| Neer i jo uv PRITCHETT—EPHEMERIS OF SATELLITES OF MARS, 1881. 357 Date. Brightness. san -diam. 2 aetna 1881 — Mm. Nov. 20.0 1.00 6”.7 ae? 26.0 1.07 ee ee 5.5 Dec. 2.0 1.15 7 3 | 5.3 8.0 1.21 7.5 5.2 14.0 1.24 ie ee 5.0 20.0 1.26 7.7 | 5.0 26.0 1.24 Ve is 5.0 Jan. 1.0 Cee ere | ae Fe From this it will be seen that Phobos, even on the most favor- able date, will be only about 14” distant from the limb of the planet. In 1877 this satellite was observed with ‘the 12} equa- torial of the Morrison Observatory when only 7” distant. In the present opposition the satellite will be much fainter, but on the ‘other hand the brightness of the planet will be considerably di- minished. It seems possible, mane that this satellite eae be seen with glasses of moderate siz Washington University, Nov., 1881. 358 TRANS. ST. LOUIS ACAD. SCIENCE. The Genus IsoETES in orth America. By Dr. GrorGt ENGELMANN. § 1. History of lsoftEs in North America. The Jsoétes, insignificant and apparently sterile as they are, were long overlooked or ignored by our botanists, so that until thirty or forty years ago very few specimens were collected, and none were distinguished from JZ. /acustris, if we except Nuttall’s guess at his Oregon discovery; but the genus has attracted so much attention, and lately so many forms have become known, that it seems to me an interesting task to trace up the history of the discovery of the different species and their varieties, and of the area of their distribution, and then the date of their publi- cation, before I enter into their scientific description. I. DISCOVERY. 1806 (?). The first notice which we have of an Jsoézes in North America is given in Pursh’s Flora, ii. 671, where he states that “ Zsoétes lacustris” grows in the bottom of Oswego river, near the falls, and adds his v. v., which means that he saw it liv- ing, and therefore probably found it himself; and as he travelled through the regions ‘near the Great Lakes in 1806, it was proba- bly in that year that he met with it. I have not seen Pursh’s specimens, but doubt not but that it will have to be referred to I. echinospora, var. Braunzi, the only form thus far known from Western New York. 1815. Th. Nuttall collected “ 7. dacustris,” abundant along the inundated gravelly and miry shores of the Delaware at Gib- sonville (now a part of Philadelphia) on Aug. 22d, according to the label of a specimen in Collins’ Herbarium, presented to me by E. Durand. It proves to be Z. réparia. 1820 (?). L. von Schweinitz obtained in the Catskill Moun- tains in New York J/. /acustrzs ; some of his specimens are now found in the Herb. Philad. Acad. Natural Science and one in the St. Petersburg Imperial Herb. ome of them are labeled ‘‘ Catskill Mountains” and others “Bethlehem,” the latter, which was von Schweinitz’s residence, probably by mistake. One of the specimens was loaned by the late Elias Durand—in whose possession it was—to Durieu de Maissonneuve, who founded on ENGELMANN—THE GENUS ISOETES IN N- AMERICA. 359 it his I. macrospora. No date being indicated on the labels, the * above-mentioned year is a mere 1825 (?). Jens Vahl collected in Greenland a small Jsoétes, referred to Z. /acustris, which proves to be one of the forms of I. echinospora. 1831. J. W. Robbins gathered an /soé¢es near Uxbridge, Mass., which I recognize as /. riparia. 1832. C.J. Moser, who collected for the German Unio itine- raria, obtained specimens on the Lehigh river near Bethlehem, Pa., and near Philadelphia, both of which were distributed to the subscribers as /. Jacustris. One of these (in Herb. Bernhardi, now in the Herb. Missouri Bot. Garden) represents /. Enged- manitt; another, which I have seen in Europe, is I. riparia. 1834. Th. Nuttall discovered an /soétes on the Columbia river in Oregon, which I saw in E. Durand’s Herb. with Nuttall’s own label, Z. ofaca ; it was afterwards named I. NuTTA.uu. About the same year Drummond collected “ J. dacustrts” on the Saskatchawan, according to Hooker’s Fl. Bor. Am. ii. 268, which I have not been able to compare and to identify. 1840. J. W. Robbins found Z dacustrés near Uxbridge. 1842. Rugel discovered an Jsvétes in Lake Imonia in Florida, which was soon afterwards distributed in Europe by Shuttleworth under the name of I. FLaccipa. None of his specimens are be- lieved to exist in America. 1n the same year N. Riehl and myself found near St. Louis, Missouri, the species which from my specimens was by A. Braun named I. ENGELMANNI. 1843. Chas. Geyer found in Western Idaho 7. Nuttalliz, ac- cording to A. Braun, who examined the specimens in the Herbarium. In the same year S. Tuckerman collected /. /acustris in the Echo lake in New Hampshire. 1844. Wm. Zantzinger rediscovered the /soé¢es on the banks of the Delaware near Philadelphia. His specimens, sent to me, are the type of my I. RIPARIA. 1845. T. W. Robbins found in Massachusetts P i echinospora, yar. Braunii. 1848. E. Tuckermann discovered near Boston the species which was by A. Braun named for him I. TucKERMANI. 360 TRANS. ST. LOUIS ACAD. SCIENCE. 1850. A. W. Chapman found in Northern Florida a peculiar Lsoétes, which proved to be a large-spore form of Z. flaccida, and was named var. CHAPMANI. 1853. E. Hall discovered in his fields near Athens in Central Illinois the ates which was afterwards named by J. sa. I. ME- LANOPOD 1856, ‘Soued L. echinospora, var. Brauniz, in n Lake Winni- piseogee in New Hampshire, the type of I. Braunu, Durieu. _ 1857. E. D. Eaton obtained 4. Axgelmanni for the first time in the New England States. 1860. Wm. Boott found near Boston the form of J. echino- spora, which was named from his specimens I. MuricaTA by Prof. Durieu, the present 7. echinospora var. muricata . Porter discovered near Lancaster, Pa., the largest Agios Noahs I. Engelmanni, var. VALIDA. In the same year G. Vasey found /. melanopoda in Iowa. 1863. I. Macoun obtained J. echinospora, var. Braunti, in West Canada. In the same year Wm. M. Canby discovered in Maryland I. SACCHARATA. 1865. Leidy and Porter collected Z. /acustris near the outlet of Lake Superior. In the same a 1. Tuckermani was rediscovered near Bos- ton by Wm. B 1866. Chs. sean discovered I, CuBana in Eastern Cuba. In the same year H. Bolander found two new species in the Sierra Nevada of California, I. BoLANDERI and I. pycmaa. 1867. Wm. Boott got near Boston the species named after him I. Boortu. now known as J. echinospora, var. Boottiz. 1869. Wm. M. Canby discovered on the Stone Mountain in Georgia the curious little I. MELANOSPORA. In the same year S. Watson found /. echinospora, var. Brau- att, in Utah. 1871. E. Hall gathered beautiful specimens of 7. Muttalliz on the Columbia river. 1872. The same traced /. melanopoda to Texas. 1873. T. P: James got /. echinospora, var. Braunii, in Nova Scotia and C. C. Parry found Z, Bolandert in Yellowstone lake in Wyoming. ENGELMANN—THE GENUS ISOETES IN N. AMERICA. 361 1875. G.D. Butler discovered in the Indian Territory the spe- cies named for him I. Burieri, and with it a new locality for LI. melanopoda. 1878. C. G. Pringle found in Lake Champlain the form of Z. oe aes I have designated as var. ROBUSTA. 1879. E. Jones met with 7. Bolanderi in Utah 1880. ee Gattinger discavered near Nashville, mega a LZ. Butleri, var. \WMACULATA. 1881. I collected JZ. dacustrés var. PAUPERCULA in Grand Lake, Middle Park, Colorado, and C. G. Pringle found the same in Northern California. 2. PUBLICATION, 1753. Linnzus published in his py aaed Plantarum, ed. i., his Jsoétes dacustris, the only species known to Neither Michaux nor any of the older writers on American plants knew of any North American J/soé¢es. 1816. Pursh, Fl. Am. Sept. ii. 671, mentions “* J. lacustris” from Oswego river, Western New York, which is most probably I. echinospora, var. Braunii, the only species thus far known from that region. 1818. Nuttall, Gen. ii. 253, has “‘Z. dacustris” from the miry -shores of the Delaware near Philadelphia, which cannot be any other than Z. riparia ; he also gives Pursh’s habitat. In the same year Barton, Fl. Philad. ii. 213, has “7. dacustrzs” from Philadelphia, which may include both Z réfaréa and Z, Engelmanni. 1824. Elliott knows no Jsoétes. 1826. Torrey (Comp. Fl. North. & Middle States) gives as habitat of ‘615, 7. econ bottoms of lakes, evidently without having himself seen n the Flora Gaeiiiecn of the same year Darlington does not sediion the genus. et = Syst. Plant. iv. 9, knows only JZ. lacustris with three ~varie a Beck in his Botany repeats Pursh’s stil Nuttall’s lo- calities. 1840. Hooker, Fl. Bor. Am. ii. 268, mentions “ Z. /acustris” from the Saskatchawan. This may be the true d/acustrts or a 262 TRANS. ST. LOUIS ACAD. SCIENCE, form of echinospora, either of which may be expected in those regions. 