occupied by elms while the rim is fringed with willows. An example of a ‘‘minor tension.’ After photograph by Professor W. R. Appleby. side or path. The principal difference between the two is the duration of the causes at work. Between the prairie and the forest the tension has been in existence possibly for thousands of years, while between the knoll and the ravine possibly for but a few decades or centuries. As a result there have come to exist in the old warring formations structural peculiarities char- acteristic of each, so that, to the eye of the observer, they pre- sent very different appearances. Where the struggle is of more recent origin and of more limited extent the differences are not so great and, therefore, not so evident. Forests of Minnesota and of the world. We cannot well consider forest as it exists in Minnesota apart from the general forest which covers the northern part of the continent. From Minnesota Plant Life. 15 the plant’s point of view, Minnesota is not a province, for, to the plant, political boundaries as established by man, have slight significance. Nor does the prairie, which occupies the south- ern part of the state, exist as a special Minnesota prairie. Rather is it the northeastern extension of the great plains which occupy the whole central area of the continent from the foothills of the Rockies back to the forests of Kentucky, Tennessee, Indi- ana and Wisconsin. The question then arises how did the for- ests come to consist of the plants which dominate them, and how did the prairie come to have its particular inhabitants rather than others? If a census be taken of all the kinds of plants in the forests of North America and be compared with a similar census taken in the forests of Europe and Siberia there will be perceived a great similarity between the plants of the two regions. But if in like manner the plants of the prairies of the United States be compared with those growing upon the steppes of Russia and Siberia it will be discovered that the similarity is not by any means so great. A very much larger number of plants are common to the forest districts of Europe, Asia and North America than are common to the steppes and prairies of the two hemispheres. Yet, in this latter instance, there are many groups which are similar and not a few identical species. Sup- pose, further, that the forests of the northern hemisphere, of which the Minnesota forest is but a portion, be compared with the deciduous forests of the southern hemisphere, including those of the Transvaal Republic, Chili and the Argentine, New Zealand and Tasmania, it would be noticed that almost no com- mon species, and but few common groups of species can be found. Or if the pampas of the Argentine be compared with the prairies of the United States, again would it be discovered that the common species are exceedingly scarce. It would seem, then, that the greatest differences which exist between plant populations of the world are between those of the north temperate and the south temperate regions. The occasion of this will be understood if it be remembered for a moment what are the opportunities for the expansion of plant- life in the tropics and under the equator. There for countless thousands of years plants have been developing and competing 16 Minnesota Plant Life. with one another amid favorable conditions of temperature, moisture and illumination. The equatorial region of the world is at once the cradle and the crucible of plant-life. In that tre- mendous struggle for existence many of the modern improve- ments and refinements in plant structure began to originate. During the centuries, forms unfavorable were eliminated and destroyed, leaving the stronger in a condition to migrate north or south as rapidly as they accommodated themselves to the increasing obliqueness of the sun. Evidently, then, the great- est differences should be expected not between the plants of North America and Europe, both of them tenanted by north- bound immigrants from the equatorial region, nor even between the north temperate regions and the tropics, since the plants in the former are but the traveled relatives of those at home in the latter region. But the greatest difference should be expected to exist, as 1t does, between those plants which have left the tropics and have slowly made their way, changing their form and habits as they wandered, some to the far north and others to the south. North American flora. If the North American continent were quite flat, without differences in elevation above the sea, and were connected with the tropics by a continuous stretch of land, it could be imagined that the forest region might have extended directly across the northern half of the continent. It is, however, not such a level plain, for two great mountain ranges run from north to south and the continent is connected with the tropics by a narrow isthmus, so that there are factors which prevent an even division of forest and prairie. Mountain ranges extending from north to south are not, as mountain ranges extending from east to west would be, barriers against plant distribution from the tropics toward the poles. ‘This is the reason why North America has what the botanists call a “richer flora” than Europe and Asia. In the Old World the principal mountain ranges, such as the Pyrenees, the Alps, the Appenines, the Carpathians, the Caucasus and the Himalayas are transverse, extending in a generally east-and-west direction. For this reason when the glacial period came on, unfortunate European or Asiatic plants as they migrated south, found them- selves compelled to climb some mountain range in order to Minnesota Plant Life. 17 make their escape to the temperate climate beyond the influ- ence of the ice, and under these conditions most of them must have perished as wretchedly as did so many of the troops of Hannibal when they crossed the Alps. Moreover, when the gla- cial period came to and end in Europe and Asia it was difficult for plants to return over the mountain-passes, and as a result, these continents are tenanted by a less diversified vegetation than that of North America. The longitudinal mountain ranges of the New World have rather aided the movements of plants than hindered them, for they have assisted northern plants to find their way along high altitudes to constantly lower latitudes, while at the various stages of their journey such plants have enjoyed the opportunity of climbing down the mountain sides and out upon the plains, if they were able to accommodate themselves to the higher tem- perature. This movement has taken place not only on the western side of the continent, but also along the Alleghenies. Yet owing to the greater height of the western range it is found that northern genera of plants like some of the roses and willows have developed more abundantly toward the southwest than toward the southeast, simply because they have followed an easier path along the cool high ridges of the Rockies than along the warmer, lower Appalachian range. By these two mountain ranges, lying one to the east and the other to the west of Minne- sota, some slight influence has no doubt been exerted upon plant migration, both in the prairie and in the forest region of the state. But this effect must have been stronger in the prairie region; for the forest plants from the east and north could enter as easily from the north and would not need to depend upon any lateral movement. From the west, however, where the plains rise gently to the mountains, many plants which had found an asylum on the sides of peaks and escarpments must have, in the last ten thousand years, slowly crept down into the plains and there developed habits and structures which persist to this day. 3 (Chaptersrl: Plant Wanderings and Migrations. sy Habits of birds and animals. The habits of birds and ani- mals are of much importance in any study of plant distribu- tion; for the plant, but rarely provided with independent meth- ods of locomotion, is forced to depend upon other agencies for dissemination. ‘To the waterfowl especially, with their well- het lees. ai] ras bund Fic. 7.— Lake border vegetation of cat-tails, grasses, reeds and sedges, Lake of the Isles. After photograph by Williams, known habit of flying south in the autumn and north in the spring, do many plants owe the widening of their range. ‘Their seeds are ripened and fall upon the mud at the border of some lake or pond where they are picked up on the feet or plumage of migrant birds and are carried hundreds of miles north or south of the point where they were produced. That is one rea- Minnesota Plant Life. 19 son why throughout Minnesota the lake-shore vegetation is so homogeneous. Every bay is visited at some time during the year by wild fowl and in the mud on their feet they carry about the seeds of a variety of plants. It is therefore, those water- edge plants which have seeds not too large to be thus trans- ported that are the more widely distributed. Especially if the seed is of a kind attractive to the bird is it likely to be removed. Thus ducks, though they eat hundreds of thousands of young wild-rice plants encased in their seed-coats, nevertheless from their very habit of using these plants for food distribute them more widely than if they were not thus agreeable to their taste. Migrating animals, like the bison which once roamed in enormous herds over the whole prairie region, must have picked up in their fur, as they wallowed in the sand or on the banks of streams, countless seeds of a great variety of plants and carried them to all parts of their range. In this way, plants having seeds provided with attachment-prongs, like the tick-trefoils, beggars-lice, burdocks and cockleburrs must have obtained through the agency of animals far greater opportunities for travel than were enjoyed by species the seeds or fruits of which were hard and smooth. The fancy of animals and birds for certain sleeping places has also influenced plant distribution, and their habits of wan- dering in the woods and by the water have been utilized by cer- tain kinds of plants, and some remarkable adaptations exist, such as the curious explosive seed-pods of the touch-me-not. This common plant, when brushed against, explodes its fruits, throwing out the seeds where they may be caught in the fur of a passing animal and carried away. Certain exotic gourd- plants, too, have explosive fruits which when agitated by a slight touch shoot out the seeds and these, provided with a viscid membrane, readily adhere to the passing bird or animal. Other plants have their seeds enclosed in edible areas, as for example the gooseberries, currants, apples, peaches, raspberries, junipers and a host of others. In such fruits the seeds are themselves protected by hard coats which resist the digestive processes of the animal or bird and they can thus pass through its body with- out injury. Sometimes the instincts of animals benefit the plant, as when a squirrel carries off an acorn and buries it from 20 Minnesota Plant Life. some dim notion of secretiveness or possibly of providence. On account of the rhythm of the seasons in Minnesota the principal migrations of birds and land animals have not been from east to west but from north to south, and the principal tension-line runs in general from east to west. Insects and worms. A few seeds are peculiarly modified for insect distribution, as for example, those of some spurges and other small plants, which have little crests or grooves just fitted to receive the jaws of ants, thus making them easily porta- ble by these busy toilers. Others are assisted in their distribu- tion by burrowing worms, but this always within narrow limits. Inanimate agencies. Allusion has already been made to the inanimate agencies which are employed by plants as aids in distribution. Among these are currents of wind, currents of water and in a slight degree translocations of soil. The latter, best observed in mountainous regions where avalanches exert a considerable influence, is of slight importance in Minnesota, though upon the hillsides and cliffs along some of the northern lakes, this method of distribution exists. Wind currents. In plant distribution the most important inanimate agency is doubtless the wind. The alertness with which plants make use of it in seed-dissemination 1s well exem- plified by the new population which appears after a fire and covers burnt places in the forest. When the pines or spruces are destroyed by fire it is a fact of common observation that poplars, maples, elms, willow-herbs, milkweeds and other light- seeded plants spring up. The well-known fire-weed with its purple panicle of flowers ripens seeds that are provided with tufts of delicate hairs, and when thrown out of the pods in which they are produced the wind may catch them and whirl them away over the tree-tops for many miles. The poplars, too, and cottonwoods are famous for their winged seeds and succeed in entering promptly a burnt tract, so that within a year or two they have established themselves while there are yet to be found probably none of the heavy-seeded plants, like hicikories, wal- nuts and oaks, and but few of the plants with adhesive seeds or pulp-inclosed seeds fitted for animal distribution. It is not the seeds alone but often the fruits of plants which are trans- ported by the wind, as for example, the maple-fruits, the elm- - A Minnesota Plant Life. 21 fruits and the fruits of a great variety of dandelion-like and sun- flower-like plants. Sometimes the whole plant is distributed by the wind and examples of this are especially striking upon the prairie where the wind has free sweep. Thus, tumbling plants like the Russian thistle, the tumbling mustard and the tumbling grass, when their fruits are ripe separate all or the greater part of the stem from its attachment and curve their branches so that the whole takes the shape of a ball rolling freely for miles over the level prairies before the wind. Some- times the wind acts indirectly in the distribution of plants, as for instance, when a portion of the boggy shore of some lake breaks loose and is blown away to be anchored possibly under new conditions across the lake. Water currents. Though the agency of currents of water in transporting seeds is scarcely so universally employed as that of the wind, it should not be overlooked. This agency is par- ticularly important for heavy-seeded plants, as their seeds are often borne along a stream in its currents and eddies to find a lodgment possibly miles below the point where they were intro- duced. Other seeds, to facilitate their floating, are provided with buoyant apparatus which adapts them also for wind distri- bution. Man. One very important agent in plant distribution re- mains to be considered, namely, man. Unlike the birds and animals, man in his migrations is not so strongly regulated by the changing rhythm of the seasons. On the contrary the prin- cipal lines of migration of men since the advent of Caucasians upon the continent have been from east to west, rather than from north to south. Roads and trails have been beaten across the plains and through the forests; railway lines have been built, binding distant portions of the country together, and to connect with them steamships cross the seas. Freights are car- ried from one hemisphere to another, and along with that for which there are invoices and bills of lading comes often a con- signment of seeds or fruits, unrecorded yet none the less im- portant. In this manner some harmful weeds as well as some useful forage-plants have reached the fields of Minnesota. With the immigration of men and women from Russia has come the Russian thistle; from France and England the cockles of the 22 Minnesota Plant Life. wheat; from Italy some mustards; indeed, from all the coun- tries of Europe plants have found their way in company with man. Some of them are later immigrants than others. Those which crossed with the pilgrim fathers are now as much at home as those to the manner born. Others, the advent of which dates irom yesterday, have not yet shown all their capabilities, and doubtless even now the dangerous new weeds of the next decade are some of them precariously existing as little colonies upon ballast-heaps or along the lines of eastern or western rail- ways. Associations between migrating plants. \Vhen plants travel they do not always travel alone, but in company as man does, who when he migrates brings with him his horses, oxen, sheep, fowls, dogs, and other domestic animals which have become attached to him. So the plant when it migrates often takes with it other plants. Thus where the maples go, there go also those curious fungi that grow upon the leaves, looking like little drops of tar. Wath the willow as it is uprooted and floats down a stream, perhaps finding a foothold for its twigs somewhere below, go the lichens and mosses upon its bark. There is something about the proximity of certain kinds of plants which is very agreeable to other varieties, so that gen- erally with pine trees one finds wintergreens associated, and with peat-mosses, cranberries. ‘The latter are not associations like the associations between the maple and the fungus upon its leaves, but are rather indications of kindred tastes in habita- tions. The establishment of one kind of plant over an area may be the natural, and, perhaps, the necessary prerequisite for the development of another plant which has formed the habit of attaching its fortunes to those of the first one in the field. Plants, also, by their position and attitudes strongly influence the distribution of other plants. If plants, which are accus- tomed to depend upon winged seeds for their distribution, find themselves gradually enclosed by the foliage of strong-growing neighbors it will be difficult, perhaps, for them to extend farther the range of their seeds. Or, possibly, the berries which were attractive during a season when neighboring plants were not in fruit may not be so attractive another year when the adjacent forms are ripening their own larger, more highly colored, more highly scented or sweeter fruit. = 4 Minnesota Plant Life. 23 Where the story of plant migration is recorded. It is im- possible to mention except in a more extended account the many and various ways in which plants influence the distribu- tion of each other or receive influence from outside sources, but enough has been said to indicate the general laws under which the State of Minnesota has received the plants which now inhabit its territory. They have come from all points of the compass, from all parts of the world, bringing with them habits acquired through countless generations of struggle and adapta- tion. To the enlightened eye, the form of a plant tells a story of its life and of the experiences it must have undergone to develop one type of structure rather than another. Just as in the formidable defensive armor of an extinct armadillo may be read somewhat of the story of its struggle with its enemies, so in the three hundred feet of solid trunk and in the massive girth of a living Big-tree in the Sierras one may read the story of its struggle in the ancient forests when its allies and com- petitors were perhaps more numerous and more vigorous in their aspiration for light than are the neighbors of to-day. In the Minnesota valley, not far from New Ulm, there are found upon rocks exposed in the river-bed by the erosion of the waters, some specimens of the little prickly-pear cactus, a desert plant which has found its way from the plains of Arizona and New Mexico. By all its characters it indicates how it must have been trained in a school of life different from that in which the plants around it receive their education. Its solid, leafless, flattened stem with a resistent rind is fitted to withstand the evaporation of moisture—a character much needed in the des- ert, but less necessary in the valley of the Minnesota. Its strong root system extending out a yard or more on every side was indispensable to collect what little moisture there might have been in the arid soil of the southwestern desert; with a smaller root system it could do very well in its northern home. The sharp thorns and spines with which it is covered were a necessary protective armor where vegetation was sparse and grazing animals hungry; without this armor it could live very well on the hills of New Ulm, for there dwell other plants with- out armor nor do the herds destroy them. Such a plant, evi- dently a wanderer from another land, is like a man of medieval 24 Minnesota Plant Life. times who should be reincarnated in a modern society and should insist upon wearing the coat of mail and carrying the rapier which were necessary in another age, but would be rec- ognized as altogether out of place in the life of the present day. The pine trees, with their needle-shaped leaves fitted to trans: pire water but slowly and with their strong branches able to carry the weight of the snow which is piled upon them in their northern home, when they find their way down the river to the comparatively genial climate of Iowa cannot at once abandon the structures which they developed under the stern necessity imposed by the severer climate of their native land. The mat- plant, such as a purslane or carpet-weed, adapted to life on a flat plane where it is not shaded by surrounding plants but spreads out all its prostrate branches in a discoid body, cannot erect itself into the slender wand of the aster, taught to assume this shape by centuries of existence in the underbrush above which it had to lift its leaves that they might catch the sun. The aspiring spruce telling in its form a story of other spruce trees close beside it crowding each other as they all reached upward for the light, if it is planted in one’s dooryard with noth- ing near to shade it cannot abandon the character which it developed of old. Plants when they migrate from place to place must take with them those structures and habits which are fitted best to the whole history of their species. In their migrations they select places which resemble as closely as pos- sible those to which they are accustomed. They allow them- selves a certain freedom just as men do, but even as regards men it is well-known that they prefer to migrate along the same parallel of latitude, so that the inhabitants of Minnesota have come rather from the forests of New England and New York, from Canada, from Scotland, and from Scandinavia, than from the highlands of Mexico, from Italy, Africa, or Brazil. Struggles of migrating plants. It must be apparent from all that has been said that the laws governing the migration of plants are substantially the same as those that govern the migra- tion of other living beings. It is an instinct with all living creatures to maintain their own existence as long as they can and to do this they wrest from others, weaker or less fortunate, the right to food and sunshine which they in their turn demand Minnesota Plant Life. 25 of nature. It is even so with men: the dervishes of the Soudan must give way before civilized England. Thus also must the feeble plants of a meadow’s edge yield before the onslaught of trained roadside plants, brought in from other parts of the world and fitted to cope with the conditions of existence in a stronger and better way. As one looks at a placid meadow, its grasses bending in the breeze, he should remember that under- neath the calm serenity of the scene there is a bitter struggle, a relentless internecine warfare between the plants that are already in the meadow and those that are striving to enter from without. Comparison of plants with animals. Next to and even stronger than the instinct to exist is the instinct to persist, and plants sacrifice their own lives for their offspring just as readily in their sphere of life as will a human mother give up her life for her child. In dealing with plants the mind must be rid of the mistaken notion that they are dull, stupid things which stay where they are set without ability to better themselves and their offspring. On the contrary the plant should be regarded as a living organism with definite necessities and definite in- stincts. Plants are quite as much alive as animals, and, indeed, they are greater ground-gainers on the surface of the earth than animals are, for if all the plants of the world should be weighed in one scale pan of a gigantic balance with all the ani- mals in the other it would be seen that as organizers of dead matter into living substance the plants far outrank the animals. In dynamic force, in the ability to apply energy in some definite direction, the animal is indeed superior, but in those purely con- structive vital powers no organisms are so skillfully adapted and so perfectly organized as the plants. They are not altogether of a lower type of life than animals, for they do their work in the world after their fashion, and that is all that animals can do. They are rather to be viewed as other kinds of living things, and are to be regarded not as merely subservient to the needs of animals, not solely as a food-supply for grazing cattle or roving birds, but of interest for their own sake and possessing an indi- viduality to be respected. Ghamter ene Slime-Moulds and Blue-green Algae. IS Number of plants in the world. In the whole world there are now living about 300,000 different kinds of plants, and it is possible that nearly as large a number of forms are extinct. The relics of past plant life in Minnesota are not very abundant, but in the older rocks there are a few fossil sea-weeds deposited on the mud flats of an ancient ocean which covered the region now occupied by the land, and in the red sandstone which oc- curs in the Minnesota valley in limited quantities, there have been found imprints of leaves belonging to by-gone genera. For example, in those days palm trees flourished in the state and have left their replicas along with the remains of red-woods, big-trees, cycads, magnolias, tulip-trees and other varieties, which are not now found within hundreds of miles of Minnesota. From old peat deposits and from soil masses lying under the glacial clays, fragments of charred wood and vegetable debris are sometimes exhumed. Such fossils often show that the dis- tribution of plants before the glacial period was quite different from that of to-day. Number and sorts of plants in Minnesota. At the present time, of the 300,000 living species of plants, about 7,500 are probably to be found growing without cultivation in Minnesota. The figures are in the nature of an estimate, for by no means so considerable a number has yet been discovered. But it must be remembered that the larger proportion of these plants are not the conspicuous objects which are usually in mind when the word “plant” is used, but are rather the insignificant micro- scopic forms, difficult to discover and often of such slight differ- ence from each other that they would be recognized as distinct varieties only by the most trained observers. Minnesota Plant Life. 27 An estimate of the distribution of these 7,500 species of Min- nesota plants among the different groups is approximately as follows: slime-moulds 150; bacteria and algae 1,000; fungi and lichens 3,250; liverworts and mosses 500; ferns and flowering plants 2,600. It is evident, then, that most plants of the state belong to the lower orders of vegetation. There may now be given a general account of the Minne- sota vegetation, avoiding the use of technical terms and describ- ing where it is possible certain common forms of each group, so that the reader may have within small compass a comprehensive view of the classes just named, as they are represented in the state. Slime-moulds. The plants (or more probably animals) known as slime-moulds constitute a very peculiar group of organisms. It is by no means certain that they are plants at all, although they have some vegetable characters. In other respects they resemble the lower animals, and botanists and zoolo- gists have often debated to which of the two great realms of life they really belong. One of them, which is known to occur in Minnesota, may possibly have come under the observation of some of the readers of this book. The roots of cabbages and turmips, when pulled from the ground, are sometimes found to be covered with a curious irregular growth of little spherical tubers, about the size of hazel nuts,—sometimes larger, though often very much smaller. The occasion of the appearance of such tubers is the development of singular little slime-moulds too small to be seen by the naked eye but sufficiently active to cause gall-like swellings in the tissues of the root. Because of the ruptured appearance which the root has when affected by these tiny organisms, the whole structure, root and slime-mould, is known as a root-hermia or as club-root. Most slime-moulds do not, however, live thus as parasites on other plants, but are found on decaying leaves, rotten twigs, fallen logs and other debris of the forest-floor in shaded places. They sometimes grow up from a mucilaginous base, forming little brown, cylindrical plumes, not more than half an inch in height and clustered together, a score or more, ina group. The brown plumes are found upon careful examination to be deli- cately woven masses of threads, between which is a fine brown 28 Minnesota Plant Life. < dust which can be shaken out upon the hand or upon a piece of paper. This brown dust, under the microscope, is seen to consist of innumerable tiny spheres, the spores of the plant. If the spores be placed in water, after a time their shells break and out of each comes a little mis-shapen drop of jelly-like substance, which oozes away with a slow and viscid movement. If several of these tiny bits of jelly find themselves close together—per- haps after a rain upon the bark of some rotten log—they crawl towards each other and fuse into a common patch. The patch then moves imperceptibly over the wood, increasing in size as it extracts nourishment from the decayed material. Sometimes the jelly-masses grow to the size of a man’s hand. A common sort is found in tan yards and often upon railway ties resembling very much a piece of ordinary thin jelly and generally cov- ered with a sulphur-colored powder. After the jelly-mass has increased in size to a certain point it breaks up into little clusters which afterwards develop fruit-bodies more or less like the brown plumes spoken of above. Another kind of slime-mould crawls up the stems of various plants in meadows and deposits itself upon the leaves in little foam-patches looking very much like drops of spittle. There are some insects which make similar spittle-masses on leaves and an expert investigation is necessary to determine whether such objects are insect products or the plant bodies of slime-moulds. Some slime-moulds have the power of incrusting their tiny fruit-bodies with lime which they extract from their soil or from rain-water that falls upon them. Such forms are often observed in Minnesota upon dead wood, or fallen leaves, generally in moist shady places in the deep forest. Sometimes the fruit- bodies are almost round, resembling the familiar pills of the homeopathist. In other species they are worm-like, coiled like loose snail-shells, but very much smaller, yet not so small that they cannot easily be discovered if searched for in the places that they have chosen. A few slime-moulds will be encountered among mosses, forming little brown scurfs upon the moss tuft or displaying themselves as yellowish patches around the bases of the leaves. None of these plants have any economic import- ance. ‘The most conspicuous one in Minnesota occurs upon dead logs as pink, hemispherical bodies, about the size of the Minnesota Plant Life. 29 end of one’s finger. Usually these fruit-bodies are seen in clus- ters of a dozen or more. If one of them is cut into it will be discovered that the interior consists of a brown moist powder, which when dry blows away in an impalpable dust. In a single fruit-body such as one of these, millions of spores originate which, washed away by the rains or blown about through the atmosphere, may fall upon suitable decaying substances, open and liberate each its tiny bit of living jelly that by itself or with the assistance of others gradually builds up a new plant-body. Algae. The plants known as algae secure their best develop- ment in the sea, where under the name of sea-weeds they are universally known and many of them admired for their beauty of color and gracefulness of form. Of the algae there are five principal groups; I, bacteria; 2, blue-green algae; 3, bright- green algae; 4, brown algae; 5, red algae. The red algae and brown algae are chiefly marine, although a few varieties of at least the red group are found in the fresh waters of Minnesota. Most of the algae in fresh waters belong to the blue-green or bright-green groups, while those lowly and most extraordinary of plants, the bacteria, are of such various occurrence in soil, water, air, and the bodies of other organisms that I shall con- sider them in a special chapter. Blue-green algae. The plants of this group may generally be recognized by their bluish-green color, approaching some- times the hue of verdigris and never the pure grass-green which distinguishes the bright-green group. One of the most com- mon of them is the so-called “water flower” which in summer develops in such vast quantities in the lakes of Minnesota. The tiny, bluish, jelly-ball of the water-flower, ordinarily not larger than a pin-head, if examined closely will be found to have a bub- ble of gas at the centre, by means of which it floats. If this bubble is analyzed by chemical methods it will be ascertained to be more highly oxygenized than the atmosphere. It is pro- duced by the growth-activities of the plant and incidentally serves the important purpose of keeping it near the surface of the water where it may obtain the light. At Lake of the Woods I have seen these plants in such enormous numbers that the water looked more like green paint than lake-water and at Lake Minnetonka the cottagers often complain of the abundance of 30 Minnesota Plant Life. the water-flower and inquire for methods of exterminating it. There is, however, no practicable way of destroying it, for if the water should be poisoned enough to kill the water-flower other living things, pond-lilies, bulrushes and bass would also disap- pear. Structure of the water-flower. A microscopic examination of the water-flower will show that each tiny jelly-ball consists of a number of delicate algal threads intertwined and imbedded in a common mass of jelly which they secrete. \Vhen a jelly- ball becomes sufficiently large it commonly breaks in two and the pieces continue growing as before. If the jelly be dissolved hundreds of tiny coiled threads escape from it and multiply, developing hundreds of new jelly-balls. In the autumn these little creatures drop to the bottom of the lake, or remain in a dormant condition frozen in the ice until the warmth of another season stimulates them into renewed activities. Larger jelly-balls, in appearance very much like green plums, but with the characteristic bubble of gas at the centre are often found floating in ponds. These belong to another species of blue-green algae but they are closely related to the water-flower and their structure and life-habits are not essentially different. Still another variety of blue-green algae is common as little hemispherical lumps an eighth of an inch in diameter attached upon the stems of bulrushes, just beneath the surface of the water. Still other kinds form tufts and stringy masses several inches in length floating near the surface of stagnant pools. A curious form which has lost the blue-green color, and may be classed also as a bacterium, is sometimes found growing in the outlets of springs, where it resembles a mass of iron rust dis- solved in water. The red color is not a deception for it is ac- tualiy due to iron oxide extracted from the water by the micro- scopic filaments oi the plant. Rock-forming algae. Some of the blue-green algae have the power of encrusting themselves with lime, and in watering- troughs and tanks there sometimes occurs a calcareous forma- tion reminding one of the deposit in old tea-kettles. Such a crust is true limestone extracted from the water by the chemical activities of the algae. Upon a large scale the blue-green algae play their part in the formation of rock. ‘The best place in 31 Minnesota Plant Life. ction is at ira ional Park, where great masses of traver- in the world, to observe the America and, indeed, the Yellowstone Nat It is en- 10. shown in fig. After photog ank reen algae. et Fic. 8.—Portion of a board which had been standing in th raph by crusted with lime stone deposited by a colony of blue-g From the 4 Miss Josephine E. zelle. vlanical Ga , ¢ Tilden. il « 1 congeni e c l hn¢ ravertine is a kind of limestone; sinter is 1e round the hot springs ilg © c e -forming formed, covering acres a K hich the blue-green rocl home. v - ise) a v pus) « - “= yn _ ~~ om 4 Co = Cire = = ee St oe) of 1 kind © c a3 Minnesota Plant Life. silica or sand rock and it therefore appears that not only can some blue-green algae extract lime salts from the water, but other varieties can form quartz as well. No doubt very much of the limestone and even of the granite that occurs in ledges over the continent was begun in ancient warm seas by the action of organisms similar to the blue-green algae, while at the Yel- lowstone Park, or upon a smaller scale in one’s watering trough, the same rock-forming processes are still going on. Skin-algae. Still another variety of blue-green algae pro- duces broadly expanded membranes, or skins, along the bottom of springs, and on pebbles in streams or lakes. In general the plants of this group may be recognized by their color and they are among the lowest of the algae. Chapusr 1 ¥- Bright-green Algae. se By far the greater number of Minnesota algae belong to this group. Pond-scums. Probably the most easily recognized is the familiar pond-scum, which is by many people regarded with aversion and is supposed to be in some mysterious way con- nected with the presence of frogs. If the slimy bright-green scum be lifted from the pool, taken upon the fingers and closely examined, it will be seen to consist of long delicate unbranched hairs, not much thicker than a spider’s web. As it dries in the hand it curls and shrivels, but under the microscope the hairs are beautiful objects. They are jointed and in each joint lie coiled one or more green bands, like ribbons in a glass jar. By means of the green bands the plant can construct starch out of the carbonic-acid gas in the bubbles of air scattered near it through the water, using also the water itself in the process. By the breaking of the threads between their joints the plant abund- antly propagates itself throughout the summer. When autumn arrives a very remarkable breeding-habit comes into play. Two of the pond-scum threads extend them- selves close together in the patch and from the joints of each, little protuberances arise which become blended into tunnels, uniting ordinarily the joints of one filament to the neighboring joints of an adjacent filament. ‘Through such tunnels the entire living contents of one joint creep over and combine with the living contents of a neighboring joint. The fused-body then contracts like a sponge, expressing much of its sap and secreting about itself a firm clear membrane. After such a process, repeated throughout the patch of algae, the walls of the old joints may slowly break or dissolve, and the hundreds or thou- sands of oval fused-bodies, inclosed in their special membranes drop to the bottom of the pool, where they lie dormant until the 4 34 following spring. Minnesota Plant Life. Then each membrane dissolves or breaks and the fused-body extends itself into a new pond-scum thread, becoming jointed as it grows and elaborating in each of the joints the green ribbons by means of which it pro- duces its food from water and carbonic-acid gas just as did its parents the preceding season. By the breaking in pieces of this filament in the way that has been described and by the subsequent growth of the pieces a large patch of scum, enough to cover the surface of a small pool, will be produced before the summer is at an end. Desmids. Related to the pond-scum are a large number of tiny crescent-shaped and star-shaped plants called desmids. These are often particularly well-developed in the water of peat-bogs, so that if one goes to the nearest tamarack swamp and brings away a tumbler full of water which he has squeezed out from among the peat-mosses, and sets the tumbler in the window, within a few hours a green film of desmids will be likely to form upon the side of the glass turned toward the light. Like the pond-scums these little plants have their breed- ing habits and like them they are able to maintain and distribute themselves throughout the water of their pool. If in the autumn, the pool becomes dry, the little eggs of the desmids lying among the particles of soil may be caught up by the wind and carried to distant pools where they continue developing as before. Rolling algae. © Not uncommon in Minnesota is another bright-green alga which appears in quan- tity in pools as green globules somewhat smaller than pinheads. If placed in a saucer of water and observed closely one of these green globules will be seen to roll over and over in the water and make its way from one side of the saucer to the other. Fic. 9.