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IOWA
GEOLOGICAL SURVEY
Bulletin No. 4
THE WEED FLORA
OF IOWA
Eby L eee ales
GEORGE F. KAY, STaTE GEOLOGIST
JAMES H. LEES, ASSISTANT STATE GEOLOGIST
DES MOINES:
PUBLISHED FOR IOWA GEOLOGICAL SURVEY
1913
DES MOINES
ROBERT HENDERSON, STATE PRINTER
JOHN M. JAMIESON, STATE BINDER
1. OF D.
WAY 7 1914
GEOLOGICAL BOARD.
Eismihxcellency, George W. Clarke: .)o2.. -.. 0.2.2. 0.055 Governor of Iowa
EEKCHAMmme OLATIbere Mls] CAV CLV As atiaha io sire rat opoustonitcle anets: sysbadeceon je speielaraieitele Auditor of State
PCN eMES OWI ELMe ss ley arrete ste ciee) vie susie President State University of Iowa
ey monly Aes SATS OM rer c.0 seo) «scsi, si eueseieleve miso President Iowa State College
(CPPCC Vic cis cc cies exe a ere eia. eee President Iowa Academy of Science
ADMINISTRATIVE OFFICERS.
GeOGe mE) RAY oso. oasis s Ce, RARE IAT, MMM OU POT at Rte a State Geologist
20083 IST Ieee oping dsich oon veo umes poeta Assistant State Geologist
EIDE RUMEN EG wimaiiee ec AN ee es hoy uns oa SOCRetAry
LETTER OF TRANSMITTAL
Iowa Geological Survey.
To Governor George W. Clarke and Members of the Geological
Board:
GENTLEMEN: I submit, herewith, a bulletin on The Weed Flora
of Iowa and recommend that it be published for distribution among
the people of the state.
‘The thanks of the whole state are due Dr. L. H. Pammel of the
Iowa State College of Agriculture and Mechanic Arts for the
preparation of a comprehensive and thorough report, represent-
ing many years of careful and painstaking scientific work, on a
subject that is most intimately related to agriculture, the industry
that far exceeds in importance all other industries of our great
state.
The Survey wishes to express its thanks to Dean Curtis, Director
of the Iowa Agricultural Experiment Station, for his co-operation,
and for his kindness in permitting the Survey to include in the
bulletin on weeds results of investigations which were carried for-
ward by Doctor Pammel while connected with the Experiment
Station.
The Iowa Geological Survey had the honor, about ten years
ago, to publish a complete monograph by Doctor Pammel on the
Grasses of Iowa. This publication proved to be of great value,
and it is with the fullest confidence that the bulletin on The Weed
Flora of Iowa will be of equal if not of greater service to the
agricultural and related interests of the state that it is now pre-
sented for publication as Bulletin 4 of the lowa Geological Survey.
I have the honor to be,
Yours very sincerely,
Grorce F. Kay,
State Geologist.
THE WEED FLORA OF IOWA
By L. H. PAMMEL
WITH THE COLLABORATION OF.
CHARLOTTE M. KING J. N. MARTIN J. Cc. CUNNINGHAM
ADA HAYDEN and HARRIETTE S. KELLOGG
TABLE OF CONTENTS
CHAPTER I.
Page
MS Cregeen LAIN alleneyeyeic et ecu wenenneietes cre Row ccna lreallel alone, seer ervunoe le clahelbie era wee 1
CHAPTER II.
The General Characters of Seeds. BORSA ch i a eI Fey aN A/a Ml Dele ie 405
CHAPTER III.
The Microscopic Structure of Some Weed Seeds....................-.. 503
CHAPTER IV.
Morphology of Flowers and Leaves.......... Per aan ey a Asta cepa n aerate oak ne NUN oe 589
CHAPTER V.
Cale rg mG lem OUS starccet ste ous tetera orca Gia reevencl seatm a: St Setar atireene slave: maecsie balers 627
CHAPTER VI.
ECOULSH AMC OOt-StOCKS! Ob NVECUSm anne daistccde aelsule oss a ee cae one ome 641
CHAPTER VII.
Number and Kinds of Weeds in Different Soils........................ 655
CHAPTER VIII.
MMA UNO MISTS SHOeNVCCUS Hare pace cake se alors lara ecdtava seus oe aereractte, oe MNecciteensiale Ceeeiece 669
CHAPTER IX.
NCCC am VIN eae OMmec erento auc aun ska Rhos Bas er eels Wendie) am ht e 685
CHAPTER X.
ISA SG LAST WHY SRG) ai ssn ste see aCe Petco eae RS Te RS a A TTA
CHAPTER XI.
ENEMMIOO Sy Ole WICC US a eters seers seis ie o's p.oleisiors wate alee bea do weahe edhe ivan 783
CHAPTER XII.
Weed! Bing! Seeel SIRNAS Se Ramee rec oe oleae et Re ier ry rer oc 791
CHAPTER XIII.
ISUISIONPA BANG! TEMTOIbIOVSR FEN olalira yoke Hike Amiens arte Ele Gee ane a 817
GIOSSEIAT ~ iodo 5 5) 5 S!SfD ie as Ho Goa Eee EEO Eee ed es 862
PREFACE
Weeds do an enormous damage to the crops of lowa. A con-
servative estimate places the injury at $25,000,000 annually. This
loss could be largely avoided if we had more concise information -
on the subject, and if we could conserve: the matchless resources
of our soil by keeping the weeds down, the farmers would be greatly
benefited in a financial way. It would seem appropriate, therefore,
to publish a volume of the Weed Flora of the state at this time.
_ The need of a volume dealing with Iowa weeds as a feature of
the flora of the state has long been felt by the public schools.
Many papers have been published by the Iowa Agricultural Ex-
periment Station, but these papers are mostly out of print. This
work is much more comprehensive than anything heretofore pub-
lished in this state. The title indicates that it is not a weed book,
but rather ia weed flora. Much stress has been laid on the geograph-
ical distribution of weeds. It is a contribution to the local flora
of the United States.
The chapter on the geographical distribution of weeds will be
found of special interest to the phytogeographer. I desire to ex-
press my thanks to Dr. M. L. Fernald, Messrs. R. I. Cratty, F. W.
Paige, O. M. Olson, J. P. Anderson and Prof. B. Shimek for assist-
ance in giving the geographical distribution of Iowa weeds. The
chapter on the microscopic structure of weed seeds brings together
in English much on the subject which has hitherto been inacces-
sible to the student not familiar with German or French ltera-
ture. The chapter on morphology will greatly help the student to_
understand the changes occurring in the development of the flower
and the formation of the seed. The chapter on the use of weeds
in medicine will be of interest to those who occasionally make use
of wild plants for medicinal porposes. The chapter on seeds de-
scribes a large number of weed seeds; this will be found of value
to those engaged in a study of seeds.
The chapter on various weed laws gives a summary of laws
in various states in the Mississippi Valley. In compiling these
xii PREFACE
laws I have been aided by Mr. Small of the Iowa State Library,
Mr. Moore of Wisconsin, Mr. Michel of South Dakota, Dr. Howard
of Missouri and H. L. Bolley of North Dakota.
In the preparation of this Weed Flora, I have been greatly
assisted by Professor J. N. Martin, who has written the chapter
on morphology of the plant; Miss Ada Hayden, who has written
the chapter on dissemination; Professor J. C. Cunningham, who
has written the chapter on roots and underground organs; Miss
Charlotte M. King, who is the joint author of the chapters on gross
characters and microscopic structure of seeds. Miss King is also
responsible for many of the excellent drawings. The chapter on
medicinal weeds was prepared by Miss Kellogg. I am greatly in-
debted to her for painstaking editorial work and for preparing the
bibliography and the index. In the matter of bibliography, it has
seemed best to divide the subject into various sections so that the
student may easily find the desired literature. The bibliography
is not complete but enough papers are given to enable the student
to find the important literature. JI am indebted to Dr. Clark, of
the Canadian Seed Laboratory, for the privilege of using some
of the admirable illustrations of the Canadian work on weeds,
also to Dr. Ernest Bessey for illustrations from Beal’s Weeds
of Michigan, and the classical Hillman seed figures in the Michi-
gan bulletin, and to the Nevada Station for the use of the Hill-
man cuts. Some of the Hillman and a few other figures have
been taken from the government publications. I am also indebted
to various publishers for figures which have been taken from sev-
eral textbooks of botany, as the Bergen & Davis book published by
Ginn & Co.; several botanical works like Thomé’s published in
German, and to the Connecticut Experiment Station. A few fig-
ures have been taken from the Botanical Gazette. Credit is given
under each figure. The photographs were made by F. E. Colburn,
photographer at the Iowa Agricultural Experiment Station, G. T.
Hart and C. R. Quade. The clerical work of the volume was per-
formed by Miss Bertha Herr and my daughter, Miss Harriet.
Mr. Burlingmair assisted in a study of weeds in different fields.
To Mr. James H. Lees for his assistance in proof reading and edi-
torial work I am also indebted. To all I wish to express my sincere
thanks.
The reader will find it advisable to have several of the recent
treatises on weeds. Mention may be made of my work ‘‘ Weeds of
the Farm and Garden,’’ a general treatise of three hundred pages
PREFACE xiii
with numerous illustrations; the work of Fletcher and Clark of
Canada; Bolley’s *‘North Dakota Weeds;’’ Blatchley’s ‘‘Indiana
Weed Book;’’ W. J. Beal’s ‘‘The Weeds of Michigan.’’ A list of
these publications and where they may be obtained will be found
in the bibliography.
Ames, Iowa, December 18, 1912. .
: L. H. PAMMEL.
Page 754
Page 837
Page 838
Page 842
Page 858
Page 861
Rosenberg, 1882 should be 1782.
Patrick, P. E., should be Patrick, G. E.
Blankenship should be Blankinship.
L. T. Henderson anol be L. F. Henderson.
Panton, J. H. Weeds of Ontario should be listed on
page 845.
T. L. Williams should be T. A. Williams.
CHAPTER I.
DESCRIPTIVE MANUAL
L. H. PAMMEL
CHAPTER I.
KEY FOR FAMILIES.
I. Plants without true flowers; not producing seeds...Pteridophyta.
Stemsmyoimted, TUShliKe. jac ccs cero ders ec ne le ss ec Hquisetaceae.
I. Plants with true flowers, stamens, and pistils and producing seeds.
Spermatophyta.
II. Ovules not borne in a closed ovary (Pine, Spruce)..........
Gymnospermae.
II. Ovules borne in a closed ovary (Rose, Willow, Corn, etc.)....
III.
ITI.
Angiospermae.
Stems endogenous without central pith; no annual rings;
parts of the flower usually in threes; single cotyledon...
: Monocotyledoneae.
1. Grasslike plants 2.
2. Flowers enclosed by chaff-like scales.
Stems hollow; sheaths of leaves split...Gramineae.
Stems solid; sheaths of leaves not split. Cyperaceae. ©
2. Flowers not inclosed by chaff-like scales. .Juncaceae.
1. Plants not grasslike; flowers with a perianth of 6
DICCESGMSCAIMENISS Gah eienevatel svar cnoveusrate eben cis atcher cere Liliaceae.
Stem formed of bark, wood, and pith, exogenous; ieaves
netted-veined; embryo with a pair of cotyledons.........
Dicotyledoneae.
1. Corolla absent
7, IPMGNOES WSN; Op SCUNPA TS Gia bonoodbodE Chenopodiaceae.
2. Plants not fleshy or scurfy 3.
3. Ovary free 4.
4, Flowers unisexual.
Ovaryral=celle@ dl We erciesletere ate we eranestcleisns Urticaceae.
Oviatyars-¢ clledeea anes eiciseo Huphorbiaceae.
4. Flowers perfect.
Calyx and bracts greenish and scarious......
Amaranthaceae.
Calyx generally corolla-like.