1843. Torrey, Flora of New York, ii. 514, “7. lacustris,” a mere repetition of Pursh’s statement. 1844. Bory ee the Genus, which until then had been very much neglected, and adds to the three then known species (JZ. lacustris, Coromandelina, and ph three new ones discovered in Algeria by Durieu de Maissonneuve. 1846. A. Braun, in Regensburg bot. Zeitung, No. 12, briefly characterizes /. r/parza, Engelm., from Philadelphia; 7. Eaged- manni, A. Br., from Missouri, and /. facctda, Shuttlew., from orida. 1847. The Amer. Journ. Arts & Sciences, n. ser, iii. 52, pub- lishes a translation of the above notice. 1848. A. Gray, in the first edition of the Manual Bot. North. States, p. 640, distinguishes the then known three northern spe- aie L. lacustris, 1. riparia, and 1. Engelmannt. 1853. Darlington, Fl. Cest. ed. ii. p. 402, mentions “Z. /acus- tris” as growing in shallow ponds in his district. This must refer to J. Engelmanni, the only species growing there in such lo- calities. 1856. A. Gray, Manual, ed. ii., gives an almost verbal reprint of the first edition. 1860. Chapman, Fl. South. States, p. 602, describes 7. flac- cida as growing in ‘‘lakes and clear streams” in Middle and West Florida. In the same year E. Tatnall, Cat. Pl. Newcastle Co., Delaware, enumerates L. réparéa and 1. Engelmannt, both of which names here probably stand for the latter. 1861. Durieu de Maisonneuve, Prof. of Botany at Bordeaux, in apse Soc. Bot. France, viii. p. 164, distinguishes and characterizes ° North European species /. /acustris and J. echinospora, heretofore eects together. 1864. The same author, Il. c. tor, 102, indicates four Ameri- can /soétes: muricata from Massachusetts, Braunii from New Hampshire, w/acrospora from the Catskill Mountains, and mela- nopoda Gay (or Gay and Durieu) from Illinois. In the same year A. Braun published a most important treatise on the Genus in his account of the /soéfes of the Island of Sardinia, in which our species are frequently referred to ENGELMANN—THE GENUS ISOETES IN N. AMERICA. 363 1867. In the fifth edition of Gray’s Manual, p. 676, I for the first time published Z. echénospora as an American species, dif- fering in several varieties from the European type—var. Braunié (1. Braunit, Dur.), var. muricata (1. muricata, Dur.), and var. Bootti (I. Boottiz, A. Braun in lit.), all of them from the North- eastern States; also 7. Zuckermanni, A. Braun in lit., from Mas- sachusetts, and /. saccharata, Engelm., from Maryland. 1874. In Dr. Parry’s Botanical Observations in Western Wyo- ming, Am. Naturalist, viii. 214, 215, I gave an account of the three western species: /. Bolanderi, Engelm.; J. pygmea, En- gelm., and 7. Nuttalliz, A. Br. in lit. 1877. My notice of Z. melanospora, Engelm., from Georgia was age in the Trans. Acad. Sci. St. Louis, ili. 395, note. 8 n Coulter’s Botan. Gazette for January, p.1, I gave an account oe Butleri, Engelm., found in the Indian Territory west of Arkansas. § 2. Morphology of Isoétes. The species of /soé¢es are the simplest vascular plants known. They consist of a short trunk* with root-fibres at its base and leaves on its top, normally withoul branching and without any axillary productions. he TRUNK is generally depressed, broader than high, or flatter in some species (. Exge/manniz), and thicker dnd more funnel-shaped where the leaves are inserted, while the underside shows in almost all the N. American species two grooves and in many exotic ones three grooves, dividing the trunk more or less deeply into two or into three lobes. The number of lobes rarely varies, so that among the many hundreds and even thousands of American specimens which have passed through my hands, I have found only asingle, normally bilobed, one with three lobes ; this was an /. r¢parza from Philadelphia. In the 3-lobed species f the trunk is given by H. Mohl in Linn xiv. ss (840) 18 wank of the whole plant and its psi aa Ried ss A. Braun in he Tsoétes ae dinien. Monatsber. d. Berliner Acad. W 1864. on a ee m8 Isoétes — has — seen peer probably i in consequence of some injury; I mysel pelt baw seen a specimen of J. Tuckermani with four nari lanai! 1 fr trunk. K. Goe an found a (Asggnaye Tsoéles wzith lateral shoots in place of spore cases. Bot. Zeitung, 1879, N' 364 TRANS. ST. LOUIS ACAD. SCIENCE. the transverse section is rather circular, but in the 2-lobed ones it is usually oblong or often somewhat rectangular, narrower in the direction of the grooves and wider in the opposite direction ; the vertical section of the trunk shows a thickness of from 1 to 6 lines, and the transverse diameter a width of a few lines to more than one inch. In the centre of the trunk we find a small ligne- ous body, fibres from which enter the leaves and the roots. The mass of the trunk is a white parenchymatous or rather cortical tissue, the cells of which are filled with starch. The growth pro- ceeds from the centra! ligneous body outwardly in two or three directions, corresponding to the two or three lobes, so that these lobes would spread laterally if their enlargement were not limited by the decay of the older (the preceding year’s?) parts. We thus find that at the period of the most vigorous growth, about the beginning of fructification, the extreme lateral portion of the lobes ‘becomes discolored, brownish, atrophied, and at last black, and is separated from the living tissues by a distinct line of demarca- tion, and at last generally falls off at the end of this or the be- ginning of the next season as a black mould-like mass. In some species, e.g. 7. Jacustris, and in colder climates the atrophied cortical parts continue to cohere for several seasons, and in the Mediterranean /, ystr?x they do not seem ever to be detached, so that the trunk of this species reaches a larger size than any other. The decaying portions are pushed obliquely upwards when the base of the trunk grows faster than the upper part (often in I. Engelmanni, and much more so in the Australian /. ¢r7pus), or horizontally outward (the ordinary case), or downward when the upper or leaf-bearing part expands more than the lower, root- bearing part. This last is the case in 7. Hystrix, where the © dead parts are turned downwards. As the growth of the trunk takes place from the centre out- ward, the roots, originating from the youngest parts, start from the groove itself; and fresh and living, whitish, ones are only found in or near this groove: as they get older they are pushed to the sides, and finally die, becoming brown and black.’ The mass of roots found on /soé¢es specimens are mostly the entan- gled dead fibres, which, by the way, often conceal spores of the previous year, and therefore must be carefully examined when ENGELMANN—THE GENUS ISOETES IN N. AMERICA. 365 no fresh spores are attainable. The root-fibres, sometimes longer than the leaves, are always dichotomously, and often many times, branched. — The upper, concave, surface of the trunk bears the leaves, the innermost or youngest ones often yet immersed in the trunk. The LEAVES are subulate or sometimes almost filiform tubular organs from a broad membranaceous sheathing base, mostly more or less quadrangular (broader and with sharper edges on the up- per or ventral, narrower on the dorsal side), or in our terrestrial species more triangular and keeled on the back. Their sheath- ing bases form the 4/6, which can be compared to the bulb of liliaceous plants; in fertile specimens it is always larger and thicker than the trunk, and in some of the larger ones, e.g. Z ngelmanni and L. melanopoda, attains a diameter of one or two inches. The leaves above this base contain four longitudinal air cavities, /acuma@, separated from one another by two dissepi- ments, a transverse and a median one, and irregularly divided by very thin tramsverse septa. The dissepiments are of different, pretty constant, thickness inthe different species, thinnest in the amphibious and thickest in the terrestrial species, consisting in the former often of only 2 to 4, in the latter of 6 to g layers of parenchymatous cells; the median dissepiment is generally a little thicker than the transverse one. The anterior /acune are mostly somewhat larger than the posterior ones, The epidermis of the leaf consists of rectangular cells, mostly much longer than they are wide; only in Z. Aygme@a are they comparatively short, and sometimes even square. In a few spe- cies the epidermis is entirely destitute of stomata, in the others it is pierced by stomata which communicate with the air-ducts, over which alone they are found. The presence or absence of stomata furnishes a very important character for the diagnosis and classi- fication of the species. It