— Portion of a pond-scum thread, show- ing how it is made up of transparent- walled cells with a coiled green ribbon in each, much magnified. After Atkin- son. It does this because its surface is covered with tiny contractile threads, which lash about in the liquid like so many little whip- cords and roll the whole ball from one point to another as the Minnesota Plant Life. — 35 needs of the plant may determine. Because of its rolling habit this little plant is called Volvox, or the rolling alga. Flower-pot algae. Somewhat related to the Volvox, but by no means so interesting an object, is the bright-green alga which forms a scurf on flower-pots in green-houses, upon curbstones near hydrants, upon the foundation stones of houses standing upon damp places, upon damp soil, and often upon fallen trees in the deep forest. A microscopic examination of the green Fic. 10. Patches of pond-scum floating in a tank. A lime-encrusting alga grows on the boards up to high-water mark. Near Minneapolis. After photograph by Mr. R. W. Squires. scurf on a flower-pot would show that it is made up of countless very tiny green spheres, fifty of which could be laid side by side across the dot over a lower case “i” on this page. The way in which these little plants multiply is as follows: While they are finding food in plenty in the moisture about them, the con- tents of each of the spheres will be seen to divide into two, four or eight smaller balls. The membrane of the old sphere then dissolves and the little balls tumble out and grow to the size of 36 | Minnesota Plant Life. the one which produced them. This process is rapidly repeated and in a few days such a geometric progression will bring into existence an enormous number. A variation of the process sometimes occurs when there is an unusual abundance of mois- ture, as after a heavy rain. Each of the little balls formed under these circumstances is provided with a pair of extremely delicate lashes by means of which it propels itself through the water with a curious rotating and wabbling movement, something like that of a rifle-ball, only, of course, very much slower. It takes some moments to travel an inch, yet, on account of the very small size of the plant, its movements viewed under a microscope seem fairly agile. Red snow. ‘The famous red-snow plant, which is found upon mountain heights in the Alps, in Bolivia, or in the Selkirks, is a relative of the green-slime so common upon flower-pots in the Minnesota conservatories. ‘The color of the red-snow plant is adapted, no doubt, to the cold region which it has chosen for growth, and, in general, red coloring substances in plants have been described as warming-up colors—thus the autumn leaves turn red not because they are dying but for very much the same reason that men wear overcoats and woolens. Redness may be regarded as one of the plant’s ways of protecting itself against a low or falling temperature. Water-nets. Among the bright-green algae a conspicuous but not extremely common form in Minnesota is the water-net. This plant grows in quiet pools and resembles very much a piece of green mosquito-bar rolled up in an irregular cylinder, three or four inches long, and an inch or more in diameter. Each side of a mesh in the net is a joint or cell of the plant, and in each cell the living contents have the power of arranging them- selves into a tiny net. When the wall of an old cell dissolves the tiny net begins to grow, enlarging all of its mesh-sides equally, until it has become as large as its parent. Besides this propagative process the water-net has the power of breeding somewhat as does the pond-scum, and produces curious little microscopic jackstone-shaped fused-bodies which remain dor- mant at the bottom of pools during the winter months. A great variety of bright-green algae are found growing upon peb- bles, upon the stems of submerged vegetation and upon twigs or Minnesota Plant Life. AG) branches which have fallen into the water. Their characters are all more or less similar to those which have been already de- scribed. Leaf-dwelling algae. One remarkable alga, very rare in Min- nesota, is found in a peculiar habitat. On the leaves of the jack-in-the-pulpit there may occasionally be noticed watery blis- ters, in which, under the epidermis of the leaf, slender green threads branch and grow, giving a pale green tint to the central portion of the blister. Here is an example of a parasitic alga, forms similar to which are more frequent upon leaves in tropical forests than in temperate regions. Sphere-algae. Another bright green alga which appears to be uncommon in Minnesota, but sometimes forms floating tufts of slender green threads in the waters of overflowed meadows, is remarkable for its production of true eggs and spermatozoids. As in the pond-scum, each thread of the body is an unbranched row of joints or cells all of which are shaped like long glass cylinders closed at each end. In some of these cells the living contents break up into a dozen or more spherical green eggs, which lie close against the wall of the mother-cell and, by fer- ments which they secrete, make little punctures. Other cells of the filament convert their contents into thousands of motile spermatozoids which dart about in the cell-cavity in a compli- cated dance which finally results in some of them perforating the wall, and through the apertures all escape into the water. After swimming about for a time many of them find their way through the pin-holes which the eggs had made in the walls of their mother-cells. They enter the egg-mother-cells and one of them buries itself in the substance of each egg. When the eggs in a tube have been thus fecundated each encloses itself in a spiny membrane, assumes an orange color, and after the wall of the mother cell has broken or dissolved each fused-body escapes into the water and divides internally into a little group of spores. ‘The spores in turn escape and develop new filaments of the alga. This alga is called the sphere-alga on account of the tubes full of spherical eggs which characterize it. Green felts. Among the other algae of this group should be mentioned the green-felts which form plush-like masses in springs and ditches. ‘They are remarkable for the unjointed 38 Minnesota Plant Life. character of their filaments and their breeding habits remind one in some respects of the sphere-alga, for they form true eggs and spermatozoids. Bass-weeds. Of all the algae of Minnesota, the largest and most conspicuous are the bass-weeds. These plants are familiar to fishermen because tufts of them are commonly entangled by trolling-hooks which have been dragging along the bottom out- side the bulrushes. The bass-weeds have stems the thickness of a knitting needle, with distinct nodes and internodes. Upon the nodes whorls of branches are produced and upon the branches subsidiary leaflets. ‘The whole plant, in the more common form, is encrusted with a limestone deposit, which gives it a brittle and stony feeling to the touch. Hence these plants are also called stone-worts. Many of them have the habit of forming diminutive bulbs which separate and serve to propa- gate the plant, and they also produce near the bases of their leaflets very definite oval, brown eggs, not much larger than a pin-point and inclosed in a little spirally twisted jacket of cells leaving an opening at the top through which the spermatozoids can enter. ‘The spermatozoids are derived from curious little spherical organs of a reddish color, and each spermary, not larger than a small pin-head, forms as many as 30,000 actively moving spermatozoids, thousands of which are destined to be lost in the water, but enough are produced so that the eggs are reasonably certain of fecundation and may then, after a dormant period which extends over the winter months, develop into new bass-weed plants. During the cold weather the eggs and many of the propagative bulbils lie safely at the bottom of the lake too deep to be injured by the frosts. Some varieties of bass-weeds, slenderer than the others, are not provided with the limestone sheath which characterizes the more common form, but may be recognized by their general similarity of structure. When taken out of the water they are limp, though not slimy like the pond-scums. Bass-weeds form an extremely abundant vegetation, generally distributing them- selves in the deeper waters of a lake, outside the zone of pond- weeds, or of bulrushes. Sometimes they are very common in shallow waters, and I have seen them in Glenwood lake, and in some of the northern lakes of Minnesota, growing vigorously in water only a few inches deep. Chapter V. Brown Algae and Red Algae. so Brown algae. Almost all of the true brown algae are marine and they are remarkable as comprising the longest plants in the world. It is a popular impression that the big-trees of Cali- fornia, the Eucalypti of Australia and the Rotang palms of Java and the Orient are the longest-stemmed plants in existence. This, however, is a mistake for some of the gigantic seaweeds of the Antartic ocean extend their stems for over a thousand feet, making them nearly three times as long as the trunk of the tallest big-tree in Calaveras county, California. Such huge brown algae are not unknown along the sea-coast of the United States, and the giant kelp of Puget sound sometimes reaches a length of more than three hundred feet. By means of its long cable- like axis, it attaches itself to the rocks and floats its immense leaves many fathoms out upon the surface of the sea. Other brown sea-weeds develop enormous strap-shaped leaves in tufts, attached by hold-fasts to the rocks. Some of them have their leaves perforated with numerous holes, an adaptation to prevent them from being torn by the waves. In the fresh waters of Min- nesota no such forms as these are to be found and the most abundant ones are doubtfully to be classed as brown algae at all, but from their brownish or olive-green color they may here be considered as if certainly members of the group. Diatoms. In the early spring, in rivers, one often finds olive- green membranous masses as large as one’s closed fist floating idly at the water’s edge. An examination of them would show that they consist of great numbers of microscopic boat-shaped bodies, with clear glassy walls and olive-green or brown con- tents. Such algae are known as diatoms. They sometimes occur in great fossil deposits, and in this condition are much prized for polishing powder. The walls of the diatom cells 40 Minnesota Plant Life. have the power of depositing in their interstices, silica, and it is this which gives the polishing quality to the fossil powder. Some diatoms are provided with slender gelatinous stalks, by means of which they attach themselves to objects under the sur- face of the water, but many of them are free-swimming organ- isins. The exact mechanism by which they swim has long been a puzzle to students of the group, for they are not, like the swim- ming cells of the green-slime which grows on flower-pots, pro- vided with conspicuous lashes by means of which they roll them- selves through the water. Most of them seem to have, how- ever, extremely small apertures in their walls through which the living substance probably protrudes itself and sets up an agitation in the water, so that the tiny boat moves mysteriously across the field of view of the microscope like some infinitesimal electric launch. Red algae. This group like the brown algae is essentially marine and but few forms are found in the fresh waters of Min- nesota. In rapidly flowing streams or under cataracts certain kinds display their red bodies, appearing as delicate plumes a few inches in length or as little pink or purple plates an eighth of an inch or less in diameter. ‘Their structure is more compli- cated than that of any of the algae which have been considered. They are supplied with egg-cells from which long cylindrical protuberances are developed. The spermatozoids, unlike those of the sphere algae, have no swimming lashes and are, therefore, carried to the protuberances of the eggs by currents of water, or by the ministration of aquatic insects, recalling in this latter adaptation the extraordinary relation which exists between insects and flowers. When, however, a little spherical spermato- zoid comes in contact with the slender cylinder developed on the egg-cell, it adheres and fuses and, as a result of its stimula- tion, from the egg are thrust out branches which finally develop spores, and thus the plant persists from one generation to another. Some kinds of red algae are so faintly red that they would be mistaken for brown algae, if color alone determined the classi- fication. Such are certain rather stiff, wire-like plants, spar- ingly branched and preferring for the most part the same rapid foaming water which the easily recognizable varieties select as ———— Minnesota Plant Life. AI an habitation. Yet on account of their various structural pecu- liarities botanists assign them to the group of red algae. General remarks about algae. ‘The account that has been given is very elementary and the reader must remember that it covers perhaps as many as a thousand varieties, most of which, are species of bright-green algae and diatoms. None of the fresh-water algae has any great economic importance. Some sea-weeds are employed in the manufacture of iodine, others, especially the kelps, as fertilizing material for farms near the sea-shore. The “Irish moss,” as it is called, is a red alga and is used for food; when cooked it is a kind of blanc-mange. In China several other kinds of sea-weed are regarded as edible. The Indian fishermen in Alaska use the stem of the giant kelp as siphons and for fishing lines. In Minnesota the algae are sometimes rather noxious than useful. Blue-green algae in decaying masses are known to give to the water a characteristic pig-pen odor which is very offensive. It is at times a difficult problem to prevent them from vitiating aqueducts and reser- voirs, and cattle are reported to have been poisoned by drinking water which contained their rotting remains. It is, therefore, not the water which contains the bright grass-green pond-scums that is so objectionable, though on account of the slimy charac- ter of these plants they are more repugnant to most people than the verdigris-colored water-flower. Cattle should not be allowed to drink from pools in which the algal vegetation is of a blue- green shade, but no injury is likely to result if the scums are bright-green. In past time it should be remembered that certain lime- secreting-algae and silica-secreting algae have no doubt done their part in creating the building-stones of the state. Even the quartzites and the granites may be the modified sinter deposits from some hot-water algal vegetation of former ages. In the sea, to-day, countless millions of algae are busy building coral- reefs similar to those produced by the coral polyp, while nearer home, in Lake Michigan, limestone pebbles have been found to be produced by the concretionary growth of lime-secreting algae. I have not yet found any of these algal pebbles in the lakes of Minnesota, but it is probable that they occur. If any one should chance to find calcareous pebbles the size of an egg, 42 Minnesota Plant Life. which upon being broken have a moist bluish-green interior or are hollow, he will doubtless have discovered a growth of rock- forming algae. Algae the oldest kinds of plants. The great group of algae is of peculiar interest to students of nature because it includes the oldest types of plants living upon the earth. There is reason to suppose that life originated in the sea, and that all the terrestrial forms are descendants of those which in distant epochs learned to leave the ocean and establish themselves upon the land. One reason for supposing this is that in distant peri- ods of the earth’s history there was very little land in existence, and almost the whole surface of the globe was covered by the waters of the ocean. No doubt, at first, before the ocean had cooled, when the world was still young, warm-water algae, among which the rock builders are so prominent, came into being and began their work perhaps among the very first living creatures of all the hosts that now exist. Some varieties of land- plants at present, as for example the mosses and liverworts, show clearly in their structure their relationship to the algae, and serve as connecting links between the great primal flora of the ocean and the modern flora of the land. The algae, then, are the forms from which all other plants are supposed to have orig- inated. The history of life upon the earth is one of constant improvement, and as land appeared improved forms of algae tenanted it, and may have given rise to all the myriad higher species of forest and prairie as they are now exhibited over the continents of the world. And finally there are very many excel- lent reasons for regarding the continents themselves to have arisen largely through the activities of living organisms—a proc- ess that may be observed continuing even in these days if one should visit the coral-islands of the south seas, those enchanted atolls of the Pacific. Chapter VI. The Lower Sorts of Fungi. ss Number of fungi in Minnesota. While there are nearly 200,- 000 known species of flowering plants in existence, there have been described only about 50,000 species of fungi. Yet in Min- nesota, while there are but 2,500 or 2,600 flowering-plants grow- ing without cultivation there are probably not less than 3,000 fungi, so that the state furnishes a field for the development of a greater comparative proportion of fungi than of flowering plants. Like the mosses and liverworts, the fungi are believed to have arisen from primitive algal types and students recognize two principal series. The lower series known as the algal fungi, the structure of which is more directly suggestive of algae, is much poorer in forms than the higher series of true fungi in which all the peculiar fungal structures and characters have had an opportunity to be unfolded. Black moulds. Of the algal fungi a very widely distributed group is that of the moulds. Among these the black mould is omnipresent, and easily cultivated. Ifa slice of bread be dipped in water, placed in a saucer, a tumbler inverted over it and then set in a warm place, perhaps behind the kitchen stove, in a few days the tumbler will be filled with a white cloud of fungus threads and presently little black, spherical spore-cases will arise at various points on the fungus network. The white threads are the vegetative plant-body of the mould; the black knobs (white when young), smaller than a pin-head, are the fruit-bod- ies. The black color of each fruit-body is occasioned by the presence, in a swollen cell, of some hundreds of little black spores, which have developed by the division of the living con- tents of their mother-cell or spore-case. When the spore-cases are broken and the living powder is disseminated, it is caught in air currents and is held suspended in the atmosphere to such 44 Minnesota Plant Life. an extent that in the dust of the air in every living room in Min- nesota, hundreds of such spores are already floating. It is nec- essary, therefore, only to dip the slice of bread in water and set it aside, for the spores which have fallen upon it in the process to begin their development. It would be a mistake to suppose that moulds originate spontaneously. A mould plant can no more come into existence without the cooperation of some mould-spore than could an oak-tree without the assistance of an acorn. It is because of the presence almost everywhere of incal- culable numbers of mould spores floating invisibly in the atmos- phere that this seeming spontaneity of development impresses one. There are, however, many places where bread will not quickly mould if set out in a saucer, for example, if carried to some high mountain top where the air is pure and free from spores, or if exposed in a chamber which has been purified and sterilized by a spray of carbolic acid. The black moulds have a breeding habit reminding one of the pond-scums. ‘Two of the white threads close together or touch- ing each other, may develop little side branches the ends of which blend and gradually convert themselves into a black fused-body with very much the character of a fecundated egg and capable of growing into a new mould thread. Other kinds of moulds. ‘There are several other varieties of moulds belonging to this group of algal-fungi, but the well- known blue-moulds, or green-moulds, with their verdigris col- ored fruit-bodies are classified in a higher group. Some of the moulds have curious habits. One, called the pill-throwing mould, produces a mass of spores upon the end of a filament, then underneath this mass there develops a swollen cell in which pressure is exerted, so that after a time the mass of spores is shot off into the air by the explosive mechanism of the stalk-cell. Moulds on moulds. Still another mould has the peculiarity of attaching itself to the vegetative body of the black mould. It lives as a kind of mould-louse, extracting its nutriment from the body of the larger and more vigorous black mould. A plant which thus fastens itself upon another living creature and absorbs nutriment from it to the injury of the host is called a parasite. Minnesota Plant Life. 45 Fly-cholera fungi. Related to the moulds are the singular fly-cholera fungi. Many persons will have noticed sticking to the window-panes in autumn the dead bodies of flies surrounded for some distance by a faint yellowish film upon the glass. This film consists of spores of the fly-cholera fungus which have been shot into the air by a mechanism similar to that described for the pill-throwing mould. The vegetative body of the fly-fungus lives within the body of the fly where, growing luxuriantly, it interferes with the life-processes of the insect, kills it, and con- verts a large portion of its body into food for its own use. Other flies approaching the infected individual are peppered with the tiny spores of the fungus, or they receive the contagion while walking upon an infected window pane or in a spore-strewn cor- ner. In this way every autumn unnumbered millions of flies are killed. A closely related cholera-fungus attacks the Rocky mountain locust and is of great economic importance because it keeps this dangerous insect in check. Still other varieties attack other insects, but these two will serve as examples. Cell-parasites. There are a large number of microscopic algal-fungi of very curious behavior. Some of them find their way into the skin-cells of flowering plants and there live as para- sites, while others insinuate themselves into the eggs of algae and devour them. Some of them are found in the soft sub- stance of swamp plants; some may be discovered in pond-scum filaments where they consume the cell-contents; some find their way into desmid cells and destroy them; some enter the pollen- grains of flowering-plants, notably of the pines, and feed upon the living contents. They invade the diatoms and various algae; they infect the spongy tissues of the peat-mosses; they penetrate the wall of fish-mouid eggs and by their omnivorous habits impress it upon us that no organism 1s too small or incon- spicuous to escape its enemies. Fish-moulds. Related to the fungi which sometimes injure their eggs are those surprising organisms, the fish-moulds, that are often found forming gray fur coats on the bodies of dead minnows or dead frogs. ‘They are especially unwelcome in fish hatcheries where they attack the eggs of the fish and destroy them. Some varieties are found upon the dead bodies of aquatic insects and others grow upon decaying substances when sub- 46 Minnesota Plant Life. merged in the water, although the majority are parasitic upon living plants or animals, or make the dead bodies of these their habitat. The life of a fish-mould differs from that of the black mould in some important particulars from its being an aquatic organism. Its spores are not mere passive spheres of micro- scopic size like those of the black mould, but are provided with swimming lashes, so that they may propel themselves through the water in search of other fish or insects upon the bodies of which they may be fortunate enough to obtain a lodgment. One fungus related to the fish-moulds, not yet discovered in Minne- sota, but possibly occurring somewhere within the state, is noteworthy in botanical annals as being the only fungus known to produce motile spermatozoids like those of the algae and, as will be seen later, of the ferns and mosses. Mildews. Closely related to the fish-moulds are the mildews. These are fungi which live as parasites upon land plants. A striking example of the group is the mildew of mustards, which occasions a rotting of the stems and leaves in the shepherd’s- purse. Another causes a rotting of potato tops and is one of the most serious diseases of the potato with which cultivators have to contend. Still another which occurs in Minnesota is the mildew of the grape-vines, inducing the leaves to wither and decay. ‘The lives of mildews are in many respects similar to those of the fish-moulds, but with certain differences owing to their non-aquatic habits. For example, the mildew of the vine when it attacks the leaves goes about the task somewhat in this fashion. From the air, into which from other mildewed leaves the spores have been projected, certain spores come to fall upon the surface of a healthy leaf. They lie upon the skin of the leaf and extend little infecting tubes which crawl around upon the surface of the leaf until they find one of the air-pores with which the leaf is provided for respiratory and vapor-excretory pur- poses of its own. Into such apertures the fungus insinuates itself, and as its infection-tube crawls beneath the skin of the leaf among the soft cells filled with leaf-green and starch, it finds there plenty of food material. Into each cell it drives a little sucking organ and extracts the nutritive substances and converts them into its own body. Going thus from cell to cell it finally saps the life of so many of them that the usefulness of ee Minnesota Plant Life. 47 the leaf is destroyed, and thus the vigor of the whole vine is defi- nitely impaired. When the mildew has accumulated in this manner sufficient nutriment for its needs it puts forth a branch which grows out through one of the air-pores of the leaf and here, in the open air, spore cells are formed. These are sepa- rated from the branch which produced them and are carried away by wind-currents to other vine leaves. Moreover the mil- dew within the tissues of the leaf breeds after its fashion, form- ing little spherical eggs which after they have been fecundated divide up internally into a considerable number of tiny motile bodies, provided with lashes, so that, when the rotting mass of the leaf has broken down after some rain, these motile cells can be washed out and swim to fresh parts of the leaf or fall with the rain drops to other leaves upon the same plant. Such egg- cells of the mildew serve to bridge over the winter season, and it is, therefore, important, if potatoes, vines, or lettuce should be in the habit of mildewing, that all dead leaves in the autumn should be burned. This diminishes for the following season the danger from fresh infection. Chapter Vik Smuts and Rusts. v Higher fungi. The plants already described may suffice as examples of the algal fungi. The higher or “true” fungi con- stitute a very large group of various forms, some of which are parasitic, attaching themselves to the bodies of plants or of animals, while others live upon decaying organic matter. No fungus has leaf-green and consequently no fungus can manu- facture starch out of carbonic-acid-gas and water, but its nutri- tion is rather animal-like, in that there must be provided more complex food-substances. A fungus cannot live on a diet prin- cipally of air, salts and water as do the algz, mosses, ferns and most flowering plants. Smuts. Among the higher fungi the smuts are a well-known group. Every one is familiar with the smut of Indian corn which occasions the appearance of great distorted kernels, many times as large as the ordinary ones, composed almost entirely of smut threads and a very copious black mass of smut spores. Other kinds of smut are found upon oats, upon wheat, upon millet-grass, upon sedges, and upon sand-burrs. Generally the smut spore-masses develop themselves in the seed-areas of plants, and substitute for the seed their own fruit-bodies. Hence the smut fruit-body in the Indian corn takes the form of a greatly enlarged corn kernel and the stinking smut of wheat fills the wheat grain with a mass of spores, allowing the wheat to produce only the shell of the fruit while the interior is a solid mass of smut. Sometimes a whole flower-cluster is infected as in the sand-burr smut. Ina few plants the stamens are attacked by smut fungi and an example is furnished by the corn-cockle, a weed belonging to the pink family and to be met with in cul- tivated fields. Here the stamens, when mature, open in the or- dinary way to cast out their pollen, but if the smut that some- Minnesota Plant Life. 49 times affects them has gained a foothold, they might as well save themselves the trouble, for all the pollen grains will have been destroyed and in their place will be the spores of the smut. Peat-moss smut. Still another kind of smut develops its spores in the capsules of the peat-moss, and under such condi- tions when the capsule opens to eject its spores there are no moss-spores present, but only the smaller black reproductive cells of the smut. Until recently this condition of things caused bot- anists to labor under a misapprehension concerning the life- history of the peat-moss and in most of the books peat-mosses are described as producing two kinds of spores, some large and others small. The supposed small spores of the peat-moss are, however, not peat-moss spores at all, but are developed on a par- asitic plant which has the interesting habit of forming them in exactly the same little round capsule which the peat-moss had been to the pains of developing for its own spores. The life of a smut. A large number of plants in Minne- sota are affected by smuts and sometimes two or more va- rieties will be attacked by the same kind. More often, how- ever, the smuts which are found on different kinds of higher plants are themselves specifically distinct. The life of a smut is interesting because it is typical of the manner in which many parasitic fungi develop. ‘There may be selected for description the stinking smut of wheat. Inside the affected kernels clusters of spores are formed which upon the breaking of the kernels, during the threshing of the wheat or while it is being shovelled about in bins or while it is standing in its head, are liberated and fall upon the ends of other uninfected kernels. ‘There they are caught in the little hairs which are present at the germinal end, and when the wheat kernel is sown and germinated the smut spores germinate also and their delicate threads grow in the tis- sues of the wheat plant keeping pace with the host as it extends higher and higher into the air. When the wheat flowers are formed and the rudiments of the fruits begin to appear some of the smut filaments grow into the young kernels and, as these develop, the smut filaments begin dividing themselves into spore-cells, exerting a disintegrating effect upon the interior of the kernel, so that finally one thus infected becomes filled with thousands of spores of the smut. The process may then be re- 5 50 Minnesota Plant Life. peated and thus smut is perpetuated from year to year. On account of the habits of the smut it is a disease of grain which can be eradicated by the intelligent farmer, if he will take the trouble to kill all the smut-spores which are clinging to the hairy ends of his seed-wheat kernels. This can be done by ‘“‘blue- stoning,’ or by immersing the seed-wheat for five minutes in wa- ter of 132 degrees Fahrenheit. By such means the vitality of the smut spores is destroyed, for they are exposed at the end of the grain while the wheat plantlet itself inside the kernel is pro- tected by the firm fruit-wall and is not injured by the poison or by the heat. By such methods if generally and continuously employed, it would be possible to terminate the enormous finan- cial losses which farmers in Minnesota and the Northwest sus- tain from the various cereal smuts. Rusts. Related to the smuts are a variety of plants which may for convenience be grouped under the general name of rusts. Of these a great many different kinds exist in Minne- sota. They infest the leaves of numerous species of plants, the Labrador tea, the pines, spruces, and tamaracks, the golden- rods, asters, thistles, bellworts and poplars, the flax, willows, horsemints and sunflowers, the junipers, pears, apples, beans, violets and a great number of others. Wheat-rusts. The forms of greatest economic interest are the three sorts of rusts which attack wheat. There are over 700 different kinds of rusts belonging to the wheat-rust type, many of which occur on grasses, but the majority on numerous other varieties of plants. The wheat-rusts are among the most remarkable of fungi from the singular custom which they have of changing periodically their habitation from wheat to other plants. Not only do they change their place of abode, but they change their form and structure as well, so that it would be im- possible, unless one knew, to recognize the wheat-rust after it had migrated to one of the other plants upon which it has ac- quired the habit of developing. The three sorts of wheat-rust which occur in Minnesota alternate on different plants, one de- veloping on barberry leaves and probably also on the leaves of some other species which has not been identified, another re- appearing on buckthorn leaves, and a third on borage leaves. It must be remembered that these are three different varieties Minnesota Plant Life. 51 of wheat-rust. They cannot convert themselves into each other but are independent plants as distinctly as are oats and rye. It is well-known that there are two stages of wheat-rust, one of which develops in the early summer and autumn and is known as the red rust, the other developing in late summer and autumn and known as the black rust. The char- acteristic colors of the two stages are given by masses of spores grow- ing in layers upon the plant-body of the rust which in turn consists of a network of parasitic threads living in the tissues of the wheat plant, the skin of which is burst by the fungus. It is the same plant body which produces the red spores forming red streaks on the wheat leaf that. ",!LrPultes of whestrus natura afterwards produces black spores After Atkinson, in equally enormous numbers occasioning the black rust stage. The red or “summer” spores are ovoid, spiny bodies, properly described as single cells. Their walls are thinner than those of the black rust. The black, or “autumn” spores have smooth walls and are divided into two cells by a cross partition situated near the centre of the somewhat elongated and pointed or rounded body. Red- rust spores, when separated from their stalks by the wind, may be carried throughout the summer to other wheat plants, and thus the infection spreads possibly over a whole field. The black-rust spores remain dor- mant during the winter upon the stub- Fic. 12.—Patches of wheat-rust, nat- : ural size and enlarged. The black ble and debris of the field. In the meme teincon. spring each of the two cells of the black-rust spore develops a tiny jointed body upon which four very small thin-walled, colorless spore-cells are produced. Now is the time selected by the wheat-rust for the periodic change of habitation. It is known that the small spores thus produced do not so readily germinate if blown upon wheat plants, but be Minnesota Plant Life. may find their way to the leaves of the barberry. When they fall upon the epidermis of such leaves they develop infection tubes, penetrate the skin and form a filamentous plant body within the soft inner tissues. At their time of fruiting they form two sorts of fruits, one upon the under side of the barberry leaves, known as cluster cups, the other, peculiar bottle-shaped fruits, upon the upper side. In the cup-shaped fruits large numbers of spherical orange-colored spores are produced which if blown away to a wheat field will infect the wheat. In the bottle- shaped fruits smaller elongated spores are formed, but it is not known how these germinate nor what becomes of them in the natural order of events. Barberries are by no means abundant in Minnesota, only a few of them existing in hedge rows, and while it is by no means inconceivable or absurd, on account of the winds which blow over the wheatfields of the Northwest, to suppose that barberries in the east might infect the wheat in Minnesota or the Dakotas, yet it is more probable, I think, that the wheat-rust passes its cluster-cup stage on some common Minnesota plant which has not yet | been identified as Ns a, i maintaining Pe his ht ron particular kind of Fic. 13.—Wheat-rust in its barberry-leaf stage; to the left a i OE that it omits barberry leaf with diseased spots; in the middle, a sin- altogether its cus- gle spot with cups; to the right, two of the cups, in top > : : view slightly magnified. After Atkinson. tomat i: migrations to other plants. It is apparent that such a disease as the rust offers difficulties to the economic farmer desirous of protecting his crop, far in excess of those presented by the smut, for while smut spores caught in the ends of the wheat kernels can be killed there by hot water, no practicable method exists of policing the atmos- phere and preventing rust spores from finding their way to the young wheat. ‘Therefore, the most feasible plan for combatting wheat rust is by the development of so-called “‘rust proof” va- Minnesota Plant Life. al rieties. While smut is, upon the whole, the easiest of the wheat- diseases to control, rust is the most difficult. The remarkable migratory habit of the wheat-rust and its allies coupled with the extraordinary change in form which the fungus assumes upon the different habitats gives rise to some very surprising conditions in rust life-histories. For after the migratory habit had been formed it would appear that some- times one or the other of the phases became extinct, so there are varieties of rusts which exist only in the cluster-cup phase, Fic. 14.—Magnified section through a cluster-cup of the wheat-rust in its barberry-leaf stage. Shows chains of spore-cells. The large cells at the sides are those of the barberry leaf much magnified. After Atkinson. and others only in the red and black-rust phases. For a long time students of the fungi thought that the cluster-cups were entirely different from the rust, and it was only because people noticed more than a century ago that “‘barberry bushes,” as the saying was, “blasted the wheat,” that a hint was given to mod- ern research, in consequence of which the astonishing behavior of the rust fungi is now more thoroughly understood. Relatives of the wheat-rust. Among the relatives of the wheat-rust there are some forms in Minnesota characterized by little peculiarities which enable botanists to classify them in dif- ferent genera. For example, the black-rust spores formed on 54 Minnesota Plant Life. some blackberries are three-celled instead of two-celled, and the cluster-cup masses on some gooseberries are developed upon protuberant filament-aggregates. Perhaps the three most re- markable forms are the pine-knot fungi which form knots some- times as large as bushel baskets upon the branches of pine trees, the so-called “‘cedar-apples,’ which occur as curious bunches, the size of one’s thumb and armed with orange horns, on the junipers, and the witch’s brooms on balsam trees. These latter are immense, disordered tangles of branchlets forming masses sometimes several feet in diameter. The disordered branching is caused by the growth of a rust-fungus of the cluster-cup sort in the substance of the twigs. When this fungus fruits it pro- duces its reproductive structures upon the leaves of the balsams, where they recall strikingly the rust produced on barberry leaves. The witch’s broom is a notable object in the swamps of Minnesota. When large ones are developed on the balsam trees they look like great crows’ nests up in the branches and very often birds and animals use the thick tangle of twigs to conceal their own dwelling places. On the spruce trees there is a similar tangle of branches produced by the agency of insects, but there is of course no development of the characteristic clus- ter-cup fruit-bodies upon the leaves. The related pine-knot fungus does not commonly fruit every year, but sometimes the whole surface of the knot will be found covered with the little orange pustules of the rust. Chapter VIII. Trembling Fungi, Club-fungi, Shelf-fungi and Mushrooms. Se Trembling fungi. | Somewhat related to the rusts, although one would hardly suppose it from their appearance, are the sin- gular gelatinous yellow or pink wrinkled masses which are often found upon decaying logs in shady places. These cannot be mistaken for the plant-bodies of slime-moulds, because they are of a firmer cartilaginous texture. They are capable of produc- ing over their surface a layer of spores which when separated by the wind or rains may propagate them upon other suitable sub- strata. From their tremulous character these plants are some- times called “trembling fungi.” Rather more highly organized but in the same general order of development are the leather- like gray skins which are often found upon the under sides of decaying twigs. Related forms are sometimes provided with little stalks and grow up cornucopia-like from the bark. Club fungi. Another family of fungi which includes forms not so very different from these skin-fungi, comprises also those which stand up on the forest-mould like little yellow Indian- clubs, an inch or two in height. The upper end of such club- fungi is swollen, and it is there that the spore-bodies are partic- ularly developed. Not all of the club-fungi are unbranched; but some of them are divided like the antlers of a deer, and yet others in which the branching is more copious grow in pearl- gray, yellow, white or pinkish tufts, several inches high, and covering spaces as large as a dinner plate. ‘They may be rec- ognized by the generally erect habit of all the branches, so that their forms remind one of the branching of certain night-bloom- ing cereuses of the New Mexican desert. Commonly the branches are more or less cylindrical and blunt, but one form, which is not uncommon in hard-wood forests along river bot- toms in the southern part of the state, has all its branches 56 Minnesota Plant Life. shaped somewhat like clam shells, so that the whole plant-bedy, often several inches in diameter, seems to be composed of nu- merous white shells overlapping each other and all attached to a common base. Prickle-fungi. ‘The prickle-fungi—at least some of them— might be mistaken for much branched forms of club-fungi; but they can be distinguished by the general downward tendency of the branches, so that in a well-known species not uncommon in the valley of the St. Croix where it grows upon decaying tree- trunks, there is a coral-like aspect to the whole plant-body. This variety is generally white, or slightly yellowish, or yellow- a ie Fic. 15.—Growth of club-fungi on decaying wood. After Lloyd. ish-brown in color, often as large as a man’s head, and made up of a group of thick, irregular branches upon the under sides of which great numbers of prickles half on inch or more in length grow downward. Not all of the prickle fungi have exactly this kind of a plant-body. Some of them outwardly resemble toad- stools, and might be mistaken for them if one did not look upon the under side where he would discover instead of the radiating gills of the toadstool the whole under surface of the cap cov- ered with a growth of prickles. Upon the surface of these prickles the spores of the plant are developed, and by their co- operation the fungus is able to maintain itself from year to year. Minnesota Plant Life. 57 In these forms, however, and in many of those to follow, the conspicuous part of the plant is really nothing more than its highly developed fruit-body, while the vegetative portion con- sisting of a spongy or cottony substance lies imbedded in the decaying timber. = Shelf-fungi. Related to the prickle-fungi are the well-known pore-fungi, or shelf-fungi, which are such familiar objects in the woods of Minnesota. Often they seem to be growing upon liv- ing trees, but it will be found upon examination that they have Fic. 16.