1. Fruit a i1-seeded achene..... Polygonaceae.
1. Fruit a 5-12 seeded berry. ..Phytolaccaceae.
Se OVA MERTON te alsa eleve eles siedele re: wicvers Nyctaginaceae.
1. Calyx and corolla present.
2. Corolla of separate petals 3.
3. Plants fleshy, flowers yellow........ Portulacaceae.
WEED FLORA OF IOWA
3. Plants not fleshy 4.
4. Pistil single 5.
5. Flowers regular.
Stamens numerous, free...Ranunculaceae.
Stamens numerous; sepals and petals pres-
ent, inserted on calyx........... Rosaceae.
Stamens 10; fruit a legume...Leguminosae.
4. Pistil compound 6.
6. Ovary free.
Ovary l-celled ........... Caryophyllaceae.
Ovary more than 1-celled 7.
7. Ovaries united into a ring...Malvaceae.
7. Ovaries not united into a ring 8.
8. Leaves simple.
With punctate dots; stamens numer-
OUSHARie aseeneener A rors ., Hypericaceae.
Leaves not with punctate dots; sta-
NNT Hosgaqasosnabdousads Cruciferae.
Leaves compound, pinnately 3-foliate.
Anacardiaceae.
Leaflets 3, obcordate..... Oxalidaceae.
Leaflets 5-7 pairs..... Zygophyllaceae.
Leaflets 3, viscid or fetid herbs.....
Capparidaceae.
6. Ovary adherent; flowers in umbels.....
Umbelliferae.
6. Flowers not in umbels....... Onagraceae.
1. Calyx and corolla present, petals more or less united.
2. Flowers regular 3.
38. Plants with milky juice.
Stamens united .............-.0e8- Asclepiadaceae.
Stamens distinct ................... Apocynaceae.
3. Plants without milky juice.
4 Plants Gwinn eee ce eesierete eters Convolvulaceae.
4, Plants not twining 5.
5. Stamens 5 or more 6.
6. Style 2-cleft; flowers not in heads; fruit
2-4 seedlike nutlets.......... Boraginaceae.
Fruit many seeded pod...Hydrophyllaceae.
Flowers in heads; anthers in ring or
tube about the style......... Compositae.
6. Style 1; fruit many seeded..... Solanaceae.
5. Stamens fewer than corolla lobes
Caulescent, flowers blue ........ Verbenaceae
Acaulescent, flowers greenish. Plantaginaceae
2 Flowers irregular.
Stems 4-angled; ovary deeply 4-lobed...... Labiatae.
Stems not 4-angled; ovary 2-celled. .Scrophulariaceae.
DESCRIPTIVE MANUAL 4)
PTERIDOPHYTA, FERNS AND THEIR ALLIES.
This group of plants, sometimes called vascular cryptogams, Is
represented in our flora by the maidenhair fern, brake, spleenwort,
shield fern, ete. The Boston fern is frequently cultivated.
Fic. 1. Common Horsetail (Hquisetum arvense). Roadsides, fields, common
everywhere in Iowa.
(Photographed by Colburn.)
Fic. 1-A. Distribution of Common Horsetail.
6 WEED FLORA OF IOWA
EQUISETACEAE, HORSETAIL FAMILY.
This small family of rushlike plants contains a few species only
and but one that is weedy.
Common Horsetail (Equisetum arvense L.).
Description—A rushlike perennial with running rootstocks and
annual stems; branches in whorls; fertile and sterile plants, the
fertile appearing early in spring with a terminal cone, yellowish
in color, bearing the spore cases (sporangia) underneath a scale;
spores provided with hygroscopic bands; sterile frond with
whorled branches.
Distribution — Widely distributed in North America, common in
sandy moist fields, on railroad embankments; common in Story,
Boone, Carroll, Crawford, Harrison, Woodbury, Clinton, Dubuque,
Lee, Page, Polk, Cerro Gordo, Emmet, Webster, Marshall, Johnson,
Winneshiek and Allamakee counties
Extermination.—This is a most persistent perennial; only by giv- |
ing frequent shallow cultivation after small grain is removed
during the summer can the weed be kept in check.
SPERMATOPHYTA, FLOWERING PLANTS.
The seed plants have stamens and pistils and reproduce by seeds.
Represented by the pine, spruce, hemlock, wheat, rye, corn, rose,
maple, ash, aster, goldenrod, squash, ete.
GYMNOSPERMAE, GYMNOSPERMS.
The seeds are not inclosed in an ovary. Trees or shrubs gener-
ally with needlelike or scalelike leaves; represented in Lowa by
the red cedar, white pine, etc. Noné are weedy.
ANGIOSPERMAEH, ANGIOCSPERMS.
Ovules borne in a closed ovary. Represented by a large number
of our native and cultivated plants, like wheat, corn, lily, rose,
clover, tomato, ete.
MONOCOTYLEDONEAE, MONOCOTS.
Plants with endogenous stem, the woody fibers in bundles dis-
tributed through the pith. Annual ring absent. Flowers gen-
erally on the plan of 3; embryo with a single cotyledon. Corn,
lily, onion, asparagus, blue grass, switch grass are representatives.
DESCRIPTIVE MANUAL ts
GRAMINEAE, GRASS FAMILY.
This large family is of great economic importance, since it con-
tains many of our food plants, including the well known cereals,
\
tn
Fic. 2. Johnson Grass (Sorghum halepense) ; a, sessile spikelets. A most trou-
blesoume weed.
(Lamson-Scribner, U. S. Dept. Agr.)
Fic. 2-A. Distribution of Johnson Grass. Reported recently from southwestern
owa.
8 WEED FLORA OF IOWA
rye, wheat, oats, barley, corn, kaffir corn and millet, besides such
forage grasses as blue grass, timothy, brome grass, foxtail, and a
few ornamental plants, ike pampas grass, ribbon grass, ete.
Johnson Grass (Sorghum halepense (.) Pers.).
Description.—A_ stout perennial, with smooth, erect, simple
culms, 3-5 feet high, and strong, creeping rovt-stocks; leaves
elongated, 14-34in. wide, acute; ligule ciliate, and on the back
where leaf-blade joins the sheath there is more or less pubescence ;
panicle open, 6-12 in. long, the whorled branches naked below, the
3-5-flowered racemes clustered towards their extremities; pedicels
of the staminate (rarely neutral) spikelets pilose with stout hairs;
sessile spikelet broadly lanceolate, acute, 2-3 lines long, pale green
or violet, becoming dark or nearly black at maturity; callus small,
obtuse, shortly and sparsely barbate; first glume coriaceous, spar-
ingly pubescent on the flattened back, 5-7-nerved; second glume
similar and equaling the first, convex below, subcarinate above,
acute, the hyaline inflexed margins ciliate; third glume a little
shorter than the outer ones, membranous, faintly 2-nerved, the in-
folded margins ciliate; fourth glume broadly oval, obtuse, nearly
1% shorter than the second, 2-lobed or bidentate at the apex, ciliate
awned; awn 5-8 lines long; palea a little shorter than the glumes,
nerveless, ciliate. Introduced and cultivated in many southern
states for hay; in many places it has become a dangerous weed,
difficult to exterminate.
Distribution.—The weed is common in the south, often a most
troublesome weed. It has been reported as persisting in the
vicinity of Hamburg, Fremont county.
Extermination.—Use the same methods as for quack grass. This
may become a most troublesome weed.
Finger Grass (Digitaria sangwinalis (L.) Secop.).
Description—A much branched, leafy annual, 1-3 ft. high,
spreading on the ground, with erect, smooth, spreading culms, fre-
quently rooting at the lower joints, joints sometimes smooth, though
more frequently bearded with deflexed hairs; sheaths loose, gener-
ally pilose, hairy, ciliate on the margins, with a membranaceous
ligule; leaves 2-4 in. long with rough margins, occasionally pilose
at the base; flowers produced in digitate spikes, hence the common
name finger grass; spikelets less than 14 in. long in pairs, 1 nearly
sessile, the other with a stalk, each flower consisting of 2 sterile
DESCRIPTIVE MANUAL
Fic. 3. Common Crab Grass (Digitaria sanguinalis). Common in fields, gar-
dens, meadows. Rooting at the joints.
(Photographed by Colburn.)
— Si
a ator Mitchel ties
ROMA SauPene * fe le
Kossuth = ote a
Ay . Bai AO z
*. ‘|: CL |RAko
+ ° . is .
mf . 2 : 2. 2
Sure .
a Tel . + dubug
Z ce . re
° 47 Sle ot
a is ee
:
5 rene eo bt t,]. Ce ole =
+. es Geet ate =
Se a hee eet = 2 Clinton
C a - tr . eo bohvsbw eis
e : es| Ma Ra eed lie +
- = = Hieiscarine
ONG fs z Keokuk =
awaited mie + 5
ote ° a5 +>
. =o
’ # Henn
/ | E ae +
a A faye Decatur a
c + | +. Fe +
the he ee Se ee ee %
Fic. 3-A. Distribution of Common Crab Grass.
glumes and the flower proper; the first glume very small, the sec-
ong about 14-24 as long as the spikelet, usually hairy on the mar:
gin, the third glume somewhat longer than the fourth, which is 5-
10 WEED FLORA OF IOWA
nerved and usually silky-villous along the marginal nerves, fourth
glume smooth and acute; fruit minute, pitted and cross-striated,
light straw color except where the sterile glumes remain attached,
which are gray in color and minutely hairy.
Distribution.—This European grass is cosmopolitan; abundant in
the eastern and southern states and in California; common in all
parts of Iowa, more particularly in gardens, corn fields, and streets.
Extermination—tThis grass is much more difficult to remove than
the foxtails because it roots so readily at the joints. Thorough
cultivation will remove the weed. Do not allow it to go to seed.
Chemical Composition—Common crab grass (Digitaria sanguin-
alis) has been used as a forage plant in many parts of the United
States and many chemical analyses have been made. Analyses are
reported from Mississippi, Tennessee and lowa. The Iowa analysis
reported by Weems is as follows:
NATURAL CONDITION
Albu~ Crude Nitrogen
Sample Water Fat Protein minoids Fiber Ash free
extract
‘he a ee 66.95 Ul 2e02 (1.98) 8.62 4.10 16.70
WATER FREE SUBSTANCE
see ase 2 | eee eee | 3.34 | 7.61 | (5.98) | 26.11 | 12.41 | 50.53
Smooth Crab Grass (Digitaria humifusa Pers.).
Description.—An annual 6 in.-2 ft. high, closely resembling D.
sanguinalis in habit, but smooth throughout, excepting for a few
hairs at the throat of the sheaths; spikelets 2-7, smaller than in
D. sanguinalis, about 1 line in length; first glume very minute or
obsolete; second and third glumes nearly equal in length, or the
second a little shorter than the fourth, pubescent at the back.
Distribution—Smooth erab grass is native to Europe but is
now cosmopolitan; in eastern North America from New England
to Texas and Mexico, Rocky mountains and Pacific coast; less com-
mon in Iowa than common crab grass; rapidly spreading in the
state, more particularly in gardens; common in lawns and pas-
tures.
SES:
[Z
= ex
aS Sc
===
SS
a
xe
Fic. 4.
Fic. 4-A.
Tt DEE
SO _
S$
S
Figure 4
Crab Grass (Digitaria sanguinalis).
Figure 4A
——
SEOQEE
Wate: Fe .
© | Mitchell ellie
: 5 . S
45 .
° is MI so |e |
elie \
. \
IaiHers| * « we
Wig. 108-A. Distribution of White Sweet Clover.
189
190 WEED FLORA OF IOWA
B bs
5 a 29
z # Ge
o 4 =
Water) 2.25225 ee ee 79.35 6.02 waren
Ash) assess et oe ae ee ee eS ne 2.10 9.57 10.18
Hither. extract): =2222 28 ee ee en ee ae 0.53 2.42 2.52
Crude fiber (222s 22 ee ae eee eee ea eee 4.78 21.77 23.16
Crude: protein, | 23-222 2s ee ee el ee eee 3.96 18.00 19.15
Nitrogen, free. extractq. 2s seo ss ee Se eee 9.28 42.22 44.99
Black Medic (Medicago lupulina L.).