was formerly thought that the sub- merged species had no stomata, and those species which bear their leaves more or less exposed to the air were provided with them; later discoveries, however, have shown that this rule does not always hold good, for we now know submerged species with stomata and emerged ones without them, and we have one sub- merged species (J. echinospora) in which the typical European form is destitute of stomata, while the American varieties show 366 TRANS. ST. LOUIS ACAD. SCIENCE. either a few stomata, often difficult to discover, or, rarely, numer- ous ones; so that in this interesting species the question arises whether the presence or absence of stomata a/ove can specifically separate forms otherwise scarcely distinguishable, as that acute observer of these plants, A. Braun, has maintained, or whether the stomata do of always play that important part in classifica- tion generally assigned to them. Below will be found directions for the investigation of the stomata. The parenchyma of the leaf consists of a few or several layers of chlorophyll-bearing cells, 1. under the epidermis, 2. around the central bundle of vessels, and 3. forming the dissepiments, which cross each other in the centre of the leaf. An important element in the leaf structure is found in the peri- pheral bast-bundles, which are present in some and absent in other species ; and their presence often, but not always, coincides with the presence of stomata, When present they commonly form four bundles, two in the two anterior angles of the leaf, rior and the posterior wall of the leaf; in 2 Muttaldi¢ I find only three bundles, the anterior median one being wanting; in ZI. Cubana six bundles are visible, the two additional ones being located where the transverse dissepiment unites with the outer wall. In some rigid-leaved land species, e.g. Z. melanopoda, often several smaller accessory bundles are found scattered under the epidermis. he examination of the fresh Zsoé¢es leaf is not very difficult ; stomata, when present, very distinctly. Where there are few stomata, the epidermis from different parts of the leaf must be examined, and especially from the tip, as they are more apt to be found there. In dried specimens the leaf must be soaked, the alge which often adhere to the surface have to be carefully scraped off, after which I make several sections } or } line wide, lay them open by a vertical slit, detach the central bundle, and then scrape very gently the inner surface so as to remove the par- enchymatous cells which obscure the appearance of the stomata This process can be aided by an immersion of the specimen in a weak solution of caustic potash. The work is often a difficult one when the specimen is very old or poorly preserved, and ENGELMANN—THE GENUS ISOETES IN N. AMERICA. 367 requires a good deal of patience. Sometimes the application of iodine will very distinctly show the stomata by coloring their guard-cells blue when only these contain amylon, but of course not when the other cells are also filled with that substange. A magnifying power of 150 to 250 diameters is best adapted to well exhibit the stomata. To find the bast-cells it is necessary to make the thinnest pos- sible transverse sections of the leaf, boil them well, and, if they do not then show under water as bundles of minute, thick-walled, darkish cells close to the epidermis, very distinct from the much larger epidermis cells, the application of a solution of caustic pot- ash, to clear the preparation, will readily bring them out. The same magnifying power which we use for the examination of the stomata may be applied for the study of the bast-bundles. I would advise anyone who desires to study the structure of fsoétes leaves to commence with well known species:and good (if possible fresh) specimens, and make himself familiar with the manipulation and with the appearance of their parts under the microscope before he proceeds to study unknown and difficult specimens. The arrangement of the leaves in the species with two-lobed trunks is at first distichous, and in /. melanospora it remains so through life; in all the others the leaves soon enter into a more complicated phyllotactic ies in the larger ones, with many leaves the $? and even the 24 order is found. The number of leaves varies from 5 or 10 (LZ. pygmea, J. me- lanospora) to 100 or even 200 (Ll. Engelmanni, var. valida), and their length from } to 1 inch (in 7. Aygmea) to 1-2 feet (in some forms of 7. faccida and J. Engelmannz) ; their color from light and fresh yellowish-green (7. Exgelmanni) to dark and dull green J. dacustr¢s); their rigidity is greatest in the terres- trial species, and also in some submerged ones; and least in most amphibious species, which often float their leaves on the surface of the receding water, or in some submerged ones, the leaves of which, taken out of the water, collapse like the soft hair of a wet pencil. The submerged species vegetate and retain their verdure throughout the winter (whence, it is said, the name of the genus is derived: Zsoé¢es, equal at all seasons), but.the others lose their 368 TRANS, ST. LOUIS ACAD, SCIENCE. leaves soon after their maturity in autumn, some of our terres- trial ones even already in summer. The broad membranaceous sheathing base of the leaf is with- out air cavities, stomata, or bast-bundles; in sterile leaves it gradually contracts into the leaf itself. Those leaves are usually sterile which develope at the beginning and the end of the sea- son. The fertile leaves have in their base an excavation which bears the spore-case, sforangium, adnate with its back to the midrib. Above this excavation, and separated from it by a deep transverse depression or slit, we find a stipule-like organ of tri- angular more or less elongated shape, cordate at hase, appressed to the leaf, which is termed the gua; it is small, and in not very fresh leaves often mutilated and difficult to make out. The morphology of these parts is obscure and their diagnostic value not great. The sporangium is oblong or circular (both forms often seen in the same species), from 4 to 1 line long in /. melanopoda; 1 to 2 lines in 7. pygmaa, Tuckermanti, echinospora, and saccha- rata; 14 to 24 lines in J. lacustris, Bolanderi and flaccida; often alittle larger.in /. Butler and Nuttalliz; 2 to 4 lines in Z. riparia, Engelmanni, melanopoda, and Cuéana; and in larger forms of Z. Engelmanut I have seen it § to g lines long. It is somewhat flattened, and often slightly concave on the ventral side ; it is entirely naked or (the usual case) it is on its sides and principally upwards partially covered by a fold of the ventral side of the leaf-base, the veil (ve/wm); in a few species (7. flaccida, melanopoda, and JVuttalliz) this fold extends over the whole sporangium, completely covering it (velum completum). The sac of the sporangium is composed of two layers of cells; the outer, epidermidal, layer consists of elongated, often variously bent or hooked and curiously interlaced cells, mostly thin-walled and transparent ; in some species (e. g- LI. riparia, I. sacchara- ta, L. melanopoda) groups of brown, thick-walled, (so-called) sclerenchym-cells are mixed with the transparent ones, giving the spore-case a dotted appearance visible even to the naked eye. The spore-case is traversed by numerous parallel strings. Some sporangia, called macrosporangia, contain larger or female spores (macrospores or gynospores), others are filled with the minute or male spores (microspores or androspores) ; these ENGELMANN—THE GENUS ISOETES IN N. AMERICA. 369 are called microsporangia. Almost all the species are mone- cious, bearing macrosporangia on the base of the outer and microsporangia on that of the inner leaves. I am not aware that any exotic species behave differently, but here we have two spe- cies which deviate from this norm. J. melanopoda in Illinois as well as in the Indian Territory, from both of which localities I have examined several hundreds of specimens, is polygamous, i.e. monecious as well as dicecious, and shows about an equal number of male, female, and monecious plants. The allied J. Butler is apparently always dicecious, no monecious plants having been discovered among about one hundred examined. In 1: melanopoda 1 have sometimes seen leaves with microsporangia irregularly interspersed among those that bear macrosporangia. The macrospores are little spheroid bodies between one-fourth and three-fourths of a millimeter in diameter. Their surface is divided by a circular rim in a lower hemispherical and an upper three-sided pyramidal part, the three faces of which consist of spherical triangles and are separated frem one another by three elevated ridges. The crusty surface of these spores, chalky-white or whitish in most species and dusky (when wet black) in marked differently from the lower hemisphere (especially in J, Tuckerman?) or are smoother than that (often in 7. melanopoda). To examine the spores well it is necessary to soak the leaf-base, refully remove some of the wet spores and let them dry on the slide, for they must be examined dry, and best under a power of or 60 diameters ; but, to study the sculpture well, a power of 100 to 150 diameters is necessary. With the aid of this we find the macrospores—1. Minutely tuberculated or warty; the warts small and mostly somewhat depressed, distinct or sometimes somewhat confluent, in 7. pygmea, Bolandert, saccharata, me- lanospora, Butler, and Nuttalliz.. 