—Shelf-fungus growing on dead stump of oak tree. After photograph by Hibbard. attacked some wounded or dead portion of the trunk, for these fungi are none of them truly parasitic. They are more com- mon, indeed, upon dead timber, either prostrate or standing. Very pretty examples of shelf-fungi are abundant upon the birch-trees of Minnesota, and this particular species is known as the birch-tree pore-fungus. The fruit-bodies hang down somewhat like bells, are of a white color, not woody but with much the consistency of punk or cork. They grow larger from year to year, the new growth covering that of former summers, and every season a new layer of pores is produced upon the BS Minnesota Plant Life. under side. In the Minnesota woods there are a great number of different kinds of pore-fungi which show characteristic dif- ferences of shape, size, thickness, color, texture, and endurance. One of them, called the sulphur-colored pore-fungus, which grows in very large masses is edible when young, but the great majority of them while not poisonous, are too tough, leathery and woody to be very appetizing. Some of them, indeed, no- tably the great shelves a foot or more across which occur upon oak trees, are almost as solid as the wood of the tree itself. Upon one occasion I noticed that in the pores of the under side of one of these fungi, a large number of mosquitoes had been caught by their legs and had afterwards been covered by a growth of cottony filaments of the fungus, and I wondered whether the plant might not derive some benefit from its ap- parent capture of insects and digestion of their bodies. It is not at all clear, however, that such a fungus should be included in the great category of flesh-eating plants, because it is a com- mon habit of the fruit-body to inclose small objects which chance to be in its way. Sometimes when these shelf-fungi grow near the ground they will be found with grass leaves pen- etrating them and in such cases it is not to be supposed that the grass leaf has grown through the fungus, but rather that the fungus has grown around and has enclosed the leaf. The pores of these interesting fungi are of different sizes and shapes. In some varieties they are almost invisible, they are so small. Other sorts have the pores much larger. In some the pores are circular, in others they are hexagonal or irregular in shape. In one kind which is common upon willows, form- ing fruit-bodies not more than two or three inches across, the pores are labyrinthine in shape, like the passages in the puzzle- gardens which are sometimes laid out in parks. ‘There is con- siderable difference too in the upper surface of pore-fungi. Some of them are white and smooth as in the birch-tree form, while others are fuzzy. Some are hard and marked by annual rings showing where the growth of each year has jutted out beyond the growth of the previous year. Some are sticky, but rarely slimy in texture; some are cartilaginous or horny to the touch, and many are spongy and soft. Minnesota Plant Life. 59 Different genera of shelf-fungi are established by botanists, principally upon the character of the pores. A genus which contains numerous highly poisonous species, is recognized by the readiness with which the pore-layer can be separated from the under side of the sterile portion of the fruit-body. One va- riety of these poisonous fungi is abundant in tamarack swamps throughout the state. The general shape of the plant is quite exactly like that of a toad-stool, a short thick stem rises from the ground, and on top of this a red cap is borne, from two to a =e = — af pS ae pee eT - Sein ‘< 3 Fic. 17.—Upper and under sides of mushroom-like pore-fungus. After Lloyd. five or even more inches in diameter. The top is of a dull crim- son or maroon-red tint, with scale-like markings resembling a serpent’s skin. Upon the under side will be seen a layer of large yellowish pores, separated from each other by thin parti- tion walls in which the coloring substance is developed. If one pulls off the cap of this fungus and breaks it in two he will find that the whole layer of pores is very easily peeled away from the rest of the cap. Suppose now that one of these pores was magnified until it was as large as an ordinary 60 ’ H ee { gash Lvs i < if Mea | - Minnesota Plant Life. well. Then if one could enter it he would see the whole wall covered with ovoid spores, now apparently as large as ap- ples. Since the pores all open downwards it is easy to see that if the spores fall from their supports they will gradually if not immediately tumble out through the opening and may then be distributed by wind or water. It is altogether best never to eat any kind of a pore- fungus in which the pore- layer is readily separable from the rest ofthe fruit- body, although there are a few harmless varieties even in this generally dangerous group. Some shelf-fungi are not truly pore-fungi, but the under side is perfectly smooth or marked at best with low, longitudinal wrinkles. These may, per- haps, be considered as forms in which the pores have either not yet come to develop, or as varieties in which for some reason the pores have become shallower until finally they have been com- pletely lost. Fic. 18.—A pore-fungus lying flat upon a decaying branch. After Lloyd. Minnesota Plant Life. 61 Mushrooms and toadstools. elated to the pore-fungi, and especially to those in which the pores are elongated or laby- rinthine, are the well-known mushrooms and toadstools. ‘There is little systematic difference between mushrooms and _ toad- stools: People are in the habit of calling an edible toadstool a mushroom, and a poisonous mushroom a toadstool. The fact is that some of the species, of the great mushroom ge- nus are edible while others are not, and it is often ex- tremely difficult even for an expert to distinguish be- tween edible and poisonous varieties. The following are very good rules to follow if one feels an uncontrollable inclination to experiment with mushrooms as an arti- cle of diet: Never eat a mushroom that is highly colored. Never eat a mushroom that has pink gills. Never eat a mushroom that seems to grow out of a little cup at the base. Never eat a mushroom that has a milky juice. Never eat a mushroom that changes color shortly Fic. 19.—Deadly variety of mushroom A fte1 after its substance is broken. Atkinson. Bulletin 138, Cornell Ag. Exp iA re ps ‘he Station. This is sometimes known as the Never eat a mushroom PEPE ES with a pungent odor. Never eat a mushroom with a sticky or slimy cap. Ty . * Never eat an immature mushroom unless absolutely certain what sort of a form it will be when mature. None of these rules is absolute. ‘There are exceptions to all of them, to some more than to others, but, together, they con- stitute a safe code and one cannot go far wrong in observing it. 62 Minnesota Plant Life. Yet a single rule, which I believe to be the best, is to eat no mushrooms of any sort unless quite sure that they are edible, for some of the deadliest poisons known to students of plant chem- istry are contained in the plants of this genus. One in partic- ular, which grows from a little cup at the base and spreads out a rather thin cap is so fatal that a small portion of it 1s sufficient to cause death. Still on the other hand, it is true that a great many edible species are to be obtained in the woods and fields of Minnesota, and it seems a pity that such excellent food should go to waste when there are many people who would be glad to avail themselves of this form of nature’s bounty. Fic. 20.—Under side of two mushroom-fruits. After Atkinson.j )Bull. 188, Cornell Ag. Exp. Station. All true mushrooms are characterized by the presence on the under side of the cap, of radiating gills or plates, hanging down like the ornamental tissue-paper decorations which are fancied by proprietors of butchers’ shops. Except for this general char- acter their forms are various and some of them with long slender stalks and thin conical or expanded caps present a very different appearance from those with short, massive stalks and broad hemispherical caps. A few are devoid of definite stalks and protrude sideways from dead logs recalling quite exactly the shelf-fungi in their general habit of growth. The largest mush- rooms are found in pastures and along roadsides, lifting them- Minnesota Plant Life. 63 selves sometimes nearly a foot into the air, and provided with basin-shaped caps, six inches or more in diameter. Another overgrown form is common on decaying timber and has no central stalk but stands out somewhat like a bracket-shelf. Deliquescent mushrooms. Not all of the fungi with radiat- ing gills on the under side are classed by botanists as true mush- rooms. One sort, which comes up in the autumn, late in Sep- tember or in October, oozes into a black and filthy slime as it matures. When young the fruit-body is elongated, an inch or so in diameter, sometimes four inches in length, white in color, with blackish scale markings. In its early stages when properly Fic. 21.—Common edible mushroom. After Atkinson. Bull. 1388, Cornell Ag. Exp. Station. cooked this is one of the most delicious of edible fungi; but after it has begun to decay it is neither appetizing nor healthful. The habit that these mushroom-like fungi have of decaying is a device for scattering their spores. They are visited by insects and the spores are picked up in the general slime to which their presence gives the black color, and are then carried away to be deposited elsewhere. Miniature mushrooms. Another relative of the true mush- room is a very delicate little plant an inch or less in height growing upon decaying leaves in the forest or in wooded ra- vines. It has a shiny black cartilaginous stem like that of the maiden-hair fern and upon the top of this a white cap displays 64 Minnesota Plant Life. a small number of loosely arranged gills on the under side. The diameter of the cap is often no more than one-eighth of an inch. Bull. 138, Cornell Ag. Exp. After Atkinson. Station. Fic. 22 —Development of mushroom-fruits on their underground vegetative tract. ty Milk mushrooms. Still another close relative of the mush- room is the milk-mushroom. ‘The various species of this genus are supplied with a milky juice, white or variously colored, Minnesota Plant Life. 65 which oozes out if the flesh is broken. One kind with bluish gills and juice, gives off, when broken, a distinctive odor some- thing like that of prussic acid and is very deadly. It is not un- common under white pine trees in the northern part of the state. A considerable difference in durability exists among the mushrooms and their near relatives. Some of them are delicate and watery in texture, lasting but a few hours after they are mature. Others are spongy, or of a texture like punk, while those found for example on railway ties become hard and woody even before they are altogether mature. The true mushrooms are classified into five principal groups, depending upon the color of the spores. 1. Forms with black spores. 2. Forms with dark-brown spores. 3. Forms with brown spores. 4. Forms with red or reddish-yellow spores. 5. Forms with white spores. Among the dark-brown spored forms are a number of edible species. Here is included the or- dinary edible mushroom which is cultivated for the market. It is an easy matter to determine the exact color of mush- room spores by cutting off the cap close to the stem and laying it down on a piece of paper with the gills towards the paper. Within a few hours hundreds of thousands of spores will fall to the paper, tracing there the gill-arrangement and demonstrating the precise color of the spores. If with the point of a pen-knife a few thousands of these spores be lifted and placed under a microscope, they will be found to be somewhat egg-shaped or spherical cells usually with smooth walls and provided each with a bit of living substance in the interior. They are produced in clusters of four all over the surface of the gills. The gills them- selves are made up of interlaced threads, which, when they come to the surface turn and grow perpendicular to it. Some of the threads expand their ends, upon which four little ears are pro- duced. The tip of each of these bulges out into a tiny egg- shaped spore. A very narrow neck connects each spore with its stalk and when ripe the spore drops off of itself. 6 (hapten. Carrion-fungi and Puff-balls. SF Carrion-fungi. Another group of fungi not very closely re- lated to the mushrooms but properly to be considered at this point includes the stinkhorns or carrion-fungi. These are among the most remarkable of all plants. During summer and au- tumn they spring up in door yards from a subterranean vege- tative body which resembles a tangled mass of white rootlets. Upon some of these rootlets little knobs the size of a pin head will be found to arise just as in mushrooms. ‘These grow rap- idly until they become almost as large as hens’ eggs, when sud- denly the top of an egg is burst by the pressure of the grow- ing parts within and in a surprisingly short time there is pushed out a cylindrical stalk—appearing very much as if it had been cut out of a loaf of bread, for it has the peculiar spongy texture of the well-raised loaf. This stalk is hollow and upon its top 1s borne a wrinkled cap perforated in the middle by an aperture. The surface of the wrinkled cap is covered with a slimy green- ish-black mass of spores and mucilage. Once seen this plant will never be forgotten. It may perhaps be described picto- rially as a vegetable confidence-game, for if there were any 1m- moral plants certainly this would be one. It has almost pre- cisely the odor of carrion and upon such an imitation of decay- ing flesh it bases its extraordinary method of distributing its spores. Attracted and deceived by the stench, various flies and burying beetles visit it and walk upon it apparently believing it to be what its odor indicates. They are even said to lay eggs upon it and to withdraw feeling no doubt that they have made that due provision for their young which their parental instincts suggest. During their investigations, however, they have in- advertently covered themselves with the sticky slime of the cap in which the spores of the plant are embedded and these they Minnesota Plant Life. 67 carry away and distribute, thus performing a work for the plant. But in a few hours the whole fruit-body decays and the eggs, if any had been entrusted to it under the apparently mistaken notion that it would be a good place for maggots to develop, all miserably perish. There seems to be no other way to describe such behavior except as obtaining service from the 1n- sect under false pretences, and if plants were really respon- sible creatures these carrion-fungi would doubtless find them- selves in some plant-penitentiary. Even more remarkable is the behavior of a Brazilian relative of the stinkhorn, which, in addition to all the devices that are employed by the Minnesota species, adds a conspicuous white veil, hanging down from the cap around the stalk. The veil is reported by travelers to be faintly phosphorescent at night and, if so, adds to the attractive influence which the plant might have upon night-flying insects. There are several species of stinkhorns in the northern United States, but up to the present time I have seen only three in Minnesota, one of which has a veil. It is quite certain, however, that others occur. The only way of eradicating them from a lawn, where they are offensive objects if produced in large numbers, is to dig up carefully and remove the underground portion, for if this is not done the plant will offer its repulsive fruits year after year. Truffle puff-balls. Some plants, not very distant relatives of the carrion fungus, produce their fruit-bodies entirely under- ground. Such forms may be described as subterranean puff- balls. They are not unlike the well-known truffle of the mar- kets in outward appearance, but are widely different in struc- ture. A few of them have been found growing in Minnesota woods. Dogs or pigs can be trained to dig them, finding them by their odor, and, indeed, this is the method which is used by truffle-hunters in the woods of Europe. Puff-balls. More familiar by far to the ordinary observer than these underground forms are the puff-balls which are so common in fields, pastures, woods and meadows throughout the state. A very considerable number of varieties of puff- balls may be found by any one who looks for them and is a close observer. One variety abundant in plowed fields, where it grows among the stubble after a corn or wheat crop has ripened, 68 Minnesota Plant Life. is the stalked puff-ball. This plant is distinguished by a gray stalk a quarter of an inch in diameter and two or three inches high. At its top is developed a little flattened spherical blad- der, perforate in the middle, within which are innumerable brown spores. If the skin is squeezed the spores puff out at the top like so much brown smoke, hence the common name, puff-ball, which is applied to this plant and its relatives. Other puff-balls have not the same slender stalk that has just been described. Several kinds are more or less pear-shaped, standing with the small end downward and variously marked in the different species. One variety is nearly smooth while another is covered with tiny warts of different sizes, sometimes arranged in patterns over the sur- face Invothers the sur face is spiny and some- times the spines occur in little clusters, with their tops drawn together like the stems of corn when in the shock. -If one of these puff-balls be cut lengthwise it will be seen that the lower part is spongy in texture and does not produce spores, so that this portion may be regarded as a short, thick stem. The upper portion, however, produces an abundance of spores which are ejected through an aperture in the ordinary manner. Still other puff-balls have no stalks, but the whole fruit-body is a bladder filled with spores and some of the commonest of all Minnesota puff-balls belong to this division. They are found abundantly in fields and pastures and, when ripe, are flat- tened dark purplish or plum-colored bodies from a quarter of an inch to an inch in diameter. The whole inside of one of these fruits consists of a fluffy mass of spores and threads—the dried- up stems upon which the spores develop. In the woods a stem- less puff-ball is found of a lighter color, growing often as large Fic. 23. Warty puff-ball. After Lloyd. Minnesota Plant Life. 69 asa turkey’s egg. Both this and its smaller relative of the pas- tures open somewhat irregularly at the end away from the ground, or perhaps at the side. Among the short-stemmed puff-balls two or three large varieties are found; one, the giant puff-ball, occurs larger than a man’s head and almost spherical in shape, while another is in outline somewhat like a dinner bell with the mouth closed and mound-like. Earth-stars. An interesting variety of puff-ball is the earth- star. This has an outer skin that splits radially, as one peels an orange, revealing the inner skin that encloses the spores. The little mouths of the earth-stars are nicely protected by a sroup of bristles which, by their sensitiveness to moisture, as- sist the distribution of the spores under conditions which are favorable for their germination. Apparently the use to the plant of ~~ ape see ed splitting back the outer skin is the additional height that it attains from which its spores can be dis- tributed. The points of the sec- tions which have split bend under and lift the central ball a half inch or more into the air, and the spores have an added opportunity of catch- ing some wind current, which, if eee eg a they were closer to the ground, Fic. 24. Tufted puff-ball. After J . Lloyd. might not distribute them so far. Slitted puff-balls. A rather large puff-ball with a short stalk and a white egg-shaped head is sometimes found in fields and door yards, the small end of the egg pointing upward and the large end hanging down over the stalk which seems to grow up into a depression there. These puff-balls open by slits close down to the stalk, and the interior is found to be occupied by irregular, broken, brown plates, radiating vaguely from the stalk-region somewhat like the gills of the mushroom. Bird’s-nest-fungi. Among all the puff-balls few are more in- teresting objects than the little bird’s-nest-fungi. There are three sorts of these common in Minnesota. None of them is very large for they do not exceed a quarter to a half inch in diameter. They are often seen growing on the planks of old 70 Minnesota Plant Life. sidewalks, in the cracks, or they may be found attached to twigs or bits of decaying wood. Each fruit-body is shaped like a vase or bowl, at the bottom of which half a dozen white or purple ege-like bodies are lying, so that it has the appearance of some tiny nest with eggs, hence the popular name which has been applied. If one attempts to pull out the “eggs” it will be found that each of them is flattened like two watch crystals placed together and is attached by a delicate cord growing from the “nest” and fixing itself upon the middle of one side of the-eggs. It must be understood that the term ““egg”’ as used here, and as used also for the young stinkhorns, should not suggest that such bodies have any of the real meaning of an egg, since it is applied solely on account of their shape. In the bird’s-nest-fungus each “ego” is a miniature puff-ball, with spores enclosed within its membrane, and the whole bird’s-nest-fungus fruit-body might be described as comparable to a little group of stemless puff- balls enclosed in a common vase or urn. Hard-skinned puff-balls. Yet another sort of puff-ball is readily distinguished by its hard nut-like shell. Such plants are called hard-skinned puff-balls and some kinds of them grow to be larger than an ordinary coffee cup. They are white or brown in color and almost spherical in shape. When they open to eject their spores the whole top splits by four or five radiating clefts, and the sections of the shell curve back from the centre some- what as did the outer skin of the earth-star. As they separate, the fluffy spores and threads of the interior are exposed as an umber mass upon which the wind has an opportunity to play, thus carrying off the spores to other favorable regions for devel- opment. Ball-tossing puff-balls. In some respects more remarkable than any of the others is the ball-tossing puff-ball. This is a small variety, not larger than an ordinary pill, but a little larger than the pellets of the homeopathist. It occurs in clusters upon decaying wood and looks somewhat like slime-mould fruit only it has a more leathery skin, and would be recognized upon close observation to be different from the slime-mould fruits in out- ward appearance as well as in inward structure. The ball-toss- ing puff-ball has three layers of skin, one outside of the other. The two outer skins become perforate at the end of the ball, Minnesota Plant Life. 71 exposing the third and innermost skin which remains intact. The hole enlarges so that there comes a moment when the in- ner skin lies like a base ball in a tea cup, surrounded by the two outer skins which have taken a vase-like form. Very suddenly the middle skin separates from the outer skin everywhere ex- cept at the edges and inverts itself with explosive force. It is as if the lining of a porcelain kettle should turn inside out. By this means the little ball at the centre may be projected several inches into the air as if shot out of some tiny catapult. In this way the whole mass of spores enclosed in the inner skin is thrown to some distance from the point where the parent plant developed, thus adding to the favorable chances of the species in distribution. Chapter X. Yeasts, Morels, Cup-fungi and Truffles. Ce All of the higher fungi which have been described, enjoy one character in common; their spores are produced upon stalks. No matter how various the form of the fruit-body may be, in this one respect all the different varieties agree. The group of higher fungi now to be considered is marked by the production of spores in sacs, hence they all pass under the gen- eral name of sac-fung1. Yeasts. One of the most simple forms is the yeast plant, familiar to housewives and brewers the world over. Yeast, as most people know, is a culture of fungi developed upon malt and hops and then transferred to various substances for purposes which differ in the different arts. In bread-making the value of the yeast lies in its power of liberating carbonic- acid-gas while it is growing in the dough. When a cupful of yeast 1s placed in a baking of bread and the dough is set away in a warm place beside the stove, the yeast-plants feed upon the substance in the dough and as they grow and reproduce they create among other waste products, carbonic-acid-gas and alco- hol. When the bread is kneaded and allowed to stand again before placing in the oven, the kneading serves to distribute the yeast-plants evenly through the loaf and they continue to grow, forming bubbles of gas and small amounts of alcohol. When the lightness of the bread is assured the loaves are placed in the oven and the heat which is applied kills all the yeast plants, but the bubbles of gas have done their part in leavening the loaf. In brewing, it is not the gas which is deemed so desirable, but the alcohol, and the yeasts are permitted to develop until the proper percentage of alcohol has been introduced. The hardening of cider, the fermentation of wine, and a variety of other processes are equally the result of fungus growth. Yeasts Minnesota Plant Life. ; 73 are sometimes impure or “bad” as the saying is. This is owing to the mixture with the genuine yeast of other fungal organ- isms, which liberate other and often undesirable substances. For example, certain acids are produced through the activity of yeast-like plants, and if such acid-forming yeasts are present in sufficient quantity, the bread or the beer becomes sour. Hence the cultivation of pure yeast is a prime necessity and when the housewife or the brewer finds by experience that yeasts in use are no longer pure, a fresh supply must be obtained from a neighbor or in the market. Yeast 1s a widely distributed plant and will often appear as if spontaneously, just as black mould does when a substance suitable for its development is exposed to the atmosphere for a sufficient length of time. The yeast-plant itself consists of thin- walled, egg-shaped cells which have the power of budding. Somewhere the wall bulges and the bulge enlarges until it is the size of the parent cell. Thus a branching body can be built up, but the branches and buds readily separate from each other and in a favorable condition of temperature and food supply the growth of the plant is extremely rapid. When the yeast- plant forms spores, which it does not do very abundantly under ordinary conditions of growth, the contents of one of the egg- shaped cells will be seen to divide into four portions each of which becomes spherical in form and secretes about itself a wall of itsown. ‘Then, when the wall of the mother-cell breaks down, the spores separate from each other and may be distinguished from the ordinary yeast-cell by their smaller size, spherical shape and thicker wall. It is on account of their thicker wall, and probably, too, in consequence of some difference in the structure of the living substance within that they are able to re- sist the harmful influence of extreme temperatures much better than the ordinary yeast-cell. If the conditions favorable to rapid growth become for any reason unfavorable, the yeast plant is likely to undertake the formation of spores. The particular substance that yeast attacks is cane-sugar. This it splits up, during its life-processes, into carbonic-acid-gas and alcohol. Such a process is called fermentation, or more pre- cisely, alcoholic fermentation, because there are various kinds of fermentation which go on under different circumstances 74 Minnesota Plant Life. through the activity of different organisms. The peculiarity of the yeast plant is its capacity for setting up alcoholic fermenta- tion and no other kind. Besides the common yeasts a number of others exist. One kind which grows in cabbage, after it is cooked, produces the substances which give the flavor of sauerkraut. Another kind when introduced into milk causes it to ferment, and im the re- gion of the Caucasus is used by the Tartars to change goat’s or camel’s milk into an intoxicating liquor. Plum-pockets. Very closely related to the yeasts is a group of parasitic fungi capable of attacking a va- riety of plant-tissues. One kind, when it infects the young fruits of the plum or cherry produces what is known as_ plum-pocket. When such a fungus grows upon a plum it distorts it and gives it a singular, ir- regular baggy appearance which is easily recognized. The poplar trees in Minne- sota are very often attacked by a pocket-fungus, which changes their green pods into yellow sacs distinctly larger than the ordinary pods (Ont icherty=trees.. ca witch’s broom formation in Fic. 2. Pocket-fungus on sand-cherry. After Bailey. Bull. 70, Cornell Ag. Exp. Station. which the growth of the twigs is disordered, results from the presence of a fungus of this group, and upon alders another witch’s broom arises under sim- ilar conditions. Morels. In the sac-fungi which have been described no conspicuous special body is developed; but in the higher forms large bodies, rivalling the mushrooms in size, and of a great variety of form and structure may be produced. Of such, one Minnesota Plant Life. 75 of the best known is the morel. This superficially resembles, to some degree, the stinkhorn. It grows upon the ground and the fruit-body consists of a hollow, cylindrical stem, some- times three or four inches in height and an inch in diameter. The texture, however, is much firmer than that of the stink- horn stem and the cap upon the end, though wrinkled like the stinkhorn cap, is continu- ous with the stem and not slimy nor vile-smelling. Mo- rels are edible and are said to be especially prized in Bohe- mia. They are often found growing in Minnesota woods and upon Minnesota hillsides, where their fruit-bodies, unlike those of the stinkhorn, ripen in the spring. If one should ex- amine under a microscope a thin section cut through the wrinkled surface of the cap, it would be perceived that it con- sists almost entirely of sacs, in each of which eight oval spores are produced in a row. Each sac is cylindrical in form and not much larger in diameter than the spores which fill it. When ripe the ends of the sacs break or dissolve and _ the spores pour out one after an- other, but they are not, as was F1G. 26. A morel fruit-body the case in the stinkhorn, uni- aes crity versally carried away by insects, for they depend rather upon the wind and the rains for their distribution. A number of plants closely related to the morel may be dis tinguished by the different shapes of their caps. In one the cap 76 Minnesota Plant Life. is saddle-shaped; in another somewhat urn-shaped; in a third the whole fruit-body is club-shaped and closely resembles some forms of the club-fungi which have been described above. In some the cap is peculiarly coiled and twisted, looking like a knot of angleworms. ‘The colors of these plants are various— white, brown, slate-colored, yellowish, pinkish or red. They occur sometimes upon much decayed logs, but the majority of them are terrestrial. A few are of an almost gelatinous con- sistency but a greater number have, to the touch, rather the feel- ing of cartilage. Several of them besides the morel are edible Fic. 27. Cup-fungi growing on decaying twig. After Lloyd. and I do not know of any that are violently poisonous, although from their texture, a number of them would scarcely be attrac- tive. Cup-fungi. Not a distant relative of the morel is the cup- fungus, which in its numerous varieties is doubtless familiar to many of the readers of this volume. | Ley the bottom a large KA Re i 5 rca roe SOS i 5° Re preceer ine" nA egg-shaped cell now 4 seneeiee Buns!) . . & -\- ee x7 inclosed in an organ 15 shaped like a bottle Fic. 42. Tip of a leafy moss plant, sectioned lengthwise and with a long, slender, magnified. The flask-shaped egg-organs, one with an egg in place, are shown. These bodies are barely visible to hollow neck. The the naked eye. After Atkinson. opening from the exterior down to the egg is produced by the transformation into mucilage of a row of cells as has been described. Reproduction of mosses and liverworts. All mosses and liverworts produce sperms and eggs. Attracted in some man- ner by chemical substances dissolved in the water near the eggs, the spermatozoids find their way to the mouth of the egg-pro- ducing organ. ‘They crowd into its neck, swimming down the canal which has been opened for them until they reach the egg lying at the bottom of the flask. One sperm more active than the others, or first upon the ground, buries itself in the sub- 128 Minnesota Plant Life. stance of the egg, and immediately the egg forms around itself a membrane by which the ingress of other sperms is prevented. Such an egg is said to be fecundated and in a short time it di- vides by a cross-partition—in a direction perpendicular to the long axis of the bottle in all mosses and liverworts with the exception of the horned liverworts, in which the first partition is parallel with this axis. The egg now consists of two cells and this two-celled body is reasonably to be considered as the first-stage of the embryo-plant of the next generation. Such an embryo normally develops into a spore-producing capsule, provided in some species with a long and slender stalk, but in other varieties having only a short nub of sterile cells at the base. In the lowest family of the liverworts there is no stalk of any kind, but the entire matured product of the embryo be- comes a little spherical capsule imbedded in the tissue of the sexual plant. Whatever may be its structure the capsule finally produces spores. ‘The function of a moss or liverwort capsule may be described in brief as the production of as many and as certainly germinable spores as possible. In high types of moss- fruits the number of spores rises into the thousands, while in the lowest forms of liverwort-fruits, the number of spores runs from sixteen to sixtyfour. What is meant by “alternating generations.” It is evident that there exist, in the moss life-history, two plants alternating with each other. One, the sexual plant, has two phases, the 1m- mature or first-stage and the mature or second-stage. The first- stage does not, except in one kind of moss, produce the organs of sex, and in this peculiar moss it is not the egg-organs but the spermaries that are formed upon it. Therefore, one may describe the second-stage of the moss sexual plant as a repro- ductive branch of the first-stage. The other, the capsular plant of the life-history, is entirely devoid of sex, but is a spore-produc- ing organism. ‘This serves to illustrate one of the very remark- able differences between higher plants and higher animals. In higher animals a fecundated egg develops into an organism like one of those that cooperated in the production of the fecundated egg, thus the egg of a fowl develops into a fowl, and the egg of a fish into a fish; but the egg of the moss does not develop into an organism like the ones that cooperated in its produc- Minnesota Plant Life. 129 tion. On the contrary, it develops into an entirely different creature, in the body of which there may be produced some thousands of spore-cells and each one of these if planted under favorable conditions, may originate a new first-stage moss or liverwort plant. Upon one of the first-stages a great number of buds might then arise initiating the second-stage of the sex- ual form. Thus it is seen that while animals can generally derive but a single individual from a fecundated egg, mosses and liverworts—and higher plants still more strikingly able to bring into existence thousands of organisms from one egg. The only thing analogous to this in animals is the phe- nomenon of true or identical twinning. When twins are of precisely the same appearance and sex it is believed that they are have developed by the two halves of the embryo in its youngest stage separating from each other. Fach half, relieved from the pressure of the other, develops now respectively not into the right or left half of the body, as it normally would, but into a separate individual. If one can imagine, not twins nor quad- ruplets, but great numbers, even thousands of individuals to arise from a single animal's egg, he would have something com- parable with the condition in plants which is known as alterna- tion of generations. The origin of the higher plants. In the light of what has been said it is apparent that the two alternating generations in the life-history of a moss or liverwort are not equivalent to each other, and one of them, the spore-producing generation, has no analogue in the life-history of those animals with which peo- ple are familiar. When, in the algae, an egg after fecundation, instead of developing at once into a new organism as an animal egg does, cuts itself in two into a pair of spores, it has accom- plished normally what happens accidentally in the case of true twins. It seems that what is an accident among animals be- came the rule in the plant world; so in other algae the number of spores thus developed from a fecundated egg was increased to four or even to eight in the sphere-alga. Then in a little alga, the disc-alga, which has been regarded as standing closest to liverworts, the number of spores was increased to sixteen; and for one fecundated egg, by this division into sixteen spores, the plant was able, perhaps, to secure sixteen new individuals, pro- 10 130 Minnesota Plant Life. vided that all the spores found the opportunity of germination. Such little clumps of spores, originating by the partition of a fecundated egg, then underwent a division of labor, so that the superficial spore-mother-cells acquired the character of capsule- wall-cells and did not ordinarily retain the power of spore- production. This was in order to protect the cells of the in- terior, which remained as true spore-forming cells, and there is, in such an instance, a fundamental peripheral sterilization of the spore-mass, so that it comes to consist centrally of functional spore-mother-cells while sterilized spore-mother-cells take the character of wall tissue. Really, by this time, a new kind of organism has come into existence, something entirely unlike anything in ordinary animal life-histories. The new organism, beginning thus simply as a mass of spores, then in higher types assuming the form of a mass of spores enclosed in a wall, underwent further improvement in other families of liverworts and mosses until finally it became a large capsule with long slender stalk, several layers of wall cells and a supporting column of sterile cells running up the middle. By means of such improvements the possible number of spores was increased and they were better managed by the plant; for when the spores of a moss are distributed from a cap- sule on a tall slender stalk they will fall farther on every side, thus obtaining more favorable chances of persistence than if scattered from a short-stalked capsule. To the philosophical botanist this profound need of coun- terbalancing the unfavorable conditions of the environment suggests itself as the occasion of erect habit in herbs, shrubs and trees. By maintaining the erect position plants can also — enjoy better illumination; but it may be safely assumed, for the reasons that have been given, that the erect position and the slender habit of growth of the moss-fruit, based as it is upon an instinctive effort to enlarge the opportunities of spores, is the precursor of all erect habits in the terrestrial spore-producing areas of plants,—and essentially all plant shoots are spore-pro- ducing areas. Pine trees, for example, develop pollen, a form of spores, in their little cones. Roots never develop spores, and may be regarded as derivatives of that original end of the cap- Minnesota Plant Life. | 131 sular plant which was nearest the sexual plant and was not thrust up for the purpose of scattering the spores. This further fact next presents itself for consideration: that among the higher plants, all prostrate forms of stems are secon- dary; for stems must originally have been erect, like the moss fruit-body. Thus it is not surprising to learn that the oldest forms of terrestrial plants were of the forest rather than of the prairie type. This, at least, is the conclusion that is reached upon a study of the most ancient plant-fossils preserved in the rocks. Chapter. Liverworts of Minnesota. De Mud-flat liverworts. The lowest family of liverworts is char- acterized by a flat and prostrate leafless plant-body, such as may be seen in the little circular forms growing upon mud-flats. These may be recognized as different from lichens of similar habit by their bright green color unmodified by any tint of gray or blue. ‘They occur as discs an inch or so in diameter and are made up of forking flat stems seeming to radiate from a com- mon centre. Theupper side has a spongy look which is caused by the existence of air-cham- bers in the plant-body. At the edge of the ‘disc are the ends of the forking branches and each of these is notched, while at the bottom of such notches le the growing-points of the branches. The tip cells of a branch do not divide so fast as the older cells and thus Fic. 43. Mud-flat liverwort, showing method of growth and branching. After Atkin_ son. the older parts protrude be- yond the true tip. Whis’ex- plains why the tips of all the branches in this family of liver- worts are notched. Floating liverworts. A close relative of the mud-flat liver- wort, of which there are several different species in Minnesota, is the floating liverwort. The plant-bodies of this variety are found in ditches and small pools of water. Sometimes in lakes they are found entangled among the cat-tails and bulrushes along the water’s edge. ‘The plant consists of delicate forking branches of a bright green color, sometimes gathered together Minnesota Plant Life. E33 by the waves into masses as large as one’s fist. The branches are ribbon-like and generally not more than a sixteenth of an inch wide, but they may be an inch or more in length. It is impossible to mistake this plant for an alga or for any form of duck-weed if one observes the notch at the tips of all the branches. The three-pronged duck-weed, which is often found with it, is a flowering plant and may be recognized by the con- vex ends of its little flat branches and the greater breadth of the stem in comparison with its extension. Swimming liverworts. Another form of lower liverworts is the swimming liverwort, which might be mistaken for a duck- weed since it much resembles it in habit. It is its custom to float in large patches upon the surface of quiet pools. Each plant dangles from its underside a tuft of root hairs into the water thus obtaining special absorptive areas and counterpoises against being turned upside down by the wind. The swim- ming liverworts differ, however, from duck-weeds in being somewhat heart-shaped, on account of their terminal notch, while duck-weeds are rather oval discs or shaped something like little trefoils as they lie upon or in the water. Cone-headed liverworts. The next higher family of liver- worts has the same general character in the sexual generation which has been described for the mud-liverworts and their allies, but the plant-bodies are in many instances larger and more perfected. The cone-headed liverwort is an example of this group. It spreads out its broad forking branches of a dark green color upon logs, cliffs and bowlders in wet places. Its surface is marked by diamond-shaped areas in the centre of each of which is seen a whitish dome-like eminence not much larger than a pin-point. The width of a single branch is from a quarter to three-quarters of an inch while it may be several inches in length. On the under side are produced numerous root-hairs and tiny purple scales along the conspicuous mid-rib. When the cone-headed liverwort is fruiting, there will be ob- served during summer and autumn certain green cone-shaped branches close to the surface of the flat stem. In this condition they remain throughout the winter, but in early spring the stem of the cone-headed branch elongates into a pale stalk a couple of inches in height and about a sixteenth of an inch in diameter. 