Description—A procumbent, pubescent, annual; compound
leaves trifoliate ; leaflets wedge-shaped, obovate, toothed at the apex;
flowers yellow, in short spikes; pods kidney-form, 1-seeded. —
Distribution.—Native from Europe, common in alfalfa fields in
the Rocky mountains and on the Pacific coast; common in waste
places in eastern North America; reported from a number of coun-
ties In Jowa, as Wright, Kossuth and Story. |
Extermination—This annual is not difficult to exterminate by
giving thorough cultivation; care should be used in planting clover
and alfalfa seed, because this weed seed is a common impurity of
the latter. The seed also retains its vitality for some time.
Chemical Composition.*
FRESH OR AIR DRY MATERIAL.
x : Nitrogen free
Water | Ash | Protein Fiber Bench Fat
78.52 | 1.37 | 3.40 | 6.31 9.20 | iar bl
WATER FREE SUBSTANOE.
| 6.4 | 15.8 | 29.3 43.4 | 5.1
*Compiled by Jenkins and Winton, Bull. Off. Exp. Sta., Bull. 11.
DESCRIPTIVH MANUAL iii
Fig. 109. Black Medic (Medicago Wwpulina). Clover and alfalfa meadows.
(Photographed by Hart.)
Fig. 109-A. Distribution of Black Medic.
192 WEED FLORA OF IOWA
Pink Parosela (Dalea alopecuroides Willd.).
Description—An erect annual from 2-3 ft. high, with pinnately-
compound leaflets; smooth flowers, whitish or light rose-color, in
cylindrical spikes; calyx villous; seeds kidney-shaped.
Distribution—F rom Minnesota to Alabama and the Rocky moun-
tains, common in western Iowa and introduced eastward in Wright,
Boone, and Story counties.
Extermination.—It is sometimes found in clover seed grown in
western Iowa, also in alfalfa seed from the west, therefore care
should be used in the selecting of seed; succumbs readily to culti-
vation.
Fig. 110. Parosela (Dalea alopecuroides). Common in western Iowa and
along railroads.
(Photographed by Quade.)
DESCRIPTIVE MANUAL 193
Fig. 110-A. Distribution of Parosela.
Rattle-box or Milk Vetch (Astragalus canadensis L.).
Description.—A tall, erect, smooth or pubescent perennial, 1-4
ft. high; leaves compound, leaflets 21-27, oblong; flowers greenish
cream-colored in spike of variable length; pods crowded, smooth,
terete, occasionally somewhat suleate; the seeds separate from the
pod, rattling, hence the common name.
Distribution—Common in the northern Mississippi valley, east
to New York and south to Georgia. Common on borders of thick-
ets, woods and native meadows.
Extermination.—This weed is easily exterminated by cultivation.
13
194 WEED FLORA OF IOWA
Fig. 111. Rattle-box (Astragalus canadensis). Woodland pastures.
(Photographed by Charlotte M. King.)
Purple or Stemless Loco Weed (Oxytropis lamberti Pursh.).
Description.—Nearly acaulescent, perennial herbs or shrubby
plants, with tufts of very numerous short stems coming from a hard
and thick root-stock containing many scaly stipules; stems and
leaves covered with silky and finely appressed hairs, or smoothish ;
leaves pinnate; leaflets linear; flowers racemose or spicate, rather
large and elongated, purple, violet, or sometimes white ; stamens dia-
delphous; keel tipped with a sharp projecting point. This is one of
the loco weeds, poisonous to cattle.
Distribution—Western Minnesota, western Iowa, and Missouri to
Texas, and New Mexico, north to British Columbia, and northwest
territory.
_Extermination.—It seldom gives much trouble in cultivated fields.
DESCRIPTIVE MANUAL 195
Fig 112. Purple Loco Weed (Oxytropis lamberti). A weed poisonous to cattle.
(Drawn by F. C. Collins.) :
Fig. 112-A. Distribution of Purple Loco Weed.
196 WEED FLORA OF IOWA
Wild Liquorice (Glycyrrhiza lepidota (Nutt.) Pursh.).
Description.—A branching perennial 2-3 feet high, leaves com-
pound of 15-19 oblong-lanceolate leaflets with mucronate points;
young leaflets sprinkled with a resinous material ; flowers in spikes;
short peduncled; whitish; pods oblong, covered with hooked
prickles, resembling a cocklebur.
Distribution—Common in the west, western lowa to Rocky
mountains, Utah, New Mexico, and Montana to Canada, also re-
bp
YY
TY
Fig. 113. Wild Liquorice (Glycyrrhiza lepidota.) Occurs in western and cen-
tral parts of the state.
DESCRIPTIVE MANUAL 197
Z a ‘ JANN Sane
ERELERERES
=
Fig. 113-A. Distribution of Wild Liquorice.
ported from the Great Lakes; commonly reported from Story,
Greene, Pottawattamie, Harrison, Monona, Fremont, and Decatur
counties.
Extermination—tThis perennial plant whose burs resemble the
cocklebur is easily exterminated by cultivation. Do not permit the
seeds to mature. Cut off the plants at the surface of the ground
to prevent flowering, if they occur in the pasture or meadow.
Where the land can be cultivated, give the ordinary plowing, fol-
lowed with harrowing to bring the roots to the surface so they are
exposed to the sun. A few days’ exposure to the sun will kill them.
Common Vetch (Victa satiwa L.).
Description.—A smooth or slightly pubescent annual from 1-21
ft. high with simple stem; leaflets 5-7 pairs, obovate-oblong to lin-
ear, notched or mucronate at the tip; 1 or 2 nearly sessile flowers
borne in the axils of the leaves, corolla violet-purple; pod linear,
several-seeded, seeds black.
Distribution —This weed has long been known as troublesome in
the grain fields of Europe, and in the northern states. It is particu-
larly abundant in northeastern and northwestern Jowa and in some
of the grain growing sections of the southern part of the state.
Extermination.—Clean seed sown in clean soil is the only method
of displacing the weed.
198 WEED FLORA OF IOWA
Fig. 114. Common Vetch (Vicia sativa). Common in grain fields, especially
wheat fields, frequently found in screenings from flour mills.
(Photographed by Colburn.)
ENE
AE
G
Fig. 114-A. Distribution of Common Vetch.
DESCRIPTIVE MANUAL 199
Chemical Composiiion.—The chemical composition of vetch (Vicia
sativa) according to U. S. Dept. Agr., 1880; p. 152, is as follows:
FRESH OR AIR DRY MATERIAL.
i=} ~~
He # 2S
= He
= 4 ay ie ur opahae a
Guiees in’ full bloom’ 2.2. | 86.20 | 1.60 | 4.14 | 2.11 | 5.34 | 0.61
WATER FREE SUBSTANCE.
| 11.6 3.00 | 15.3 | 38.7 | re
Wild Bean (Strophostyles helvola (L.) Britton).
Description.—An annual, with prostrate stem; compound leaves
ovate to oblong-obovate, with a prominent rounded lobe at the base;
corolla greenish white and purplish; pod 4-8-seeded, large, usually
- pubescent.
Distribution—Common in sandy places in northern United
States; from Wisconsin, Minnesota, and Texas east to Massachu-
setts ; common in gravel pits on Muscatine Island, along Des Moines,
Cedar and Iowa rivers.
Extermination.—Kasily exterminated by cultivation.
OXALIDACEAE, WOOD SORREL FAMILY.
This family contains the cultivated yellow and purple-flowered
oxalis. Few of the plants are economic.
200 WEED FLORA OF IOWA
Fig. 115. Wild Bean (Strophostyles helvola). Common in sandy or gravelly
soil, sandy river bottom.
(Photographed by Colburn.)
Fig. 115-A. Distribution of Wild Bean.
DESCRIPTIVE MANUAL 201
Field Sorrel (Oxalis stricta L.).
Description—aA pale green pubescent annual or perennial ; leaves
compound, with evident stipules; flowers pale yellow, cymose, 1-4,
at length deflexed ; in fruit columnar, short-pointed.
Distribution.—Common in fields and waste places from New Eng-
land to Dakota; common in Iowa probably over the entire state.
Extermmation.—Persistent cultivation and crop rotation will
usually exterminate the weed.
Fig. 116. Yellow Field Sorrel (Ozalis stricta). Common in fields. a, Trichome
or plant hair.
(a drawn by Charlotte M. King. The whole plant photographed by Hart.)
202 WEED FLORA OF IOWA
HALAL ames
ee Boe oe
US
SPENSER
wee
Fig. 116-A. Distribution of Yellow Field Sorrel.
Field Sorrel (Oxalis cormculata L.).
Description.—An erect or decumbent perennial herb, spreading
by numerous slender, pale runners; leaflets 3; flowers in cymose
clusters, yellow; peduncle ascending and sparingly pubescent.
Fig. 117. Field Sorrel (Owalis corniculata). Fields, gardens, etc.
(Photographed by Colburn. 1. Drawn by Charlotte M. King.)
DESCRIPTIVE MANUAL 203
Fig. 117-A. Distribution of Field Sorrel.
Distribution—-A very common weed in dry or moist soil through-
out eastern North America.
Extermination. —Apply the same method as to the preceding
species.
ZYGOPHYLLACHAH, CALTROP FAMILY.
A small family.
Caltrop (Tribulus terrestris L.).
Description.—The caltrop is a hairy, procumbent annual, branch-
ing from the base, producing a stem which is a foot or more long,
branches bear numerous small, compound leaves with short pe-
duncles and small stipules at the base; each compound leaf has 4-8
pairs of short-stalked leaves; small, yellow, axillary flowers about
1 in. across with peduncle much shorter than leaves; fruit very
spiny and divided into two nearly equal parts, each part consists of
2 long spines, 2 shorter and a row of very short ones, forming a
crest on the back; 5-angled, spiny fruit splits into 3-5 divisions.
Distribution.—Introduced from the Old World and oceurs from
the Atlantic states to Nebraska and Kansas; in Iowa has been found
only on Muscatine Island.
Extermination.—Caltrop is disseminated by wool, and hence the
waste of woolen mills should not be thrown in fields. The weed is
easily destroyed by cultivation.
204 WEED FLORA OF IOWA
ao YS
SR
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4 NY
te Q My “oN
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aS 87000 Sy
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SS
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WINE KZ HY) rN
agoeg We pa
Ground Bur-nut (Tribulus terrestris).
waste
scil,
Sandy
Caltrop,
Fig. 118.
Muscatine Island.
(Drawing by Charlotte M. King.) *
places,
DESCRIPTIVE MANUAL | 205
Fig. 118-A, Distribution of Caltrop.
ASA
EUPHORBIACEAE, SPURGE FAMILY.
Many of the plants of this family contain an irritating milky
juice. Few are of economic importance. The poinsettia commonly
cultivated in greenhouses, snow-on-the-mountain in gardens, and
eastor-oil bean belong to this family.
Three-seeded Mercury (Acalypha virginica L.).
Description—A smoothish or hairy annual from 1-2 ft. high,
turning purple especially in the autumn; leaves ovate or oblong-
ovate, sparingly serrate, long-petioled; sterile spike, few-flowered,
pistillate flowers 1-3 at the base of staminate peduncle surrounded
by a large leaf-like bract; capsule 3-lobed, subglobular, 2-valved
earpels. .
Distribution—F rom Nova Scotia to Texas and northward to Min-
nesota. Common everywhere in Iowa along roadsides and in fields.
Especially noticeable in the fall on account of the purple bracts.
Extermination.—Three-seeded Mercury is not a difficult weed to
exterminate. The small, reddish, striate seeds are expelled from
the plant to some little distance in a manner similar to the dispersal
of the eastor-oil bean. Thorough cultivation by preventing the for-
mation of seed will eradicate the weed.