2. With larger, broader tubercles, generally more distant and distinct, but also here and there confluent, worm-like; thus in I. flaccida, melanopoda, and Cubana. 3. With tubercles elongated into spines; these are simple and very fragile, or here and there confluent and forming sometimes short crests: JZ. echinospora and its forms, iv—2—12 370 TRANS. ST. LOUIS ACAD. SCIENCE. 4. With crests and ridges, distinct or anastomizing : I. lacus- tris, Tuckermant, and riparia. 5. The confluent crests form a regular net-work: 2. Enged- mannt. The microspores are minute bodies of an ash-gray or a dusky color (dark gray in “ pygmea, Bolanderi and melanopoda, deep brown in Z. melanospora, Butlert and Nuttailiz) and of a somewhat triangular-oblong shape, nearly straight on one and curved on the two other edges, more than half as wide as they are long, between 0.020 and 0.040 millimeters in the long- est diameter. Their surface is smooth or minutely papillose or spinulose, the edges smooth or somewhat cristate. Their size furnishes good characters, but the condition of the surface much less so. They ought to be examined under water and with a power of about 400 diameters. § 3. Biological Characters. After the maturity of the spores the leaves wither or rot away, the sporangia decay and set the spores free, which scatter near the base of the plant, often being retained between the matted roots.* The cellular mass of the macrospores developes into a prothalius, which bursts the spore-case through the opening of three valves which correspond to the three upper faces of the spore, and forms an archegonium, which is fertilized on coming in contact with the zodspores emitted from the microspores, and thus gives rise to the young plantlet hepa iid moisture and tem- perature favor this process. he germination of the late-maturing water-species probably takes place in the succeeding spring, at least in tke more north- ern localities; in our land- and marsh-species it may be observed soon after their maturity in summer or in early autumn. I have studied the whole process in 7. Angelmanni, which I kept in cultivation for several years. At the end of July the spores were perfectly mature and the leaves were coming off. On the 28th of that month I spread out both kinds of spores on a muddy surface and kept them slightly covered with water, and * ti is Serene proper to examine among the roots for spores binge ets none can be fc nt; one or the other may be discovered there and help out diagnosis which otherwise may rest in obscurity, ENGELMANN—THE GENUS ISOETES IN N. AMERICA. 371 fully exposed to the hot sunshine of that season. Three weeks later the first green points were seen and continued to come up until the end of October, while at that time the earlier ones had already developed 5 to 8 leaves, 4 to 1} inches in length. The contents of the large or female spore-cell first developed into a dense cellular mass; this, enlarging, split the cell-coats as above described and protruded obliquely upwards a minute conical point, green inside, while on the lower edge of the pra but still between the three valves (the lower hemisphere of the spore- case not being ruptured or perforated at all), a much smaller and rounded knob, the origin of the first rootlet, showed itself, bear- ing a large number of extremely fine capillary fibres; the bulk of the prothallus remained enclosed in the hemispherical part of the spore-case as a lateral knob, while the first leaf and then the first rootlet elongated; the spore-case was thrown off only when the former had acquired a length of 3 to 4 and the latter one of 2 to 3 lines, the capillary fibres still continuing at the origin of the rootlet. Soon afterwards a second leaf and a second rootlet were formed, both opposite to the laterally protruding spore-mass ; after that new leaves and new roots spring up in distichous order between the older ones, the youngest in the centre. In twelve months the young plant, not yet fertile, shows the bilobed flat or rather concave trunk, 2 to 4 lines in diameter, with both ends strongly elevated, their edges already showing small masses of black decayed tissue (the remnants of the first year’s growth). The leaves of these yearling plants, 10 to 15 in number, are 3 to 4 inches long, have abundant stomata, but as yet only a single very slender bast-bundle, median on the upper surface. The species of /soéfes, perhaps 40 to 60 in number (according to the views taken of the different forms, whether species or varieties), are distributed over the whole globe, apparently more abundant in the temperate than in the tropical zones. In North America we have 13 species, with 12 varieties, to which I add one from Cuba; from Mexico we have received as yet none. More are expected to be found when the attention of collectors is more earnestly directed to them. Most of the species may be called water-plants, growing in stagnant or in slow-running water; a few are always submerged | and are found out of water only in abnormal conditions, e.g. in 372 TRANS. ST. LOUIS ACAD. SCIENCE. unusually dry seasons. The majority are of amphibious growth, entirely or partially submerged dnring the wet seasons, in win- ter and especially in early spring ; but at the growing season they partially get out of the water, leaving only their trunk and lower part of the leaves immersed. These species do not come to per- fection when completely immersed, though they may not, be en- tirely infertile ; it seems that partial exposure to the atmosphere is necessary to their well-being. A variety of the amphibious species are the tidal ones, which are alternately emerged and submerged during the changes of the tides; they are found in the estuaries of some of our Atlantic rivers. Then we have a few species which we are justified in calling terrestrial, as we find them, when fully developed, on dry land; but it seems that for their germination and their growth in early spring they also require moisture and water; we therefore find them on low or flat grounds which may be overflowed in spring, or in springy localities, but they fully develope and become fertile only when out of water. /. melanopoda, which belongs to this class, normally matures in June or early in July, and its leaves wither before the end of that month; by keeping it immersed, however, I have kept it fresh and growing throughout the summer, but under these conditions it remained perfectly sterile. Those terrestrial species which grow on arid hills around the Mediterranean must require even less moisture, and are probably satisfied with tem- porary drenchings. The submerged and the amphibious species are generally found, some in soft mud, others between gravel and stones; the amphibious ones generally in deep mud. Our terrestrial species grow mostly in heavy, retentive soil. Systematic Arrangement. Our 14 species can be classed— 1. According to the developement of the trunk; thus we have 13 species, all our North American ones, with a dé/obed, and only the single Cuban one with a ¢rilobed trunk. 2. According to their mode of growth: a. Submerged species, which normally always grow under wa- fer: 2, lacustris, 1. pygmaa, I. Tuckermani, I. echinospora, and J. nderi. 4. Amphibious species, which grow in water but have their leaves i ENGELMANN—THE GENUS ISOETES IN N. AMERICA. 373 usually emerged: J. saccharata, I. riparia, J. flaccida, I. Engelmanni, I. melanospora, and probably 7. Cubana. c. Terrestrial species, which grow during the greater part of their life on dry (or moist) land: JZ. melanopoda, I. Butleri, and J. Nuttaltii. These divisions seemed to be the most natural ones so long as but few species were known, and when other characters, such as the presence or absence of stomata, seemed to correspond with and to confirm them; but, since we know more species and more about them, we have learned that structural and biological char- acters do not always go together; and, moreover, that some species are in some forms submerged and in others almost am- phibious (JZ. echinospora), and that some amphibious ones become sometimes almost terrestrial (7. Znge/manni). A less important objection is, that the biological characters cannot be made out in herbarium specimens. 