134 Minnesota Plant Life. In two grooves along the stalk root-hairs are produced. The fruit-branch now resembles in outward appearance a small green-headed toadstool attached to the broad flat branch below. In the cone-headed liverwort there are, apparently, two kinds of branches, the ordinary vegetative and the special repro- ductive branches which bear the capsules. If one of the cone- heads be separated from the main stem in autumn or in early spring, 1t will be found that imbedded in the under side of the cone and surrounding the cavity about the stalk lies a ring of black capsules inclosed apparently in the tissue of the cone. The number of these capsules varies from three to eight, not usually exceeding the latter number. With the point of a pin they may be dissected out, if the little cones are handled with sufficient care and tact. Each capsule removed from the tis- sues which were surrounding it will be found to show over most of its surface a dull black color. But at the end, where the pear-shaped body was imbedded most deeply, for a little dis- tance the color is green. With very great care, by the use of a sharp pin-point it is possible to remove an exterior membrane from the body which was dissected out of the cone-head and when this close outer membrane is separated a little object of a shiny black color, except at the pointed end where the color is bright green, will be obtained. If it has not been broken in the process of extraction it may now be split in the palm of the hand and a brown or blackish mass of spores and accessory cells may be removed from the interior. The shiny black capsule is the fruit-body developed from the liverwort egg and consists of a small, short green stalk or foot and a larger capsular por- tion, the whole constituting a slender pear-shaped object about a sixteenth of an inch in length. In the cone-headed liverwort and in all its allies, mingled with the spores in each capsule, are certain very curious cells with microscopic spiral bands or hoops developed on the inner sur- faces of their walls. These cells are of an elongated spindle- shape and their spiral bands are very sensitive to moisture. When placed under a powerful lens and moistened by the breath these cells writhe and struggle in a remarkable fashion, owing to the alternate shortening and lengthening of their spiral bands. The movement is not a vital one, but purely physical, like the Minnesota Plant Life. 135 warping ofa plank, yet it serves a purpose in assisting the spores to escape from the capsule. By means of the writhing motion of these curious cells the spores are separated from each other and are not permitted, in the economy of the plant, to fall in an inert mass at one place. In its stalked capsule and in the development of these elaters, as the writhing cells are called, the cone-headed liverwort marks an advance in its spore-producing generation over the mud-flat liverwort; for in that plant and its immediate allies the capsule had no stalk nor were there any elaters mingled with the spores. In the sexual generation of the cone-headed liverworts there exist a variety of other improvements in structure over the mud-flat species. The plant-body is much larger and more robust, the air-chambers are more regularly disposed, giving, as they shine through the skin of the plant, the diamond-shaped marking to the surface. Each air chamber has a central dome of colorless cells and in the middle of each dome there is an opening or air-pore which serves as an aperture through which an interchange of gases may take place between the starch- making cells that line the chamber—where they are best dis- played on its floor Another improvement is observed in the production of spe- cial branches with cone-shaped heads for the development of the ege-producing organs. In the mud-flat liverwort neither these nor the spermaries were formed on branches differing in any important respect from the ordinary branches. Therefore, in the mud-flat liverwort when the egg had developed into an embryo the spore-producing capsule found itself imbedded in the general tissues of the sexual plant, and was not able to dis- tribute its spores until the stem had decayed. But in the cone- headed liverwort with its special branches, the egg-producing organs, when their eggs had been matured, fecundated and de- veloped into embryos, were all lifted up into the air a couple of inches or so by the elongation of the slender special stem. By this means the ring of capsules on the under side of the cone- and the outer air. head gain an opportunity to scatter their spores over a much wider circle, thus adding to their chances of germination and growth. In order to eject the spores the tiny green stalk of the capsular plant elongates a little just before the capsule opens, 136 Minnesota Plant Life. thrusting the end of the capsule out beyond the rim of the cone. In this way each capsule scatters its spores under much more advantageous conditions than were possible for the mud-flat liverwort. The spermaries in the cone-headed liverwort are produced upon short blunt branches arising at the tips of ordinary Fic. 44. The umbrella-liverwort; showing the prostrate vegetative body, and the upright branches on which the egg-organs are borne, and where later the capsular plants will be found perching. After Atkinson. branches, but seeming to grow upon their surface because they are somewhat displaced in the after-growth of the whole sexual plant-body. ; the latter much mag- heads. Upon these tiny creatures the sperma- nified. After Atkin- ries and ege-organs are produced. The sperms one have two swimming-hairs like those of mosses. The gen- eral structure of the spermary and egg-organ is quite like that in the horned liverwort, and the sexual plant of the club-moss may be compared to a horned liverwort prostrate stem very Minnesota Plant Life. 157 much reduced in size. When an egg lying at the bottom of the organ which produced it has been fecundated, it segments by partition-walls. One of the first two cells develops into the embryo. Some of the cells later produced form the first leaf of the embryo plant. Another group forms the apex of the stem, and still another matures into a bulbous body which nurses upon the tissues of the sexual plant; while, much later, from the interior of a root-like elongation a group of cells pushes its way out as the first true root. In all the higher plants roots seem to have originated from inner portions of the plant-body and may be regarded as being everywhere protrusions of the sap-conducting areas, so that the root is essentially an absorbent tract, while its functions of sup- port are secondary. The embryo plant thus started on its career continues to grow, thickening its stem, forming new leaves and branches and multiplying its roots. Unlike the moss capsular plant, but like the capsular plant of the horned liverwort, it never of its own accord stops growing, but only when the growth is terminated by outward unfavorable conditions. As it grows and branches year by year, it soon becomes strong enough to form spore- producing areas of its own. In club-mosses the spores are in little pouches, one on the upper side of each leaf on the cone-shaped tip of some branch. The end of the branch which produces spores becomes cov- ered with leaves, sometimes of a different color, drier and paler than the ordinary foliage leaves. Such cones are equivalent to the cones of pine-trees which are supposed, indeed, to have arisen from similar simple types. Each cone consists of an axis clothed with spore-bearing leaves. Since the latter in most club-mosses are specialized to some extent for their reproduc- tive functions, they progressively abandon the starch-making function; hence, not needing illumination, they stand closer to- gether, overlapping each other as they would not do if depend- ent upon the sunlight for leaf-green energy. Having taken such positions they become bleached and while the general plant-body of a club-moss is provided with green, unbranched, rather needle-shaped leaves, the cones by their yellow color and flatter and more closely crowded leaves, become distinct areas of the plant. Yet in types of club-mosses lower than the ordi- 158 Minnesota Plant Life. nary Christmas-green variety, the same leaf which produces a spore-case upon its upper surface is also depended upon by the plant for leaf-green work, and the division of labor marks only the higher types. The lowest in structure of all club-mosses is a New Zealand form not more than an inch and a half or two inches in height and typically unbranched. os P52 es tudinal and transverse bands of sterile cells have been developed —something which was foreshad- =, = oes — LS a Nc zs = raw, &S Z< = <2 Ss > s owed in certain horned _ liver- worts—separating into chambers the general layer of spore-moth- er-cells surrounding the central column. It is conjectured that the sterile tissue in the ancestral plants underneath each chamber bulged out into a leaf-like expan- | sion and these leaves separated Cif, NY KS N SX iw NOSIS S. SS (} f from each other longitudinally. Therefore the axis or stem of a F16. 50. Flat-branched club-moss. After ° ; Britton and Brown. club-moss is conceived to com- pare best with the central cylinder of supporting tissue in a horned liverwort capsule and not with the stalk of a moss cap- sule. The leaves of the cone are conceived to compare with sections of the capsular wall, each section bearing on its inner surface its own portion of the spore-mother-cell tract. The root is conceived to be a new structure, and outgrowth of the central cylinder. The tip of the horned liverwort capsule is regarded as equivalent to the tip of the cone in a club-moss. All these points may be best understood by comparison with the simple New Zealand club-moss in which abundant branching of the spore- producing plant does not take place. As the spore-producing plant of the club-moss has acquired new powers and new perfections of structure along vegetative Minnesota Plant Life. 159 as well as along spore-producing lines, so the sexual plant—the one developed from the spore—has become reduced and is sim- pler, smaller and less important than the sexual plants of liver- worts or mosses. Different kinds of club-mosses in Minnesota. The different kinds of club-mosses in Minnesota are distinguished by differ- ent habits of branching, different shapes of leaves and the vary- ing distinctness with which the cone-area is blocked out in the general plant-body. Some, as the tree-like club-moss or ground- pine, have erect stems with subsidiary branches like those of a pine. Another kind has the leaves flattened in a peculiar way like the leaves of the white cedar. In still another species the plant-body branches loosely and trails over the eround, while in yet another the stem forks, and tufts » of branches are pro- duced, reminding one a little tof the true- Fic. 51. Smaller club-moss. ‘Yo the left a plant with three : ane j mosses. cones, next a single cone dissected to show the spore cases, next a single large-spore-case with four spores The rock-club- revealed, and on the right a small-spore-case with the pA small spores sifting out. After Atkinson. mosses. The smaller club-mosses or rock- club-mosses are pretty abundant throughout the state wher- ever dry rocks or rocky hills occur. The leaves in the com- mon species are pressed close together along the stem and each has at the end a white bristling hair, giving a hoary ap- pearance to the whole plant. ‘The cone-areas are not so dis- tinctly different in appearance from the rest of the plant-body as in the larger club-mosses. ‘The great peculiarity of these plants is their production of two kinds of spores. In some of their spore-cases two hundred or more small spores will be produced, each somewhat pyramid-shaped, while in other spore- there will be produced cases—perhaps in the very same cone four much larger spores with variously marked walls and of a generally spherical shape. When a smaller spore germinates, it produces a little male plant so insignificant that it never comes outside its spore-wall, but forms and matures altogether within. This little male creature produces a few sperm cells. When 160 Minnesota Plant Life. the spore-wall breaks, as 1t does eventually, the sperm-cells are liberated and swim away in the water after some rain or heavy dew. When the large-spores germinate each produces a fe- male plant which, like the male, remains within the spore and does not push out as did the sexual plants of liverworts, mosses and the larger club-mosses. The female is very much larger than the male, and each plant fills the spore from which it de- veloped. When the female is mature, one, or sometimes more, ege-producing organs are formed at the surface of the cell-mass inclosed in the large-spore. After the egg-organ with its in- closed egg has matured, the wall of the large-spore breaks just over the imbedded neck of the egg-organ. This permits sper- matozoids to enter and by means of one of them the egg is fecundated and begins segmenting into an embryo in which stem-areas, root-areas, leaf-areas and nursing-foot-areas are pro- duced. In the smaller club-moss a great reduction of the sex- ual generation is apparent. The sexual plants do not even come outside of their spore-walls. They do no independent vegetative work but the species depends for its subsistence upon the starch-making power of the spore-producing plant. Origin of the seed of higher plants. The smaller club- mosses while of sight economic importance are of extraordinary scientific interest because they illustrate how in the history of the vegetable kingdom that important structure, the seed of higher plants, probably originated. The habit of the female of remaining within the spore must have antedated the origin of the seed. In seeds not only does the female remain within the spore but the spore remains within its case and the female ob- tains fecundation of her egg by the codperation of a pollen-tube, while the spore-case need not open. When the embryo has begun to form from the egg the whole spore-case, with some adjacent layers of cells, ripens and a seed is the result. The smaller club-mosses foreshadow this still more strongly in some species where the large-spores begin to germinate internally be- fore they fall from their spore-cases. Yet no smaller club-moss- plant ever really produces a seed, for in all of them sooner or later the spore is ejected from its case and thus there is pre- vented from arising the exact combination of conditions upon which seed formation depends. hapten ay Fle Ferns and Water-ferns. SF Related to club-mosses in about the same manner that true mosses are related to horned liverworts are the ferns, a very ancient and singular group of plants. In Minnesota about fifty species occur, found for the most part in woodland. One va- riety, the brake, is an exceedingly common plant in all burned districts of the forest region. Adder’s-tongues and moonworts. ‘There are two principal groups of ferns recognized by botanists. Of the lower group, the so-called grape-ferns or moonworts and the adder’s-tongue ferns are specimens. In these each leaf consists of two lobes, one—the so called sterile lobe—being devoted entirely to starch-making, the other—the so called fertile lobe—having for its exclusive function the production of spore-cases. The fer- tile lobe grows from the inner face of the sterile lobe, occupy- ing relatively to the sterile lobe the same position maintained by the spore-case of a club-moss with reference to the leaf upon which it was situated. It is believed that the fertile lobe of an adder’s-tongue fern-leaf is equivalent to a large, chambered and overgrown spore-case as displayed in the club-mosses, and it is believed that the sterile segment of the leaf is equivalent to the blade of the spore-case-bearing leaf in the club-mosses. The adder’s-tongue ferns with their slender fertile lobes bear- ing two rows of spore-cases and their undivided sterile seg- ments, are simpler than the grape-ferns with their palmately branched leaf-segments. In these plants the spores upon germ- ination give rise to little tuberous sexual plants which lie almost imbedded in the soil and are devoid of leaf-green, being humus plants. Upon such little tubers the egg-organs and spermaries develop and after fecundation the egg forms an embryo which nurses for a time upon the sexual plant, then thrusts its own 12 162 Minnesota Plant Life. ee oat Fic. 52. Adder’s-tongue fern. After E. N. Williams in Meehan’s Monthly. Minnesota Plant Life. 163 roots into the soil and begins an independent life. The spore- producing plants like those of club-mosses are perennial, but the egg- and sperm-producing plants die within a few weeks or months after they are formed. Quillworts. A very curious group of plants known as quill- worts, found growing on lake bottoms in northern Minnesota, are considered to be distant relatives of the adder’s-tongue ferns. They produce two sizes of spores, large and small, and quite as in the life-history of the smaller club-mosses the large-spores give rise to internally developed females, while the small-spores produce diminutive males not protruded beyond the spore walls. Embryo quillwort plants originate from the fecundated eggs and when they have be- come old enough renew the production of spores. These are formed in cu- riously partitioned cham- bers at the base of, and on the inner face of the long quill-shaped leaves. The spore-producing area of the leaf occupies the same relative position with ref- erence to the starch-mak- ing area that was seen in club-mosses and adder’s- Fic. 53. Virginia grape-fern. After Britton and Brown. tongue ferns. The upper portions of the leaves contain air- chambers by means of which the leaves stand erect at the bot- tom of the lake. Some varieties of quillworts, also represented in Minnesota, grow in swamps and marshes and cannot be dis- tinguished except by the closest observation from tufts of sedge or grass. Ordinary ferns. Quite different in a number of structural details are the “true” ferns, the group to which almost nine- tenths of the Minnesota species belong. These are plants with havits of growth which are, in a general way, pretty well known 164 Minnesota Plant Life. by all who frequent the woods. Of true ferns there are nine families, only four of which are represented in Minnesota. The filmy ferns, the tree-ferns, the forking ferns, the twining ferns and the Borneo ferns are not represented by plants in- digenous to the state. The families present are the bracken- ferns and their various allies, the flowering ferns, the floating ferns and the four-leaved water- ferns. Of these the lowest in type are the flowering ferns, three spe- cies of which occur in Minnesota. One of them, known as the inter- rupted fern, is a common plant, presenting a peculiar appearance as if somewhere near the middle of the large leaf two or three leaflets had shriveled. These leaflets, unlike Fie. 54. A quillwort plant. After At- Fic. 55. Clayton’s or interrupted fern. After kinson. Britton and Brown. the rest, have a brown and withered look. If examined closely it will be discovered that this is due to their being covered with spore-cases of a brown color, while the rest of the leaflets pro- duce no spore-cases whatever. Another fern of this family is the cinnamon fern which forms leaves of two sorts, some Minnesota Plant Life. 165 much larger and green, adapted solely to starch-making, others smaller, of a cinnamon color and devoted particularly to spore- making. 1X Scouring-rushes and Horse-tails. % The peculiar family of plants known as scouring-rushes or horse-tails was very much better developed during the age when coal was being deposited than it is to-day. Most of its species are extinct, but there remain, widely distributed over the world, some forty different varieties, of which ten occur in Minnesota. They are not very closely related either to the ferns or to the club-mosses, although they clearly belong in their general vicin- ity. The unbranched forms are known as scouring-rushes on account of the usual deposit of silica in their outer layers. This mineral is useful for scouring tinware, and rushes are actually thus employed by some housewives in the country. The branched forms are known as horse-tails from their peculiar aspect as they stand in fields, in the woods or along the road- side or railway tracks. Each variety of scouring-rush or horse-tail is distinguished by an underground rootstock which shows much the same struc- ture as the above-ground portions. Sometimes on the root- stocks tuber-like propagative swellings are formed. Both the erect and subterranean branches are divided into very distinct joints which may be separated from each other like sections of stove-pipe, hence the plants are also called joint-rushes. In some species the plant produces only one kind of erect stem and at the tip of this, or more rarely at the tips of lateral branches, firm and solid cones are borne, each made up of little shield-shaped leaves with central stalks. The leaves are ar- ranged in circles about the axis, not in spirals as in the cones of club-mosses. On the under side of each of the shield-shaped leaves a ring of spore-cases is developed, commonly about eight ina group. The cones bear the leaves so close together that from their mutual pressure they assume a more or less hexagonal outline. 176 Minnesota Plant Life. Scouring-rushes with two sorts of erect stems. In a few of the species there are formed two kinds of erect stems. One is pale or reddish in color, softer to the touch, provided with longer leaves below the cone, devoid of leaf-green and de- voted to the work of spore-production. The other is repeat- edly branched, the branches arising in circles at the top of each joint of the stem. Upon such erect stems no cones are ordinarily displayed, but the whole plant-body is green and starch-producing. Both kinds of erect branches are, however, very similar in internal struc- ture. They are hollow and their wood-threads are ar- ranged in a circle, usually with air-canals between them and within them. At the top of each joint a group of leaves arises in a ring. ‘These are not used for starch- making but are reduced and scale-like and commonly blended together by their edges into a collar closely enveloping the lower part of the joint immediately above. On the special spore-producing branches the leaves are often larger and less completely fused to- gether. Sometimes the leaves are black in color with gray tips, as in a well-known joint rush of Minne- sota. In all the varieties the starch-making is done not by the leaves but by the branch-system, so that in this respect the plants resemble the well-known aspar- agus, to which they bear, however, no close botanical relation. When the spore-cases on the shield-shaped leaves open to eject their spores, the spores may be shaken out into the hand as a green dust. If one watches this dust SS Ohne it lies upon the hand immediately after of the horse-tail. having been shaken from the cone, it will be ane sineld “shaped seen that within a couple of seconds after its spore-bearing leaves are aggregated in a deposit it Auffs and becomes of a lighter cone. After Atkin- ; - son. color. By warming it gently with the breath it regains its darker hue and more solid ap- pearance, but in a couple of seconds it fluffs again as it did — before. ‘This remarkable behavior is explained if the spores be examined under a good microscope. It will then be observed that apparently attached to each of them are four delicate spoon- Minnesota Plant Life. 177 shaped appendages which are very sensitive to moisture. These, when dampened, contract around the green spherical spores, hugging them tightly, but as they dry they straighten, loosen- ing the spore-mass in the process. This is why the moistened dust seems more solid than the same dust when dry. The spoon-shaped appendages originate by the splitting of the outer wall of the spore into two ribbons, as if a couple of peel- ings had been removed. An idea of the arrangement can be obtained by imagining the cover of a base-ball unsewed and laid back. ‘The two pieces of cover would then occupy much the same position with reference to the ball as do the four longer and slenderer spoon-shaped appendages with reference to the spore. Germination of spores. Although all the spores are of the same size and appearance, yet it is the nature of some of them upon germina- tion to develop files green, mostra te males, some- thing like small Fic. 68. Scouring-rush spores; to the left a spore with appendages | ; 1 iE cm curled up, in moist air; to the right a spore with appendages ex- 1lornec 1ver- tended, in dry air. After Atkinson. wort plants, while others develop females, slightly larger than the males but in general closely resembling them. Both the male and the fe- male scouring-rush plants are provided with leaf-green, emerge from the spores, strike their root-hairs into the soil and lead an independent existence. The males produce microscopic spherical spermaries in which arise spermatozoids with large numbers of swimming threads. The females produce a few egg-organs of the characteristic bottle-shape, at the bottom of each of which a single egg is formed. After the fecundation of the egg during rains, or when in some other way plenty of water is available as a medium for the locomotion of the sperms, the embryo of the scouring-rush begins to grow very much as did that of the fern. An erect stem is first produced, then from its base a rootstock. If at the end of the year the erect stem dies, buds on the rootstock remain to form the stems of the succeeding year. By means of its underground stem the 13 178 Minnesota Plant Life. spore-producing generation of the plant is perennial, but the sexual plants die after they have performed their functions. Male and female plants. It is now possible to understand the meaning of the curious sensitive appendages of the spores. The spores when ejected are separated from each other into little groups by the writhing of their appendages. The individual spores are not, however, entirely isolated, and that degree of moisture which is favorable for germination impels the append- ages to pull the neighboring spores close together, so that when they germinate, male and female plants shall not be too far apart for the convenience of the swimming sperm. This is a very good example of the extraordinary adaptive relations which come to exist between sexual and spore-producing plants of the same species. The appendages of the spores have seemingly no mean- ing in the life-history of the spore-producing plant itself, but they function in such a way that the task of the sperm-producing plant is made easier and thus the development of fecundated eggs is insured, for the perpetuation of successive generations. Upon clay banks, where there are shade and moisture, one will often find among the young scouring-rushes or horse-tails some of the tiny sexual plants looking very much like diminutive liver- worts as they lie more or less prostrate upon the soil. Different sorts of horse-tails and scouring-rushes. The dii- ferent kinds of horse-tails and scouring-rushes in Minnesota are distinguished by slight structural peculiarities that need not be discussed in detail. The rigid, jointed, unbranched forms, three or four feet in height, which grow along shaded banks are per- haps, in their tissues, the richest in silica or sand, and are the ones which have particularly merited the name of scouring- rushes. The very much branched variety which is such an abun- dant weed in neglected fields, along roadsides, and in the edges of woods, is a different species. A third species, in which the lat- eral branches curve downward in a characteristic way, is abun- dant in northern woods and is named the forest horse-tail. Still another kind is often found growing at the edges of ponds and streams, now and then forming great patches in bays and occu- pying the same general position that is ordinarily selected by bulrushes. This, which may be termed the water horse-tail, is commonly not very much branched although under certain Minnesota Plant Life. 179 growth-conditions it is capable of branching almost as abun- dantly as the field horse-tail. A curious dwarf variety two or three inches high is sometimes found growing in tufts in deep woods. It is reported from the St. Croix river valley, but I have not seen authentic specimens of it from Minnesota. Underbrush habits of horse-tails. When the branched va- rieties of horse-tails grow in the edges of woods they often be- come very much taller than in fields. This they accomplish by thrusting out their rigid side-branches in every direction and permitting them to rest upon the twigs of surrounding shrubs or herbs. Thus they can distribute their weight in such a way that the main stem is relieved and the axis may extend itself vertically farther than otherwise. Plants which lean in such fashion upon surrounding plants are known as braced-plants. They are not exactly dependent for their well-being upon the presence of other plants as are the climbers and twiners, but they do derive some advantage from their habit of letting a portion of their weight rest upon plants near them. It is really, if one stops to think of it, quite as much of an engineering problem to erect a slender stem as to build an Eifel tower, and it is no less impossible to extend a leaf into the air without due regard to the strength of materials than it would be to build a cantilever bridge from wet paper. Plants mani- fest architectural design and the problems of structural engi- neering are not at all unlike those requiring solution by the human architect or bridge-builder when he enters upon the plans of a new structure. So it is obvious that the bracing of the side branches of horse-tails, thus diminishing the strain upon the main axis, might enable it under the same general type of structure, to reach a greater elevation into the air. In South America, by bracing devices scouring-rushes grow to a height of twenty or thirty feet, though they are not thicker than an ordinary walking-stick. Where the forest is dense and dark such a plan is seen to be highly advantageous and perhaps even necessary, but in the lighter, thinner forests of Minnesota there is no need of such extreme length. Chapter 22x. What Seeds are and how they are Produced. % About 150,000 different kinds of plants produce seeds. A seed may be defined as a young plant and its reserve-food- material enclosed within a normally protective layer. Some- times the food-material is deposited beside or around the plantlet, as in the seeds of Indian corn and wheat. Again the food-material may be collected in the plantlet itself, giving to it a white, meaty appearance, and pumpkin and bean seeds are of this structure. It is a mistake to say that plants grow from the seed, or rather it 1s a half-truth, for the question is whence did the plantlet come that is already present in the seed and needs only to renew its development when the seed germinates? This can be answered in a word. Leaving out of considera- tion some abnormal or peculiar conditions of development, it may be said that all plantlets in seeds arise from eggs. The next question 1s whence comes the egg from which the plantlet in a seed develops? The reply is, that the egg, as in all other in- stances, is produced in the body of a female plant. Still an- other question—where is one to look for the female plant of a rose or willow, or any other seed-producing species? To this inquiry the answer is, the female, like all other females in the great series of terrestrial plants, develops from a spore. Again, one inquires, where is the spore to be sought? ‘To this is the response that it is formed in the young ovule or rudimentary seed, occurring as a more or less oval, cylindrical or elongated cell in the centre of the seed-rudiment. What then is the seed-rudiment? It is a spore-case which produces at its centre the single, large, thin-walled spore. In seed-plants such a spore is called an embryo-sac and it may easily be found by opening young pine-seeds in cones not more than twelve months old. Unlike the large-spores of the smaller Minnesota Plant Life. 181 club-moss, these seed-plant spores are not ejected from their spore-cases, while, just as in the smaller club-moss, they de- velop females which are retained within the spore-wall and upon the bodies of these females egg-cells are formed. How is it possible for such an egg, developed and retained within the tissues of a spore-case, to ob- tain fecundation? Here comes into play an adaptation on the part of the male-plants of the seed- producing varieties. Where is one to look for the male cottonwood tree? Like other male plants it originates from a spore, not, however, the large-spore, enclosed in the rudimentary seed, but the small-spore known as the pol- len-grain, developed in large numbers upon special leaves known as stamens. What sort of a plant arises when a pollen spore germinates? Before re- plying to this question another must be asked. Where does a pollen-spore germinate? Not upon the soil, or in the water, F!- 69. Diagram of an ovary, with one seed- z A rudiment, in a higher seed-plant. s. The as did the small-spores of ferns stigma,where two pollen-spores have germi- and smaller club-mosses but nated; 0, wall of ovary; f, stalk of ovule; repre ai and ii, rudimentary seed-coats; n, spore- upon a certain portion of the case, with single large spore, which has germinated to produce the reduced female ie is Tal A} i aw iS Man body Ora spore-producing plant; k, the egg; e, the body which forms plant of its own species, 4 part oe albumen; b, other cells of the female. f Me The male plant is shown as a tubular usually in close proximity to thread growing towards the egg. After 7 Atkinson, the rudimentary seeds. This area upon which a spore of the smaller kind is able to germinate is known as the stigma in higher flowering plants, but in the lower families the pollen-spores fall immediately upon the im- mature seeds. Breeding habits of seed-plants. Returning now to the ques- tion, what sort of a plant arises when a pollen-spore germinates, 182 Minnesota Plant Life. the reply is, a delicate thread, like a cobweb, comes into exist- ence and grows much as a parasitic fungus filament would grow through the tissues of the immature fruit down to the surface of the large-spore, imbedded in the rudimentary seed. By this time the female has developed within the large-spore and has produced her egg. The end of the pollen-tube, as the male is termed, penetrates the wall of the large-spore and transfers a male nucleus, or sperm, which fuses with the egg and thus fecundation is accomplished. Then the egg becomes an embryo which grows and produces a short stem, one or more seed- leaves (in most plants) and a root. While the embryo is devel- oping, the tissues of the spore-case and the membranes sur- rounding it become modified into the outer layers or seed-coats. When the embryo pauses in its growth and passes into a tem- porary dormant condition the seed is said to be ripe. It may not, however, be able at once to germinate. If the reader has closely followed this explanation he will be aware that is is improper to call a pollen-producing plant a male and he will understand that there 1s no comparison at all between the sowing of pollen-spores on a stigma where they are to germinate and a breeding habit, although the older botanists supposed that such analogy existed. It is found. that seed-producing plants, like the smaller club-mosses, have two sorts of spores, small-spores producing males, and large-spores, females. As in the lower type, so also in the seed-plant, there is a retention of the female within the wall of the spore from which she originated. Unlike the smaller club-mosses, the male plant is not retained within the wall of the small-spore, but pro- trudes in the form of a thread of miscroscopic minuteness. The retention of the large-spore within its spore-case, together with the adaptation of the male plant so that fecundation may take place without the opening of either the large-spore or its case, lays the foundation for that compound and complex body, the seed. By these devices the embryo is kept in close proximity to the vegetative areas of its species and in a pine seed there are represented three successive generations. The coats of the seed and sometimes a portion of the food-supply, as in water-lilies, belong to the older spore-producing generation, for they are Minnesota Plant Life. 183 parts of the same plant that produced the large-spore. The meat of the seed, or albumen, belongs to the female, for it is produced within the large-spore as it germinates. The embryo plantlet of the seed belongs to the new spore-producing genera- tion and arises by the segmentation of an egg. After it has renewed its development—when the seed has germinated and the plantlet has become old enough—it will be able in its turn to produce spores. Therefore, the life-history of a cottonwood, for illustration, is twice as complex as that of a man. While there are only two kinds of individuals in the human species, there are four in the cottonwood: first, the pollen-producing tree or staminate cottonwood; second, the seed-rudiment-pro- ducing tree or pistillate cottonwood; third, the male cotton- wood or pollen-tube arising from the pollen-spore and growing as a parasite upon the tissues of the young cottonwood fruit; fourth, the female cottonwood, a microscopic plant inclosed in her spore deep within the rudimentary seed. Indeed there may even be five kinds of cottonwoods, for in higher seed-producing plants there is strong reason to suppose that the albumen of the seed is in reality a degenerate plantlet—a twin brother of the embryo—produced from an egg, rather than, as in the pines, a portion of the female plant-body. From this discussion it will be seen how inaccurate is the common statement that higher plants grow from seeds while lower plants are produced by spores and it is understood how erroneous is the phrase, so general, especially in popular works, that the spores are the seeds of the fungi or ferns. The higher plants produce spores just as truly as do the lower plants, but in the former a peculiar relation of dependence has come to exist, precisely the reverse of that which was observed in the liverworts. In the latter the capsular plants, that is, the spore- producing plants, were dependent upon the sexual plants for their food-supply and remained perched upon their bodies all through life. In the club-moss group these little perched plants learned how to maintain an entirely independent existence and put forth leaves and roots of their own. In the seed-plants they have become so important and powerful that they do all the vegetative work of their species while the once stronger and larger sexual plants are reduced to microscopic structures of 184 Minnesota Plant Life. an altogether dependent life-habit. A few definitions may not here be out of place and will be given in as untechnical language as possible. Definitions of certain words. Pollen is a dust consisting of small spores, capable, upon germination, of producing male plants. The embryo-sac is a large-spore developed in the rudi- mentary seed and capable of producing a female. The pollen- spores are produced in special spore-cases situated on leaf-like organs called stamens. The embryo-sacs are commonly pro- duced singly in bodies called ovules borne upon leaves known as carpels. An axis upon which stamens or carpels or both are generated is called a flower. An ovule which has matured, normally as the result of a breeding act, is called a seed. The carpel, or carpels of a flower with the enclosed seeds, is called a fruit. Two series of seed-producing plants. ‘There are two series of seed-producing plants, the lower, in which the pollen-spores fall directly upon the immature seeds and germinate, and the higher, in which the carpels close around the immature seeds and the pollen-spores fall and germinate upon a special portion of the carpel or carpels known as the stigma. Chapter 2X TL. Ground-hemlocks and various Pines. i Of lower seed-plants there are five living and at least two extinct families. In Minnesota but two of the five living fam- ilies are represented. These are the yews and the pines. Ground-hemlocks. The yews are represented by a single species, the ground-hemlock, a well-known plant of wooded banks and forests throughout most of the state. In England a species of yew exists which becomes a large tree, but of the four species in America none reaches any very great size, and the ground-hemlock is the smallest of the group. It is an ever- green shrub with leaves much like those of the balsam, and rec- ognized by its crimson berries the size of small gooseberries. The berry of the yew, however, is not a fruit but a seed, sur- rounded by a red pulp-cup which may be regarded as a basal outgrowth. Of all seed-producing plants in the state the yew gives its seeds the least protection. In pines the seeds are en- closed by the scales of the cone, and in all higher seed-plants the seeds are developed within fruits and are never, from the first, exposed, as in the ground-hemlock. The red pulp which en- circles the yew seed makes it attractive to birds and it is dis- seminated by their agency. Besides the seed-rudiments on the branches, the yew produces little round cones consisting of axes upon which are borne a few shield-shaped leaves. Each of these resembles the spore-producing leaves of the scouring- rush and on the under side of each a circle of pollen-spore-cases are developed. The yew plants, of all Minnesota seed-bearing forms, produce the largest number of pollen-spore-cases on a single stamen. Usually the number is four, often but two, while in the yew the number may be six or even more. The micro- scopic male and female yew plants are short-lived, but the spore- producing plant, beginning as an embryo in the seed, then after 186 Minnesota Plant Life. the germination of the seed achieving independence, is a long- lived shrub of somewhat prostrate habit, and with dark-green leaves and tough-fibred wood in which resin does not occur, while it does in plants of the related pine family. Pines of different sorts. The pine family includes 13 or 14 Minnesota species out of a total of about 300 distributed over all parts of the world. In these the rudimentary seeds are pro- duced upon the inner sides of scales or carpels which, like the stamens, are-aggregated into cones. The pines and their allies may therefore be said to produce two kinds of flowers, stami- nate and pistillate. Among the members of the pine family in Minnesota may be mentioned the tamarack, a deciduous tree of social habit; the pines of which three varieties, the white, the jack and the red or Norway, grow within the borders of the state and are dominant species of the northern forest; the spruces, of which there are three varieties, the black, the white and the muskeg; the balsam or fir, common in swamps; the white cedar or arbor-vitae, a tree that flourishes best in the northern part of the state; the hemlock, very rare in Minnesota, but occurring in two isolated patches in St. Louis county and Carlton county ; and the junipers, of which there are four species, one tree-like in habit and known as the red cedar, the others low shrubs and called savins or junipers. The white pine. Among all these plants the white pine, the most important timber tree of the state, 1s of especial interest. Its wood is light, resinous and easily worked. It is used in the manufacture of lumber, laths, shingles, matches, sashes, doors, blinds, woodenware, telegraph poles and the masts of ships. Many millions of dollars are invested in mills for its manu- facture into lumber, and in railways for the transportation of the logs. This tree often grows over a hundred feet in height with a trunk sometimes more than three feet in diameter. Its bark is rough and deeply divided by clefts. When growing in the open, as sometimes upon hills, for example, near lake shores in Cass county, the lower branches are much prolonged and the whole tree has a broadly conical form. But when a native of the forest the lower branches become shaded out of existence and the tree has the well-known compressed slender appear- Minnesota Plant Life. 187 ance. The topmost branches usually dispose themselves in a flamboyant manner, which makes it possible to recognize this variety of pine as tar as it can be seen. The leaves are slender prismatic needles, borne in groups of five, on special short branches. They are of a somewhat bluish-green color, and dur- ing their first winter are inclosed in small bright green buds. The staminate cones are light-brown, egg-shaped, about a third of an inch long and mature in a single season. ‘The pistillate cones are somewhat smaller at first, of a purplish color and borne on the topmost branches of the tree, while the staminate cones are usually developed on the lower branches. Originally the _ pistillate cones are erect, but during the first year of their lives they become heavier and take a hori- zontal position. At this time they are nearly goeeanch in Peneth. ‘The next year they gTOW rapidly, Fic. 70. White pines on the rocks at Taylor’s Falls. After photo- graph by Williams. become pendu- : lous, and reach their full size in mid-summer. ‘They are now six inches in length and seven-eighiths of an inch or thereabout in diameter. During the autumn of the second year, they open and scatter their brown seeds, each of which is furnished with a del- icate wing by means of which it is disseminated by the wind. Within the seed will be found an edible albumen, with, however, a strongly resinous odor, and in the centre of this stands the straight young pine with from eight to ten seed-leaves growing in a crown about the short apex of its stem. The root, before it issues from the seed, is already provided with a root-cap and the stem-area below the seed-leaves is short. The white pine contains more resin than any other variety, yet it is not ordi- narily used in the manufacture of turpentine as is the pitch pine of the south. 