206
Fig. 119.
WEED FLORA OF IOWA’
Three-seeded Mercury (Acalypha virginica). Common in many parts
of the state.
(Drawing by Charlotte M. King.)
DESCRIPTIVE MANUAL 207
Fig. 119-A. Distribution of Three-seeded Mercury.
Spurge (Euphorbia presli Guss.).
Description—An annual from 1-144 ft. high; erect or ascending ;
leaves oblique at the base, ovate, oblong, or sometimes oblong-linear,
ala
Ct mA, X
y lp EER
: ty
ay
SS
My | Sic =
My |
i 4
|
Y,
\
Fig. 120. Spotted Spurge (Huwphorbia preslii). Common everywhere in the
state. r,
(Drawing by Charlotte M.. King.)
208 WEED FLORA OF IOWA
Fig. 120-A. Distribution of Spotted Spurge.
frequently falcate, serrate, generally with a conspicuous red spot,
or margin; flowers pedunculate in terminal cymes; appendages en-
tire; pod glabrous; seeds ovate sometimes wrinkled.
Distribution.—In loose soils and fields from New England and
Canada to Wisconsin, Minnesota and Nebraska, also southward.
Extermination—tThis annual weed is easily exterminated by cul-
tivation; therefore practice rotation of crops and give thorough cul-
tivation. Seeds of several species of this genus retain their vitality
for some length of time.
Milkweed or Creeping Spurge (Euphorbia maculata L.).
Description—Slightly pubescent or hairy annual, with prostrate
stems; leaves oblong-linear, oblique at the base; pubescent or some-
times nearly smooth, usually with a brown-red spot in the center;
serrulate above, stipules lanceolate; flowers pedunculate in lateral
clusters; glands of the involucre minute; appendages usually red;
pods acute-angled; seed sharply 4-angled with 4 shallow grooves
across the sides ; trichomes several-celled, gradually tapering to apex.
Distribution.—Found in sandy fields, or generally in fields from
New England and Canada westward; common in every part of
Towa.
Extermination.—May be exterminated in the same way as the
preceding species. ‘
DESCRIPTIVE MANUAL 209
Fig. 121. Milkweed or Prostrate Spurge (Euphorbia maculata). Sandy fields.
(Photographed by Quade. a, drawn by Charlotte M. King.)
y .
Kossuth
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LG ° 5 ies
lda 3
+ reene| +- |e) ©
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5 bY ° ei ones}
+ < Zes| Moi +? ~
2 . Keokuk npc
watid mie] . ES
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.
Fig. 121-A. Distribution of Prostrate Spurge.
14
210 WEED FLORA OF IOWA
Snow-on-the-mountain (Huphorbia marginata Pursh.).
Description.—Stems stout, high, erect, hairy or smoothish ; annual,
from 2-3 ft. high; leaves sessile ovate-oblong, acute; uppermost
leaves white, petal-like margins.
The flowering spurge (Huphorbia corollata L.) with white flowers
in forked umbels; long peduncles; involucres showy, white append-
ages appearing like petals; deep perennial root; is common in gray-
elly and sandy soils in many parts of the state, and it is often weedy.
Distribution—Snow-on-the-mountain occurs from Minnesota to
Missouri and Colorado; also reported eastward to Ohio and South
Carolina. A frequent escape from gardens in Iowa; common only
in the western part.
Fig. 122. Snow-on-the-Mountain (Huphorbia marginata). A frequent escape
from gardens. a, Whole plant, one-third natural size; b, seed capsule,
natural size.
DESCRIPTIVE MANUAL 211
Fig. 123. Flowering Spurge (Huphorbia corollata). Common in sandy fields,
gravel Knolls, and roadsides.
(Drawing by Lois Pammel.)
Extermination.—This annual weed is easily exterminated by cul-
tivation. The young plant should be cut off below the surface of
the ground.
212 WEED FLORA OF IOWA
Cypress Spurge (Huphorbia cyparissias L.).
Description—Plant with perennial running root-stocks and
densely clustered stems from 6 in.-1 ft. high; linear, crowded leaves;
many-rayed umbel with glands crescent-shaped and granular pods.
Distribution.—Common westward from New England to Nebraska
usually in the vicinity of gardens and cemeteries.
Extermination.—This perennial weed because of its running root-
stocks is often difficult to exterminate. The ground should be given
a shallow plowing and the root-stocks exposed to the sun. It may
be necessary to repeat this process two or three times during the
summer. In addition to its propagation by the running root-stocks
it also propagates by its seeds.
Fig. 124. Cypress Spurge (Euphorbia cyparissias). Yellow ‘flowered’ plant
with milky juice and narrow leaves. Escaped from gardens to roadsides.
(Photographed by Colburn.)
DESCRIPTIVE MANUAL 213
>) NM =
SN
(Ce Sia
ate oe
z ee L is Perk - La
Se 9
PETELEBRRY
Fig. 124-A. “pisteanution of Cypress Spurge.
ANACARDIACEA®, SUMACH FAMILY.
Many of the plants are poisonous. “Many, like sumach, contain
tannin. Some, as the smoke tree, are cultivated for ornamental
purposes.
Poison Ivy (Rhus toxicodendron L.).
Description.—A climbing or trailing shrub sometimes erect, cling-
ing to trees or other objects by aerial rootlets; 3 leaflets ; inconspicu-
ous flowers; waxy fruit, frequently remaining on plant until late
winter or early spring. It is often mistaken for Virginia creeper
(Psedera quinquefolia (L.) Greene) which, however, has 5 leaflets.
Many persons are sensitive to poisoning from this plant, every part
of which contains the poisonous principle. The usual remedy for in-
fection from it is to wash the skin with a solution of sugar of lead.
Distribution.—Poison ivy is abundant throughout eastern North
America and the Rocky mountains. It is common everywhere in
Iowa, in hedge rows, thickets or woods.
Extermination —Poison ivy is not easily destroyed: because in
most cases it is troublesome in wood lots along fences and in yards.
It is difficult to destroy except by giving thorough cultivation. If
persistently cut off below the surface of the ground it can be de-
stroyed. Sodium arsenite at the rate of one and one-half to two
pounds to 52 gallons of water will help to destroy the weed. It is
not, however, safe to use this since it is a strong poison.
MALVACEAE, MALLOW FAMILY.
Cotton, hollyhock and okra are well known plants of the family.
214 WEED FLORA OF IOWA
Fig. 125. Poison Ivy (Rhus toxicodendron). Common in woods and along
fences. -
(Photographed by Colburn.)
Fig. 125-A. Distribution of Poison Ivy.-
DESCRIPTIVE MANUAL 215
Fig. 125-B. Poison Ivy (Rhus toxicodendron). a, spray showing rootlets;
; b, fruit. ;
(After Chesnut, U. S. Dept. Agr.)
Indian Mallow or Velvet-leaf, Butter-print (Abutilon theophrasti
Medice.).
Description.—A usually tall annual from 2-4 ft. high; plant with
strong odor; leaves velvety, roundish heart-shaped, taper-pointed ;
peduncles shorter than the petioles; corolla yellowish ; carpels 12-15,
hairy-beaked seeds rough, rather large and blackish.
Distribution.—Common in waste places, corn fields, vacant lots,
barnyards, ete. Common throughout eastern North America,
naturalized from tropical regions, probably India.
Extermination.—This plant propagates only by its seed, which
retains its vitality for some length of time, having been known to
germinate after a period of 60 years. The young plants are easily
exterminated. The plant should be pulled up before it begins to
216 WEED FLORA OF IOWA
Fig. 126. Indian Mallow, Velvet Leaf, or Butter-print (Abutilon theophrasti).
Common in carn fields, waste places, barnyards,
(Photographed by Colburn.)
flower. Wallace’s Farmer suggests the following treatment: ‘‘It
has been seriously thought of by some persons as a substitute for
manilla or sisal in the manufacture of binder twine. It is an an-
nual, and if not allowed to go to seed, the farm can in time be
cleared of it. But it will be a long time. The seeds have a most
astonishing vitality. We have known cases where it has been pulled
up for fifteen years, not a plant allowed to go to seed, and yet it
makes its appearance every spring. Fortunately, it grows only on
rich land, and is therefore found in evidence largely in hog yards
and feed lots and other places where the land is exceedingly rich.
In fact, in sections of the country where it is being introduced, it
may be found in almost every farmyard. Why farmers allow it to
mature seed passes our comprehension. It goes variously by the
DESCRIPTIVE MANUAL 217
Fig. 126-C. Pigweed, Foxtail, and Velvet Leaf, in a potato patch. Too many
such garden patches in Iowa.
(Photographed by Pammel.)
zoe
Ve =e
mAs = SEER
Fig. 126-B. Distribution of Indian Mallow.
218 WEED FLORA 'OF IOWA
names of velvet weed, butter print and in the locality of one of our
farms, Davis weed, from the fact that it was introduced many years
ago by a man named Davis, who regarded it as a rather good orna-
mental plant.’’
Sida (Sida spinosa L.).
Description.—An annual from 10-20 in. high; frequently much-
branched; leaves ovate-lanceolate; serrate with a long petiole, pe-
duncles in axils of leaves, 1-flowered; flowers small, yellow; 5 car-
pels, each 2-beaked.
Distribution—Common in the southern states, as far north as
Massachusetts to southern Iowa and Kansas.
Extermination.—This weed propagates entirely by its seeds which
retain their vitality for a considerable length of time, as the seed
coat is hard. The growing plant is, however, easily destroyed by
pulling the weed or by cultivation.
Fig. 127. Sida (Sida spinosa). Common in fields in southern Iowa.
(Photographed by Hart.)
DHSCRIPTIVH MANUAL 219
Fig. 127-A. Distribution of Sida.
Cheeses or Common Mallow (M alva rotundifolia L.).
Description.—A procumbent biennial ; leaves round, heart-shaped
on long petioles, crenate ; flowers white, petals longer than the calyx ;
a 3-leaved involucre at the base of the calyx; carpels pubescent.
Distribution.—A widely distributed weed in eastern North Amer-
ica, native to Europe, common in eastern and central Iowa in door-
yards, barn lots, etc., in Story, Marshall, Polk, Marion, Linn, Clin-
ton, Winneshiek and Allamakee counties.
Extermination.—This weed is easily exterminated by cultivation.
Do not permit any of the seeds to mature. The seeds retain their
vitality for a considerable length of time.
220 WEED FLORA OF IOWA
Fig. 127-B. Common Mallow or Cheeses (Malva rotundifolia). Common in door-
yards, barn lots, ete.
(Mich. Agr. Exp. Sta.)
DESCRIPTIVE MANUAL 221
Fig. 127-C. Distribution of Common Mallow.
Shoo-fly (Hibiscus trionum L.).
Description—A low, rather hairy annual from 1-2 ft. high ; upper
leaves 3-parted with 3 lanceolate divisions, the middle longest ; calyx
inflated in fruit, membranous, 5-winged, with numerous dark
nerves ; flowers sulphur-yellow with a blackish eye, ephemeral.
Distribution —Common in fields and waste grounds in the south-
ern states and eastward ; abundant in some places in Iowa, especially
in gardens where it has become naturalized from cultivation.
Extermination.—A. growing plant is not difficult to exterminate.
A thorough cultivation and exposing the roots to the sun will de-
stroy the plant. The seeds, however, retain their vitality for a con-
siderable length of time. A correspondent of southeastern Iowa
stated that this weed kept coming up in spite of constant and thor-
ough cultivation. This was owing to the prolonged vitality of the
seed.
HYPERICACEHAH, ST. JOHN’S-WORT FAMILY.
This small family contains a few ornamental plants with yellow
flowers, commonly found in northern states.
222 WEED FLORA OF IOWA
Fig. 127-D. Bladder Ketmia or Shoo-fly, (Hibiscus trionum). Gardens and
corn fields. Large white flower with a dark spot at the base of each petal.
a and b trichomes or plant hairs.