3. According to the condition of the velum a. A partial or narrow velum has JZ. dacustris, Cs ee L. Tuck- ermani, I. echinospora, I. saccharata, I. Bolanderi, I. ripari . Ln- gelmanni, I. Howellit, I. melanopoda, and I. Cubana. In 7 Butleri the velum is almost completely absent. 4. A complete velum has Z. melanopoda, I. flaccida, and I. Nut- tallii. The anatomical structure of the leaves, viz., the presence or ~ absence of stomata and of peripheral bast-bundles, furnishes us valuable characters, and, though somewhat difficult to ascertain and therefore less practical, may after all have to be placed in the first line, as it seems to correspond best with the essential charac- ters of the plant. 4. According to the presence or absence of stomata in the leaves: . Without any stomata are only JZ. dacustris, I. pygmea, and J. Tuckermani. The typical European J, echinospora also belongs ‘here, but the different American forms of this species must be classed among the next, though some of them have only very few stomata, often difficult to make ou . With stomata (generally ao T. echinospora (Ameri- can ewurietios), I. saccharata, I, Bolanderi, I. riparia, I. melanospora, . Engelmanni, I. Howelliit, J. flaccida, LI. melanopoda, I. Butleri, I. Nuttallii, and J. Cubana. 374 TRANS. ST. LOUIS ACAD. SCIENCE. 5. According to the presence or absence of peripheral bast- oe : @. Without bast-bundles: £ dacustris, 1. pygmaa, I. Tuckermani, < prety TI. saccharata, I. Bolanderi, I, riparia, and J. mela- ew With bast-bundles: JZ. Engelmanni, I. Howelli, 1. flaccida, I. melanopoda, I. Butleri, I. Nuttallii, and £. Cubana. The comparative size or the sculpture of the spores, and the number and length of the leaves, furnish no legitimate grounds for classification ; still it may be mentioned here, that the largest macrospores (0.45 to 0.80 mill. in diam.) are found in J. lacustris, I. Butleri, and J. riparia; the smallest (0.25 to 0.45 mill.) in Z melanopoda, I. flaccida, and 7. Engelmanni var. valida. The largest number of ea 5° to fuss are observed in the last mentioned form, in /, and in /. Nuttalliz; the small- est number, 5 to 20, in J. pines, I. melanospora, I. saccharata, and J. Bolanderi. The longest leaves (15 to 25 inches long) we meet with in 7. Engelmanni, I. flaccida, and J. Cubana; the shortest (4 to 3 inches long) in Z. pygmea, I, melanospora, and JI. saccharata. The following classification of our species is proposed as the best I can find, though by no means a faultless one. I. Trunk bilobed. A. Pee species with quadrangular leaves, without, or in 4 and 5 with . any stomata and without peripheral bast-bundles; velum in- pe te 1. J. lacustris. 2. I. pygmea. 3. I. Tuckermani. 4. I. echinospora. 5. 1. Bolandert. B. Amphibious species with abundant stomata in the quadrangular leaves. * Without € expr cronivel bast-bundles ge are intermediate be- + Velum partial 6. I. saccharata. 7. I. riparia. ~ t Velum complete. 8. 1. melanospora, * yey peripheral bast-bundles. Velum pa ra ey Engeinanni 10. £. Howell. t Velum aeahallatie. 11. £. flaccida. Terrestrial species, maturing when entirely out of water, — abundant stomata. and peripheral eave in the nearly triangular leaves. a 12. Z. melanopoda. 13. L. Butleri. ENGELMANN—THE GENUS ISOETES IN N. AMERICA. 375 * * Velum complete. 14. L. Nuttalist. II. Trunk trilo ohed, = numerous stomata and bast-bundles in the quadrangular ves; velum partial. 15. 2. Cubana. § 5. Geographical Distribution. a small part of the North American continent has been well ex- plored for Isoétes, and there, from Massachusetts to the Chesapeake Bay, they appear abundant enough; farther south, and. in the whole interior and western part of the continent, em have thus far bes found only in a few localities. Some species are quite local, as is the case also with many species of the old world, while others are widely distributed. Our two northern speci re identical with, or closely allied to, European fo) a southern a with the Mediterranean ones or those of other regions of the glo’ The old dinaesn Isoétes lacustris is the only species which has been found to extend from the Atlantic to the Pacific States, and it probably gh i species seem to nearly or quite local, 7. fygmea, in the Californian Sierra, but most of them on _ Atlantic border; thus J. weaer: mant OC- curs iat néar Boston, Z. s te streams emptying into the Chesa- eake Bay, and J. melanospora only on that peculiar and, ‘otanicatty, so i ie sor the e Mountain of Georgia. Some species which seemed local have ae assumed a little wider range, though yet quite i th nts. rom the warmer parts of North America we know only /. Cubana, from Cuba; none have yet turned up from Mexico The following table will explain itself. ” ” 3 bia St »” * » ” ‘SQ0UTAOIg 10 ‘saTozpLay, “Sajv}g OF A ” ” ” ‘BIGIOFV PUB yIOA MON ” ” : ” ” ‘Aosaa[ MAN puv viuvalAsuuag pe *sasnyousseyyy Ul punoy u9aq act jeeses pus popadl Qarmaea TRANS. ST. LOUIS ACAD. SCIENCE. I age is meh a gid vee oe eae ee . $e sees as [ : gO Tes alow mS oe abe Lott ; T 660 eben as pqRee ee Eee € vere aes ve oe I es eee Asons0g, wovsany T ate [oes pele bee ped eae [eee e rae we as re . Vue reo an PreGted “We ee | iat eee ee VER rw ee eas SS oyup domes Koos ae, a4 ee ae ed oo eee ’ ~ . ‘ wee . eee ee eae Sup s , a iy Se BAS ee. es cles. a 1 ae ae Bay Oboe IP Od abyss eg 3.) eg gl eee ee a pag So ia nie cos Mies aes geo I oe 1 eee eves +e Levee . . aes - Goypssag, wep ee Bes . Tr} PE er 7 o Arey eee Pere Or ea Aree as Pew s Gal te Sone Br ee ee eg eo [Lossy ae oie ip ce rie Pe se tee bees ve ous . oboe Ps et eee ee ear ee Vere ee ey wMO tne * Stee arene fy pe res fevee wa Pees . +a * + STOUT 5 a4 ete vale peeeedives) (ames ; ee BS : A asl ieee een . ae Te ot es ee Rak gore oealue pees e myo ve es tae . yey a Sabie hae ee Tie es e+ Beews tease pre | endian ee | aaa cawabaas RUA . ‘ oe . anes faves eee [eres o feves . os purpdan Cbs ieee ee Beg rs © roe gla ’ rast I I wes T . * . . I . on Aasaa MON . ‘ 4 Arete { see Tul ‘ - I . ase yuray sung fee eese fas seee se furee |e . . I . toe WUITUO es Ge ae a aoe ieee eee Ry ’ ‘ a re OS i a be i ee en oak Pee, re ee | Seo Bee sae qnopoanu0, y . oe l Reg seve fosee [ove save [osee [osee fects [atte fuse [oven fos ee ere ee pueysy apoy of I fas a tos fase I ee pede 1 fect [ages T sean das ees s}Josnyoussn Ww He ie I ee peer pave I Ree pees at Pee Pees one Ue Seed en oe ee qUOULIO A. jae the me Reset brews: Ieees sere beaee aBes Pease aves tay rie aayysduinyy Ave cenit . Tei . seve [owe oe Friis Peer: ry tae | CMe eee ee er beter 2 2 aure sere beans weet [owe eese fewed feces [Ee (Ge ene severed s UTOIg VAON ei eon ‘ sv ees eseees puvwoasyy tL “Hn00g “‘Mayng ‘I ppiyyod “ppyoowy “YT “Hypenoy 7 “ppyypa *sionab “piuwwd2s “7 “qapunjog °I “pIsnqos powubid ‘7 nod 8249SNID] [ pungn ‘I “nITenAAT IT URDAT UM? £ | rte “Fupwsoyony “I “quupuyjobug “T oe “pupib.0ap “DIDI NODULE *ppodounjau ‘7 ‘paodsounjaut “J “8791408 pup saqsads 7vj0], MY ENGELMANN-—THE GENUS ISOETES IN N. AMERICA. [377 § 6. Enumeration of the Species. I. Trunk bilobed. A sb agg normally growing onder water, only in unusually dry seasons coming above the surface; leaves quadrangular, lcha peripheral bast. bundles; velum incomplete * Without stomata. . I. pacustris, Lin. Leaves stout, rather rigid, ee pies nie mente but scarcely tapering, dark or olive-green, 10 to 25 in number, 2 to 6 inches long; sporangium orbicular to broadly ‘aitiesical. il spot- ted, with a rather narrow velum; ligula triangular, short or somewhat elongated ; cgpscniapuiganred 0.50 es o.80 mm.* in diameter, marked all over with distinct or some ent crests; ie re smooth, 0.035 to 0.046 mm. in the longer diameter.