188 Minnesota Plant Life. Pine trees do not spring up again after fires with nearly the vigor possessed by a number of hardwood trees. In Minne- sota hundreds of thousands of young trees are annually de- stroyed by fire and their place is occupied by plants which are comparatively worthless in the commerce of the state. The Norway or red pine. The other commercial pine of Minnesota is a somewhat smaller tree, averaging fifty to eighty feet in height. This is commonly called the Norway pine by log- gers, though a more correct name would be red pine. The bark is of a reddish tint and much smoother than that of the white pine. When standing in groves the tops of the red pines are round, not irregular and crested as are the tops of the white pine. The leaves are produced in pairs on short special branches. They are dark-green, five or six inches in length and shaped somewhat like half-cylinders. The stami- nate cones are longer and slen- derer than those of the white pine, grow in more. elongated clusters and are of a purplish color. The pistillate cones ate at first almost spherical, red in color and a quarter of an inch or Fic. 71. Jack pine. After Britton and more in length. Like cones of nes the white pine these pistillate flowers take two years to mature and finally drop from between their scales the smaller, darker seeds with wings shaped differ- _ ently from those of the white pine seeds. The seedling plant has fewer seed-leaves and is limited to eight, while five, six or seven are more common numbers. The wood is not so easily worked as that of the white pine, nor do the logs float so well in drives. The timber is, however, abundantly em- ployed in the manufacture of buildings, trestles and sometimes in railway construction. The jack pine. The third species of pine in Minnesota, the jack pine, is very prevalent in sandy soil throughout the north- ern part of the state. It is a smaller tree than either of the Minnesota Plant Life. 189 others, but may in groves reach the height of seventy or eighty feet. ‘The top is more pointed or spire-like than that of the red pine and the bark is rather thin and irregularly divided, a little like elm bark. The leaves arise in pairs and are much shorter than those of the red pine, varying from three-quarters of an inch to one and a quarter inches in length. The staminate cones are produced in clusters much like those of the red pine, but smaller. The pistillate cones are nearly spherical in shape, FiG.72. Rock-vegetation near Duluth. White pines, white cedars and junipers. After pho- tograph by Williams. purple in color and appear on the topmost branches of the tree. \When the pistillate cones mature during the second season of their lives they are generally curved to one side, by which char- acter they may be recognized and distinguished from the short cones of the red pine. The seeds are small, winged, and black- ish in color and the embryo plantlet has only four or five seed- leaves. ‘There is no difficulty in discriminating even between the seedlings of the three species. The wood of the jack pine 190 Minnesota Plant Life. is not strong and is little used as lumber, though it is cut for firewood in some parts of the state and occasionally employed in the manufacture of posts or ties. This pine is particularly abundant in the region around Brainerd, where it covers hun- dreds of square miles in an almost unbroken forest. The white cedar. The white cedar or arbor-vite is a tree fifty or sixty feet high with a short, thick trunk. It is especially abundant in the far northern region of the state, not coming south so readily as the pines. It is prominent along lake shores on the international boundary and its branches jutting out over the water make picturesque scenery on the shores of most lakes east of Rainy lake. The leaves are large and remote on older shoots, but on the younger, which are arranged in flat, fern- like groups, they are short and tightly lapped over each other like shingles. The flowers, opening in the spring, are purple in color and the fruits ripen in a single year. The seeds are winged along both margins, thus differing from the pines in which the wings are principally terminal, and are only an eighth of an inch long. Seedling plants of the white cedar have but two seed-leaves, in this respect resembling most higher seed- plants. The wood is very light and peculiarly durable, sweet- scented and brown in color. It is highly prized for railway ties, shingles and fencing lumber and is used by the Indians in the manufacture of paddles and as ribs for their canoes. ‘They em- ploy also the inner bark in the manufacture of mats, cutting it up into strips which they dye and plait elaborately in quaint and traditional patterns. Young arbor-vitz plants are used in Minnesota for hedges. The hemlock. ‘The hemlock is a tree sometimes 110 feet in height with a trunk four feet in diameter, but in Minnesota, in the two small patches where it is known, it does not reach this size. ‘The lower branches are generally drooping and the leaves are short and flat, dark-green above and lighter below. The cones are slightly longer than the leaves. ‘The wood is soft and light, brown or white in color and the general appearance of the twigs with their foliage is quite similar to that of the ground-hemlock—hence the common name of the latter. The two plants, however, are really members of different families. Hemlocks are of much economic importance from their bark, Minnesota Plant Life. IOI to the exclusion of other varieties, being employed in tanning. The substance known as tannin is abundant in hemlock bark and by its action upon hides they are cured and converted into leather. The tamarack. The tamarack differs from the other Min- nesota pines in its habit of shedding its leaves in autumn. The leaves are never of the dark rich green of the spruces, firs or pines, but are of a paler color. In autumn they turn golden yel- low before they fall and after the severe frosts of November Fic. 73. Tamarack swamp with sedge border. After photograph by Williams they separate from the twigs by means of cork layers and the tree passes the winter in a leafless condition. ‘Tamaracks oc- cupy wet ground, forming by their growth the well-known feature of the landscape known as the tamarack swamp. ‘The cones of the tamaracks are small. ‘The wood is hard, resinous and durable, weighing twice as much as that of white cedar, and is used in the manufacture of railway ties, as fence poles and for fire-wood. Occasionally, too, it is manufactured into tele graph poles. 192 Minnesota Plant Life. The spruces. The spruces are known for their spire-like habit of growth and serve as the Christmas trees of the children. They do not grow to any great size in Minnesota although the white spruce under suitable conditions may reach a height of 150 feet. In Minnesota the black spruce seems to be rather more frequent and together with tamaracks, or to their exclu- sion, forms characteristic swamp growths, the trees standing very close together. A slightly different variety, the muskeg spruce, with peculiar drooping branches is particularly abundant in such localities. Spruce leaves are short and four-sided, spreading in all directions from the twig. The cones are small and plump, with shell-shaped scales closely lapping over each other. In the white spruce the cones are oblong and some- what cylindrical in form, while in the black spruce and muskeg spruce they are egg-shaped in general outline. When the leaves of the black spruce die they fall, leaving little hummocks on the twigs. None of these plants except the true pines has special leaf-bearing branches which separate as a whole when the leaves have finished their work. The balsam. The balsam or fir is a slender tree growing in somewhat drier soil than that preferred by the tamaracks and black spruces. In Minnesota it rarely exceeds a height of 40 feet. The leaves are flat and sessile, arranged apparently in rows right and left on the twig, but really in spirals. The twigs aave a much flatter look than the twigs of spruces. Only one species occurs in Minnesota and this has a smooth bark in which resinous blisters are formed. The whole plant is sweet-scented and the wood is soft and light. From the resin blisters is de- rived the product known as Canada balsam. ‘The balsam tree may be known from the spruces by its erect cones as well as by the flat branch systems, for in spruces the cones are pendu- lous. The junipers and red cedar. There remain to be men- tioned the junipers, a group of evergreens remarkable for trans- forming their pistillate cones into little round blue berries. "The scales of the cone become fleshy, inclosing the seeds. They are fragrant and an extract of juniper is used in the flavoring of gin. Birds pick the berries, thus providing for the distribution of the seeds. Therefore, as one would expect, the seeds are not winged Minnesota Plant Life. 193 as in most of the other pines. One of the junipers, the red cedar, grows in Minnesota as a tall tree. It is not very com- mon in the state, but is found at Redwood Falls and on lake shores and bluffs at a few isolated localities in the southern part. The leaves are short and broad with sharp points and are developed in four rows. The red cedar is the most widely distributed plant of its family in North America. The wood is light, perfumed, of a reddish color, except in the outer layers, where it is white. It is largely used in cabinet making, in the Fic. 74. Red cedars on the banks of a Minnesota lake. After photograph by Williams. manufacture of lead pencils, and is believed to be so particularly distasteful to moths that closets in which woolen clothing and furs are to be hung during the summer months are sometimes lined with it. The other junipers of the state are low shrubs. One 1s char- acterized by spreading awl-shaped leaves arranged in whorls of three, and this form sometimes grows into a low tree. The others are prostrate shrubs creeping over the rocks or sand, and are abundant in the northern part of the state where they form a distinctive vegetation on some of the islands in Lake of the 14 194 Minnesota Plant Life. Woods and Rainy lake. Their leaves, like those of the red cedar, lap over each other, are short and slightly pointed. They stand in four rows, giving the branch upon which they are borne a square appearance. Characters of lower seed plants. There are a number of features in which the yews and pines agree. The seeds of each are produced in such a way that when young the pollen spores may fall close to their ends, so that the only tissues through which the pollen-tube must grow to reach the female plant are the cells of the spore-case that surrounds the large-spore in which the female plant is situated. For this reason the lower seed-plants are sometimes called the naked-seeded plants. While the seeds are maturing they are enclosed, except in the ground hemlock, quite as truly as are those of higher forms. In the juniper-berry, for illustration, when it is full grown, the scales which constitute the little fleshy cone are blended at their edges in such a manner that the seeds are entirely enclosed and can- not at all be termed naked. In the pines proper, too, the young cones appress their scales so tightly that the seeds are quite as effectually protected as they would be in the closed fruits of higher types. At first, however, even in the junipers, the scales of the immature cone are open and it is possible for pollen- spores to fall between them, thus reaching the ends of the young seeds growing upon their inner surfaces. A character in which the lower seed-plants all agree is the production of albumen in the seed before the egg of the female is fecundated by the sperm-nucleus of the pollen-tube. In the higher seed-plants the albumen of the seed, when present, does not form until the egg which is to produce the embryo has re- ceived its fecundation. The albumen of the seed may be re- garded as the body of the female plant and the young embryo nurses upon it during its life within the seed just as the young spore-producing plants of a liverwort or moss nurse upon the vegetative body of the sexual plants of their species. In still another respect the lower seed-plants agree and differ from all the higher seed-plants. In them, on the body of the female plant produced within the large-spore, true egg-organs are formed, each enclosing an egg and provided with a short neck the end of which is near the inner surface of the spore- Minnesota Plant Life. 195 wall. In higher seed-plants there is no definite egg-organ, but the egg lies loosely among the other cells of the extremely re- duced and degenerate female. Relation between lower seed-plants and primitive seedless plants. A very remarkable character, which shows clearly the connection between smaller club-mosses and lower seed-plants, is not known to be presented by either of the Minnesota fam- ilies of the latter group, though it is now described for two that are exotic. It is, however, a fact of such extreme interest that it should be mentioned at this point. IG. 75. Rock on the St. Croix river, near Taylor’s Falls. Shows zonal distribution of trees. White pines stand on top of the rock, and birches and poplars on the sides. After photo- graph by Mr. H. C. Cutler. In the sago-palms and ginkgo trees the pollen-spores fall as n other naked-seeded plants, upon the ends of the immature seeds, then germinate and produce their pollen-tubes. In the nd of each pollen-tube in these plants there develop a pair of notile spermatozoids provided with swimming lashes. In the ryead family to which the sago-palm belongs, are a few Amer- can species finding their home in Florida. In these when lhe pollen-tube comes close to the egg a motile spermatozoid | SBS ‘ jwims into it, peeling off its swimming-lashes in a spiral coil | | ’ 7 | 196 Minnesota Plant Life. and leaving them at the edge of the egg just inside its wall. The remainder of the sperm-nucleus finds its way to the centre of the female cell. In higher forms of naked-seeded plants, of which the yews and pines are examples, the swimming-lashes of the spermatozoids seem to have been quite abandoned. They are indeed no longer necessary, for the old algal type of aquatic reproduction has been finally outgrown. It is a most remark- able and impressive fact that in all the terrestrial forms, from the liverworts up to the cycads, including all the ferns, club- mosses and their allies, the primitive aquatic nature of the plant reasserts itself during the reproductive phase and one finds such plants as the granite-mosses, accustomed to life upon bare, dry rocks, quite unable to bring their sperms and eggs together except immediately after heavy rains, when the surface of the rock is flooded with water, thus enabling the aquatic sperms to use their swimming threads. This long persistence, ages after the aquatic habitat had been abandoned by the ancestral algae from which the higher plants are supposed to have arisen, is a striking example of the really profound inertia of living struc- tures. Chapter X XII. From Cat-tails to Eel-grasses. 9 Higher seed-plants. The characters of this group are as follows: the rudiments of the seeds are protected by the fusing together of the specialized leaves upon which they are borne into a fruit-rudiment known as the ovary. The leaves which thus fuse are called carpels. In some types the ovary consists of a single carpel, in others, of several carpels blended into a single fruit-rudiment, while the number of carpels in a flower varies in the different families. ‘The female plant, produced in the large-spore of the seed-rudiment, consists of a few cells, commonly eight in number, near the time that the egg is fecun- dated. The albumen of the seed is not of the nature of a female plant, but is rather to be considered as the twin of the embryo, and does not form until after the sperm and egg have fused. In the latter characters it will be seen that the higher seed-plant differs from the lower. The lower class of higher seed-plants. ‘There are two prin- cipal classes of higher seed-plants. The lower class is distin- guished by the production of embryos with but a single seed- leaf. In such plants the stem develops fibrous or woody threads which become entirely mature and do not blend into a cylinder from which to form a layer of growing tissue between the wood and the bark. Hence the stems of perennial plants of this class do not show “annual rings” of growth like those of the other and higher class. For the most part the leaves have parallel veins although some, such as those of the jack-in-the-pulpit, the smilax and the skunk-cabbage have netted veins. The flowers are ordinarily made up of five whorls of leaves, the two lower and outer whorls constituting the perianth, then two whorls of stamens and, in the centre, one whorl of carpels. ‘The number of leaves in a whorl is generally three, but in certain types the number varies, especially in the three inner whorls, so that water-plantains, for example, produce a large number of sep- 198 Minnesota Plant Life. arate carpels at the middle of a flower while grasses produce but one. A variety of plants belonging to this division of the vegetable kingdom exist in Minnesota. The class is divided into orders of which eleven are recognized, and the orders are divided into families. Cat-tails. The cat-tails belong to a small order, including also the bur-reeds and the screw-pines, the latter of which are not represented in the state. Cat-tails, however, are common enough at the edges of marshes, swamps and lakes, and a single species, the broad-leaved cat-tail, is familiar in such localities. It is provided with a creeping rootstock which lies imbedded in the mud. The leaves are slender and flat, sheathing the upright branches of the rootstock by their bases. The flowers are of two sorts, some containing only carpels and others only stamens. The two kinds are produced in the same spike-like cluster, the staminate aggregated above and the pistillate below. The brown cyl- inder or “‘cat-tail’” is the compact mass of pistillate flowers. The little fruits are provided with cottony hairs and burst when they have been lying in water for a short time. Fach seed consists of a hard shell within which is considerable albumen surrounding a single embryo plantlet. Bur-reeds. There are at least six sorts of bur-reeds in Min- nesota. They occupy similar habitats to those preferred by the cat-tails. Their prostrate creeping rootstocks are rooted in the mud and from them erect branches arise. On these are developed grass-like leaves. The flowers are of two sorts as in the cat-tails, and are gathered in globular heads, varying in size from a pill to a large marble. The staminate heads are Fic. 76. Bur-reed. After Britton and Brown. Minnesota Plant Life. 199 smaller and higher on the stem than the pistillate. The fruit has but a single cavity. The seeds are furnished with con- siderable albumen and within this the embryo stands nearly straight. These plants are sometimes mistaken for sedges, but are easily recognized by their globular flower-heads of two sorts on the same general branch. Sometimes the heads are pro- vided with stalks; in other varieties they are sessile. The second order in the ascending series includes seven fam- ilies, of which five are represented in the Minnesota flora. Fic. 77. Lakeside vegetation. Just off shore is a growth of the floating pondweed, then of arrowheads, while further out are reeds and rushes. After photograph by Williams. Pondweeds. ‘These are for the most part submerged plants growing in ponds, lakes and slow streams throughout the state. About twenty Minnesota species are known to exist in such localities. They all root at the bottom of the water. Their stems are slender, often branching, and when taken out of the water are limp, owing to their poor development of woody tis- sue. The flowers are commonly collected in spikes which in spring are barely thrust above the water in order that the wind may carry the pollen from the stamens to the stigmas. These spikes are the little objects upon which lake-flies like to perch 200 Minnesota Plant Life. —as must often have been observed by every one who has fished in Minnesota lakes. The different species of pondweeds may be distinguished by their leaves. In one common variety leaves of a somewhat oval shape float upon the surface of the water, but besides these there are present upon the submerged portions of the plant short, reduced, grass-like leaves. In another with leaves some- what similar, but crowded together and altogether submerged, there will not be found the special grass-like leaves. Still an- other has clearly two very different sorts of leaves, some finely dissected and others elliptical in outline. In yet another the leaves are all delicate and thread- like. .A great vatiety = iieae shape and size of pondweed leaves may be observed upon looking down through the clear water upon submerged bars where they grow so luxuriantly. In all these plants the seeds are curved or straight and the embryo has no encasement of al- bumen. The fruit, in which are the seeds, consists of four little . £ bodies much like diminutive Wa Ff dha ! peaches. Very closely related to Fic.78. Clasping-leaved pondweed. after the pondweeds are the naiads Britton and Brown. 6 Sec E which may be distinguished by the solitary pistil which forms the fruit. They grow in exactly similar localities and one species is common in Minnesota. Arrow-grasses. A third family is known as the arrow-grasses. Four species are described from Minnesota localities and are to be found in some abundance in tamarack swamps, especially in the northern part of the state. The leaves are rush-like and the flowers, arranged in terminal, loose spikes, produce stamens and pistils upon the same axis, while from three to six carpels fuse together to make the fruit. One variety of arrow-grass is discriminated by the small number of flowers in the spike. All of these plants are perennial and some of them are to be pretty generally met with in all portions of the state, while others are Minnesota Plant Life. 201 rare. They should be sought in rather moist peat-bogs or in marshes at the edges of lakes. Water-plantains and arrowheads. A fourth family includes the water-plantains, the arrowheads and a few related plants in which the flowers are similar though the leaves are of differ- ent appearance. ‘The common water-plantain is known by its large oval leaves, two or three inches in length and with several strong longitudinal ribs. The flowering stem is much branched, bearing a number of pretty flowers each with three round white petals, from six to nine stamens and usually several separate f= = a Fic. 79. Evening scene in Minnesota. Arrowheads, bulrushes and willows in foreground. After photograph by Williams. carpels which form, as the structure matures, a little fruit- cluster. The embryo in the seed is curved like a horse-shoe and there is no albumen. These plants produce large masses or colonies in favorable localities. ‘They are abundant in ditches and pools and along railway tracks, as well as in pond margins and in marshes, but they do not commonly occur in peat-bogs or tamarack swamps, except at the edges. Related to the water-plantains are the arrowheads, plants of similar habitats and generally to be distinguished by their broad leaves, shaped like spear-heads. The arrowheads, like the pondweeds, frequently put forth two kinds of leaves, and if a 202 Minnesota Plant Life, plant is pulled up by the roots it will be discovered very possibly that there are broad or slender grass-like leaves submerged in the water. In one Minnesota va- riety the arrow-headed leaves float upon the surface of the water like those of the pond-lilies, but more commonly they are not natant. In some species all of the leaves are grass-like or slender, while the plants must be recognized rather by their characteristic flowers. A large number of separate carpels are pro- duced in each flower and when it ripens the group of carpels become a more or less spherical head. In each of the closed carpels or ovaries : j ; Fic. 8). Arrowhead. After Britton is a single erect seed slightly curved. and Brown. In Minnesota there are at least six species of arrowheads. Eel-grasses. A fifth fam- ily in this second order in- cludes the well-known eel- grass, the plant which gives so delicate a flavor to the flesh of the canvas-back duck, which is very fond of pulling it and eating the soft parts of the leaves and stems. There is something very remarkable about the way in which this plant pro- duces its flowers. The gen- eral plant-body consists of a short stem rooted in the mud on the bottoms of lakes near their edges. The leaves Fic. 81. Eel-grass. After Britton and Brown. gre long, grass-like and ofa diaphanous translucent green, rarely floating at the surface, more generally submerged and ascending. The pistillate flow- ers are produced at the end of a very long, slender spiral stem Minnesota Plant Life. 203 which rises in sinuous coils through the water, bringing the flower just to the surface. The staminate flowers are in clus- ters on a short stem deep down in the water. When they are nearly ripe they separate from the stem and rise to the surface, where they open, revert their perianth leaves and are free to be blown about on the quiet surface of the pool like so many min- lature boats. Some of them thus approach the pistillate flowers and the pollen-spores can fall upon the stigmas where they ger- minate. After pollination the long, coiled stem contracts and pulls the pistillate flower down into the depths where it may ripen its fruit in safety. The fruit itself is a cylindrical capsule with numerous seeds. In near affinity to the eel-grass is a little plant which is some- times called ditch moss or water weed and is known by its short leaves of a crisp texture when taken from the water. The leaves are opposite, rather close together and commonly not more than half to three-quarters of an inch in length. Their points are often turned back so that a characteristic appearance is given to a branch. Chapter 2 i Grasses and Sedges. 9 The third order is not represented in Minnesota, but the fourth order, which includes the grasses and sedges, is abun- dantly represented by a large variety of forms. There are in the state about 160 different species of grass and about the same number of sedges. Grasses. Grasses are characterized by their habit of forming the sort of fruit which is termed a grain. They are, in Minnesota, all of them annual or perennial herbs, but in In- dia and the Orient some va- rieties become large trees, in which condition they are termed bamboos. The stems are for the most part hollow, the leaves slender and sheath- Fic. 82. Wild rice and pond lilies. After N83 ee Sone PS a photograph by Williams. es have broad leaves—or even ovate leaves in certain foreign species. The flower clusters are generally spikes composed of little spikes known as spikelets. In the flower clusters and flowers, the leaves are developed as chaffy scales and the flowers themselves lack any colored perianth. ‘There are usually three stamens and the ovary has but one cavity producing but a single seed. The ovary is conceived to consist of one carpel, the other two having disappeared. The branched stigma on top of the rudimentary fruit is feather-like, and for its pollination the chief agent is the wind. The ripened fruit inclosed in its chaffy scales is called a grain. The seed inside the grain is not sep- arate but fills up the fruit-cavity so that the whole is one solid — Minnesota Plant Life. 205 body. ‘There is always albumen in the seed and the embryo lies toward one side, nursing on the albumen by its peculiar sucker-shaped seed-leaf. This may be seen when one carefully removes the embryo or germ fone a.com ituit or from a wheat kernel. It will then be, noticed that the embryo has on one side a flattened disc which presses itself against the albu- men, and by it the plantlet nurses as the seed begins to germinate. There are several tribes of grasses recognized: the maizes, to which Indian corn belongs; the bluejoints, including also the sugar-cane; the panic-grasses, with which the barnyard grass, ee ples yee pebe op the sand-burrs and their allies are grouped; the rices, of which the Minnesota representative is the well-known wild rice or Indian rice; the canary-seed grasses; the timothies and millets, in- cluding also some sand-bind- ing grasses and tumbling- grasses; the oats, comprising the well-known wild oats and a number of kindred genera; the fescue grasses, with blue- grass and reed-grass as types; the buffalo-grasses, and the barleys with which tribe are also grouped both wheat and rye. Only two of the large tribes of grasses are unrepre- sented in Minnesota by native varieties. These are the maizes Fic. 84. Barnyard grass. After Britton and . ee and the bamboos; but Indian corn, one of the maizes, is so abundantly cultivated that it may rightfully be regarded as a Minnesota plant. 206 Minnesota Plant Life. Varieties of grasses. It is not possible in the space at com- mand to give any adequate idea of the various species of grasses which grow within the borders of the state. The majority of them are turf-forming plants and are marked by strong underground rootstocks which branch and creep beneath the surface of the soil, sending lateral offshoots into the light. A great many different types of flower clus- ters are to be met with, varying from the solid spikes of the timothy or millet to the very loose and straggling clusters of the tumble- grasses and blue-grasses. A few ee pment cc grasses are aquatic, permitting their leaves to float on the surface of the water. These may be recognized, when in flower or in fruit, by the characteristic grass-like aggregates which they produce. Some are semi-aquatic, finding their homes on the edges of lakes or swamps, as, for ex- ample, the reed-grasses and the wild rice. A number of varieties are found only in tamarack swamps and marshes or where there is an abundance of shade. / A few, with sparsely clustered flowers and rather broad, thin leaves, frequent the depths of the forest, but the great majority are to be looked for in meadows and on the prairie. Some of them, like the buffalo grass, with their shriv- eled aspect and vigorous root- WD WN) CD OD) fi d) J )) SD Fic. 86. Beckman grass. After Britton : and Brown. system, indicate a strong adap- tation to dry regions or deserts. Indian corn. Sometimes in the grasses the flowers are sep- arated so that the staminate flowers occur in different clusters Minnesota Plant Life. 207 from the pistillate, just as in the cat-tails. It is so with the Indian corn, where all the stamirate flowers normally develop in the area known as the tassel, where all the pistillate flowers are gathered together on a thick stem and form the ear. In the Indian corn the process which cennects the stigma with the ovary is long and slender and is known as the silk. Surround- ing the cluster of pistillate flowers on their thick stem or cob is a group of somewhat modified protective leaves known as the husks of the corn. Since the plant depends upon the wind for carrying the pollen-spores to the stigma, the silk threads protrude in a little tuft at the end of the ear. By selecting ears which have not yet opened to expose their silk and inclos- ing them in a gutta-percha bag it would be possible to pre- vent the devel- opment of the a poe ee Pa kernels. Nee NT 2” | Anumber of yc. 97. cultivated vari- Indian corn in the shock. After photograph by Williams. eties of Indian corn are recognized, differing in minor peculiar- ities. Hybrids between different varieties are interesting and sometimes red and white corn are crossed; in that instance tinted kernels may develop upon the cob. Or if red, white and black varieties are grown together in the same field some kernels may be fecundated by male plants arising from one kind of pollen while others depend upon males developed from other pollen, so that the ears contain kernels of each color. Wild rice. Another grass which is of interest from its 1m- portance as an economic plant among the aborigines of the state, is the wild rice or Indian rice. The Chippewas call this plant manomin and gather it in the autumn of the year for food. 208 Minnesota Plant Life. It occurs in large quantities, especially in narrows between lakes, in outlets or inlets, but not so commonly in bays or stagnant water. It is not so frequent in lakes without an outlet. The After photograph by Williams. Fic. 88. Wild rice in a Minnesota lake. grain is longer and thinner than the rice of the orient, but when boiled is quite as agreeable to the taste as the cultivated form. The Indians collect it in September, beating it into their canoes, Minnesota Plant Life. 209 and after harvesting it is winnowed by hand. Under the crude manipulation of the Indian much chaff is usually left with the grain, so that the wild rice cake or porridge which the In- dian makes is not always so ap- petizing as one might desire. The wild rice, when it flowers, behaves somewhat like Indian corn, but both varieties of flower- clusters are rather broad panicles. The spikelets contain one flower each and the pistillate spikes are borne higher on the stem than the staminate, thus reversing the relative position in the Indian corn. Each staminate flower con- tains six stamens. ‘The pistillate flower consists of a single ovary with two divergent feathery stig- Fic. 89. Wild rice. After Britton and mas Brown. Wheat. More important to man than any other grasses in Min- nesota are the wheats, which form the principal agricultural prod- uct of the state. In the wheat the flowers are perfect, not separated as in the corn or wild rice. Sur- rounded by its own cluster of stamens each pistil is normally sure of pollination. When the fruit develops it forms an ovoid grain with the embryo basally and laterally disposed. A large number of varieties of cultivated wheat are known, the hybridiza- tion and selection of which are of the utmost importance to the agriculture of the future, since by Fic. 9. Kalm’s brome-grass. After such intelligent methods will it Britton and Brown. ; eventually be possible to produce varieties which are rust-proof and far richer in flour-making sub- stances than are the wheats of to-day. 5 210 Minnesota Plant Life. Distribution of grass grains. A few grasses in the state have interesting special methods of distributing their fruits. The sand-bur, for example, encloses its fruits in bur-like scales. If carefully examined, the points on the burs will be found to have barbs directed backwards along their sides, so that a bur sticks very closely to the fur of an animal or to clothing and ‘ thus brings about the dissemina- tion of the fruits within. sition with reference to each ~ other, so that the flowers were arranged loosely upon the plant. In higher forms defi- nite flower clusters of particu- lar shape came into existence and the law of condensation finally permitted the produc- tion of the flat-topped cluster of the sunflower in which hun- dreds of flowers are gathered together on a broad circular disk. Among these flowers of 3 5 Fic. 210. Corn-flower. After Britton and LU one Brown. the disk a division of labor Minnesota Plant Life. A415 arose so that some flowers abandoned their stamens and pistils and became converted into neutral ray flowers, useful in adding to the attractiveness of the cluster, thus possibly inducing in- sects to visit it more freely. The heads of flowers came them- selves to stand in definite compound clusters, so that just as there was a spike of flowers in the plantain family there later came to exist a spike of fower-heads, as in blazing-stars, and just as the flowers of the high bush cranberry learned to stand in flat-topped clusters, so in the thoroughworts and asters. heads of flowers were arranged in similar inflorescences. Each flower of the composite head shows a high degree of fusion between its parts. That is to say, it is a flower of high rank. The originally separate carpels are blended in pairs into the fruit-rudiments, one to each flower. The stamens in all Minnesota genera of composites except one are fused. The petals of the corolla are blended into a tube which in some of the flowers becomes split, to make the strap-shaped corolla of the dandelion or the strap-shaped ray flower of the daisy. The calyx parts are blended together into a calyx tube and this be- comes fused with the surface of the fruit-rudiment, developing in many of the genera a distributing apparatus made up of bristles, variously arranged and of various structure. The leaves below the flowering head, in such forms as the burdock and cocklebur, become modified to assist the distribution of the seeds. Three types of higher plants may be regarded as terminal, the orchids standing at the top of the series of plants with one seed leaf, the dogwoods at the top of the lower series of two seed-leafed plants, and the sunflowers, dandelions and thistles at the top of the highest series. Among orchids, the flower cluster was not highly improved as such, but the perfecting tendencies worked rather toward the production of a much complicated floral mechanism, irregular in shape, reflecting the strong influence of those forces which develop bilateral sym- metry, and very exact in its adjustment to the habits of the insects which co-operated in its pollination. The clusters of the dogwood, although not so fully perfected as those of the sun- flower, showed, in the arrangement of their flowers, some tend- ency towards the perfection of the flower cluster as a unit. 416 Minnesota Plant Life. Especially in the flowering dogwoods and dwarf cornels, with their conspicuous bracts below the heads of flowers, did there arise an adaptational response to the tastes and habits of insects, equivalent to that secured in sunflowers by the specialization of the ray flowers. In the bunching of the edible fruits of dog- woods and in their high coloration, the frwit-cluster, as such, became a definite factor in the mechanism of seed distribution ; for the aggregation of the fruits made them more attractive to birds and animals, therefore more likely to be disseminated than if they had been scattered loosely over the general surface of the plant. In composites, winged distribution has, for the most part, been adopted, and in this family highly colored, pulpy and edible fruits do not exist. The aggregation of the flowers, how- ever, is perfected and the co-operation of the calyx, from which the pappus is formed, makes the distribution of the fruits quite as certain as among the dogwoods. A sunflower head may, upon the whole, be regarded as the most perfect structural response to the static conditions of the plant world, just as the human head, with its wonderfully per- fected brain and sense organs, may be regarded as the highest structural response to the dynamic conditions of the animal world and of animal life. Chapter eke, Adaptations of Plants to their Surroundings. GF It has already been remarked that plants which resemble each other in external form must not for that reason alone be con- sidered as related. Indeed, quite the opposite is often true, and plants that are outwardly very dissimilar are found upon careful examination to bear the marks of kinship. Thus, the locust tree and the pea vine are really connected with each other much more intimately than are locusts and ashes, although the latter are similar in size, in habit of growth and even in the production of such special types of starch-making organs as pinnately-com- pounded leaves. Plants may, however, for purposes of investi- gation be arranged in groups according to their adaptations to the various conditions of life and growth. Such adaptational groups will include plants of widely different genealogy, but throughout there will be discovered certain similarities of struc- ture and habit. Thus, for example, among aquatic plants there are often striking likenesses in structure between comparatively unrelated forms, and it is in many instances a puzzling problem to determine just which structural resemblances are indicative of true relationship and which are indicative of similar adapta- tions to similar conditions. The submerged leaves, for illustra- tion, of the water crowfoot or water buttercup are in general appearance not particularly different from the submerged leaves ofthe bur-marigold. 