(a and b drawn by Charlotte M. King. The general aspect photographed by
Colburn. )
Fig. 127-E. Distribution of Shoo-fly.
DESCRIPTIVE MANUAL 223
St. John’s-wort (Hypericum perforatum L.).
Description.—A branched perennial, 114-2 ft. high with runners;
leaves elliptical, or linear-oblong, with pellucid dots; flowers
numerous in cymes, petals deep yellow, black-dotted, twice the
length of the lanceolate sepals.
Distribution.—Common in eastern North America in clay soils.
Abundant in Jowa only in eastern counties, especially northeast-
ward.
Extermination—This weed spreads both by seeds and by runners.
It is difficult to exterminate. Clark and Fletcher give the follow-
ing methods: ‘‘Close cutting several times during the summer will
reduce it in pastures. An application of salt—a small handful to
Fig. 128. St. John’s-wort (Hypericum perforatwm). Old fields and woodland
i pastures, eastern and northeastern Iowa.
(Photographed by Quade.)
224 WEED FLORA OF IOWA
y TRS
Fig. 128-A. Distribution of St. John's-wort.
each plant after close cutting in hot dry weather—will kill it and
may be practicable where the pest is not abundant and the land
cannot be brought under cultivation. Prevent it from going to seed.
St. John’s-wort is easily suppressed on land that cart be cultivated
under a systematic rotation of crops. Where it is established, it
would be well not to seed to grass until it is suppressed. ’’
ONAGRACEAE, EVENING PRIMROSE FAMILY.
A small family, some plants with showy flowers, a few cultivated
for ornamental purposes.
Evening Primrose (Oenothera biennis L.).
Description.—aA stout, erect, pubescent or hirsute perennial, 3-5
feet high, sparingly branched; leaves lanceolate, or rarely ovate-
lanceolate, denticulate, acute, bracts shorter or as long as the cap-
sule; flowers yellow, petals obovate, stigma lobes linear, capsule sub-
cylindrical; seeds small, brownish.
Distribution—Common everywhere in eastern North America,
Rocky mountains and Utah. Occurs in every county in Iowa.
Extermination.Spreads by seed. This plant is not difficult to
exterminate. Cut off the young plants a few inches below the sur-
face of the ground.
UMBELLIFERAE, CARROT FAMILY.
Carrot, celery, parsnips and caraway are members of this family.
Kt includes also many poisonous plants.
DESCRIPTIVE MANUAL 225
Tig. 129. Evening Primrose (Oenothera biennis). Fences, gardens, meadows
and pastures.
(Photographed by Hart. a, drawn by Charlotte M. King.)
\e tchell
2 .
Fig. 129-A. Distribution of Evening Primrose.
15
226 WEED FLORA OF IOWA
Caraway (Carum carvi L.).
Description—A smooth, erect, slender herb 1-214 feet high with
fusiform roots; leaves pinnate with filiform divisions; flowers in
umbels, white; calyx teeth small; fruit ovate, or oblong with fili-
form ribs.
Distribution—Common in eastern North America, the Rocky
mountains, Utah and scattered in places in Iowa.
Extermination.—Easily exterminated; cut off the plants below
the surface of the ground.
Fig. 130. Caraway (Carum carvi). Commonly escaped from gardens. Flowers
white.
(Photographed by Quade.)
DESCRIPTIVE MANUAL 227
Fig. 130-A. Distribution of Caraway.
Wild Carrot (Daucus carota L.).
Description.—A bristly, hirsute biennial from 2-214 feet high;
leaves pinnately decompound; involucral bracts foliaceous; flow-
Fig. 131. Wild Carrot (Daucus carota). Common in clover meadows. Flowers
in white umbels.
(Photographed by Colburn.)
228 WEED FLORA OF IOWA
Fig. 131-A. Distribution of Wild Carrot.
ers in compound umbels, white, or occasionally pink; fruit oblong,
flattened dorsally, carpel with 5 slender bristly primary ribs, and
4 winged secondary ones, each of these bearing a single row of
barbed prickles. canna ; 0 pean
' Distribution—Common in eastern North America, especially in
dry fields. Becoming common in Iowa clover fields in Scott, Story,
Polk, Franklin, Linn, Clinton, Cerro Gordo, Boone, Webster, Sac
and Clay counties.
Extermination.—Plant clean seed in a clean field. Easily killed
by cutting off the plant a few inches below the surface of the
eround.
Parsnip (Pastinaca sativa L.).
Description.—A tall, stout, glabrous biennial with grooved stem;
leaves pinnately compound, cut-toothed; flowers yellow, small;
calyx teeth obsolete; fruit oval, flattened dorsally, the lateral ribs
with broad wings.
Distribution—Common in eastern North America, Rocky moun-
tains and the Pacific coast.. Common on roadsides in every part of
Towa.
Extermination.—Propagated by seeds. Easily exterminated by
cultivation ; cut off the young plants a few inches below the surface
of the ground.
DESCRIPTIVE MANUAL ; 229
Fig. 132. Wild Parsnip (Pastinaca sativa). Common along roads.
(Mich. Agr, Exp. Sta.)
230 WEED FLORA OF IOWA
Fig. 132-A. Distribution of Wild Parsnip.
Cowbane (Cicuta maculata L.).
Description.—A smooth, marsh perennial, 2-5 ft. high, with pin-
nately compound leaves, 2 or 3 times pinnate; leaves with long
petioles; coarsely serrate leaflets lanceolate to oblong-lanceolate,
1-5 in. long; stalks of umbellets numerous and unequal; flowers
white; fruit broadly ovate to oval, small, 1144 in. long. The plant
grows in marshes and in low grounds, the stems springing from
thick fleshy underground roots tapering at the lower end, usually
numbering from 3-8 although single specimens are also met with.
On cutting the roots there is given off a sharp pungent odor, which
becomes intensified on boiling.
Distribution.—Common throughout the northern states, south-
west to Louisiana, Rocky mountains and Utah. Very common in
low grounds and swales in northern Jowa, less common in southern
Towa.
Extermination—The field where cowbane occurs needs drain-
age; plow the field, break.up the sod, and expose the fascicled
roots to the sun. This will soon destroy the weed.
DESCRIPTIVE MANUAL 231
Wig. 133. Cowbane (Cicuta maculata). In low moist meadows and roadsides.
(Photographed by Colburn.)
Fig. 133-A. Distribution of Cowbane.
23
Fig.
WEED FLORA OF IOWA
133-B. Cowbane (Cicuta maculata).
(Photographed by Caughey.)
In low woods.
DESCRIPTIVE MANUAL 233
Fig. 133-C. Cowbane roots (Cicuta maculata). In low places.
- (Photographed by Gardner.)
234 WEED FLORA OF IOWA
Cow Parsnip (Heracleum lanatum Michx.).
Description.—A stout, hairy, pubescent perennial 4-8 ft. high;
leaflets broad and large, irregularly cut-toothed; flowers white, in
broad umbels.
ig. 134. Cow Parsnip (Heraclewm lanatum). Common in woodland pastures.
. (Photographed by Charlotte M. King.)
Distribution—From the Atlantic coast, Newfoundland, through
the northern states and Allegheny mountains to California.
mon in the Rocky mountains.
Com-
APOCYNACEAE, DOGBANE FAMILY.
In the tropics several species are important rubber producing
‘
plants. They are commonly called milk-weeds in Iowa.
DESCRIPTIVE MANUAL 235
Spreading Dogbane (Apocynum androsaemifolium L.).
Description.—Root-stock horizontal, smooth, or rarely soft-tomen-
tose, branched above, spreading, leaves ovate, petioled, cymes loose, .
spreading, both terminal and axillary; the latter pale rose color,
open, bell-shaped; calyx segments shorter than the tubes of the
corolla.
Distribution—Common along borders of thickets from eastern
Canada to British Columbia to Arizona and Georgia. Abundant
in Iowa in grain fields near thickets.
Fig. 135. Distribution of Spreading Dogbane (Apocynum androsaemifolium).
Extermination.—Spreading dogbhane produces long, creeping
roots, which are quite tenacious of life. In order to destroy the
weed, the field should be given a shallow plowing after the grain is
harvested, followed by a disking in a week or ten days, depending
on the character of the weather. This should be followed by a
harrow. If the fall is dry dragging will probably get the larger
number of these weeds.
Indian Hemp (Apocynum cannabinum L.).
Description —Glabrous or more or less softly pubescent; 2-3 ft.
high, smooth, terminated by an erect, close, many-flowered cyme;
corolla lobes nearly erect, the tube not longer than the lanceolate
segments of the calyx, greenish white; appears in July and August.
Distribution.—Common species eastward and troublesome as a
weed in northern Mississippi valley. Common in small-grain fields
and pastures.
236 WEED FLORA OF IOWA
Figure 136 Figure 1364
Fig. 136. Indian Hemp (Apocynum cannabinum).
Fig. 136-A. Apocynum cannabinum hypericifolium. A low growing variety of
the above, but with leaves broader at base and more abruptly pointed
at apex.
(Schuyler Mathews in Mich. Agr. Exp. Sta. Bull.)
DESCRIPTIVE MANUAL 237
136-B. Distribution of Indian Hemp.
Extermination—This weed should be treated like spreading
dogbane.
ASCLEPIADACEAE, MILKWEED FAMILY.
A few plants, only, are of economic importance. Some are cul-
tivated for ornamental purposes. In Jowa they are commonly
ealled milkweeds.
Showy Milkweed (Asclepias speciosa Torr.).
Description.—A perennial 1-4 ft. high, white-tomentose or ca-
nescent; leaves thick, broadly ovate or oval, petioled; pedicel
elabrate above; flowers borne in dense umbels or rarely solitary,
the pedicels stout; corolla purplish green, large, follicle erect or
spreading on the recurved pedicels.
Distribution—Showy milkweed is common from Minnesota to
southern Iowa, Kansas, the Rocky mountains and Utah. In Iowa
it is abundant in Emmet, Palo Alto and Dickinson counties.
Extermination.—This weed should be treated like common milk-
weed.
238 WEED FLORA OF IOWA
Fig. 137. Showy Milkweed (Asclepias speciosa). In grain fields, meadows and
roadsides, northern Iowa.
(Photographed by Colburn.)
Fig. 137-A. Distribution of Showy Milkweed.
DESCRIPTIVE MANUAL 239
Milkweed (Asclepias syriaca L.).
Description—A perennial herb with a stout stalk 2-5 ft. high,
finely, softly pubescent or tomentose; leaves oblong, oval or ovate,
obtuse or roundish at the base, the young leaf somewhat pubescent
above, soon becoming glabrate; petioles stout, flowers from a few
to many, borne in umbels; peduncles pubescent or tomentose; co-
rolla dull purple or greenish purple, occasionally pale in color;
fruit a follicle and borne on erect pedicels; trichomes multicellular
from a single cell, somewhat floccose.
Distribution —This milkweed is common from New England to
North Carolina and Kansas. In Iowa it is abundant in oat fields,
on highways and in gardens throughout the state.
Fig. 1838. Common Milkweed (Asclepias syriaca). Fields, meadows, roadsides,
ete. a trichomes or plant hairs.
(Drawing by Charlotte M. King; general aspect photographed by Colburn.)
240 WEED FLORA OF IOWA
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fore hE a ae || tae :
. . . ens .
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7 | ? FE L ‘ ‘ \oaes| Morbes
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Fig. 138-A. Distribution of Common Milkweed.
Extermination.—Both milkweeds have the same habit of growth.
The weed is perhaps known by its long roots which are frequently
10-15 ft. in length; another important point is that it produces ad-
ventitious buds at frequent intervals from which new shoots arise.
Fig. 138-B. Common Milkweed (Asclepias syriaca). Grain fields, waste places.
(Photographed by Charlotte M. King.)