— Syst. Veg. aaron 3; Durieu Bull. Bot. Soc. ss 8, p. 164, 1861; Gray Man. ed. 5, p Var. PAUPERCULA with fewer (10 to 18), ul oe (2 to 3 inches) leaves stir smaller spores (macrospores 0.50 to 0.66 mm, diam.; micro- spores somewhat granulated, 0.026 to 0.036 mm. long). A northern species of Europe and aes generally gregarious on gravelly soil in the bottom of lakes under 1 t ie - feet of water, farther south only on mountains; maturing in Se d Oct. Catskill Moun- tains, N.Y. Sc hweinitz, Echo Lake, eH it oicaaal & N.H. Tuck- 2 Saulte de Ste. Marie on Lake Superior, Porter and Leidy. The ee recognized by its rigid, rather thick, not gradually tapering dark green leaves, which do not collapse when — out of the water, = he the size and sculpture of the spores. The variety Jaufercuda is bas n western mountain specimens, and is c seat by the smaller POSE of all parts, and especially of the (for the — unusually small micro- spores. Durieu, l.c. 11, p. 101, distinguished orm with exceptionally large macrospores (0.70 to 0.80 mm. diam.) as 7 macrospora from a sin- gle specimen from the Herb. Acad. N. S. Philad., with the label ‘‘Catskill Mountains” in the handwriting of Schweinitz ; but others show sometimes spores of similar dimensions, e.g. specimens from Lake Superior; and such have also been found in Europe, reat there the spores rarely reac a size ng over 0.65 to 0.70 mm. MA, Engelm. One of the smallest species with a few (5 to 10) moe a to 1 inch inks stout, rigid, bright, green leaves, abruptly g * I adopt for the smaller measurements the metrical system, which will gradually but surely supersede the old _ surrey gtcnatee while in the igi measurements, as the length of leaves, I still adi d inch as the one yet best understood. illimeter is, Pe is well laine, equal to very slic half a ina: 378 TRANS. ST. LOUIS ACAD. SCIENCE. tapering to a fine point, with very short, often almost square, pelea ce cells; orbicular sporangium not spotted, with a narrow velum: ma spores 0.36 to 0.50 mm. thick, marked with minute, rather bipuints aati or rarely cohdiient warts; microspores 0.024 to 0.029 mm. long, almost — and brown.—Am. Naturalist, 8, 214. und only once, deeply immersed ina cold alpine stream on the east- ern sips of the Mono Pass, California, 7,000 ft. alt., HW. Bolander.—This the lower surface, but become sometimes confluent on the upper side. 3- I. Tuckerman, A. Braun in litt. A small plant with very slender tapering olive- green leaves (10 to 30 in number, mostly 2 to 3 inches long), leaf; sporangium mostly oblong, white or rarely brown-spotted, the upper third covered by the velum; macrospores 0.44 to 0.56 mm. diam., the up- per segments marked with prominent, somewhat parallel and branching ridges, o Face) half team microspores smooth or nearly so, 0.026 to 0.032 mm. long.—Engelm. in Gray Man. l.c. 676. In several ponds and etna near Boston, maturing from August to October; "ieee discovered by £. Tuckermann, 1848, in the Mystic river seen them straighter and over 5 inches long. The sculpture of the spores is very characteristic, wavy, som ewhat branching ridges run from the ere i ie Mr. Boott at the end of October seem to i ndicate a er g within the circle of microspore-bearing leaves, and after the outer ones with their macrosporangia had d fallen, an inner growth cis macrospo- rangia was noticed. ne of his specimens is particular morphological interest, as it shows four heads or leaf-buds rom the axis did not result from any proliferation of the wae but most probably from a lesion of the centre of vegetation. and is of very rare currence in this genus, where the simplicity of the axis is so particularly marked (see above p. 358). ENGELMANN—THE GENUS ISOETES IN N. AMERICA. 379 4. I. ECHINOSPORA, Durieu. One of the smaller species with 10 to 30 or 40 soft bright green or sometimes reddish leaves, gradually and regu- larly tapering from a thick base to a very slender elongated point abso- t : : : lute thout stomata, sometimes 5 inches long; sporangia orbicular to broadly oval, unspotted, with a narrow acrospo ra) hick, sely covered with delicate, erect. truncate, or smooth.—Bull. Bot. Soc. Fr. Europe from iis Italy to Germany, France and ees cart eeteaatag to faiaree and Iceland, but apparently not in Amer slightly gta spinules ; rere 0.030 to 0.034 mm. long, alm 104 n this countr I eries of forms which have been sotancabad by eminent pentane especially on account of the presence of stomata so various in number and often so difficult to discover, and of a slight differ- ence in the form and size of the micro scopic spinules which c cover the ma- ment, if not doubt, which view ought to be preferred. Nearest to the Eu- oh ee true 7, ident debe stands the var. Braunii and the other extreme var. muricata, wide-ranging forms of a single type. The same difficul- tes, a8 same ia ears = the same solution, we find in studying some Pp y those allied to 7. velata of the ‘dat of Europe. * Btomate f few. J. RCHINOSPORA, var. BRAUNII, Engelm. Rather small, with 13 to 15 green or reddish-green erect or spreading, puke short (3 to6 inches long), to little longer, covered with broad, retuse spinules, sometimes somewhat confluent, and then dentate or incised at tip; microspores 0.026 to 0.030 m. long, smooth.—Gray Man. l. c. Z. Braunii, Durieu l.c. 11, p. Tor. most common species of our flora from New Jersey and Pennsylva- 4 Lobelia Dortmana, he anium, Scirpus, Eleocharis, etc. New Jersey: i ater of St a de ved form, C ‘orter & Catskill Mountains in the lake near the hotel, G. W. per his Round Lake L. Lesquereux ; Luzerne Lake and in Niagara river below Buffalo, G. W. 380 TRANS. ST. LOUIS ACAD. SCIENCE. Clinton ; at the head of Goat Island, Niagara, between stones, G. Engel- mann ; Oneida Lake, ¥. A. Parne ; in Oswego river, F. Pursh, probably Hammond’s Pond, W. G. Farlow ; Concord’ brook, gregarious, on firm Lu. i in Grafton Pond and several other ponds, J. W. Robbins. Vermont: Mt. Mansfield, in the Lake of the Clouds, C. G. Pringle, H. Mann, on gravelly bottoms, 1 to 2 feet deep; Lake Dunmore, A. W. Chapm New Hamp- shire: Lake Winnipiseogee, in mud with Gratrola aurea, Eriocaulon, etc., G. Engelmann (these specimens were the types of Durieu’s Z, Braunzt), Hf, Mann, W. Boott ; Echo Lake in the Franconia Mountains (where : Tuckerman and myself had found Z. lacustris), W. Boott. Maine: Moose Lake on Kennebunk river, C. E. Smith. Nova Scotia, Shelburne, 7. P. Fames. Greenland, in the south, “ Tessermint,” Z. Vahl (perhaps this is ° 5 3 co Q. Q ie} 3 & = re) ee ag ~ 3 ee) wa @ o 5 o o q g ts a a < oO - Ea at 9,500 feet alt., S. Watson ; this is the most western and highest, quite isolated, locality known to me. This form is most closely connected with the European type; the leaves are perhaps not quite so finely tapering; stomata can always be found, at least near the tip of the leaf; the sporangia, white in the type, are spotted with brown sclerenchym cells; the macrospores I cannot distinguish either in size or sculpture; the microspores I find a little smaller. I may state here that the name of Z. Braunii is preoccupied, as it has a eady been spores of which have been discovered in the German Brown Coal strata; Prof. Braun therefore proposed for our plant, if it should eventually be considered distinct, the name of J. ambigua. Var. ROBUSTA, Engelm., similar to the last, but much stouter, with 25 to 70 leaves, 5 to8 inches long, with abundant stomata all over their surface; velum covering about one-half of the large, spotted sporangium; macro- spores 0.36 to 0.55 mm. thick, with the sculpture of the last; microspores the same as in last. In Lake Champlain, on the north end of Isle La Motte, on a firm sandy . soil with silt, in 1 to 2 feet of water, C. ringle. Larger and stouter than any form of the last, but principally distinguished from it by the abun- dance of stomata. G. Var. Boorrit, Engelm. |.c. Leaves erect, soft, bright green, fewer (a2 to 20) short (4 to 5 inches long); stomata, mostly few, near the tip; spo- rangia nearly orbicular, pale-spotted, 3 or more covered by the broad velum; macrospores 0.39 to 0.50 mm. thick, with longer and slenderer ENGELMANN—THE GENUS ISOETES IN N- AMERICA. 381 delicate, Leia a spinules; microspores 0.026 to 0.030 mm. long. I. Boottit, A, Braun in litt. Near nes in the Round Pond, Woburn, 2 to 3 feet under water, and in the brook of Tofit Swamp, Lexington, sometimes out of water, Wm. Boott. Very striking on account of the delicate green color of its soft leaves, and the long and slender spinules of the spores Var. MURICATA, Engelm. l.c. Leaves (15 to 20) long (6 to12 inches), (0.40 to 0.58 mm. thick), with shorter and more confluent, therefore some- times almost crest-like spinules: macrospores slightly rough on the edges, 0.028 to 0.032 mm. long.—J/. muricata, Durieu l.c In the shallow and more rapid parts of Woburn creek, and in Abajona which form sometimes crests so that Durieu could compare it with JZ. riparia 5. I. BoLranpeRI, Engelm. One of the smaller species with erect, soft, bright green leaves tapering to a fine point, 5 to 20 or 25 in number, 2 to. 44 inches long, with thin walls and partitions, and generally not many stomata; sporagium broadly oblong, mostly without any spots, with a narrow velum; ligula triangular; macrospores 0.30 to 0.49 or rarely 0.45 mm. thick, marked with minute low tubercles or warts, rarely confluent to i Saag geo 0.026 to 0.031 mm. long, generally spinulose; rarely, int cky Mountain tity smooth, deep brown.