1n both plants those leaves produced un- derneath the surface of the pond in which they live are dis- sected into fine, threadlike portions. Again, the quillworts, plants belonging to the fern alliance, bear the same type of cylindrical hollow leaves that is distinctive of the water lobe- lia—a member of one of the highest families of flowering plants. Or, passing to plants of a different habit of growth, it may be noted that the curious, compressed forms of vegetation charac- teristic of cacti are almost exactly reproduced in members of 28 418 Minnesota Plant Life. the unrelated spurge family at the Cape of Good Hope. The pitcher-plant and sundew have developed apparatus for catch- ing small insects and converting them into food for their own uses, and somewhat similar contrivances are met with in the bladderworts and butterworts; but the two groups of plants, so far as true relationship goes, are very widely separated. With such facts in mind, it is apparent that, if genealogical connection be ignored, plants may be grouped according to their adapta- tions. By this means certain interesting truths may be em- phasized concerning the influence, upon plant structures and habits, of the surroundings. Before entering upon any discus- sion of the various adaptational groups of plants represented in Minnesota, such as water plants, desert plants, carnivorous plants, perching plants, mat plants, wand plants, shade plants, sun plants, rock plants, marsh plants and a number of others, it may be briefly noted what are the principal external conditions to which plant structure and habits are adapted. Gravity. A plant, like any other natural object, must main- tain itself under the constant influence of the force of gravity, and it is, therefore, necessary that it should be architecturally well constructed. An imperfectly constructed tree trunk could not bear the weight of its branch-system, nor of its thousands of leaves and possibly of fruits, unless—precisely as in works of man, such as elevators, aqueducts or bridges—the laws of en- gineering had been obeyed. Certain necessary ratios exist, therefore, between the thickness of tree trunks, the tenacity of the wood, the height of the tree, the number of branches, and the angles at which they stand upon the main axis. For this reason a limit is fixed for the height of land vegetation, beyond which it is extremely difficult to pass. If, however, in the life of the plant some method is found by which support can be obtained from without, much longer stems can then be produced and they can remain of slenderer habit. Thus the climbing bittersweet, the wild grape vine, the trumpet-creeper, the pipe- vine, or the bean, are enabled to produce stems much longer in proportion to their thickness and strength than would be pos- sible if they did not utilize neighboring vegetation to help bear the weight of their leaves, twigs, flowers and fruits. The sup- port that is obtained by a plant stem need not necessarily con- Minnesota Plant Life. 419 sist of the vegetation around it, but the stem may lie flat upon the ground, as does the strawberry runner. Thus supported, it can remain slim and fragile, but it could not do this if it main- Fic. 211.—Bur oak and bracken fern. Illustrates relation between strength of stem and the weight to be borne. After photograph by Hibbard tained an erect habit. Again, water surrounding the stem and leaves of a plant may furnish the necessary support, and the plant is free to produce slender organs which collapse when 420 Minnesota Plant Life. removed from the water that buoys them up. Thus, in the pipewort, which, from the bottoin of a lake, lifts a thread-like stem ten feet or more in length, an organ is formed that could not be thus developed under ordinary terrestrial conditions. A great many other adaptations besides these simple ones of length and thickness of shoots might be discussed at this point. For example, it is necessary that seeds or fruits, borne at the tops of trees, should not be of such structure that they would be broken and injured by falling to the ground. Cocoanut seeds, therefore, which are heavy and are produced at a considerable height, have thick, hard shells and are not injured by their fall. A definite relation commonly exists between the stem of a leaf and the blade, or flat portion, so that the leaf 1s extended in a position such that its leaf-green can do the work of starch-mak- ing under the influence of sunlight. So the stems of large leaves are generally strong and often of a half-cylindrical shape, giving the strength of an arch to the lower surfaces. The net- work of the large leaf is stronger than that of the small leaf, just as a large umbrella must have a stronger frame than a child’s parasol. If leaves or fruits are produced close to the ground they may become larger, while remaining more delicate in struc- ture, than if they were produced at a considerable height. In the one instance the fall would be harmful, while in the other the influence of the wind would enter as a factor. Mechanical forces. besides being exposed to the force of gravity acting constantly upon its structure, and consequently rendering due attention to strength of materials a prime requi- site in plant architecture, the organism is subjected to various forces which would tend to demolish it unless it met them with properly constructed areas. As examples of such agencies, there might be mentioned currents of air, which if violent are often known to damage the bodies of plants; currents of water, to which plants growing in rapid streams are particularly exposed; the action of waves, to which the various surf plants must adapt themselves; and the pressure of soil, air and water, by which the different parts of plants are constantly affected. In erect ter- restrial vegetation elasticity is to a certain degree a requisite of structure. This is particularly true of such stems as are slender, unsupported, and exposed to the influence of wind or surf. Minnesota Plant Life. 421 Beautiful examples oi elastic plant organs are furnished by any field of grain over which a gust of wind is passing. The stems with their heavy heads of fruit, under the breeze bend almost to i 7 Fic. 212.—Willows and bulrushes. ‘The latter are typical surf-plants. After photograph by Williams the ground, then as the air becomes calmer elastically swing back again into the erect position. Or, when it 1s blowing a great 422 Minnesota Plant Life. gale along the lee shore of some Minnesota lake, one may see the bulrush stems beaten into the water by the wind and surf, only to rise again erect and unharmed when the waves are calm. Such elasticity is procured by special structural areas in the stem, disposed in highly accurate fashion so as to take up the lateral strains evenly and effectively. The cross-section of a bulrush stem shows it to be as cunningly constructed as the finest bridge-truss, with girders, flanged in the regulation style, made up of the so-called “tension pieces” and “compression pieces” of the architect, and constituting an altogether admi- rable piece of structural engineering. Such contrivances are not needed by plants growing under other conditions and will not be found. Elasticity, for example, is not a noteworthy char- acteristic of the stem of submerged aquatic plants living in quiet pools; but if the stem grows in running water it 1s some- times more elastic. Roots, in general, being underground in their habit, are not so much exposed to occasional displacing forces as are stems and, therefore, are by no means so elastic. It is easy to compare, in these regards, a grass stem and a grass root. If the living erect-stem of a rye plant is bent down it quickly resumes its original position; but if the root is bent to one side the resumption is but slight, or there is no resilience. In certain parts of the world, where heavy falls of snow occur, a weight is in this way piled upon the branch system, and the plant perhaps responds to such a climatic state by growing in the form of a flat, prostrate shrub, as many of the heaths have done. Or, if it be a tree, it learns to produce strong drooping lateral branches like those of the spruces. When grown in a lawn, these trees retain the droop of their branches or branch- lets—originally a structural device for shedding masses of snow, that might otherwise break the branches by their weight. Plants that produce abundant and heavy fruits must, if they support the weight of these fruits, develop strong branch sys- tems, or otherwise the body of the plant will be broken. Of this the apple trees of orchards furnish good examples. The branches of the apple are pulled into a more horizontal posi- tion by the increasing weight of the fruit and many of them actually droop. The main branches will, however, be found to be strong and-well buttressed against the trunk. Very often, Minnesota Plant Life. 423 under a heavy branch the trunk of the tree is especially strength- ened to bear the weight. And so, too, against the massive roots of a tree, the trunk is often buttressed because it is against these points that the pressure is exerted, when the tree top is pushed laterally by the wind. Plants with comparatively slen- der branch systems may mature large fruits if they let these fruits le upon the ground. This is the device adopted by the gourd family, and the gigantic pumpkins and squashes whicb are so often exhibited could scarcely be borne, except under very exceptional conditions, upon plants that carried the whole weight of such enormous bodies themselves. Some plants, it is true, manage to suspend extremely heavy fruit areas. Thus, the banana forms a bunch of fruits weighing in the aggregate some scores of pounds. But it is borne close to the main trunk and is hung in such a way that the strain is not unbearable. Cocoanuts, which form heavy fruits at a considerable height, have them placed close to the center of the tree, not out near the tips of the branches like those of the apple. The relation between the sizes of leaves and their exposure to the winds has already been mentioned. It is not possible for large, thin and delicate leaves to maintain themselves under climatic conditions in which heavy winds are prevalent. If large leaves occur in windy districts, their edges are strengthened by special adaptations of the leaf network. Very beautiful ex- amples of strengthening devices for the edges of leaves may be seen in milkweeds, basswoods or catalpas. In the latter tree, especially, the edges of the large, heart-shaped leaves are faced by arch after arch of network, making the margin of the leaf very strong against any lateral tearing agent. A consideration of the points which have been thus briefly presented will show how reasonable it is that the longest stemmed plants in the world should be oceanic, for such stems have water on every side to support them. It will be equally apparent how reasonable it is that the most massive plant struc- tures and the strongest should be the trunks of trees on land, for these, of all plant organs, have the greatest need of strength if they are to perform their work and meet the forces to which they are subjected. The difference of elasticity between differ- ent plants growing under different conditions, or between two 424 Minnesota Plant Life. differently conditioned organs of the same plant, will appear altogether comprehensible. After such facts have become familiar it should not be difficult to infer something of the his- tory of a plant from its general architectural construction. ‘The droop in the branches of a spruce tree comes to have its sig- nificance, and the prostrate bodies of the cranberry or par- tridgeberry tell a similar story of the flattening effect produced by heavy falls of snow. Heat. Another natural force to which plants must necessa- rily adapt themselves is that of heat. Therefore, under different temperatures different forms and habits of vegetation may arise. The range of temperature under which dormant life can be maintained is apparently a pretty wide one—between 400 and 500 degrees centigrade. The spores of some bacteria can en- dure boiling for an hour or more and, for a short time, a dry heat somewhat higher, while certain seeds have been exposed for a season, without killing them, to the low temperature of liquid aid. But the limits of plant growth, so far as regards tem- perature, are considerably narrower. night, | to increase | morning. 432 Minnesota Plant Life. While light has a retarding influence upon the growth in length of stems, it has a strong directive influence upon organs, so that they tend to place themselves parallel with the rays, or transverse to them, as their nature may be. It is well known how the leaves of geraniums growing 1n the window turn to- ward the light. Nasturtium vines turn very quickly and if one of these plants be put in the window, it will in a short time stretch out its leaves toward the light and place them vertically to the rays, thus securing a maximum illumination for the starch-making apparatus. Some plants are not thus sensitive FIG. 216.—Leaves of the sensitive fern, a shade-loving variety. After photograph by Hibbard. to light. For example, such climbing plants as the ivy or the woodbine do not instinctively bend toward the light, because to do this would tear them from their supports; therefore, they remain either insensible to the directive influence of light, or they actually turn from it, as do most roots. Where the light is strong and abundant, there are often de- veloped purple layers on the under sides of leaves to utilize the surplus light by converting it into heat and employing it for the growth-energy of the plant. This is true of such large Minnesota Plant Life. 433 floating leaves as those of the water-shield, in which the upper side of the leaf is green and the lower is purple. ‘The giant lily of the Amazon, sometimes cultivated in aquatic gardens of parks in Minnesota, has great shield-shaped leaves, two feet or more in diameter, and fitted to float upon the surface oi the water. The edge of the leaf is turned up to prevent ripples from break- ing over the surface. While the upper side is green the under side is violet or purplish. The surplus light, not used in starch- making, is,in sucha leaf converted, by the purple coloring mat- ter, into heat, and is not lost. When leaves form rosettes an adaptation for saving the sur- plus light is often noticeable. Thus, the under sides of dande- Fic. 217.—The Virginia creeper on the walls of the old round tower, Fort Snelling. This plant does not turn towards the sun, but clings to the shaded wall. After photograph by Williams. lion leaves are commonly purple; and in a great many other rosette-forming plants the leaves of the rosette will have the color scheme which has been described. Hanging or swing- ing leaves that are swayed by the wind, for reasons that are sufficiently obvious, do not so often have the two sides colored in this manner. Protection of the leaves against an illumination strong enough to injure the starch-making machinery within, is of various types. Sometimes the leaves are covered with scales, or hairs, thus tempering the light. Sometimes they are capable of changing their positions, so that when exposed to direct sunlight they shift from the transverse to a more ver- 29 434 Minnesota Plant Life. tical position. This is true of leaves in the compass plant and many leaves on a variety of herbs. In some of the Austra- lian blue-gum trees the leaves stand with their edges ver- tical, and similar positions are very often maintained by grasses of the prairie. When a plant has adopted the mat habit of growth, indicating the absence of shade around it, it commonly shows very small leaves, and no Minnesota mat plant, lying exposed to the full glare of the sun as it does, has large leaves. Moisture. ‘The adaptations of plants to moisture are vari- ous. Some plants live quite submerged in water, and others find Fic. 218.—‘* Gallery woods,’ near Minnesota Falls, valley of the Minnesota, in the prairie district. Dependence of trees upon moisture is illustrated by their grouping in declivities. After photograph by Professor R. D. Irving. their most congenial home in deserts, or on the surfaces of inhos- pitable rocks ; while between these two extremes of station there are a great number of intermediate conditions worthy of care- ful and extended investigation. All plants need some moisture. Usually this moisture is absorbed by a special area of the plant known as the root system. But leaves are, in some varieties, able to absorb moisture, and aquatic plants characteristically absorb over their whole surface. There are sometimes pres- entations of liquid to the plant which it finds undesirable. For example, foliage guards itself by a variety of devices against the heavy rains of the tropics. Many of the same contrivances Minnesota Plant Life. 435 may be seen in plants of northern regions. If leaves are ex- posed to a heavy rainfall the surfaces are often lacquered or waxy, and, by means of the coating, rain is diverted and there can be little danger of the tissues becoming water-logged. Upon such leaves grooves or furrows may be developed. Through these the water is quickly drained and is not allowed to accumulate. Slender points are distinctive of leaves upon which too much moisture accumulates for the good of the plant, and especially in tropical forests are these rain-tips, as they are called, ordinary characters of the leaf. It has even been shown that trees growing in the spray of waterfalls develop leaves slightly different in shape from the ordinary leaves of the species and marked both by furrows on the upper side and by elongated tips. Because of the danger of rain or dews clogging the air pores of leaves these tiny apertures are in most instances assembled on the lower surfaces of leaves, where they are protected. Or, if they occur on the upper surfaces there are hairs, or pegs of cell wall substance, or blooms of wax or shellac, which guard them and make it difficult for them to be wet. Such protections against moisture are particularly common in flowers, where it is essential that the pollen should be kept dry. The shapes of the petals, the positions of the stamens, and a variety of other adaptations make the wetting of pollen by rain improbable. Many fruits are furnished with blooms of wax or with hairs by means of which they easily shed water. No such contrivances are to be looked for in the root system, or on the leaves or stems of submerged plants. In water-lily leaves and other floating varieties, where the air pores are all upon the upper surface of the leaf, decidedly waxy coatings are often developed to keep the water from the pores. In some varieties, as, for instance, the oleander, the pores open into special chambers or depressions, on the under sides of the leaves, and the mouths of these are guarded by “non-wettable” hairs, thus affording absolute protection to the air pores. Many of the different positions, shapes and textures of leaves and flowers are to be ascribed to such adaptations against unfavorable moistening. The root tract of plants, which in most instances is the spe- cial absorptive area, is fitted by structure and position for the work it has to do. The young roots are furnished with in- 436 Minnesota Plant Life. numerable delicate hairs and these are thrust between the crev- ices of the soil to collect whatever moisture there may be present. If, however, the roots are immersed in the water and hang down like the little balancing roots of the duckweeds, root hairs are not then so abundantly produced because moisture is plentiful everywhere around the root and no special arrange- ments for its collection are necessary. Moisture, after having been collected by the plant through the activities of the absorb- ing surfaces, is evaporated, and the residue is left in the plant, either to be combined with other substances in the plant chem- istry or to remain as a useless by-product. Evaporation and transpiration of water vapor are the ordinary methods by which plants rid themselves of the superfluous water they have ab- sorbed; but some varieties exude it in drops from special water- excreting glands. Thus, fuchsia leaves, if well supplied with water at the root, will excrete it in little drops from each tooth of the leaf margin. There are at least three conditions under which plants find it undesirable to excrete or transpire water rapidly. One condition is that of the desert, where there is very little water to be obtained, and its rapid transpiration by large evaporative surfaces would result in the wilting of the whole plant. Another condition under which rapid evaporation is undesirable is that of bogs and marshes, and the reason 1s just the opposite. Here there is such an abundance of moisture that the rapid evaporation of it might maintain an unneces- sarily strong stream through the plant tissues. A third con- dition is where the soil-water is impregnated with salts, and if rapidly evaporated it would be as rapidly absorbed, and the salts would accumulate in the plant tissues to such an extent that they might interfere with vital processes. Consequently there are three groups of plants so situated that, while they permit water to evaporate from their leaves and stem, their adaptations of structure are for slow transpiration. The cacti, with their sclid stems and reduced leaf surfaces, are examples of one class. The tamaracks and spruces, with their small needle-shaped leaves, are examples of another, and the sea- blites and glassworts of the salt marshes furnish examples of the third. Minnesota Plant Life. Aa7 A variety of contrivances have been devised by plants to retrench their evaporation. A simple one is the reduction of the evaporating surface. Thus, leaves become small or are altogether abandoned, as in the cacti and glassworts, or the leaves may become thick and succulent, as in the purslanes and claytonias. Sometimes the skins of the leaves are greatly thick- ened and the air pores are reduced in number, as in the leather- leafed wintergreens and heaths. Often the margins of the leaves are rolled in so as to cover the air pores and protect them from the rays of the sun, as in many prairie grasses, or in the crowberries. Sometimes the leaves are covered with scales or scurf, as in the buffalo-berries. Sometimes strong ethereal oils are produced. These form a “‘scent-vapor-sheath” around the plant, and thus temper the rays of the sun. For such a reason many desert plants are strongly perfumed, as are wormwoods or sage-brushes. The positions of the leaves upon the stem, and their shapes, are often automatic, regulative devices, con- nected with the evaporation of moisture. Good examples of leaf-position unfavorable to rapid evaporation are furnished by the cat-tails, flags and sweet-flags of marshy places. In these the ribbon-shaped leaves stand erect and their surfaces are not exposed to the strong illumination of the sun. Hence the evaporation is slight. Electricity and magnetism. The adaptations of plants to the forces of electricity and magnetism are not well understood, nor have they yet been fully studied. It has been suggested however, that points on leaves, and spines or thorns, may in some instances be devices for the collection of atmospheric electricity. The soil or substratum. ‘The relations of plants to the soil are somewhat various. The texture of the soil may be either loose or firm. Good examples of loose soil are furnished by sand dunes, and there are a variety of special sand dune plants, the underground parts of which, meeting with little resistance, branch copiously in every direction. The low fertility of drift- ing sand makes such a broad expansion of the root area essen- tial, and as a consequence the plants that are able to grow on sand dunes commonly bind the sand by their extensive root systems, and may even, if they have become sufficiently estab- lished, stop its drifting. In very resistant soils, such as hard 438 Minnesota Plant Life. clays, less copiously branched root systems are produced. The temperature of the soil, as well as its texture, has a variety of well-marked effects upon root areas, as has also the consist- ency, the chemical constitution and the aeration. Soils which are very poorly aerated, such as those disposed underneath sheets of water, often make it necessary for roots developed in them to send up aerating tubes or organs. The well known “knees” of the swamp cypresses of the Atlantic region are ex- amples of such organs. A greater or less percentage of nitrog- enous substance, lime, magnesium, iron or silica, in the soil has a distinct determining effect upon the forms of plants. Especially interesting is the soil known as humus, a type which contains a large percentage of decaying organic material. In such a soil many plants without leaf-green are enabled to grow, and upon the humus of the forest floor a wealth of mush- rooms, club-fungi, cup-fungi, slime-moulds and various related forms are displayed. Some seed-producing plants, such as the pine-drops, the Indian-pipe, and the pine-sap, together with the coralroots and others, have learned to abandon their leaf-green and have adopted the habits of life similar to those of the fung1. Other living things. The proximity of other living things is a condition of the surroundings that cannot be disregarded in the discussion of plant adaptations. These neighboring crea- tures may be either plants or animals. In response to their presence a large variety of curious structures and habits have come into existence. The carnivorous plants catch and eat small insects with which they come in contact. Parasitic fungi, such as the caterpillar fungus or the fly-cholera fungus, attack certain small animals and use their bodies for a soil in which to grow and mature. ‘The roots of louseworts, toad-flaxes, and cancerroots, reach out and attach themselves to the roots of neighboring plants, in some instances deriving their whole sustenance in this manner. A great variety of little fungi develop upon the leaves, twigs, flowers or fruits of other plants, having become accustomed to eke out an existence in this dependent manner. Many plants perch upon other plants; thus, the Spanish moss of the south hangs in festoons from the live-oaks, and the orchids of South America sit in rows, like so many partridges, upon the branches in the forest. The lichens Minnesota Plant Life. 439 of more northern regions similarly perch themselves upon the trunks, or branches, of trees; and with these, too, a number of mosses and liverworts will be found. Sometimes the perch- ing-plant adroitly selects a position where it will receive more moisture than elsewhere. So, many mosses grow around the bases of tree trunks,—for the tree with its branches serves as a drain, by which the water of rains is brought to the position pre-empted by the moss. Lichens and mosses alike select the degree of illumination that they prefer, and in northern lati- tudes arrange themselves on the southern sides of tree trunks if they require stronger illumination, but on the northern sides if their requirements lie in the other direction. Some perching plants acquire the habit of driving their roots into the branch upon which they stand. Thus originated the parasitism of the mistletoe and related plants,—quite a different method of its development from that shown by the cancerroots, which learned to clutch the roots of neighboring plants and drive little suck- ing organs into their soft and nutritious tissues. Another result of the mutual proximity of plants is the development of climbing or twining species. Some climb by means of prickles, thorns or hooks, and thus the brambles or tear-thumbs lift themselves upon surrounding vegetation. Others, like the scouring-rushes, brace themselves by means of lateral branches and lift their slender stems farther into the air than they could without assistance. The clematis vines twist their leaf stems around twigs that chance in their way and thus show a tendency toward tendril production. Other vines, like the smilaxes, the grapes, or the wild cucumbers, develop per- fected tendrils, and by aid of these lift themselves high up on the stems or branches of neighboring trees. The bittersweets, morning-glories and hops learn to roll spirally their slender stems around the shrubs that stand near them, thus twining to a considerable height. All such habits must have arisen by degrees, and each of them, when accentuated, might encourage dependent habits of nutrition, finally resulting in parasitism. Thus, the twining habit of some morning-glory vine may have given, in some earlier epoch, opportunity for the production of the parasitic dodders. 440 Minnesota Plant Life. Intra-specific adaptations. A last group of adaptations that may be considered here are those connected with spore distribution and seed distribution. It is necessary for the well being of the species that new individuals should be given an opportunity to develop. Thus arose such simple primitive adaptations as the elongation of the spore-bearing plant in mosses and liverworts, so that the spores could be distributed over a wider area. More perfected apparatus enabled the spores to be distributed under conditions of moisture such that they would most certainly germinate. As spores assumed a division of labor, devices were adopted by which the two sexual plants might be produced close together, thus insuring fecun- dation of the eggs. The ancestors of the seed-bearing plants originated methods of keeping the young embryo close to the vegetative areas of the preceding individuals in the species line. In this manner there arose in the plant kingdom such complex structures as flowers and seeds. With the added complexity of structure it became possible for a great number of slight differences in detail to exist and thus the highest division of the plant world, that of the seed-bearing plants, is also the one in which the greatest number of different species are described. A vast number of intricate adaptations for pollination, embryo- nursing, and seed distribution came into existence. In some families of plants wind pollination, or wind distribution of seed, became the rule, while in others the seeds are distributed by animals and the pollen spores are planted on the stigma of the flower by the same animate agents. All the manifold variety of form in flowers and fruits may be regarded as due to adapta- tions, more or less perfect, by which the two sexes of plants are developed sufficiently near together, by which the young plants may derive benefit from supplies of nourishment produced by maturer individuals of their species, or by which they are placed under conditions favorable for their growth and for the best interests of the species as a whole. Minnesota Plant Life. 441 Fic. 219.—Dandelion fruiting in shady spot. Shows the slender stems and erect root-leaves of the shady habitat, and fruits adapted for wind distribution After photograph by Hibbard Chaprer cer Hydrophytic Plants. %F The different adaptational groups of plants may be best classified under three main divisions, according to the relation between the structure of the plant and the moisture of sur- rounding conditions. For one series of plants the moisture of the surroundings may be considerable, for another it is ordi- narily slight, while for the third a middle condition is main- tained. ‘Thus, there are three principal adaptational groups, known respectively as hydrophytes, of which aquatic species are typical; werophytes, of which desert inhabitants are char- acteristic forms; and mesophytes, in which group may be classi- fied the common herbs of meadow and forest, growing under medium conditions of moisture. It should be noted in pass- ing that while the essential structural adaptation of desert plants is toward the slow evaporation of moisture, there are also other conditions, besides those of desert life, that make rapid evaporation undesirable. Hence plants growing in peat-bogs, such as tamaracks and spruces, or plants grow- ing in saline localities are said to have the xerophytic type of structure and, like true desert plants, are slow to transpire moisture. A number of different subdivisions of the three main classes may be described, and one should regard the marsh and swamp varieties, and those living in saline soil, as furnishing the transition to the true middle group, that of the mesophytes, which will here be discussed after a brief account of the other two. Out of fourteen classes of hydrophytic plants described by Eugene Warming, in his classic work upon adaptational groups of plants, eight are represented in Minnesota. Those unrep- resented are either arctic or alpine, such as the snow plants, or marine, such as the seaweeds, and the mangrove swatmps of oceanic coast lines. Minnesota Plant Life. 443 Plankton. ‘The first class of hydrophytic vegetation is that known under the technical term of plankton vegetation. By this is meant the passive, free-floating vegetation, not rooted or attached to the soil in any way. To this type, no doubt, belong the earliest forms of life that appeared upon the crust of the earth. Here are to be classified many algz—such as the familiar water-flower of Minnesota lakes, which, as will be remembered, is a type of blue-green algze. A number of Min- nesota varieties belong to the algal plankton, for here are in- cluded not only the water-fHlower, but such forms as the sphere- alga, the pond-scum, the desmids and diatoms, the rolling alga and a number of others. Some of these plants are characterized by the production, between their filaments, of interlocked gas bubbles, by which they are enabled to float at or near the sur- face of the water, and thus to receive the sunlight. In many of them there are formed reproductive bodies provided with swimming lashes, and by the aid of such little motile cells the plant may be distributed throughout the water of a lake or pond. Another group of plankton vegetation is constituted by the bacteria that live in water. A great many different sorts are known; not only from fresh water, but from the sea. Any drop from a Minnesota lake or river, if carefully examined by the proper methods, would be found to contain great quantities of the bacterial organisms. Still another group of plankton vegetation is what may be called derived, or secondary plankton. This group is composed of passive, free-floating plants which are, from their structure, evidently derived from ancestors that were rooted. To this divi- sion belong the little water fern Asolla, the duckweeds, form- ing such abundant scums on stagnant pools, and the bladder- worts, together with some varieties of liverworts, such as the swimming Riccia and the floating Riccia. A number of pecul- iar adaptations exist in plants of the derived plankton. Often in their bodies there are air chambers by means of which they float. ‘These may be seen in cross sections of duckweed plants or Riccias. Sometimes the air chambers are developed as spe- cial pouches or bladders, as in bladderworts, where they also fulfill another function—that of capturing smali animals for food. If the plant floats on the surface of the water, with its 444 Minnesota Plant Life, upper side exposed to the air, as do the duckweeds, certain special structures are necessary. First of all, proper counter- poises must be carried to prevent the plant from being turned upside down by the ripples. In the duckweeds these counter- poise areas are readily seen to be roots, or groups of roots, but in the smallest of the duckweeds no counterpoise exists as a special organ, since from the very small size of the plants they are able to ride the waves without their upper surfaces being wet. In one of the water ferns—the little Salvinia plant, common in greenhouses, where it grows in tanks—two rows of leaves on the floating stem are thrust down into the water and act as counterpoises; but in the wild water fern—the tiny Azolla— just as in the duckweeds it is the slender roots that perform this function. Sometimes skillful combinations of counter- poises and floating apparatus are effected, as in the handsome water-hyacinth of conservatories—a species which has become a great pest in the rivers of Florida. In these plants the bases of the leaves, which arise in rosettes, are swollen into spongy, spherical floats, an inch or more in diameter. Below such a circle of floats a tuft of roots hangs down into the water, and it is quite impossible for any ordinary gust of wind to turn the plant upside down. A second group, also, of adaptations are interestingly de- veloped in the free-floating higher plants by means of which the upper surfaces of natant organs are protected against wet- ting. Sometimes the surface is very smooth and glistening and the water rolls from it in the spheroidal form just as it does from a buttered plate. This is the condition to be ob- served in the larger duckweeds. The upper surface of the small disc-like stem of these plants is somewhat convex and very smooth. If water is poured upon a group of duckweeds as they float upon the surface of a pool it will roll off as from the pro- verbial duck’s back, and will leave the little plants as dry and glistening as before. One of the duckweeds, the three-cor- nered variety, is a partially submerged plant and therefore has not this power of shedding water. Another arrangement is seen in the water fern, Salvinia. The upper surfaces of the floating leaves are provided with curious tufted hairs, the tips of which spread out in three or four branches If one of the Minnesota Plant Life. 445 Salvinia plants is taken between the thumb and finger and thrust under the surface of the water, air is imprisoned between the tufted hairs and the whole plant glistens as it is submerged. If it is released it rises instantly to the surface, buoyed up by the air chambers in its leaves and stem, and when it emerges the upper sides of the leaves will be found perfectly dry. Of the planktonic flowering plants of Minnesota, some de- pend upon the wind for pollination, as do the duckweeds, while others, such as the bladderworts, are adapted to insect pollina- tion. The flowers, therefore, of the duckweeds are extremely inconspicuous, while those of the bladderworts are pretty, yellow, snapdragon-like and elevated upon stems some inches in length, so that they become noticeable objects and are easily found by wandering bees or flies. Some free-floating or plankton plants are particularly protected against the attacks of small aquatic grazing insects or animals, while the bladderwort actually catches and eats the little insects that gather in its vicinity. The Salvinia plant is provided, on its submerged counterpoise leaves, with sharp-pointed hairs, and these stand out on every side in bristling defence. The sharp-pointed hairs are par- ticularly useful because the fruits of the Salvinia are borne under water, on the submerged leaves, and it is important that they should be protected. The under sides of the floating leaves have also a defence of sharp-pointed hairs, but the hairs on the upper side, since they have a different purpose—that of keeping the surface dry—are of different structure. Swimming plants. Closely related to the plankton, or free floating vegetation, are the animal-like little plants that swim about in the water seeking decaying organic substances upon which to feed. They are abundant in stagnant water where there is sufficient organic food material. A Minnesota plant, known to botanists by the name of Euglena, is an example of this class of hydrophytes. It is able, by means of its green color, to assimilate carbonic-acid gas in the presence of sunlight. It takes up its nitrogenous food from the organic substances dis- solved in the stagnant water and is, therefore, in its method of nutrition, partially dependent. The Euglena plants are of microscopic size and countless myriads of them in stagnant pools often form dense green scums of a granular appearance. Zoologists consider them animals. 