DESCRIPTIVE .MANUAL 241
Wallace’s Farmer says concerning this weed: ‘‘We would ad-
vise our correspondent to plow this field as scon as_ possible
and prepare his seed bed for winter wheat. By plowing it again
next August he will undoubtedly weaken the stand. He will
fail, however, unless in working his corn he uses surface cultiva-
tion. These weeds have no doubt been distributed through the
field during the three years it was in corn by using a shovel cul-
tivator, which takes up the roots and carries them over the field
in the same way that many northern farmers are now seeding their
fields with quack grass and damaging them to the extent of from
five to twenty dollars per acre. By giving these two thorough
August plowings and taking care of the roots that may be thrown
up, then preparing the seed bed very thoroughly for corn and
giving it as far as practical surface cultivation, he will probably
get rid of these noxious weeds.’’
Climbing Milkweed (Gonolobus laevis Michx.).
Description.—A climbing perennial; leaves oblong, cordate with
a deep, narrow sinus; flowers borne in axillary umbel-like cymes,
5-10 flowered, large greenish flowers; calyx 5-parted; corolla 5-
parted, wheel-shaped, the lobes narrowly linear-lanceolate, obtuse,
larger than the calyx; anthers horizontal under the flattened
stigmas ; pollen masses 5 pairs, follicles with soft warty projections.
Distribution.—Troublesome in woods and fields in the southern
states. It is reported as troublesome from a few counties in south-
ern Iowa.
Extermination.—This perennial weed is as difficult to destroy as
common milkweed. Give thorough cultivation. If this will not suf-
fice get the field into a meadow.
CONVOLVULACEAE, MORNING-GLORY FAMILY.
Few economic plants. Sweet potato and cultivated morning glory
are representatives.
16
242
Pig.
WEED FLORA OF IOWA
139.
Climbing Milkweed (Gonolobus laevis).
southern Iowa.
(Drawing by Ada Hayden.)
Troublesome in fields in
DESCRIPTIVE MANUAL 243
rere] S
y Bren iS Masset a N
yi ES \ Baer \ ae
h
Wy phim oy 1] i S x ee AC
IN {|
Fig. 139-A. Distribution of Climbing Milkweed.
Morning-glory (Ipomoea hederacea Jacq.).
Description— Stems retrorsely hairy; leaves heart-shaped,
3-lobed, the lobes usually acute; peduncle variable in length; 1-3
Fig. 140. Blue Field Morning-glory (Ipomoea hederacea). Fields, common
southern Iowa and Missouri.
(Photographed by Colburn.)
244 WEED FLORA OF IOWA
FSI DSRS
EPR
Fig. 140-A. Distribution of Morning-glory.
flowers; calyx densely hairy below; corolla funnel-form, white and
purple or pale blue; lobes of stigma and cells 3.
Fig. 141. Annual Morning-glory (Ipomoea purpurea). A frequent escape from
gardens into fields,
(Photographed by Colburn.)
DESCRIPTIVE MANUAL 245»
Fig. 141-A. Distribution of Annual Morning-glory.
The I. purpurea has heart-shaped leaves with retrorsely hairy
stem; peduncles long, umbellately 3-5 flowered, purple to white.
Distribution.—Common in waste and cultivated grounds from:
New England southwestward; abundant from Missouri southward;
native from tropical America; rare in Iowa. The J. purpurea is.
commonly cultivated and is a frequent escape from cultivation in.
Hardin, Story, Marshall, Wapello and Marion counties.
Extermination—It is an annual and is easily destroyed; how-
ever, the seeds retain their vitality for some time, frequently
springing up for several seasons after the most thorough ecultiva-
tion. )
Hedge Bindweed or Morning-glory (Convolvulus sepium L.).
Description—Smooth, occasionally, however, pubescent, twining
around supports or trailing; leaves triangular, halberd or arrow
shaped, the tip acute, or pointed, the basal lobes obliquely trun-
cate or sinuate lobed; flowering peduncles 4-angled with 2 leaf-like
bracts which are commonly acute; corolla white or tinged with
rose purple.
DistributionHedge bindweed or morning-glory is common in
the northern states and in the southwest from Texas to Canada,
also in the Great Basin country. A form of it is also found in
Europe and Asia. Common in every section of Iowa not only in
corn fields, but along highways and in small-grain fields.
246 WEED FLORA OF IOWA
Fig. 142. Morning-glory (Convolvulus sepiwm). Common in grain, corn fields
and meadows.
(Photographed by Colburn.)
Fig. 142-A. Distribution of Hedge Bindweed or Morning-glory.
DESCRIPTIVE MANUAL 247
Extermination —The morning-glory must be treated like horse
nettle since it is a perennial. In addition to the usual methods of
cultivation sheep have been recommended to destroy the weed.
This method is certainly applicable where the weed occurs in pas-
tures.
In Wallace’s Farmer, Mr. L. C. Greene’s experience in killing
morning-glory is given as follows: ‘‘A large farmer had 145 acres
of corn. One piece of twenty acres, fall plowed, on a south slope,
was planted to corn the first of May, and by the time the plowing
and planting were all done it was near the last of May. The early
planted field was thick with-morning-glories and had received no
cultivation since they commenced to grow. By the time the corn
was four inches high the morning-glories were eight or more inches
tall, growing in mats on the ground hunting for something to climb
upon. The proprietor viewed the field, and instead of sending out
the cultivator sent out three stirring plows and the planter soon
followed. In two days the field was plowed and planted again and
a fine crop of corn was raised with very little bother from the vines,
and even the following year the vines bothered but little.
‘‘Some years ago I fall plowed a small field that was badly in-
fected with morning-glory vines and smartweeds. The 24th of the
next May I was ready for that field, but from a little distance it
looked as if a mowing machine and a rake would be the proper tools
to use. I plowed rather deep to do a good job, the planter im-
mediately followed, and in four days after the planter some corn
could be seen, and it was eight inches high when the cultivator
got to it. It was just a matter of stirring the soil all season, for
there were no large weeds to kill.’’
The Prairie Farmer makes these suggestions concerning the
eradication of morning-glory: ‘‘ Another way to fight the morning-
glory is to grow two or three pasture crops a year on the land for
sheep. One of them ought to be a cultivated crop. The morning-
elory would not be able to hold out long against such treatment.
The strong point in favor of this method is the profitable character
of the work.’’
Wallace’s Farmer says concerning its destruction: “‘They do
not spread rapidly except under cultivation, as they grow
mostly from the roots, and these are distributed over the fields:
by cultivators. If when the farmer first discovers a patch out of
cultivation for a year or two he plows it shallow and frequently
248 WEED FLORA OF IOWA
and harrows he can get rid of them. If he cultivates the plants
with the rest of his field it is only a short’ time until he will find
these weeds scattered all over his field. A great many ways have
been suggested to get rid of this troublesome weed. Special at-
tachments have been invented for the use on corn cultivators
known as the morning-glory blades. These are designed to shave
off the plants just below the surface of the ground.”’
‘“We certainly would fence up this pasture, or part of it, and
would sow a mixture of grains that would furnish hog feed, and LA
while we were at it would sow clover and timothy, and when the
grains were three or four inches high turn in the hogs. The only
trouble is that there are not enough hogs to go around the whole
tract. We had a field in that condition twenty years ago. We
made a hog pasture of it, and while the morning-glories are yet
to be seen in the road alongside, there are none of them in the
f ,
pasture, and have not been since the first year.”’
European Bindweed or Morning-glory (Convolvulus arvensis L.)
Description.—The European bindweed or morning-glory is a
deep-rooting perennial; stem procumbent, twining or creeping.
Like the horse nettle, this species propagates freely by under-
ground root-stocks; leaves 1-2 in. long, ovate, oblong, arrow-shaped,
lobes at the base running to a point; flowers borne in 1-flowered
peduncles with very small leaf-like bracts some distance from the
flowers; flowers an inch or less long, short, broadly funnel-shaped,
white or commonly of a rose tinge.
Distribution.—European bindweed is a troublesome weed in Eur-
ope and in eastern North America. It occurs also in the southern
states and on the Pacific coast. It is scattered in many parts of
Towa in small patches.
Extermination.—A short rotation of crops should be practiced,
including late sown roots or other cultivated crops: rape is useful
for this purpose. Frequent use of a broad-shared cultivator will
destroy new growths and exhaust the vitality of the plants. Sow
no crop seeds containing those of field bindweed. Applications of
salt or lime, sometimes recommended to kill this weed, are useless
unless appled in large quantities.
SS
DESCRIPTIVE MANUAL 249
ra
mae
>
a
\
Fig. 143. European Morning-glory or Bindweed (Convolvulus arvensis). Com-
mon in gardens and becoming frequent in Iowa.
(Photographed by Colburn.)
Fig. 143-A. Distribution of European Morning-glory.
250 WEED FLORA OF IOWA
Prof. H. A. Hitchcock in Farmer’s Review, says: ‘‘The black
bind-weed or perennial morning-glory (Convolvulus arvensis),
which I suppose is the kind meant, is a great pest and difficult to
eradicate. If a patch is not too large, heavy mulching is the best
way to destroy it. Then watch the patch closely and eut off im-
mediately any stray shoot that may appear above its surface.
Nothing but persistent watching and the careful cutting off of
all parts above the ground will eradicate this weed.’’
Prof. Ten Eyck, quoted in Wallaces’ Farmer, states that the only
method of culture applicable to large areas which promises any
great degree of control or destruction of the pest is very late fall or
winter plowing. The plots which were plowed in November (no
plowing was done later than November 20th) showed a very scat-
tering and feeble growth of bindweed on April 26th, the date of
inspection.
The weeds were thinner and more feeble also on the unplowed
land which produced a crop of sowed cane or sowed kaffir last
season, than they were on any of the lots cultivated in intertilled
crops.
Clover Dodder (Cuscuta epithymum Murr.).
Description.—A spreading, climbing plant; yellowish or reddish
with a few minute scales in place of leaves; flowers whitish or pink-
ish in heads, small, globular, urn-shaped; cylindrical tube longer
than the nearly erect, acute sepals; scales large-toothed; stigma
elongated; style longer than the ovary; stamens exserted, fruit in
capsules.
Distribution—This weed has long been known as troublesome
in Europe and has been more or less common in the Rocky moun-
tains on clover and alfalfa. For some years also frequent in the
east; becoming more abundant on clover and alfalfa.
Extermination—Where the plant occurs cut down the clover at
once and burn. Sow the patch or field to another crop, preferably
to small grain or with corn.
Clark and Fletcher recommend the following treatment: ‘‘As
soon as the pest is noticed, the infected patches should be at once
mown with a scythe and the refuse removed and destroyed. Fields
DESCRIPTIVE MANUAL 251
Fig. 144. Clover Dodder (Cuscuta epithymum). . S49 dt Ea eo
; ; Kossuth = ~ state C
© OBrien ; : Sees 50
° ary eee 0, 2 ° “4 ely * fe 0
+ °
. . i) +H * |e s + 04
Loy AUS; SAIRSSSI o wll *,\ 728k | *
PS s L
sige ly A. Solo lol eae 5 ‘ SG * qubuque
+ "af e Ma, a ae a . . t 2. : e
OOO 2g rene Pies ° : 4
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e| ¢ irs . > > 2
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5 Tataranine|
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5 . ° . A A
. 5 °
, . ° 0
Fig. 153-A. Distribution of Hoary Vervain.
a, drawn by Charlotte M. King.)
266 WEED FLORA OF IOWA
AA SESS
sani
Fig. 153-B. White Vervain, Nettle-leaved Vervain (Verbena urticaefolia).
(Mich. Agr. Exp. Sta.)
DESCRIPTIVE MANUAL 267.
taba Ee.
Cue hey
Fig. 153-C. Distribution of White Vervain.
Common Vervain (Verbena bracteosa Michx.).
Description.—A widely spreading, hairy annual; leaves wedge-
lanceolate, cut-pinnatifid or sometimes 3-cleft; flowers in spikes,
i
‘ oe
d
‘ :
7
2 os
EES
ee
i
Fig. 154. Prostrate Vervain (Verbena bracteosa). a, Plant hair or trichome.