—Am. Natural- ist, 8, sean ees Engelm., name only in Gray Man. l.c. estern mountain species, found gregarious in ponds and shallow lakes of the Sierra Nevada of California, northward to the Cascades and in Mary’s Lake near the summit, ,000 feet alt., in small lakes about Cisco 4,500 to 5,000 feet alt, ‘‘ mostly gregarious in mud covering gravel, in 1 or 2 teet of water,” H. Bolander ; Ice Lake, near Soda Spring station, 7,500 feet alt., with ogtbny O trifoliata, Engelmann; in sae lakes of the high sierras, reported by A. Ke ellogg; on Mt. Adams, Washington Terr., Suk. Sista , inthe soft muddy bottom ofa uhatiow st te near the falls of the eleeisial river in Wyoming, nearly covering the m G: Parr at Alta, Wasatch Mountains, Utah, M E. Fones, and in a lake in unnison region, Western Colorado, covering ten acres of ground with Menyanthes, T. S. Brandegee.—This species has much the appearance of I. echinospora var. Bootti, with its soft bright green leaves; the stomata. are often difficult to make out. 382 TRANS. ST. LOUIS ACAD. SCIENCE. » B. sans gsi partially meet, es in the earlier period of their gro rily * Without peripheral castillo: ; > between the sub- ged and the truly amphibious speci Velum partial I. SACCHARATA, Engelm. A small plant, usually with a flat, de- pressed trunk; leaves subulate, olive-green, spreading, to to 20 in oe 2 to 3 inches long; sporangium oblong, spotted, with a narrow velum ligula triangular; macrospores 0.40 to 0.47 mm. thick, covered with very minute distinct or sometimes a little confluent warts; microspores papil- lose, 0.024 to 0.028 mm. long.—Gray Man. l. c n the banks of the Wicomico, below Salisbury, and of the Nanticoke rivers which empty into the Chesapeake Bay, eastern shore of Maryland, above salt water, scattered on a thin stratum of mud covering a bed o gravel, overflowed by the tides, i in company with aco giniay pusilla, Eri- ulon, 7 Canb in the direction of the groove; about one inch of the base of the leaves is pale, and covered with mud agitated by the tides, the upper part is olive- green and when out of water apt to be borne down by mud; stomat abundant; macrospores as if sprinkled over with minute white grains of sugar, whence the name. _ 4. I. repartA, Engelm. A larger plant with slender but rather rigid deep green leaves (about 15 to 30 in number), 4 to 8 inches a rarel longer ; stomata numerous, dissepiments thick, consisting of ab among the largest, 0 45 to 0.65 mm. in diam., marked with jagged crests isolated, or Aegutegen sis especially on the siics surface, which thu becomes ‘what reticulated; microspores more or less ES PA 0.028 to ea mm. long.—Flor a, Re = ensb. seit 1846; Am. Jour. Arts & Sci. 3, p. 52, 1847: Gray M On the banks of the lower Teloaee river between the limits of the tides in mud covering gravel, from Burlington A. Conra M. Canby, and especially about Philadelphia, where Nuttall first dis- covered and W. S. Zantzinger, E. Durand and th abundantly collected it, associated with Elatine, Limosella anthe- mam, Sagitiaria pusilla, etc.; also in millponds and still parts of streams ge, F. W. Robbins, Brattleborough, C. C. Frosz and northward, maturing in August and Septembe >». Ss = pores approach- ing it in size and sculpture, but readily distinguished by its stoninte an nd by the spots on the sporangium; from J. echinospo: Aes smaller forms it may possibly be confounded; it c ways be known by the darker, stiffer leaves and especially by the character = the spores. Some of the Uxbridge specimens, entirely submerged 2 to 4 feet ENGELMANN—THE GENUS ISOETES IN N. AMERICA. 383 deep in water, have slenderer and longer (even 12 inches) leaves. The trunk, mostly thick, I have once found 3-lobed. Germinating spo res and young plantlets were found in June by Mr. Durand indicating germination spring and early summer. Farther northward, in Maine, ¥. W. Chickerrng, and in Canada West, Crow river, Hastings Co., ¥. Macoun (here in running water with Bra- senta and Potamogeton), a form occurs with very few stomata on leaves and apparently two weak bast-bundles, an upper and a lower one, very pale spots on the sporangia and smoothish microspores, which might be designated as var. Canadensis, ‘it 1 too little is known about it as yet to form a definite opinion. t+ t Velum complete. ELANOSPORA, Engelm. One of the smallest species, with a flat, tichous, slender, tapering, light green, spreading; sporangium orbicular or almost obcordate, 4 to 1 line teikigy te entirely covered by the velum, unspotted; ligula short-triangular, obtuse, or about semi-orbicular; ma- wide! ars oO. 35 to Q. — mm. in diameter, roughened with distinct or rarely , dark colored; microspores 0.028 to 0.031 mm. hong: ong or por papillose.—Transact. St. Louis Acad. Sci. 3, as abe Stone Mountain near Atlanta, Georgia, covering the bottom of shallow ex besa ns on the naked granite surface, a few inches deep and a few feet in diameter, holding about one inch of light, black soil and at best a couple of inches of water supplied only by rains and dews, and completely dried up and baked for weeks or months under the action of the glaring south- ern sun on the bare rock, when only the little shrivelled trunks with their black withered sor roots remain, = revive under a fresh supply of M. ened, and, vegetating in the room through winter, fully developed in early summer, and afforded a fine opportunity for studying this curious tite species, interesting on account of its native locality, its endurance of drought, its mode of growth and the phyllotactic arrangement of its leaves, its entire velum and its dark spores; it seemed to thrive ae when only and only slightly grooved vai eter and on one side, only about 4 to 1 line thick and 2 to 4 lines in the longer and not much more than half as much in the shorter » diameter gictihvows leaves soft and slender, their The macrospores, only $ to 20 in each sporangium, are black when moist 384 TRANS. ST. LOUIS ACAD. SCIENCE. and dark gray when dry; in some I find the warts much smaller than in others, but never wanting; microspores also quite dark brown. * * With peripheral bast-bundles. ~ Velum partial. - ENGELMANNI, A. Braun. Our largest species with numerous (25 as mm. thick, delicately i war microspores 0.024 to 0.028 mm. long, generally smooth.—Flora |. c.; Am. Jour. 1. c.; Gray Man. l.c. Var. GRaciuis, Enge Often submerged, with fewer (8 to 12) cl g to 12 inches long; the se bundles sometimes quite small, or only tw of them.—Gray Var. VALIDA, Bagel.’ The stoutest of all our species; leaves 50 to 100 or even 200, 18 to 25 inches long, keeled on the upper side; sporan. gium often linear-oblong (4 to 9 lines long), 4 or often } or even 7 covered by the broad velum; macrospores rather smaller, 0.32 to 0.48 mm. thick; microspores 0.024 to 0.027 mni. leng, spinulose,—Gray Man. l.c. Var. GrorGIANA. Similar to the type; leaves few (in the only speci- mens seen 15, 10 to 12 inches long), rather slender; oval sporangium with narrow velum; macrospores larger, 0.48 too. 56 mm. thick; microspores 0.028 to 0.031 mm. long, smooth. In ponds and ditches, immersed in mud, rarely found in slow-runnin streams, in pee ith the ordinary vegetation of such localities, Bidens, Polygonum, Lycopus, Carices, Leersta, etc.; mature in summer; probably cise uheil the middle States, but Gicis far only fo ound — from oburn, nd: Newport, W. ar. Catnee ticut: Meri , ow. to N ork: Peekskill, W. A. Leevett. New Jersey: &. Durand, C. F. Seppe and others. Pennsylvania, Beth- le . ¥. Moser, BE. Durand, S. Delaware Water. £ Rain a Wolle; pet i ~*~ G. Hunt;