446 Minnesota Plant Life. Rain-water plants. A little class of obscure plants are re- garded as of hydrophytic character, since they live on rain- water. The green slime that forms upon mud flats, the bacterial skins that arise upon soil highly charged with or- ganic substances, the blue-green algz that thrive between the particles of sand upon a moist beach, and the curious algal or bacterial organisms that live under the surface of damp sand- stone cliffs, looking like cobweb threads when a bit of the cliff is chipped off, might be given as examples of this class. Attached water plants. Another adaptational class of hydro- phytes is furnished by those species which live attached to stones, either at the bottom of streams or lakes, or upon the surfaces of wet cliffs, or those of bowlders exposed to spray. Several algze are found in such localities. On wet cliffs a variety of green algz are to be looked for, and here, too, especially near waterfalls, will be found the very few kinds of red alge which occur in Minnesota. Sometimes a dark brownish-purple skin of slimy alge may be seen on cliffs wet by the spray of waterfalls, and this may be a growth of red alge. In similar localities, and on stones in rapidly running streams, the wire like, reddish-brown algz of the Minnesota flora are to be sought. Some higher plants select similar localities—for example, the river moss so common in swift, rock-bottomed streams, where it grows attached to stones and lies in tufts with the cur- rent. ‘The very curious riverweed, of which one variety exists in Minnesota, affixes itself to stones in waterfalls, and closely re- sembles an alga. It is remarkable because it is the only kind of Minnesota flowering plant that opens and pollinates its flowers entirely below the surface of the water. A character- istic structure of attached rock plants in rapid water is the holdfast, an organ which has more the office of an anchor than of an ordinary root. In the river moss the ordinary slender root hairs characteristic of mosses are gathered together in strands, thus giving additional strength, and by means of these little cables entwined around the rough corners of the stones the plant holds itself in place. Plants of this sort with hold- fasts and with submerged vegetative tracts naturally do not have abundant air chambers as in the floating varieties. On Minnesota Plant Life. 447 the contrary, air chambers are often entirely absent. Where, too, the plant is anchored and free to undulate its branches with every ripple of the water there is little occasion for strong mechanical tissues, and no need for air pores or any of the devices for protecting them. Elastic tissue is, however, some- what useful, and in many plants of this class it is formed. A great number of the submerged plants are slimy to the touch, especially in the ocean. ‘This is well known to be true of sea- weeds and it is also the case with river moss and riverweeds. Such slime-coverings may be useful as protections during periods of low water, or they may reduce the friction, upon the tissues of the plant, of the flowing water. Still another class of water plants are attached under water to loose soils, sand or mud. The water eel-grasses may, perhaps, be taken as examples of this group. Holdfasts are not here de- veloped simply as anchors, but there may also be branching root systems upon which, however, root hairs are often wanting. Shore and bar plants. The most important class of water plants that are of genuine aquatic habit, so Fic. 220.—Vegetation of ravine. ‘The home of far as developed in Minne- mosses and liverworts. The plants in R front are touch-me-nots. After photograph sota, are those which may by Williams. 5 ON Soom be known as the shore ryan : 5 a ed +4 plants and bar plants. These are attached or submerged vari- eties, growing upon loose soil, generally in communities, with the plant body either entirely submerged or with the leaves floating. The flowers are entirely aerial and pollination cannot go on under the water. It is difficult to distinguish this class of aquatic plants from the related swamp plants that grow close down to the water’s edge; and in fact, sometimes the same 448 Minnesota Plant Life. kind of plant appears both as a lake-border and as a marsh plant, as, for example, the common yellow pond-lily, which may grow upon mud flats, or more ordinarily out a little dis- tance in the pond. Of the shore and the bar plants a number of different varieties belonging to various groups occur in Min- nesota. Among the alge, the bass-weeds, so common as the outer zone of shore plants in almost every Minnesota pond or lake, are most prominent. In some ponds, especially the smaller ones of swales, prairies or meadows, the water mosses are abundant. ‘These have a different adaptation from the river mosses. They do not have strong holdfasts by which to maintain themselves in rapidly flowing water, but are spongy masses of vegetation and evidently near relatives of the carpet Fic. 221.—Stream-side vegetation. Ironweeds, thoroughwort, mullein, sedge, speedwell and shrubbery. Hydrophytic vegetation in water’s edge. After photograph by Williams. mosses of the woods. When they fruit, the spore cases are sometimes thrust above the surface of the water, but often the spores are shed below the surface. To this group of plants may be referred also the water lobelias, pipeworts, quill- worts, the four-leafed water fern and others, including a variety of flowering plants, such as the eel-grass, the water buttercups, starworts, water-lilies, water smartweeds, floating arrowheads, pondweeds and water milfoils. A number of different and interesting adaptational charac- ters exist among the shore plants. Commonly, when alto- gether submerged, they have very much divided leaves, as do the water milfoils or water buttercups. If part of the plant Minnesota Plant Life. 449 is submerged and part exposed, the leaves of the submerged portion may be finely dissected, while the leaves of the emerg- ent area are simple and but slightly notched. Of this the water bur-marigold is an example. Again, the leaves are all submerged and ribbon-shaped, as in the water eel-grass, or they may be quill-shaped, with air chambers, as in the quill- worts and water lobelias. When some of the leaves are float- ing and others are submerged, the floating leaves are often larger and broader than the submerged. Thus, in the float- ing arrowhead the natant leaves are arrowhead-shaped, while the submerged leaves are grass-like; or, as in the water-shield (not, however, the Minnesota variety), the floating leaves are shield-shaped and the submerged leaves are finely dissected. In other instances, as in the water-lilies, the difference be- tween thesubmerged and floating leaves is not so great, but a slight variation in textures net shard to observe. The fine dissection of thesub- merged leaves of so many aquatic flow- ering plants is evi- dently an adaptation, by which a considerable absorptive power is added to the ordinary starch-making function of the leaf. Such finely dissected leaves are easily maintained under water, but they would be likely to shrivel on account of too rapid evap- oration if developed in many land forms. ‘The floating leaves, like those of the planktonic vegetation, have adaptations against moistening, so the upper side of the shield-shaped leaf of the Minnesota water-shield will be found to be waxy and difficult towet. ‘The generally oval or circular shape of floating leaves, Fic. 222.—Birch trees along a lake shore. Bar vegeta- tionin background. After photography by Williams. or floating stems like those of the duckweeds and swimming Riccias, may be regarded as a response to the equal lapping of the waves against the edges of the leaf from all directions. These floating leaves, or stems, are very often purple on the under side, so that the surplus light is converted into heat. 30 450 Minnesota Plant Life. Ribbon-shaped leaves are not so common, but are found as the submerged variety in those arrowheads which have two sorts of leaves, and in some of the pondweeds, as well as in the ordinary eel-grass. More frequent are small, numerous, narrow leaves, or leaves cut up into small and narrow divisions. A number of the pondweeds have such submerged leaves, as also the water milfoils, the waterweed, the mare’s-tail and the water starworts. Least usual is the quill-shaped leaf, found however, among Minnesota species in the quillworts and in the water lobelias. Some of the pondweeds have broad, thin, papery leaves, crisp like lettuce, in some varieties, but of a texture different from that of land forms. In general, sub- merged leaves have no air pores, or these are very sparingly produced. The epidermis or skin of the leaf is not as strongly developed as it is in the case of terrestrial leaves that are fitted for evaporation. Such leaves are decidedly more absorp- tive than are those of land plants, this function being favored by the thin walls of the skin cells. In originating the forms of aquatic leaves the illumination had probably something to do, and the elongated, ribbon-like leaves on submerged por- tions of arrowhead plants may be considered, perhaps, to be extended on account of the semi-darkness caused by the water. The stems of these water plants are as various in structure as the leaves. Sometimes, especially where the soil is loose, the stem becomes a creeping, branched rootstock. This may be embedded in the soil at the bottom, as in pondweeds and water-lilies, or it may creep along the bottom, as in water but- tercups and water milfoils. Sometimes the stem is short with the leaves arranged in-rosette fashion—for example, the water eel-grass and the quillwort. In all of these plants the stem is perennial. A few annual water plants, however, exist, such as the naiads. In such, the stems die when the water freezes and the plant comes up from the seed the following spring. By far the great majority of water plants are perennial. ‘The mass- ive storage organs of bulbous land plants such as the jack-in- the-pulpit, or the onion, are not typical of aquatic vege- tation. In general their stems are characterized by a consid- erable development of the cortical region, together with a poor development of the vascular region. Mechanical tissue is not Minnesota Plant Life. 451° at all abundant in the greater number and most of the stems and leaves are limp when taken from the water. In the cortex of the stems and leaf-stocks air chambers are common. A variety of propagative processes are characteristic of water plants. Sometimes they pass the winter in an evergreen state at the bottom of ponds under the ice. The eel-grasses and water starworts do this. Sometimes their leaves are destroyed by the winter’s cold and new ones are produced from storage areas of the rootstock, from buds, or from special propagative bodies. The special propagative bodies of water plants are very interesting. The pondweeds sometimes form little buds, that are separated from the plant body and become distributed to a distance. “The bladderworts are remarkable for their pro- duction of green winter buds, known as hibernacula, which, in the autumn of the year, or in the spring, may be seen at the end of bladderwort stems. In such buds the leaves are very densely crowded together into a diminutive green cone and the sections of the stem with crowded leaves may be sepa- rated from the general plant body and serve to propagate the species. The calla,—rather a marsh than a water plant, but often living in the water,—has a similar habit of separating win- ter buds as propagative organs. The distribution of different kinds of shore and bar plants depends upon a variety of conditions,—the character of the soil, the depth of the water, its quiet or agitation, and its tempera- ture. The bass-weeds form the deep water zone. Warming states that they may grow in 75 feet of water, but usually they do not grow nearly as deep as this. The waterweeds pre- fer shallower water, the pondweeds still shallower, while the water-lilies grow close to the reed-grasses and bulrushes. The latter are accounted also as marsh vegetation, because so much of their starch-making surface is lifted above the water. The reproductive processes of water plants of this group retain the characters of the original land habitat, so far at least as the flowering plants are concerned. Thus, the flower clus- ters are always produced above the surface of the water, and pollination is effected either by the wind, by currents of water, by wind and water combined, or by insects. \Where the flowers are conspicuous, as is true of water-lilies or pond-lilies, insect 452 Minnesota Plant Life. pollination is the rule. Where they are inconspicuous, as in the pondweeds and water milfoils, wind pollination is the rule. A peculiar case is that of the eel-grass, which produces its pollen-bearing flowers in large numbers on submerged spikes. Each pollen flower separates from the spike and rises to the surface of the water, where it opens. ‘The pistil-bearing flow- ers are produced singly on the ends of long, thread-like stems, and open at the surface of the water. The little pollen-pro- ducing flowers are blown about like so many tiny sail-boats, either striking their stamens against the stigmas of the pistil- late flowers, or giving the wind an opportunity to carry the Fic, 223.—Trees along a river bank. Soft maple and cottonwood. Minnesota river. After photograph by Williams. pollen from one flower to the other. In the naiads and in some of the pondweeds, the pollen-spores are carried in the water, by ripples on its surface, from one flower to the other. The majority of these water plants retract their fruits under the surface to ripen them. Sometimes the stem of the fruit-bear- ing flower shortens spirally, coiling down into the water as in the eel-grasses. Sometimes the stem curves and thrusts the young fruit under the surface. A few water plants mature the fruits above the surface of the water, and of such the Indian lotus is an example. Minnesota Plant Life. 453 The depth at which quondam land plants are able to grow is in some instances very great. Thus Magnin is authority for the statement that one variety of moss was found at a depth of nearly 200 feet in an Alpine lake, showing on the part of an originally terrestrial plant a very high degree of adaptation to the aquatic life. Nothing of this sort is known to occur in Minnesota, and beyond 25 feet only algz and bacteria are likely to be discovered, while into such deep water pondweeds and waterweeds rarely extend. Abyssal vegetation and modified hydrophytes. The vari- ous classes of hydrophytes which have been discussed may be grouped under the general name of aquatic vegetation. Some forms of aquatic vegetation are scarcely represented in Minne- sota,—for example, hot spring vegetation, the various seaweed classes, and snow vegetation. Those which have been discussed comprise the bulk of Minnesota aquatic species. The class de- scribed by Warming as abyssal vegetation occurs, however, in the deep waters of Minnesota lakes from 50 feet below the surface to greater depth. The darkness is so great in such abysses that green plants scarcely exist, though blue-green algz and diatoms are known to occur at depths from 250 to 300 feet, being able to utilize the extremely smail amount of light which penetrates to them. Most abyssal forms are bacteria. These occur in the deepest waters, either suspended or in films along the bottom, forming, in such depths, a living slime or ooze, as may be determined by microscopic examination of deep lake soundings. ‘The bacterial vegetation occurs also in moist or- ganic substrata, such as the bodies of animals, where a large percentage of the substance is water. So the parasitic bacteria of disease, either of plants or of animals, might possibly be described as forms of hydrophytic vegetation. The bacteria, too, which live upon decaying organic matter, such as the sul- phur bacteria and the ferment-producing bacteria, may be re- garded as constituting a sort of water-loving vegetation, and, therefore, may be classified here. Swamp vegetation. The remainder of the hydrophytic classes may be included under the general term of swamp vegetation. ‘This is the plant group that shows itself typic- ally in swamps, in bogs, in marshes, moors and_tundras, 454 Minnesota Plant Life. Several different classes exist, all of them characterized by the development of the underground portions of the plant—that is, the roots or rootstock—in moist soil, while the aerial por- Fic. 224.—Marshy place at the edge of a wood. After photograph by Murdock. tions, especially the starch-making areas, are exposed to atmos- pheric evaporation. Like the majority of aquatic plants, most of the swamp plants are perennial. A great many of them Minnesota Plant Life. 455 produce underground or prostrate rootstocks. These organs are underground in sedges, scouring-rushes, reed-grasses, sweet-flags, cat-tails, some of the cranberries, brambles and primroses. They are above ground and prostrate in many of the heaths and club-mosses. as those of water plants, likely, in a variety of species, to be spongy. Thus, the rootstocks of the cat-tail, the rootstocks and stems of the scouring-rush, the leaves of many sedges and The tissues of swamp plants are, the leafless erect stems of bulrushes contain a great number of air chambers, giving them a spongy consistency. Some Fic. 225. Ferns in tamarack swamp, Lake Calhoun. After photograph by Hibbard swamp plants have special aerating organs, of which cypress “knees” are examples. But these structures do not occur, so far as I know, on any Minnesota species. Most swamp plants have adaptations for limiting the tran- spiration of water from their shoots and leaves; that is to say, they are in this character like the xerophytes of desert regions. Among the various devices for reducing transpiration may be mentioned the hairiness of many swamp plants, such as the swamp-saxifrage. Sometimes special pegs are produced around 456 Minnesota Plant Life. the air pores, as in many sedges and smartweeds. Sometimes that region of the leaf where the air pores are the most abundant Fic. 226.—Swamp saxifrages. The large root-leaves are adapted to the shade of the swamp. The whole plant is hairy. Tamarack swamp, Lake Harriet. After photograph by Hib- bard. is covered with a cottony or woolly coating, as are the under sides of the leaves in the Labrador tea. Again wax coatings 456 Minnesota Plant Life. “es and smartweeds. Sometimes the air pores, as m man 1 that r€eion of the leaf where the ai are the most abundant ss toot-leaves are adapted to the shade of mad - ~ “ ti Tag he ikTy ' Pot : Wobrs Yamearnck swamp, lake Harriet. After photageapat 4 —_ : L,4 Re 7) = « a. . +. hee. = is covered with a cottony or woolly coating, as are the under . . . 3 c j Roe? Siete sides of the leaves in the Labrador tea. Again Wax GG@UEIRY oe a ae ee ee Minnesota Plant Life. 457 may be found on the leaves, as on those of the rosemary, the cranberries, and the swamp blueberries. Sometimes the epi- dermis of the leaf or stem is very thick, as in the bulrushes and sedges. Sometimes the leaves are leathery, as in partridge- berries, cranberries and Kalmias, and this is a common adapta- tion among heaths. Sometimes the leaves are small, slender, and with but little surface for evaporation, a character that may be seen in many heaths and sedges. In some varieties the leaves are greatly reduced, as in the scouring-rushes, the bul- rushes, some of the sedges related to the cotton-grasses and many ofthetruerushes. Or, if present, the leaves may be almost cylindrical, as in the Scheuchzerias. Again, the leaves may be needle-shaped as in tamaracks or spruces. If the leaves are broader they often stand vertically so as to expose only their edges to the direct rays of the sun. This is well illustrated by the blue flags, the sweet-flags, the blue-eyed grasses, the yellow- eyed grasses and the cat-tails. Where these broader leaves do not stand vertically they are sometimes rather few in number. This may be seen in the reed-grasses and wild rice. Broad leaves of swamp plants are often rolled in along the mar- gins—the same adaptation found among desert grasses. Thus, crowberry leaves and many sedge and grass leaves in the swamp-dwelling species, are rolled. Sometimes the air pores are developed but very poorly on the upper surfaces where the leaves are spread out to the sun. All of these characters may be regarded as limiting the transpiration of the shoot and leaves. Special reasons may be given for the leaflessness of some swamp plants, as for the bulrushes which belong to the cate- gory of surf plants. ‘Their leafless, whip-like stems are adapted to withstand the impact of surf. The temperature, also, of the water has something to do with the appearance of the xerophytic characters. ‘They are more prominent where the water is cold. So especially in peat-bogs and cedar swamps does one find a variety of sedges, heaths, rushes and cone-bearing trees, all characterized by slow evaporation. Reed marshes. ‘To the class of reed marshes belong a variety of shore formations and swamp formations common in Min- nesota. Here should be classed the wild rice beds and the beds 458 Minnesota Plant Life. of rushes and reed-grasses. Here, too, should be included the beds of cat-tails, of blue flags, of arrowheads, burweeds, callas, sweet-flags and sedges. In such regions a variety of accessory plants habitually develop, such as the swamp butterweed, the buck-bean, the swamp-docks and several members of the pars- ley family. These plants often arrange themselves in zones dependent upon the relative moisture of the soil, or upon the depth of the water that covers the rootstocks and roots. Thus, along the borders of Minnesota lakes, bulrushes generally grow i Sa a ‘ — a “ted mi Ae ee iF Fic. 227.—A marsh-loving sedge, showing fruit clusters. After photograph by Hibbard. outside of reed-grasses, and reed-grasses outside of sedges, showing the exact adaptations of these kinds of plants to the moisture-content of the soil and to the water covering their un- derground portions. Most of the plants in reed swamps are provided with rootstocks by means of which they propagate. The strong rootstocks of bulrushes and cat-tails may serve as examples. While pushing a boat through a bed of bulrushes a careful observer will notice that the rushes stand in rows, and these rows designate the position of the prostrate rootstock in the bottom. From such branching rootstocks, common to Minnesota Plant Life. 459 sedges, cat-tails, bulrushes and reed-grasses, the aerial or lateral branches arise. The rootstock commonly bears scale leaves. These may be well seen if a cat-tail plant is dug up and washed. Among the perennial rootstock-forming herbs, which are the characteristic plants of reed swamps, a few shrubs are often found growing, such as willows and alders. Wet meadows. A second class of swamp vegetation is known as swamp-moor or wet meadow. In such regions there is a high percentage of ground water, but under ordinary conditions the subterranean portions of the plants are not directly covered bystanding water. Such meadows exhibit in Minnesota a variety of plants, for the most part sedges, grasses and rushes, but with a strong intermixture of other plants, including such varieties as the shield-ferns, marsh-marigolds, the Parnassias, some gen- tians, buck-beans, orchids, willow-herbs and parsleys. Here, too, swamp-saxifrages and pitcher-plants are often to be found. Mingled with the herbage which is the predominant vegeta- tion of such wet meadows a variety of shrubs may grow, in- cluding dogwoods, willows, dwarf birches, buckthorns, and spireas or meadowsweets, and, in northern parts of the state, heaths or crowberries. A considerable moss vegetation exists in such wet meadows, including sometimes peat-mosses, but also carpet mosses, hairy-capped mosses and others. Some- times moss meadows occur, forming a transition to peat- bogs and peat-tundras. In arctic regions such wet meadows are inhabited often by lichens to the exclusion of other plants. As is also true of aquatic vegetation these wet meadows are tenanted for the most part by perennial species. Peat-bogs. A particular type of swamp vegetation is the peat-bog. It differs from the ordinary wet meadows in the chemical character of its soil. Chalk and potassium are pres- ent in peat-bogs in smaller quantities than in wet meadows, and it has been shown that the nitrogenous content of peat- bogs is less than that of wet meadows. Humus, therefore, forms better in wet meadows than in peat-bogs. On account of the low nitrogenous content of the peat-bog there is a poorer development of bacteria and vegetable remains are, therefore, better preserved if sunken in peat than if embedded in the bacterial soil of a wet meadow. The distinctive plants 460 Minnesota Plant Life. of peat-bogs are the peat-mosses, the most abundant and in some respects the most remarkable of all the mosses. A con- siderable number of different species occur in Minnesota. They are extremely spongy and contain a large amount of water in special cells of their leaves and stems. Besides the peat-mosses a number of other mosses will be found in peat- bogs, with a variety of liverworts. Here, too, is the favorite home of many sedges, suchas the cotton-grasses, of many grasses. and lilies, of rushes and of orchids. Heaths are a marked fea- ture of peat-bogs and almost all the Minnesota varieties are to be looked for in such localities, where one finds the Labrador tea, the Kalmias, the rosemarys, the cranberries, the snow- berries, the leatherleafs and the bilberries. Mingled with them are a number of other peat-bog-dwelling plants belonging to various families. Here one will find the sundews and pitcher-plants, the dogwoods, brambles and sweet-ferns, the myrtle-leafed willow, the tag-alder and the crowberry. Espe- cially distinctive of such areas are spruces and tamaracks and these are the most characteristic trees of peat-bogs in the Min- nesota region. ‘They are often very much dwarfed by the cold water and by the low percentages of mineral salts which these waters contain. Especially when growing in the wet region of the bog are the trees diminutive; and spruce trees 75 years old and but little over an inch and a half in diameter have been found in Minnesota peat-bogs. It is probably on account of the low nitrogenous content of the water that carnivorous plants, such as the pitcher-plant and sundews, have developed particularly in peat-bogs. They are able by their insect-catching habits to supply, from the bodies of their victims, nitrogen to compensate for the scantiness of this element in the soil. Most of the species in peat-bogs are perennial. On account of the open, meadow-like character of typical peat-bogs the snow accumulates in heavy sheets and this will perhaps account to some extent for the prevalence of prostrate shrubs like the heaths. No doubt also the prostrate habit is resultant from the necessity for slow evaporation. Since the heaths do not lift their leaves into the air on erect shoots so abundantly as do other kinds of shrubs, they avoid that agitation by the wind which would promote evaporation. Minnesota Plant Life. 461 Peat-tundra. The type of vegetation known as peat-moss tundra is sparingly developed in Minnesota. It may be de- scribed as a kind of dry peat-bog. I have seen isolated and Fic. 228. A pitcher plant in flower; tamarack swamp. The leaves are converted into insect- traps. After photograph by Hibbard limited peat-moss tundra formations at Lake of the Woods, where, on some of the rocky islands near the Northwest Angle 462 Minnesota Plant Life. Inlet, dry peat-moss turfs form in the depressions of the rock. Mingled with the peat-moss were the reindeer-moss lichens and the bluebells and juniper bushes, which are such distinctive rock plants of this region. Swamp underbrush. Another type of swamp vegetation de- veloped in Minnesota is known as swamp shrub or swamp underbrush. This consists for the most part of birches, wil- lows, buckthorns, black haws, hollies, dogwoods, alders and poison sumacs. Where a reed swamp or wet meadow has grown up to underbrush this sort of formation appears. When the swamp underbrush has arisen, sufficient shade is produced to permit the development of certain accessory herbs that would not otherwise be so abundantly present. In such re- gions, for example, violets and touch-me-nots, gentians and thoroughworts are often abundant. Such swamp underbrush sometimes grows along the edges of peat-bogs and lakes and in this situation willows and dogwoods particularly abound. Wil- lows, also, very often form rings around the shores of small, low islands, mud flats, or sand bars in lakes or streams, while the higher land of the centre is occupied by elms, cottonwoods, maples or basswoods. ‘This is a very common example of zonal distribution in Minnesota. There have now been passed in review the principal types of hydrophytic vegetation. Apparently the strong preponder- ance of water in the substratum, as for the swamp plants, or surrounding the plant body, as for aquatic vegetation, has a number of definite influences not only upon the structure of plants, but upon their grouping. The depth of the water, the character of the soil, the chemical substances held in solution in the water, the temperature, agitation, or quiet, and other conditions, all have their influence and it is not at all an acci- dental matter whether a particular moist region develops as a peat-bog, as a reed swamp, as a wet meadow, or as a swampy underbrush. In all the hydrophytic vegetation classes peren- nial species are predominant. A great many of them are herbs, while some are shrubs, and a few are dwarfed or spe- cialized trees. Chapter ei 1- Xerophytic Plants. se The plants classified under the general name of xerophytes are, in their selection of habitats, just the opposite of aquatic plants. They grow typically under conditions of slight mois- ture and some of them are able to maintain themselves in the most arid regions of the world. Thus, a distinctive desert vegetation, such as may be found in the Sahara, or in the deserts of Arizona, has come into existence. A number of plants, although not inhabitants of the desert, find it difficult te obtain sufficient moisture and assume the xerophytic type of structure. Good examples of these are the orchids that live in tree tops and dangle their roots in the damp air of tropical forests. Since this is a slow way of accumulating moisture, such plants are often cactus-like in form. Not being exposed to the attack of grazing animals, as are the cacti, they do not become armed with thorns and spines, but they have often the same massive bodies that are found in true desert plants. A great variety of secondary conditions serve to modify and regulate the ap- pearance of xerophytic structural characters. Thus, some xero- phytic plants living in sand differ decidedly from others living upon rocks. Those developed in soil rich in nitrogen differ from those that have but a scant supply of this element avail- able for their roots. The saline substances present or absent in the soil may modify the plants growing upon it. For this reason a difference arises between the vegetation of limestone and granitic regions and some plants are known to be indica- tive of limestone soils just as others are of the presence of quartz. Desert plants. A variety of devices are employed by xero- phytic plants to regulate the evaporation or transpiration of moisture. Sometimes during extremely dry seasons desert plants abandon their leaf structures entirely, thus responding to the arid conditions quite as plants of temperate regions re- spond to the approach of winter. ‘Trees in deserts often drop 464 Minnesota Plant Life. their leaves after the short rainy season is over and pass into a winter-like condition, during which they evaporate much less moisture than would be necessary if their leaves were expanded to the ardent rays of the sun. For this reason, too, a great many desert plants are annual, and in the compact form of seeds withstand the dry season of the year. When the rain has come again the seeds germinate rapidly and in a short time the flowering and fruiting processes are completed. It is remark- able, in a desert, when the rainy days are at hand, to observe the extraordinary rapidity with which plant organs of various sorts appear upon what was before an arid waste. Many desert plants develop underground bulbs and root- stocks which persist without sign of life during the dry time of the year and, when there has been a short season of rain, suddenly put forth flowering stems and foliage. Another way of meeting the aridity and dryness of the air is by the rolling up of the leaves. This is well seen in the buffalo-grasses, in some of the wormwoods or sage-brushes, and in a variety of sedges, grasses and mosses. By means of this reduction of the evaporating surface at the critical time, the desert plants which employ these adaptations are able to prevent too great evaporation. Another method adopted by plants in arid re- gions is the modification of their leaf positions, and a number of leaf-movements are regarded as protective against undue evaporation of moisture. Many plants of the pea family in desert regions have such special leaf-movements. Still another method is the setting of the leaves on edge, as in compass- plants; and the rosinweed compass-plant and the lettuce com- pass-plant of the Minnesota flora, by twisting their leaves so that only their edges are presented to the direct light, illustrate such adaptations. Since the strongest illumination in the northern hemisphere is from the south, these compass-plants turn most of their leaves so that the flat sides face east or west, and thus they are exposed to the least direct sunlight possible. In the desert regions of the world, leaves sometimes hang from the stems so that the light strikes them as little as pos- sible during the day. Still another device for limiting tran- spiration, common among desert plants, is the formation of leaf structures that evaporate moisture but slowly. The prismatic Minnesota Plant Life. 465 leaves of pine trees, the leathery leaves of heaths and hollies, the scale-covered leaves of buffalo-berries and silverberries, the slender cylindrical leaves of many rushes, the ribbon-shaped leaves of many grasses and sedges are all examples of such protective structures. Some leaves are fleshy and succulent, like those of the live-forever, the purslane, the spring-beauty or the portulaca. The leaves of century-plants are types of this kind of adaptation. Not only are leaves variously modified, but stem areas as weil, in the above-ground portions of xerophytic plants, re- spond to the conditions around them. Thus, some stems are leafless, as in certain of the cacti. Such leafless stems may be somewhat flattened and may have green rinds by which they carry on their starch-making. Sometimes the stems are cylin- drical, as in the bulrush. Sometimes, as in the asparagus, the leaves are absent from the plant body, or are reduced to scales and their place is taken by little needle-shaped branches that carry on the starch-making function. Sometimes the stem is converted into a solid gourd-like body, as in the melon-cacti and prickly-pears. By such forms and structures of leaves and stems the transpiration of moisture is greatly reduced. Another modification appears in those plants which have coatings of one sort or another to protect the leaves and stem. Thus, the bloom on the leaves of a century-plant, the hairs and bristles on a mullein leaf, the clusters of dead leaves that are retained by some plants for a year or more, the incrustations of chalk, wax, slime, shellac or gum, all have their value in re- ducing evaporation. The internal sliminess of the leaves of cen- tury-plants is a familiar fact. Well known, also, is the resin- ous matter so commonly seen to exude from the leaves of pines and their allies. Various other adaptations exist which cannot be discussed at all fully. The intimate structures of leaves, the position of the starch-making bodies in the leaves, the position and character of the air pores, all have a significance. Some plants have glands the function of which is to secrete salty deposits on the leaves. ‘These salty deposits have a strong affinity for moisture and may serve to collect it from the ex- terior. Many desert plants are known by their pungent odor, very perfect examples of which are the wormwoods or sage- brushes. It has been shown that the vapor of the ethereal oils, 31 Sec a ne me 4yysuM Aq ydersojoyd 1393p ‘ayeurutopaid sasse13 pue s1ejdod ‘susay sourd ‘sjromypoq ‘stodrunf ‘OLrejyUO ‘UNeMsay Tea ‘SpoOM JY} JO DAR’T ‘WONRLJasaa WoY—'Gzg “OI Minnesota Plant Life. 466 Minnesota Plant Life. 467 existing in such plants, when commingled with the atmosphere reduces its permeability to heat, and thus the constant exhala- tion of perfume from the body of a wormwood is to be regarded as a device for tempering the heat of the sun. No doubt some of these strongly scented substances are of value, too, as dis- couragements to grazing animals. By all such adaptations in the above-ground portions of a plant it is clear that a reduced transpiration is effected. The below-ground organs, such as the roots or rootstocks of desert plants, are often important as reservoirs of moisture. Some varieties, like the wild morning- glories, produce very large roots, and often the root system of a desert plant is much greater in extent than the above- ground portion. A number of classes of xerophytic plants exist, many of them represented in Minnesota. While the state does not include any desert regions, yet there are numerous tracts upon which xerophytic plants would find a habitat—for example, sandy barrens, dry rocks, sand dunes and high sand beaches, high prairies and meadows, or the dry branches of trees. Some of the characters of these different classes may be discussed more in detail. Rock plants. Rock vegetation is well defined and includes a number of species that are not common elsewhere. A large portion of it is made up of mosses and lichens; and on dry cliffs, exposed bowlders or crags, as well as upon ledges of rock, a number of rock lichens and rock mosses are prolific. These plants require but a small amount of water and are often provided with several of the special adaptations against transpiration. The common little black tufts of moss which are found upon bowlders, under ordinary conditions look perfectly dry and shriveled, but if wet they quickly revive and their green color becomes more apparent. Many of the lichens growing upon rocks have the same shriveled, dry appearance betokening adaptations affecting evaporation. In order to attach them- selves to the bare surfaces of rocks, lichens secrete, as has al- ready been stated in the chapter on lichens, certain acids able to corrode limestone or quartz. ‘The plants cling closely to the corroded surface and they cannot possibly be detached with- out destroying them. Some alge are capable of living on 468 Minnesota Plant Life. rocks and there pass into a dry, dormant condition, except when the rock is wet with rain. In Minnesota a number of pinks, rock-roses, purslanes and Canterbury-bells make their home upon rocky ledges or shores. Here, too, there are to be met with a variety of ferns, such as the cliff-brakes, the polypody and others. With them may be found numerous grasses, plan- tains, verbenas, evening-primroses, ragweeds, capers, and sax1- frages. Upon such rocky ledges may also be discovered, espe- cially in the northern part of the state, the juniper bushes and the ground-hemlock. Rock-succulents are not common in Fic. 230.—Growth of hardwood trees upon a rocky island. Northwest angle, Lake of the Woods. After photograph by the author. Minnesota; but the prickly-pear cactus of Pipestone and the rock purslane of the Minnesota valley, are examples. More often grasses with rolled up leaves, junipers with needle-shaped or scaly leaves, saxifrages with hairy leaves and other adapta- tional types will be present. The larger rock plants, needing more soil for their root areas, grow in crevices and may be found abundantly wherever the rocks have been split and soil has formed in the clefts. Moss heaths. Another class of xerophytic vegetation in- cludes the moss heaths. These are dry, moss-covered stretches. Minnesota Plant Life. 469 Mingled with the mosses there may sometimes be small shrubs or herbs. Such moss heaths are to be found upon some of the islands in Lake of the Woods and Rainy Lake. Lichen heaths. A related class may be described as lichen heath. The characteristic plants of this formation are the rein- deer mosses; and very beautiful examples exist along the north- ern limits of the state. The dry, rounded, thin-soiled islands in Lake Saganaga give perfect examples of lichen heaths. A few trees and shrubs are present, but the characteristic and pre- dominant vegetation is composed of reindeer mosses with little heaths, grasses, rushes, verbenas, and vetches mingled with them. Shrubby heather. Another class not so extensively repre- sented in Minnesota as elsewhere is the shrubby heather, in which the ground is covered by little heath bushes, mosses, club-mosses and junipers. Yet such heaths to a limited extent exist in the northern part of the state. Mingled with the heaths proper are a number of composites, such as those goldenrods, asters, and fleabanes which prefer dry open localities. All of these rock and heath groups of plants are strongly xerophytic in their general features. They are, in many in- stances, to be regarded as responses to sterility of soil rather than aridity of climate. Sand plants. Very closely connected with rock vegetation is the sand vegetation of dunes, beaches and barrens. The sand is lacking in moisture, which percolates through it readily, lacking also in nitrogenous substances and, therefore, to some degree not unlike a rock tract, hence naturally presenting similar types. A great many plants which can grow upon rocks can also grow upon sand dunes and, as a result, in the northern part of the state, junipers, for instance, occur in about equal frequency upon bare rock ledges and upon sand dunes. A special type of sand vegetation is that of sandy beaches, where the proximity of lake water makes the soil moister than it would otherwise be. For this reason the plant inhabitants of beaches are often mesophytic rather than xerophytic in char- acter, while close to the water’s edge true hydrophytes may establish themselves. Dunes are particularly characterized by 470 Minnesota Plant Life. sand-binding plants, such as the wild rye, the junipers, some sedges, rushes and grasses. Mingled with the herbaceous plants are a few shrubs and trees, such as the hackberries, choke- berries, poplars, oaks and ashes, with brambles and roses as underbrush. Sand barrens in Minnesota fall for the most part into three classes, jack-pine-barrens, oak-barrens and sandy wastes. The distinctive plant of the pine-barren, a common formation in the central portion of the state, is the jack-pine. Along with trees of this species, a number of underbrush plants, herbs, mosses and lichens establish themselves. Here blueberry bushes are abundant and other heaths. In such woods the de- i he. Pe ggpret. 5 ae : ‘¥ — gy r Fic. 231.