Common along roadsides, streets, and gravelly places; small, blue flowers, —
(General aspect photographed by Quade. a drawn by Charlotte M. King.)
268 WEED FLORA OF IOWA
Basse et
Hit bets Bee oe:
ee GRE
PSSese
AREER
C/A are:
Fig. 154-A. Distribution of Prostrate Vervain.
with large bracts, small, purple; trichomes few-celled from a broad
several-celled base.
Distribution.Common in waste places, roadsides, walks, gravel-
ly and sandy fields from Virginia to Wisconsin and Minnesota and
southward.
Eaxtermination.—It is easily exterminated by cultivation.
LABIATAE, MINT FAMILY.
The common pepperment, scarlet sage, catnip, pennyroyal, thyme
and basil belong to this family. All are aromatic plants.
Mint (Mentha arvensis L.)..
Description.—This perennial weed has freely branching stems
1-114 ft. high, retrorsely pubescent, leaves oblong to ovate, rounded
at the base, minutely pubescent, closely serrate, petioled or nearly
sessile; flowers white, pink or violet. The varity canadensis has
lanceolate to oblong-lanceolate, pubescent leaves and is the common
form in Iowa in low grounds. Several other species occur in Iowa,
namely: peppermint (Mentha piperita) along brooks, a smooth
and pungent-tasting herb with ovate-oblong leaves and running
root-stocks, and spearmint (Mentha spicata) with oblong or ovate-
lanceolate unequally-serrate leaves.
Distribution.—This Eurasian species occurs from Newfoundland
to Nebraska and the Pacific coast.
Extermination.—Easily exterminated by giving thorough culti-
vation and dragging the soil to bring the root-stocks to the surface
of the ground.
DESCRIPTIVE MANUAL - 269
Fig. 155. Mint (Mentha arvensis var. canadensis). Common in low meadows;
whitish flowers. Plant with odor of peppermint.
(Photographed by Colburn.)
Fig. 155-A. Distribution of Mint.
270 WEED FLORA OF IOWA
Fig. 155-B. Peppermint (Mentha piperita). In some gardens,
(Photographed by Colburn.)
Carpenter Weed, Self-heal (Prunella vulgaris L.).
Description.—A low, perennial weed with ovate-oblong, entire or
toothed leaves, hairy or smooth; flowers collected in heads of
3-flowered clusters, corolla violet or flesh-color, or rarely pale in
color, longer than the purplish calyx which is tubular bell-shaped.
Distribution—Widely distributed in northern United States,
west across the continent in clay soils and woods, also from New-
foundland to Florida.
Extermination—This weed is not difficult to exterminate by
giving cultivation with a cultivator and hoe. The weed is mainly
spread by seed. The seed of this is not uncommon in clover seed.
DESCRIPTIVE MANUAL 271
Fig. 156. Self-heal (Prunella vulgaris). Common along roadsides, wooded
pastures.
(Photographed by Quade.)
Fig. 156-A. Distribution of Self-heal. ae id
272 WEED FLORA OF IOWA
American Germander (Teucrium canadense L.).
Description —A_ perennial, downy, erect herb 1-3 ft. high with
running root-stocks; leaves pubescent, short-petioled, downy be-
neath, ovate, lanceolate, serrate with a rounded base; floral leaves
small; flowers in ample wandlike spikes; calyx 5-toothed, the up-
per lobes obtuse; corolla purple, rose or whitish.
Distribution—From New England to Mexico and northwest to
Manitoba. Common in Iowa alluvial grounds in pastures, mead-
ows, grain fields, ete.
Extermination.—A very troublesome weed in the north. It is,
however, an excellent bee-plant. Should have the same treatment
as quack grass. The root-stocks should be exposed and allowed to
dry. After plowing the field follow with a dise and harrow once
a week after the small grain crop is removed.
Fig. 157. Germander or Wood Sage (Teuchriwmn canadense). Common in fields
and woods.
(Photographed by Colburn.)
DESCRIPTIVE MANUAL 273
Fig. 157-A. Distribution of Germander.
L. H. Pammel in the Weekly Register says: ‘‘Germander is a
troublesome weed found in many parts of northern Iowa. It pro-
duces root-stock very much like mint and quack grass. Each sev-
ered portion produces a new plant, and for this reason it is some-
what difficult to destroy. The only way to exterminate this weed
is by thorough cultivation. Plowing in the fall during the dry
season, then plowing again in the spring and giving thorough cul-
tivation during the growing season should destroy the weed with-
out difficulty.’’
Catnip (Nepeta cataria L.).
Description.—A perennial, erect herb, 1-3 ft. high; leaves ovate,
cordate, coarsely serrate, petiolate, whitish, downy underneath;
flowers in cymose clusters; corolla whitish, dotted with purple;
trichomes several-celled, rough, thick-walled.
Distribution—Native to Europe; widely naturalized in the
northern states.
Extermination.—Give the same treatment as to motherwort.
Chemical Composition.—According to the University of Min-
nesota*, it is as follows :—
k Nitrogen free
Dry Matter Crude Protein Ether Extract Extract and Ash
Fiber
94.30 22.25 | 2.66 | 63.07 12.77
*Snyder: Bull. Univ. Minn. Agr. Exp., 101.
18
274 WEED FIORA OF IOWA
Fig. 158. Catnip (Nepeta cataria). Trichome or plant hair at the right. Com-
mon in waste places.
(Photographed by Colburn. Drawing of hair by Charlotte M. King.)
+ Jared \
. 4 AUS
Figure 158A Figure 158B
Fig. 158-A. Plant hair or trichome from leaf of catnip.
(Drawing by Charlotte M. King.)
Fig. 158-B. Distribution of Catnip.
DESCRIPTIVE MANUAL 275
Ground Ivy (Nepeta hederacea (L.) Trevisan).
Description.—A creeping, trailing perennial, with leaves all
alike, petioled, round, kidney-shaped; crenate, smooth, green on
both sides; flowers light blue in axillary whorls of about 6, ap-
pearing in early spring and summer.
Distribution.—Native to Europe, widely naturalized in the
northern states, especially in shady places. Common everywhere
in Jowa.
Extermination—Somewhat difficult to exterminate in lawns,
but thorough cultivation will destroy the weed.
Fig. 159. Ground Ivy or Creeping Charley (Nepeta hederacea). Common in
some gardens.
(Photographed by Colburn.)
276 WEED FLORA OF IOWA
eee
si
Fig. 159-A. Distribution of Ground Ivy.
Motherwort (Leonurus cardiaca L.).
Description.—Tall perennial herb with erect stem, 2-6 ft. high;
leaves long-pointed, the lower round and palmately lobed, the up-
ig 160. Motherwort (Leonurus cardiaca). A common weed in waste places
and gardens.
(Photographed by Colburn.)
DESCRIPTIVE MANUAL 277
eee
Fig. 160-A. Distribution of Motherwort.
per crenate at the base, 3-cleft; flowers pale purple, in close axil-
lary whorls; corolla bearded.
Distribution.—Native to Europe, widely naturalized in the north-
ern States.
Extermmation.—This perennial weed can be exterminated by
plowing the field with frequent cultivation subsequently.
Blue Sage (Salvia lanceaefolia Poir.).
Description—A_ slightly pubescent or nearly smooth annual,
1-214 ft. high; leaves petiolate, lanceolate serrate or nearly entire;
flowers in interrupted, erect spikelike clusters; calyx bilabiate,
upper entire, the lower 2-cleft; corolla, blue, slightly exserted;
stamens with long connective, attached to a sterile anther which
blocks the throat of the corolla; pistil 1, deeply 4-lobed. Plant
related to the cultivated garden salvias.
Distribution.—Chiefly west of Missouri river, Kansas, Nebraska,
Texas, and Arizona, Missouri and Indiana, introduced in Ohio.
Common in Pottawattamie, Fremont, Monona and Woodbury coun-
ties, less common in Story, Boone, Polk and Muscatine counties.
Extermination—tThis weed is easily exterminated by cultivation.
Do not allow the plant to produce seeds.
SOLANACEAE, NIGHTSHADE FAMILY.
Potato, tomato, tobacco, ground cherry, jimson weed, flowering
tobacco and black henbane, belong to this family.
278
WEED FLORA OF IOWA
Fic. 161. Lance-leaved Salvia, Blue Sage (Salvia lanceaefohe).
DESCRIPTIVE MANUAL 279
Wig. 161-A. Distribution of Lance-leaved Salvia.
Ground Cherry (Physalis lanceolata Michx.).
Description —aA hirsute perennial with short, stiff hairs, some-
times nearly smooth; forms short and stout underground stems;
leaves oblong-ovate to lanceolate, sparingly angulate-toothed or
more often entire; flowers in axillary peduncles, calyx hirsute, co-
rolla yellowish with a dark eye; berry reddish. The P. virginiana
Mill., is also an erect perennial with narrowly ovate acutish leaves
or acutish or rounded teeth, corolla pale yellow. The P. subglab-
rata MacKenzie and Bush, has ovate or ovate-oblong leaves, oblique
at the base, entire or repand, and brownish corolla; berry, large,
reddish or purple. The P. heterophylla is perennial, leaves obtuse
repand, or obtusely toothed; trichomes several-celled, glandular
and non-glandular.
Distribution—The P. lanceolata in southern Iowa and south-
ward, the P. virginiana common everywhere in Iowa, in dry grav-
elly soil, from Connecticut to Jowa and southward; the P. sub-
glabrata from Rhode Island to Minnesota and southward.
Extermination —All of the perennial ground cherries are diffi-
cult to destroy because of the strong underground root-stocks which
freely spread the weed. These plants are also scattered by seed.
To exterminate the perennial weeds plow shallowly and expose the
plants to the sun; give frequent cultivation.
280 WEED FLORA OF IOWA
Wig. 162. Ground Cherry (Physalis lanceolata). Common in gravelly and
sandy soils; waste places and gardens. 1, leaf; 2, flower.
(Photographed by Quade. Drawing by Charlotte M. King.)
Fig. 162A Figure 162B
Fig. 162-A. Trichome or plant hair from leaf of Ground Cherry (Physalis
heterophylla).
(Drawing by Charlotte M. King.)
Fig. 162-B. Distribution of Ground Cherry.
DESCRIPTIVE MANUAL 281
Fig. 162-C. Distribution of Virginia Ground Cherry (Physalis virginiana).
Common Nightshade or Stubbleberry (Solanum nigrum L.).
Description.—Annual, low-branched and often spreading; glab-_
rous or hairy, hairs roughened on the angles; leaves ovate, petioled,
Fig. 163. Black Nightshade (Solanum nigrum). Shady places, gardens and
fields.
(Photographed by Colburn.)
282 WEED FLORA OF. IOWA
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Fig. 168-B. Black Nightshade (Solanum nigrum).
DESCRIPTIVE MANUAL 283
flowers white in small, umbel-like, drooping, lateral clusters; calyx
spreading, the lobes obtuse, much shorter than the white corolla;
= glabrous, globose, black; occasionally large.
- Distribution—Found in northern United States; abundant
everywhere in Towa in shady grounds and fields. A cosmopolitan:
weed.
Horse Nettle (Solanwm carolinense L:).
Description—aA deep-rooting perennial, propagating freely by
its underground root-stocks, the running roots often being 3 ft.
long; stem 1-2 ft. high, somewhat straggling, half shrubby at the
base; stem hairy or merely roughish with minute hairs which are
star-shaped, also armed with numerous stout, subulate, yellowish
prickles; leaves oblong or sometimes ovate, obtusely sinuate-toothed
or lobed, or deeply cut, 2-4 in. long; flowers borne in one-sided
racemes; calyx consists of slender lobes, ¢orolla light blue or white,
an inch or less in diameter ; flowers followed by yellow globose ber-
ries 14-84 in. in diameter; small yellowish seeds, a little less than
1/,, in. long, minutely foudhened: Flowers and yellow berries
resemble those of the potato. The spiny character of the leayes and
the further resemblance of the flower to the potato should render
it easy of, detection.