ee in Lake Immonia, north of Tallahassee; lately rediscovered by A. P, Garber in a hummock. near Manatee, on the muddy border of shallow ponds in water from a few inches to 1} feet deep, the long leaves floating or spread out on the mud, the inner ones erect; inature in Apriland May, disappearing in June. Var. rigida was found d by the same collector on entirely emersed and erect. I°-. A. H. Curtiss seems to have met with a similar form in a muddy swatkp on Indian river; none of all of these had any mature microspores. Var. Chapmani was discovered by A. W. Chapman near Mariana, West Florida, filling a lakelet of pure limestone e where it emptying into Chipola river, ouechae with Nasturtium lacustres : ; but the Isottes has not been seen in it since: its larger macrospores, some- wat floatonit. The closed velum an nga sculpture of the macro- spores readily distinguish it from its alli es C. Terrestrial species, maturing when entirely out of water, with abundant sto- mata and peripheral ae a thick dissepiments, and small air cavities in the nearly triangular lea * ‘Velum partial or almost wanting. MELANOPODA, J. Gay. a trunk si ERI a a black at base suche leaves icles stiff, eno t green, usuaily (15 to60 in number, 5 to 10 0r iisely even 18 inches long) ; ae ~ . ENGELMANN—THE GENUS ISOETES IN N,. AMERICA. 387 mostly oblong (2 to 4 or even 5 lines long), spotted, with narrow velum, ligula triangular-subulate; macrospores among the smallest in the genus, 0.25 to 0.40 in diam., with depressed tubercles often confluent into worm- like wrinkles, or almost smooth; microspores also smaller than usual, 0.023 to Oo. AaNg or rare - 0.030 mm. long, spinulose.—Durieu in Bullet. I. c.; Gray Man, l.c. ar. PALLIDA. A larger plant, leaf-bases pale, velum usually much Sa covering } or $of the sporangium; macrospores only 0.30 to 0.35 mm. thick. An exclusively western species, in low prairies and fields overflowed with at least one inch of water in spring, or in shallow ponds which dry up in summer, in stiff clayey soil, in company with the ordinary vegeta- tion of such localities, e.g. Mast nersiaes sessilifiorum, apenas mutilum, Elatine, Penthorum, Ludwigia, Ammannia, Alisma, Funcus, etc., from occurs, &. Hail, Maturing in June or beginning of July.— Mr. Hall was accidentally led to the discovery of this plant ¢ on his farm in a by find- s] w, and wet seasons, when the water is deeper than usual about the plants, the mature later or not all. In ordinary seasons the leaves disappear entirely in July and nothing but the trunks remain, and about them the numerous spores, bot ‘which are eagerly sought after by mice and ber with perfectly mature spores; but it is scarcely probable that these could have es seedlings of the preceding summer, though Mr. Hali is feitaed to think so. The apes ous sa naqed of this species has been alluded to on page ed. ‘The dissepiments of the leaves consist of 6 to 9 layers of cells, the lower median being the thickest. Besides the normally 4 peripheral bast-bundles we find here often several smaller accessory ones, which increase the rigi- dity of the feaves. In no species have I seen the macrospores so variable 388 TRANS. ST. LOUIS ACAD. SCIENCE. in size in the same sporangium; large and small ones are indiscriminately justify the name given by that ne botanist, Jacques Gay, who in his 75th year was still anxious and « able to climb the salt mountains in the Now and then a paler specimen is seen, and the Texan form is always ost and distinguished also by its broader velum I. ButrLteri1, Engelm. Dicecious, week: than the last, with a subglobose trunk and thinner and more rigid bright green leaves, 8 to 12 r ba Catinny marked with knobs or warts, distinet or sometimes confluent; microspores 0.028 to 0.034 mm. long, dark brown, papillose. — Bot. Ga- zette, 1878, D. I. Var. imMAcULATA. Larger, leaves sometimes as many as 60, 6 to 9 inches poe ; sporangium without spots; macrospores rather ae 0.40 to 0.56 mm. in diam.; microspores 0.029 to 0.031 mm. long, spinulos' In the ants flats (called alkali flats, but impregnated with spats of the Indian Territory, near Limes Gap, between Arkan nd rivers, associated with the few coarse plants which can live in those Pa ities overflowed in winter and spring, and baked hard in summer and autumn, such as Jva angustifolia, Ambrosia psilostachya, Arenaria ike: and with /soétes melanopoda, but in rather drier localities than this; maturing in May and June, G. D. Butler. The variety near Nash- PP aiage: pated Talinum, Sedum datchetinss Schenolirion, several Funct, ete., A. Gattinger.—This species, also peculiar tothe Mississippi Valley, also more or less tuberculated, while in other species they are quite mooth. * * Velum complete. 14. I. NurraLLu, A. Braun in Herb. Similar to the last two speci with an almost globose slightly grooved trunk and 20 to 60 slender eight green leaves, 3 to 9 inches long, with only 3 peripheral bast-bundles; spo- ENGELMANN—THE GENUS ISOETES IN N. AMERICA. 389 rangium oblong or oval, entirely covered by the velum; macrospores very variable in size, between 0.25 and 0.50 mm. thick, densely covered with minute but prominent rounded warts, or, rarely, almost smooth; micro- spores 0.025 to 0.028 mm. long, oe brown. — Engelm. in Am. Nat. 8, p- ars Of ee Nutt. in Hb. A On flats or springy 9 See in the valley of the Colum- bia river, , Nuttall; abundant about Silverton in the Wallamette valley, Z. Hall, No. 693; at Milwaukee, Oregon, ee Howell (with almost smooth macrospores) ; aieiciat Co., Washington Terr., on Kamass Prairie and at the base of Mt. Adams, 2,100 feet alt., W..N. Suksdorf; eastward on ose guish this readily from the two other terrestrial speeies; it is the onl species on which I observe constantly only 3 uate. aseaeae bast-bundles, one on each of the three edges, the upper middle one being absent. e me- dian dissepiment of the leaves consists of 8 or 9 and the transverse one of 6 to 7 layers of cells. IL. Trunk trilobed, bast-bundles and in the quadrangular leaves ; velum partial. 15. I. Cupana, Engelm. One of the larger species; leaves 30 to 40, 15 inches long, fresh green, with 6 bast-bundles; sporangia oblong, un- spotted ; _velum very narrow; macrospores 0.30 to 0.40 mm. t thick, marked with coarse round depressed, never confluent tubercles ; microspores 0,024 - to 0.027 mm. long, papillose, pale. —Sauvalle Fl. Cub., p. 203, name only. On the bottom of rivulets in the pine woods of aes Cuba, Chas. form 3 distinct bundles from the 3 grooves; the bast-bundles are found at the four intersections of the dissepiments with the outer walls and at the upper edges of the leaf. i TABULATED CHARACTERS OF THE NORTH AMERICAN ISOBTES. ANAT I ONS. et 6, very birelhict closed apntied i Sp, spotted with teee sclerenchym-cil 5 E LEAVES. : g MACROSPORES. MICROSPORES. |) : 5 rie : Sig | Bead a | NATIVE COUNTRY. 2|)| Num ength Eis meter, Jength, Cott ‘ 2 E ber. | finches = : = | B | millimeters. RUPRNE- millimet.| Surface. | 1, J. lac siaote’ subm, | 2 0-25 | 2-6 0 9 | a, | wv. 0.60—0.80 Cristate 0.085—46 |Smooth.. ‘North’ "nN. York to Lake Sup?r var. pommperenia # 2} lW-Is| 2—4 0 0 |b. je. Ora Oa gc et ees ae ye a 0.026—36 Nearly do. Galiton Sig oar pcan nia fs. ¥ 2 5—10 | w— 1 0 0D bm.) w, 0.36—0,50 Minutely tuberculated | 0,024~29 ornian Moun . Fee 8 chermeavd 3 30} 2-3 0 0 | 6. | sp.| | 0.44-0.55 nese above, reticu- : DOW ay ce + 0.026—-32 |Smoothish New England. 4. J. big abe ha : var. Braunii,. ' 2) | 46—30 6 few | 0 | b. | sp.|| 0.40—-0.50 an | Rr oe ar 0.026—30 saree i: Pennsylvania northward and northwestward and to Utah. var. robusta... “ 2|| 25-70 | 5—8 | [many] 0 | db. | sp.!| 0,.36—0.55 With longer gs eh : | spin es 0.026—31 |Smo New England. var, Boottii.... if 2) | 12-30] 4-- few | 0 | bb.| sp.| | 0.40—0.50 0.026—3 Smoothish vir, muricata. . 4 2|) 15-380 | 6—12 “« 10 | bb] w.]) 0.44- 0.58 With movies conflu- | = s Ont epines «.. sei. 6.5 0.028—32 sf rf 5. I. Bolanderi ... a 2 5—20 | 2— 4% bs 0 |b. | we. 0.30—0.45 nie 0.026—31 |Papillose . aut, Oreg., Rocky Mount'ns. 6. 1. saccharata .. amph. /2 a 2— 3 | |many| 0 | n. | sp a, 0 0.024—26 sf be ry iand. Ge oe rere 2 be 4— 8 sf 0 | b. | sp.) | 0.44—0.65 028—34 i en At is yivania to NewEngland. 8.4. melanospora, s 2 5-10} 2-2 i DO | on) wo 0.35—0.45 0.027—30 |Smoothish Rents 9. 1. Engelmann’. “ 2] | 26-100! 9—20 - 4 in, | w. 0.40-0,52 .024—28 « Delaware ton. Eng.& Missouri. var. gracili sh 2/| S— 12] 9-12 ged CE eee ee 0. : 0 .024— “ ennsy det ogy ew England, var, valida .,., 2 | | 50—200] 18—25 ‘s! £410, bw, 0.32—0, x 0.24—27 |Spinulose. | Bennsyiva var. Georgians ke: 2 15 1W—12 “ 4 in, | wv, 0.48—0 0.028—31 |Smooth... Georgia. 10. 1, How oe fe 2} | 10-25 | 5— few | 4 | 8. | w. 0.43—0. re | Oregon, ll. I. flaccida,..... subm.?) 2} | 10-35 | 15-24 | Imany| 4 | c. | w.] | 0,30—0.42 ! : onflu went a Sree ae '|Florida var. rigida,. mph. | 2} | 10-15 | 5—6 Te dept wt ORO Ras Re te pee a ae pe er te th est var. ¢, apmant, is 2 30 18 ten Te eee a 0.4—0.55 sai * eesegiy yen3oth Snoie 0.027—30 illose , ie e 1B _ ape ade terr. : a a y uF 7 sp. }o 25-0.40 “oe “ 0.023—30 he nulose, engi to Indian Territory. : var, cae ‘ fa of ep. : seep Soetiee Sak Neue erie ada 8a Wha. Sot magne mes 13, f, Butleri . « 2 8-12 | 3-7 ome tae = 0.50-0.63 |Minutely tuberculatec| | 0.025—8t 'Papillose . lfudings Territory. var.immaculata “ 2) / 20—60 | 6— 9 “ 4 | nn.) wv, 0.40 - 0.56 do. or nearly smooth} | 0.029—31 |Spinulose. ||'Tennessee. ; i. ; Puna. rea “ 2\|15—60 | 3—9 ee Ou) wey 0.32—0.52 |Minutely tubérculated| | 0.025—28 Papi illose . [agg nu Idaho to Oregon. Cubana. amph,?} 3 | | 30—40 Wb le 6 | nie. 0.30—0,40 Coarsely tubercula ulated .| | 0.024—27 06€ - *HONAIOS *GVOV SINO'T*LS ‘“SNVULL