—Vegetation of sand dunes, Isle saux Sables, Lake of the Woods. In the foreground is the sand cherry and scrub poplar, in the center, a juniper bush and in the background, plums. After photograph by the author. velopment of wand plants is common, and in the autumn the forest floor is resplendent with the yellow heads of sunflowers, the purple spikes of blazing-stars, and the white or blue inflo- rescences of asters. Sandy wastes are characterized by the de- velopment of mat plants, such as carpetweeds and spurges. Mingled with these are to be sought many rosette plants like the evening-primrose and the plantain. Minnesota Plant Life. 471 The prairie. A most characteristic xerophytic formation in Minnesota is the prairie—especially the high rolling prairie, which differs considerably from ordinary meadow or pasture. Much of the level prairie is mesophytic rather than xero- phytic. Here a variety of grasses, pulses and composites grow luxuriantly. Such a region is the home of tumbleweeds, com- pass-plants and prairie turf-building varieties. Some strongly xerophytic lilies, such as the onions, are found in profusion upon the plains. Over unbroken prairie, between the plants established upon it there exists a great competition. This goes on not only between the under-ground portions, but also Fic. 232.—The valley of the Minnesota river in the prairie district. Abundant grass vegetation. After photograph by Professor R. D. Irving. between the erect structures. Thus, some prairie plants grow tall and strong in order to get the light that they require. Sun- flowers, indeed, may be regarded as the kings of the prairie. Their erect, vigorous, annual stems are like trees as compared with the more humble grasses, and where they occur in abun- dance they may, to the seeing eye, be regarded, perhaps, as in- dicative of how the forests of the world will appear hundreds of thousands of years in the future. One may look forward and imagine sunflowers and their kind grown taller and stronger, a hundred feet or more in height, and even able to usurp the place of the trees that are now abundant in the woods. 472 Minnesota Plant Life. A great many prairie plants are annual, but some of them are shrubby and perennial. The shrubs are for the most part low. This is no doubt in response to the moisture-condition, because if they were high and loose, like the dogwoods and willows of moister localities, their evaporation would be too great. All of the formations that have been described are distinctly xerophytic and in all of them the moisture-content of the soil is comparatively small, while its temperature may be high. Pine forests. At this point it might be well to call atten- tion again to the xerophytic characters of coniferous forests, especially tamarack and spruce swamps, balsam thickets, and river-bluff lines of junipers or red cedars. Probably the whole pine forest may be regarded as xerophytic. The needle-shaped leaves of the white and red pines are slow to transpire moisture, and the pine forests reach their highest perfection along ridges equivalent, in their topographical character, to the ridges of rolling prairie. The moisture-content of such soil must be below the average. Along with the pines a number of xero- phytic mosses, such as the hairy-capped moss, of ferns, such as the bracken ferns, and of flowering plants, including the wintergreens, several heaths, and a variety of asters, are com- mon. In such forests wand plants grow luxuriantiy along with the shrubby underbrush. Air plants. When growing upon a substratum in which nutritive substances required by the plant are lacking or small in amount, the surrounding atmosphere is drawn upon for the food supply. Plants that habitually do this are termed air- plants. The Spanish moss, tree-top orchids and perching ferns of the tropics afford typical examples. In temperate regions the perching vegetation is composed principally of lichens, mosses, liverworts and alge. Much of the rock vegetation previously mentioned may also be included in this class, and here, too, may be classified the lichens and mosses that attach themselves to the bark of trees, to fence rails, to the walls of buildings or to absolutely arid soil. Chapter EIT: Halophytes and Mesophytes. wf The adaptational type of vegetation known as salt vegetation, or the halophytic group, is very sparingly represented in Min- nesota. It reaches its best development in the mangrove swamps of the seashore, and on salt-impregnated beaches or marshes close to the ocean. A few salt plants are, however, to be found in the state. In the Red river valley they are some- times most prolific upon saline or alkaline soil. Here are en- countered the sea-blites, the glassworts and the Russian thistle, together with several salt-loving goosefoots, salt-loving purs- lanes and grasses. One of the plantains is capable of growing in salt marshes. The most general character of salt marsh vegetation is its sparseness—a character presented, for example, by a growth of Russian thistles. Such plants are usually some distance apart, not close together as in most other formations. Salt plants, like many bog plants, are stamped with the xero- phytic structural adaptations. The succulence of the gtass- wort and the great reduction of its leaf surfaces is distinctively suggestive of the cactus type. The fleshy leaves of the goose- foots and purslanes call to mind similar characters of rock or desert succulents. If the body of a glasswort is chewed a strong saline taste will at once be recognized and will serve to demonstrate that salts are carried from the soil, where they exist so abundantly, into the juices of the plant. The typical salt-succulents are not ordinarily armed with thorns or spines as are the typical desert-succulents. This may be because there is not such absolute sparseness of vegetation in the general locality and they are, therefore, not called upon to bear the brunt of attack by hungry animals. Succulents in general. At this point it may be desirable to bring together for comparison the different sorts of succulent plants. ‘They may be divided into two general groups, leaf- succulents, such as the purslanes and century-plant, in which the 474 Minnesota Plant Life. leaves are the principal succulent organs; and stem-succulents, such as the cacti, in which the leaves are reduced to thorns and the stems have become fleshy. Of adaptational types there are the following: desert-succulents, generally armed with thorns; rock-succulents, more commonly unarmed; salt-suc- culents, like the glassworts, sometimes armed; and tree-top- succulents, generally unarmed. Of the latter group tropical orchids furnish illustrations. Some of the leaf-succulents de- velop their leaves in rosettes and belong also to the class of Fic. 233. Cottonwood trees on the Minnesota river. After photograph by Williams. rosette vegetation: the century-plants, the live-forevers, and the little hen-and-chickens are examples of this group. The tree-top-succulents, also, of the orchid family, to be seen in greenhouses, in a number of instances develop their leaves in clusters upon short stems. Other leaf-succulents, however, have the stems slender and branching. This is true of the purslane, the rock purslane and the Russian thistle. Succulents may have arisen through direct influence of the environment, by the warming of the soil. This would tend to increase the Minnesota Plant Life. 475 absorptive power of the roots, so that desert-succulents in par- ticular might be regarded as plants that in a warm soil have swollen themselves full of water and, during the course of gen- erations, have adopted permanently the fleshy structure. Mesophytic vegetation. A number of other plant forma- tions remain to be catalogued under the general head of meso- phytic vegetation. The term is applied to those plants which are intermediate, in their reaction to moisture, between hydro- phytes and xerophytes. The characteristic mesophytic forma- tions of Minnesota are the hardwood forests, the meadows, the - Fic. 234.—A Minnesota meadow bordered by shrubbery and deciduous forest. After photograph by Mr. W. A. Wheeler. cultivated fields and gardens, the roadsides and the mesophytic shrub, such as underbrush at the edges of forests, or the widely distributed scrub, composed of little oaks, sumacs and maples. In all these formations the plant-covering is thick and a large number of perennial species exist. Meadows. Meadows or pastures are composed for the most part of grasses and accessory herbs, such as verbenas, flax, sor- rels, buttercups, anemones and thistles. Here, too, gentians and speedwells will be found, together with primroses and 476 Minnesota Plant Life. thoroughworts. Occasional xerophytic plants enter such meadows and one may find in them mulleins or scouring-rushes growing among the typical mesophytic grasses and herbs. In such localities plants of xerophytic tendencies may often be distinguished by their rosettes of leaves. In the meadows mosses and sometimes ferns occur. With the meadows should be compared the broad expanses of mesophytic prairie, es- pecially those of the Red river valley and the Minnesota. Cultivated fields. Cultivated fields and gardens, where the soil is stirred by the plow or spade, come to be occupied by a group of vegetation classified by the farmer as crop and weeds. This is, of course, a purely economic classification, and to get the proper botanical idea of a cultivated field all thought of human interest in the kinds of plants that grow must be elim- inated. It will then be discovered that the field is occupied by a dominant formation which owes its selection and abun- dance to the distribution of its seeds or fruits through human agency. A number of accessory plants are also developed, in- cluding a variety of common grasses and herbs. Into such fields some xerophytic forms, like the purslanes, introduce themselves, but the majority of the plants will not show con- spicuously the xerophytic adaptations of structure which have been described; that is, the weeds of a cultivated field are not predominantly silky or strong-scented, or succulent, or plants with the edges of their leaves rolled in together. In such localities, rather, will be found the thistles, the fox-tail grasses, the oxeye daisies, the amaranths, pigweeds and wild parsleys, together with some kinds of buttercups and clovers. Such a field in its general composition bears a close resemblance to pastures or meadows. A particular kind of field is produced when the soil is sandy or alkaline. Or, if the soil is very hard, composed of clay closely packed together, the vegetation cov- ering it will be different from that of ordinary cultivated fields. Sand-loving plants or mat plants will come in and establish themselves prominently along with carpetweeds, purslanes, thistles and wild lettuce. Roadside vegetation. With such wastes of weeds as have been described, roadside vegetation may be connected and the q 7 ‘ Minnesota Plant Life. 477 strong resemblance between it and that of a neglected field is at once apparent. Mesophytic shrub. Of mesophytic vegetation classes, in which shrubby or woody plants are predominant, a number of Fic. 235.—Roadside vegetation in summer. After photograph by Williams. special varieties might be described for Minnesota. Here would come the oak scrubs, the sumac and maple underbrush, Fic. 236.—Roadside vegetation in winter, St. Anthony Park. Oaks, sunflowers and golden rods. After photograph by Williams. the hazel scrub which is particularly abundant in Minnesota and the poplar scrub in which the dominant plant is the com- 478 Minnesota Plant Life. mon poplar. Dogwoods, roses, hawthorns, plums, ashes and other shrubs are prominent as components of this general formation. Along with these go usually a number of wand plants, herbs that thrust their slender stems up between the shrubs, thus getting illumination. Of these the goldenrods, the willow-herbs, the evening-primroses and the asters are ex- amples. Here, too, one will find a variety of climbing or twin- ing herbs or vines, and the wild beans and wild peanuts, the bindweeds and morning-glories, are to be expected. The floor of the underbrush will be occupied by a number of little grasses Fic. 237.—Autumnal underbrush, Mississippi river, between Minneapolis and St. Paul. Golden rods, asters and sumac. After photograph by Williams. and low herbs, some of which may be vagrant xerophytes with the rosette habit of growth or with other characters by which they can be recognized. Hardwood forest. ‘The hardwood forest of Minnesota, espe- cially as developed along river bottoms, where it is made up of ashes, maples, basswoods, oaks and elms, furnishes an ex- ample of what is meant by mesophytic forest. Upon sand bar- rens where the bur-oak finds a congenial home the conditions are almost xerophytic and, therefore, oak-barrens were men- tioned under a previous topic. Minnesota Plant Life. 479 Certain conditions of the forest floor arise, owing to the decay of the falling leaves, that make such a region favor- able for the development of humus plants, and a num- ber of them are likely to be found there, as, for example, the coralroots, Indian-pipes and wintergreens. Many shade plants hide in the dense woods and one finds, in their depths, the trilliums, the jacks-in-the-pulpit, the broad-leafed asters and broad-leafed goldenrods, and upon moister ground, the touch-me-nots, the anemones and the clintonias. In such woods a number of vines have their growth, such as the wild grape and the climbing bittersweet, or, of slenderer habit, the hop and the clematis. A character- istic of hardwood forest is the remarkable luxuriance with which spring flowers of various sorts are produced. Before the leaves have come out upon the trees the forest floor is covered with flower- ing herbs. The autumn flowers of the forest are not sO conspicuous as in the prairie regions, perhaps be- cause there is not so much possibility of attracting the Fic. 238.—Neglected corner in the Minneapolis : ES : manufacturing district. Weeds and shrub- attention oi insects ata dis- bery. After photograph by Williams. tance, owing to the prox- imity of tree trunks and to the shadows thrown by the leaf crowns. In the spring, before the leaves have appeared, such conditions are minimized and the development of a conspicuous flower might be of more advantage to the plant. General considerations. It must not be supposed that every plant formation in nature is purely hydrophytic, purely xero- phytic, or purely mesophytic. On the contrary, mixed forma- tions are exceedingly common. A little change in the topo- graphical features of a region, a difference in illumination or in 480 Minnesota Plant Life. exposure to wind, a slight modification of the chemical or phys- ical condition of the soil, or any one of innumerabie other varia- tions in the surroundings may suffice to alter the vegetation which has become established. Thus, in a well-kept lawn, where conditions are normally mesophytic, plantains and dande- lions—both of them mesophytic in structure—will prob- ably be among the most troublesome weeds. But let the lawn be established on a soil-too porous and easily dried, or let the season be below the average in rainfall, and very promptly xerophytic mat plants, such as spurges and prostrate verbenas, and xerophytic grasses, such as the sand-burs and other similar Fic. 239.—Modern hardwood forest of the’St. Croix valley, near Osceola. After photograph by Professor W. R. Appleby. vegetation, will begin to encroach upon the turf. Vegetation coverings, wherever they are formed, are quite as sensitive to changes in surrounding conditions as is a city lawn, and for this reason the infinite variety of woods, fields, marshes, swamps and prairies has come to exist. A very broad classification of the influences which affect plant adaptations is that made by the German authority, Schimper. He distinguishes essentially—1, climate; 2, substratum, and 3, neighbors. By climate he means the complex of atmospheric and cosmic influences, including, for example, all the influences of solar light and heat and those of atmospheric vapor and wind. Minnesota Plant Life. 481 By substratum he means the soil, whether it be rich in calcium, sodium or nitrogen. By neighbors he means the surrounding plants and animals which by their proximity affect the habits or structures of the plant in question. Thus, in accordance with the origin of their most characteristic adaptations, he divides vegetation into three fundamental groups, viz., climatic formations, substratum formations, and neighborhoods. Desert plants, for instance, may be grouped among the climatic, salt- succulents among the substratum, and carnivorous plants among Fic. 240.—View of Fort Snelling, showing midsummer vegetation After photograph by Williams. the neighborhood formations. The further extension of such a classification is perhaps sufficiently apparent without multi- plying examples. Aquatic plants would form a special class. Yet under even so general an analysis it must be evident that very many plants—indeed, most of them—will appear in one group or another, as attention is diverted to one or another aspect of their adaptation. The tree-top orchid as an air-plant falls into the group of climatic formations, but as a plant en- abled through the co6peration of its root fungi to use decaying 32 482 Minnesota Plant Life. Moe materials for food, it comes within one of the neighborhood _ formations. No adaptational classifications that have yet been devised are altogether accurate, but those by Warming and a Schimper are the most practicable. (chapter Sey. Maintenance of the Plant Individual. SF Like every other living thing the plant must maintain itself or die. For different kinds of plants the normal duration of life may greatly vary. Thus, the microscopic females of cer- tain orchids, hidden, as they are, deep within the rudimentary seeds of their species, may exist for but a few days or weeks. On the other hand, in the canons of the Sierra Nevada, there still stand, challenging the winds and the winters of the cen- turies, Sequoia trees that were saplings when the pyramids were new, noble trees when Rome was in her glory, and already giants of the western forest when Columbus set sail on an un- known sea. Whether the life of a plant be long or short, it may be de- scribed as arising and continuing through a series of adjust- ments, complex, subtle, immemorial, between the forces and the substances of Nature. The materials of which the plant is made are certain ordinary chemical elements. Their num- ber and their character can be determined by recorded methods of analysis. The energy manifested by the plant in its assim- ilative processes, in its growth, and in its movements is but a transformation of the energy with which it is supplied through its food and through the warmth and illumination of the sun. Yet it is impossible to reduce the living plant to the terms of an equation in chemistry and mechanics. ‘That this cannot be done is because the plant is really a microcosm. ‘The problem of its existence is as difficult and as profound as that of the universe. ‘There it stands beside one’s doorstep, humble, passive and inarticulate. Yet it responds to the forces of light and gravitation reaching it from the depths of infinite space. It is touched by terrestrial dews and breeze, and, after its fashion, reacts to such local stimuli. It is moulded by the inheritance which comes to it through an ancestral line reach- 484 Minnesota Plant Life. ing down the dim and distant ages to the very moment when the first living particle appeared on the surface of the earth. Thus, the child of two infinities, it baffles interpretation; for in the heart of every flower is the riddle of the Sphinx. From such a conception the poet may derive his inspira- tion and the moralist may instill his lesson. But it is the duty of the student of science to put aside all feelings either of ex- altation or depression and to endeavor to collect such facts as are attainable, even when he recognizes that ultimate explana- tions lie far too deep to be reached by the plummet of human thought. In such a spirit the plant has been questioned by modern science and somewhat is known of the story of its life. In very simple fashion I shall endeavor to picture it as an organism at work. Living substance. ‘The essential groundwork of every living organism is a material known as living substance, or protoplasm, By no means all portions of an organism actually consist of this living substance, although all portions have arisen through its activity. It is as the spiders spin their webs, or as men build their cities. The living substance is the organizing body and the completed plant or animal is the resultant organiza- tion. As long as the organism contains this living substance it may be said to be alive; but when the living substance 1s destroyed throughout its body the organism is then said to be dead. No longer held together by the forces inherent in its builder it may be resolved again into the elemental sub- stances from which it was constructed. Just so, to continue the illustration, will a city, if abandoned by its inhabitants, fall into ruins and finally crumble into dust. Death of an organism may be sudden or gradual. Thus by fire, for example, a plant or animal may in a few moments be converted from a living being into a handful of ashes and a wreath of smoke. Again, death may be slow, creeping from organ to organ, and even when the organism as a whole is no longer living there may in some of its tissues still remain por- tions of the living substance. The whelming of Pompeii by the fires of Vesuvius might be taken as an illustration of the first condition and the gradual but relentless march of a pesti- lence might illustrate the other. Minnesota Plant Life. 485 Since plants have no nerves by which shocks are transmitted to a central system and thence to every portion of the body, they die much more slowly than do animals. Location of the living substance. Only in very lowly crea- tures, such as the slime-moulds, does the greater part of the body consist of living substance. The jelly-like masses de- scribed for such organisms are among the best examples of pure protoplasm. Generally the body of the plant consists, for the most part, of wood, bark, cellulose, starch, oils, water, sugar, ash and a great variety of other compounds manufac- tured at different times by the living substance. One exam- ining a tree or herb in the ordinary way can neither see nor touch any of the living substance, whatever, but must lay his hand upon leaf-skin, cork or some of the various other periph- eral materials of the plant. It is not otherwise if an animal be investigated in like superficial manner. The living sub- stance lies concealed within the walls of the city it has built. To see it and to study it most delicate manipulation is neces- sary. Certain portions of plants are transparent and at the same time contain living substance. Such areas are favorable for observation. If, for example, some of the hairs that grow along the stem of a tomato-vine are carefully removed, placed in a drop of water and examined under a sufficiently powerful microscope, it will be discovered that they are composed of cylindrical joints. Each joint has a wall transparent as glass, and, within, most of the interior is occupied by water. There is also present, however, a pellucid slime, very conspicuous when once identified. It keeps up a remarkable streaming motion and tiny granules in it are carried along like boats in a rapid current. The direction of the stream changes from time to time. Eddies form in the current. Sometimes the streams flow together from different parts of the cell interior and a mound of slime is formed. Sometimes the streams fork again and again, making a network within the cell. The mo- tion may cease if the temperature is lowered or raised beyond certain limits. It ceases, also. if the cell becomes dry or 1 it is exposed to the vapors of ether or chloroform. A slight electric shock stops the movement, but after a time it may 486 Minnesota Plant Life. begin again. A strong electric shock stops it forever. This streaming, pellucid slime is the living substance. Not only in hair-cells does the living substance commonly occur, but in many other portions of the plant. It is found at the tips of all young roots and buds. In the green cells of leaves it is always present. It will be found in certain of the conducting-areas of the plant—in the leaf network and in the young fibers of the stem. In trees and shrubs it occurs neither in the mature bark nor in the mature wood of the trunk, branches or woody roots. Between the bark and wood there exists, however, 1n ordinary trees a thin layer—no thicker, in- deed, than tissue paper—-known as the cambium. In this layer of cells the living substance will be found. It occurs in all spores, eggs and spermatozoids, in all very young organs and tissues, and in general in all growing parts of the plant. Physical structure of the living substance. Yearsago when investigation of the living substance was in its infancy it used to be described as a “structureless slime” or as “living jelly’— these phrases indicating how little was really known of its or- ganization. ‘The researches, however, of the last fifteen years in particular, have revealed that the intimate structure of the living substance is extremely complex—so much so, indeed, that a new science, the science of the cell, has developed, until to-day libraries can be collected in this field alone. It would appear that, just as the body of a plant or animal is composed of cells and their products, so the particle of living substance in each active cell is itself composed of smaller bodies and their products, the whole constituting an organism of extreme coml- plexity. It may properly be said that there are now known three hierarchies of life—social life, individual life, and cell life. In the first of these man has his place as a component body, in the second he exists as a self-sustained individual, while in the third lies the living basis of his organization. Modern research has shown that the motion seen in a living cell lying under the microscope of the observer is by no means disorderly or unrelated. On the contrary the kaleidoscopic changes in the living substance are now known to have pro- found significance in nutrition, growth and heredity. The dif ference between the old idea and the new may be suggested by Minnesota Plant Life. 487 an illustration. Suppose some observer stationed in an air- ship many miles above the battle-field of Waterloo. Per- haps by the use of powerful glasses he could have made out a vague commotion far below him, but he could scarcely have distinguished what actually was happening. ‘To an observer on the hills near by, the battle would have presented a very different meaning. Thus, the earlier students of living sub- stance, because they could not see all that is revealed to the observer of to-day, fell into the error of thinking that they had under their microscopes a “‘structureless slime.” Living substance is by no means homogeneous. Sometimes it shows a fibrous structure made up of innumerable meshes and threads. Again it appears as a foam or emulsion consisting of an intricate combination of larger and smaller bubbles. At one time, when more saturated with water, it is liquid, plastic and mobile. At another, when like a sponge it has expelled a portion of its moisture, it seems almost solid and is passive and immobile. ‘Thus the living substance in the active cells of a growing hair and in the dormant cells of an ungerminated seed may seem very different. By the absorption or expul- sion of water living substances may pass from one condition to the other. Chemical composition of living substance. ‘The following chemical elements are components of living substance: carbon, oxygen, hydrogen, nitrogen, sulphur and phosphorus. In the higher plants the following metals are also necessary for the formation of living substance, although they do not become essential components of protoplasm: iron, potassium, mag- nesium and calcium. Numerous other elemental substances, such as sodium, lithium, manganese, silicon, chlorine, bromine, and iodine are frequently found in the bodies of plants; but they do not appear to be everywhere either essential compon- ents of the living substance or necessary reagents for its con- struction. It must not be supposed that all living substance is of exactly the same chemical composition. ‘To say that no two particles are precisely alike would probably be nearer the truth. Al- though the number of the essential elementary components is so small, many atoms of each kind are present and the varia- 488 Minnesota Plant Life. tions in their relative positions and combinations might be al- most infinite. Certainly, however, the difference between one piece of living substance, such as the egg of a fish, and another, such as the egg of a fern, consists less in chemical composition than in physical structure. Chemically, all living substance lies within limits which have been just outlined. Physiological character of living substance. The following are the most 1mportant physiological characters of protoplasm: 1. Assimilation, the power of initiating and maintaining com- plex chemical changes by which not-living matter 1s brought into the living condition and into relation with the living sub- stance. 2. Growth, a term here applied to the increase of living substance in mass. 3. Irritability, the quality of responding, after a manner determined by heredity, to impulses originating within or without the body. 4. Reproduction, the power of separating, from the body, portions of living substance that, under the influence of heredity, may recapitulate the develop- mental stages of the parent. Together with assimilation, in its broad sense, goes on a variety of chemical processes. By these, waste products are formed and excreted, accessory products are combined and modified, and a variety of complex substances are broken down into simpler forms, thus liberating energy that is either used in growth and movement or reappears as body- temperature, phosphorescence, electrical disturbances or some form of mechanical work. Requisitions made by living substance on its environment. In order to maintain its physiological processes, living sub- stance must have a supply of matter and a supply of energy. The supply of matter, or the food of the organism, may be of great variety, provided that it contain the necessary chemical elements in assimilable form. The great primal source of energy is the sun and upon its light and heat all living things, in the final analysis, will be found depending. Some, however, like the fungi and the animals receive much of this energy indi- rectly. It is utilized directly by the green plants, the color of which indicates the presence in their tissues of that extraordi- nary accessory product of living substance—leaf-green, or chlor- ophyll. ‘This leaf-green that stains either the entire living sub- stance of the cells that are set aside for starch-making, or cer- Minnesota Plant Life. 489 tain specialized portions, is a form of “light-engine’ by which the energy of the sunlight is set at work building up starch out of such simpler substances as carbonic-acid gas and water. The food of plants. In general the diet upon which a plant can live is simpler than that necessary for an animal. The important elements are principally obtained from sources as follows: Carbon is collected from the carbonic-acid gas of the atmosphere ; oxygen both from the atmosphere and from water ; nitrogen from salts in the soil, but not from the atmosphere; and hydrogen from water. Sulphur, phosphorus and _ the metals are obtained from soluble salts in the soil. In excep- tional instances the sources may be other compounds than those mentioned. Thus nitrogen and possibly hydrogen may be taken from ammonia products, but this would be very unusual. What has been stated refers to green plants alone, for plants without leaf-green demand a much more complex diet. Their carbon they may obtain from sugars and from proteids; their nitrogen from proteids; their oxygen and hydrogen from water, from sugars or from proteids; their sulphur and phosphorus from the soil, or perhaps from proteids; and their metallic sub- stances from soluble salts in their substratum. The plant does not ingest solid particles of food as does the animal—though to this certain carnivorous plants are quasi ex- ceptions—but receives its nutriment either as gases, liquids or solutions. The absorptive tract of the plant is often specialized so that one area is fitted better for absorption of gases and another for absorption of liquid solutions. Thus in the ordi- nary green plant it is the foliage that characteristically absorbs carbonic-acid gas and oxygen, while the root-system absorbs water with nitrogen compounds and metallic salts in solution. Aquatic plants are more generalized, as are also air-plants— although the latter use their exposed root-system very much as if established on a firm soil. Humus plants and parasites obtain their food from the bodies of other plants or animals or from decaying organic substances. Partnerships for obtaining food. Some extraordinary part- nership arrangements for securing food have been developed in the plant world. Thus, in the lichen-body a fungus and an alga live in partnership and obtain their food quite as if they 490 Minnesota Plant Life. constituted an independent green organism. So, too, do many humus plants, such as coralroots and pine-saps, depend upon the presence, in their underground portions, of root-fungi. By aid of these they can secure from the soil organic substances that alone they could not collect. In return for such service they harbor the fungus in their tissues. Intra-specific partnerships. Among higher plants a remark- able division of labor exists. By it the spore-bearing plants of the species exist as the primary food-gatherers, while the egg- producing and sperm-producing plants live dependently upon them, having no original food-collecting capacity of their own. Thus, among flowering plants the female, quite devoid of leaf- green, lives upon substances stored up for her use in the rudi- mentary seed borne by the spore-producing plant. The male, also, among flowering plants, lives parasitically upon the tissues of the immature seed or fruit. Similar conditions are known to exist among certain ferns and club-mosses. Other highly interesting inter-relations for nutrition are those between the mother plant and the offspring, as in cone-bearing trees; or between the twin embryos in seeds of higher flowering plants. In the latter instance one of the twins customarily gorges itself with food for the benefit of the other, and by the latter it is ultimately devoured. In such a life-history as that of the sun- flower, for example, only the ordinary green leaf-bearing plant of the species is an independent collector of food. Upon it depend the male and female plants, the albumen-plant of the seed, and, for a time, the embryo-plant that is later to develop into a new leaf-bearing individual. Storage of food. After absorbing its food materials from the air, soil, water or bodies of other organisms, these are re- combined by the plant into characteristic products. In green plants the first visible product of assimilation is starch. This substance originates in the leaves and other green portions under the influence of sunlight. It arises as little white gran- ules. ‘These may grow to a considerable size, but are ordi- narily attacked by ferments, converted into soluble sugars and conveyed along the conduction-paths of the plant either to growing areas where they are used in construction, or to storage areas, such as bulbs, tubers, fleshy roots, seed-albumen or bud- Minnesota Plant Life. 491 cores in which they are deposited as starch or as oils. Proteid substances, originating also in the foliage of the green plant, may be carried away in the form of peptones to growing tracts, or to storage organs, where they may take the shape of little granules, known as farina grains or aleurone grains. Storage layers commonly occur along the conduction-paths, while spe- cial storage organs are produced in a variety of plants. Of such storage organs an ordinary potato, onion, beet or carrot may serve as familiar examples. Ultimate disposal of the food. ‘The materials taken into the body of the plant and subjected to the elaborative processes initiated by the living substances must be either retained as part of the body or excreted. ‘The high manifestation of energy that characterizes the animal is by no means so characteristic of the plant. In other words, constructive processes prepon- derate in the plant-world and a greater proportion of material received as food remains in the body of the plant than in the body of the animal. Excrements are, therefore, not so abun- dant among plants as among animals. Indeed the principal plant excreta are gaseous. From the leaves are given off oxygen, a waste-product of starch-making, and water vapor, Water in the fluid state is also rejected by many plants. Car- bonic-acid gas, a waste-product of respiration, is excreted from the surface of the plant, both in the area of the shoot and of the root. Solid excreta, however, are not formed by plants. When retained in the body of the plant, food materials may assume a great variety of forms. A certain portion is utilized in the production of new living substance, but by far the greater amount is stored as cellulose, bark-substance, wood-substance, gelatine, crystals, organic acids, coloring material, tannin, alka- loids, glucosides, oils, fats, resins, gums, reserve-food and cell sap. Many thousands of plant products are known, so marvel- ous is the chemical activity of the living substance. Growth. ‘The term growth is rather an ambiguous one, since it is applied in several different ways. It should at least ex- clude nutrition, and should generally indicate increase in size. Sometimes, however, there may be an increase in mass without a visible increase in size, and it seems difficult in such an in- stance not to apply the term growth to the process of enlarge- 492 Minnesota Plant Life. ment. For the sake of clearness at least three types of growth should be distinguished: 1, growth of living substance; 2, growth of cells, and 3, growth of tissues and organs. The first takes place as a result of constructive assimilative processes, and may or may not be accompanied by a visible increase in size. ‘The second may go on without increase in mass either of the living substance or of the organ to which the growing cell belongs. The third may occur while mass of living sub- stance and cells are increasing, but sometimes even while mass is stationary or diminishing. Thus by change in shape of its component cells.an organ may elongate, though while it does this there may be no actual increase in substance. Neverthe- less such an elongation might appear as visible growth. Such an analysis is somewhat disregardful of refined and technical terminology, but is not seriously at variance with the truth. Growth of living substance. The most important fact to be kept in mind concerning the growth of living substance, is that it is not simply an accretion of new material. Growth goes on in varying degree among the innumerable component parts of the living substance, each growing in its own way and at its own rate. Thus results the growth in aggregate of the whole. To illustrate this, let there be imagined a village full of children. After a year or two had passed the children would have grown and the total human weight of the village would have increased. Some, however, of the children would have grown more than others,—some, even, might not have grown at all. The final result, however, a general increase in weight, was not obtained by mere accretion. In such fashion does a microscopic piece of living substance grow. It grows as an organism, not as an office-building nor as a snow-drift. For living substance, the limits of growth above which me- chanical support, such as partition walls, strengthening beams, and retaining membranes, becomes desirable, are generally be- low the limits of unaided vision. For this reason most plant cells are of microscopic size. The cell may, in a complem tissue or organ composed perhaps of millions, be regarded as . resulting from the necessity of individualizing small pieces of living substance. It is true, cells vary greatly in size. The smallest are those of the bacteria. The largest are those of Minnesota Plant Life. 493 certain oceanic relatives of the green felt—an alga belonging to the bright-green group. Yet even in the latter, the body. as large as a hen’s egg, which exists without partition walls cutting it in all the planes of space is equivalent rather to a cell-aggregate than to a single cell. Just why the limits between which cells vary in size should be what they are, is a difficult question to answer. The cause must be sought in the structure and qualities of the living sub- stance and in the conditions of the outer world as they react upon it. A proper comparison would be with the towns and cities of the human species. These vary in size between mere hamlets to cities like London, Paris and New York. Cities with fifty million inhabitants, however, do not exist, because with human society organized as it is they cannot be main- tained. To explain exactly the causes that have fixed 6,000,- ooo rather than some other number as a population limit be- yond which human cities have not yet developed, would re- quire a more exhaustive knowledge of anthropology and soci- ology than any one possesses. Still more impossible is it to state why the limits of cell size are precisely what they are. It is, at the same time, clear that, as in the instance of the cities, the reason lies essentially in the nature of the organism—that is, the living substance which builds the cell. The largest masses of living substance in which cell com- partments have not appeared are the jelly-like bodies of the slime-moulds. These aggregates of protoplasm, in patches the size of a dinner plate, are sometimes found on decaying timber. Because they are not provided with internal mechan- ical support they lie flat and shapeless upon their substratum. Origin of the cell as a structural unit. One is now in a position to understand why living substance almost universally displays itself in the microscopic individualized portions known as cells. ‘The cell is an adaptation fitted to enable the living substance, under the stress of outward conditions, to perform its physiological functions in a better way than if this adapta- tion had not been called into being. There is reason to sup- pose that mechanical support and protection against shock might have been the principal necessities under which primal masses of living substance came to develop the cell-habit. In 494 Minnesota Plant Life. both plants and animals cell structure is almost universal and both kinds of creatures are said to be composed of cells. It must be observed, however, that the cells are not the funda- mental units of structure, but are themselves individualized areas arising through adaptation of the living substance to its surroundings. The growth of cells. Certain distinctions appear to exist between the growth of cells and the growth of living substance. When the living substance grows there is an actual increase in its mass. A cell, however, may grow by distending itself with water and there need be no absolute increase in its liy- ing substance.