Distribution.—Horse nettle is indigenous to thé southern states,
but now oceurs from Connecticut to northern Iowa. This weed
is most abundant in southern Iowa and has been reported from
Floyd, Story, Boone and Linn counties; in the north half of the
state, however, it is a recent introduction. ead ew
ee aiinction —There are two ae ne ne ondedt Oi: one by
seeds, the other by perennial roots. It is so exceedingly tenacious
a weed, thatit is almost impossible to remove it when fully estab-
lished. ‘The following very suggestive methods have ‘been given.
Smothering. This is an effective method of removing the plant.
For this purpose probably rape or sorghum is the most suitable
crop. If the soil is not already rich, a liberal dressing of barnyard
manure should be applied during the winter or spring. The soil
should be harrowed or cultivated frequently until the time of seed-
ing, which may be any time during the months of May or June.
This cultivation will prevent the weed growth, and will also assist
284 WEED FLORA OF IOWA
in the retention of moisture. If the rape is sown in drills about
two pounds of seed per acre is sufficient quantity and three pounds
if sown broadcast. When the crop has attained a rank growth it
may be pastured or removed and fed to stock. Where land is lack-
ing in vegetable matter it is good practice to plow the crop under
when it is properly manured. The latter is not necessary when the
object is to destroy the nettle, as the rank growth of the crop is
very effective in completely smothering the weed.
Hoed crops. Planting of corn or roots is a method much in ~
vogue for the destruction of this vile intruder. As in the previous
method the plant should be kept down before seeding time. When
the crop appears above the ground the use of horse and hand hoe
should not be sparing. When the welfare of the crop prohibits the
use of the horse hoe, the hand hoe should be used at intervals until
the crop is removed; even after this, it is sometimes necessary to
give attention to the pest. There is no question about this mode of
treatment being effective if properly carried out, but often failure
results from negligence during the latter part of the season.
The Iowa Homestead suggests the following treatment: ‘‘Corn
land that has grown up to horse nettles this year should be burned
over, if possible, next spring, as this will destroy many of the
seeds. Afterwards the land should be plowed lightly and kept cul-
tivated at intervals until somewhat late in the season. A surface
cultivator will be all that is necessary, and this need not be run
deeper than two or three inches, just enough to effectively cut the
plants off below the surface. By checking the growth several times
before planting corn the root system becomes much weakened, so
that ordinary cultivation the remaining part of the season will often
keep them completely in check. Where nettles have been going to
seed for a number of years it may require considerable time to free
the land because these will germinate as they are brought near the
surface by the various plowings. However, it should be kept in
mind that any perennial root system may be killed outright in one
season if it is not allowed to develop roots or stems.’’
Buffalo Bur (Solanum rostratum Dunal.).
Description Herbaceous; woody when old, somewhat hoary or
yellowish, 8 in.-2 ft. high, covered with copious stellate pubescence ;
branches and main stems, when it begins to branch, covered with
sharp yellow prickles; leaves somewhat melon-like, 1-3 times pin-
Fig. 164. Horse Nettle (Solanum carolinense).
sometimes extend 3-4 feet in the soil.
the potato.
DESCRIPTIVE MANUAL
Common in southern Iowa.
(Photographed by Colburn.)
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Fig. 164-A. Distribution of Horse Nettle.
- 285
Deep rooted perennial, roots
Flowers and berries somewhat like
286 WEED. FLORA OF IOWA
Fig. 165. Buffalo Bur (Solanum .rostratum).. Pastures, gardens, railways, ete.
‘ (Photographed by Colburn.) :
CRETE
Fig. 165-A. Distribution of Buffalo Bur.
DESCRIPTIVE MANUAL 287
aatifid, lobes roundish or obtuse and repand, covered with soft
pubescence; hairs stellate, flowers yellow, corolla gamopetalous,
about an inch in diameter, nearly regular, the sharp lobes of the
corolla broadly ovate; stamens 5, declined, anthers tapering up-
ward, linear-lanceolate, dissimilar, the lowest much larger and
longer, with an incurved beak, hence the technical name rostratum ;
style much declined; fruit a berry but enclosed by the close-fitting
or prickly calyx, which has suggested the common name buffalo
bur; pedicels in fruit erect; seeds thick, irregular, round or some-
what longer than broad, wrinkled, showing numerous small pits
and surrounded by a gelatinous substance.
Fig. 165-B. Buffalo Bur (Solanum rostratum); a, general sketch showing
habit of plant; b, flower; d, seed natural size; c, seed enlarged.
(After Dewey, U. S. Dept. of Agr.)
288 WEED FLORA OF IOWA
Distribution.—Buffalo bur is originally native of the plains
region, between the Missouri river and the Rocky mountains. It
has spread eastward in the northern states and extensively in
' Texas, Mississippi and Arkansas. It is not infrequent from
Tennessee to New York. It has been found in Germany. ‘This
weed is widely scattered in small patches in many parts of the
state of Iowa.
Extermination—Inasmuch as this weed is an annual, it can be
easily exterminated by cutting off the young plants below the
ground and this should be done before the pods are formed. If
plants are older they should be cut off and burned.
The Iowa Homestead says concerning this weed: ‘‘On account
of the fact that the buffalo bur is an annual its destruction or
eradication is simply a matter of preventing it from maturing its
seed. Corn fields that are badly infested may need but little at-
tention after the regular time for laying the corn by, for which
purpose the one horse cultivator may be pressed -into use.’’
Dr. C. E. Bessey in Breeder’s Gazette recommends as follows:
‘“To get rid of it the best thing is first not to allow the weed to
get a good start, as its deep roots are hard to get out. Second, if it
has a good start, the plants must be cut down frequently so as to
prevent their seeding and thus starting new plants. In the third
place, the deep roots must be killed by digging out or by smother-
ing. This can be done by using a very heavy dense crop like some
of the sorghums, or by covering the patch with wet manure. Of
course constant stirring of the soil will kill them. It will pay to
watch this weed wherever it appears.’’
Purple Thorn-apple, Purple Stramonium, or Jimson Weed
(Datura tatula L.).
Description—A glabrous annual from a few inches to 5 feet
high ; stem purplish ; leaves thin, ovate, acute or acuminate; flowers
consisting of a 5-toothed calyx and a 5-lobed funnel form corolla,
with stamens included; filiform filaments inserted below the mid-
dle of the corolla tube; capsule globular, prickly, 4-valved and
2-celled. The common thorn-apple (Datura stramonium) is a glab-
rous annual with green stem, sinuate-toothed leaves and white
corolla.
DESCRIPTIVE MANUAL 289
Fig. 166. Purple Jimson Weed (Datura tatula). Barnyards, roadsides.
(Photographed by Colburn.)
er ee ————
a Mitchell
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Fig. 166-A. Distribution of Jimson Weed.
19
290 ; WEED FLORA OF IOWA
Distribution.—Both species abundant in field and waste places
from New England to North Dakota and Texas and naturalized
from Europe; originally native to India.
Fig. 166-B. Jimson Weed or Thorn-apple (Datura stramonium). a, flowering
spray; b, fruiting capsule.
(U. S. Dept. Agr.)
RASS
PACE
th
ny fis ml Sie val
ee
Fig. 166-C. Distribution of Thorn-apple.
DESCRIPTIVE MANUAL 291
Extermination.—Both of the jimson weeds are easily destroyed
by cultivation. They produce an enormous amount of seed which
probably retains its vitality for a considerable length of time. How
long, however, has not been determined.
SCROPHULARIACEAH, MULLEIN FAMILY.
Snapdragon and Simpson honey plant belong to this family.
Mullein (Verbascum thapsus L.).
Description.—A tall, densely woolly annual or biennial herb 2-6
ft. high; leaves oblong, thick, covered with branched hairs, the
basal leaves margined, petioled; flowers in long dense spikes; corolla
Fig. 167. Mullein (Verbascum thapsus). A hairy biennial, common road-
side weed; gravel hills along Mississippi river, old fields.
(Photographed by Colburn.)
292 WEED FLORA OF IOWA
Seem
oe
Figure 167A Figure 167B
Fig. 167-A. Glandular trichome from viscid pod of Moth Mullein (Verbascum
blattaria).
(Drawing L. H. Pammel and Charlotte M. King.)
Fig. 167-B. Distribution of Mullein.
rotate, yellow or rarely white; stamens unequal, the 3 upper
shorter, woolly, with short anthers; the 2 lower smooth with larger
anthers; trichomes many-celled, branched with central axis.
Distribution—From Nova Scotia west across the continent.
Southwest to Missouri and Kansas and Utah. Common in waste
places, especially in eastern Iowa.
Extermination.—Mullein is easily destroyed by cutting the plant
off a few inches below the surface of the ground. This may be
done in the autumn after the appearance of the root leaves, or in
the second season when the plant shoots up.
Toadflax (Linarva vulgaris Hill.).
4
Description.—Persistent, deep-rooted perennial, 114-214 ft. high,
with erect, slender stem; leaves smooth, sessile, crowded, alternate-
linear, somewhat fieshy ; flowers in racemes, showy, pale yellow and
orange lips; corolla 2-lobed, closed; seeds small, dark brown to
black and roughened; flowers from June to October.
Distribution.—Introduced from Europe first as a cultivated
plant from whence it has spread to roadsides, meadows, and waste
places. Somewhat widely distributed in this state, but particularly
common in Clayton, Allamakee and Winneshiek counties; local in
Story county.
DESCRIPTIVE MANUAL 293
Roadsides, gardens,
Fig. 168.. Toadflax or Butter and Eggs (Linaria vulgaris).
etc. ier
(After Clark and Fletcher.)
294 WEED FLORA OF IOWA
Fig. 168-A. Distribution of Toadflax.
Extermination.—F letcher and Clark recommend as follows:
‘“‘Short rotation of crops with deep, thorough cultivation in spring
and fall will suppress it. Hand-pulling when the soil is wet is
effective in pasture lands that cannot be cultivated. Badly in-
fested meadows or pasture lands should be brought under cultiva-
tion by plowing in July, summer-fallowing until autumn, and
planting with hoed crop the following spring.’’
Simpson Honey Plant (Scrophularia marilandica L.).
Description—aA glabrous, somewhat glandular, pubescent peren-
nial, 3-5 ft. high; stems 4-angled; leaves thin, ovate, or ovate-lan-
ceolate, sharply serrate; flowers cymose; calyx lobes ovate, about
the length of the tube, corolla brownish purple; capsule subglob-
ular; seeds small, numerous.
Distribution—Common in woods and thickets from Maine to
the Rocky mountains. Abundant in woods and adjacent fields.
Extermination.—Simpson honey plant produces a large number
of small seeds. However, but little is known of their vitality.. The
weed is easily killed by cultivation and easily crowded out by
clover and small cereals.
The Scrophularia leporella Bicknell, is similar as regards the
foliage, the rudimentary stamen is, however, yellowish-green in-
stead of brownish-purple as in the 8. marilandica.
DESCRIPTIVE MANUAL
296
Fig. 169. Simpson Honey Plant (Scrophularia marilandica).
waste places.
(Photographed by Colburn.)
Woods and
Vwirchel eel |
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IS Buller. aN =
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ida
J
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Forrawattd mie
Fig. 169-A. Distribution of Simpson Honey Plant.
296, WEED FLORA OF IOWA
Purslane Speedwell, Neckweed (Veronica peregrina L.).
Description.—A glabrous, glandular, or nearly smooth, branch-
ing annual 4-9 in. high; leaves petioled, upper oblong, linear and
entire; floral leaves like those of the stem but reduced; flowers
axillary and solitary, white; capsule orbicular.
Distribution—A common weed in fields in Iowa and in eastern
North America from Nova Scotia southward; also west to Texas and
the Pacific coast. Found in South America and in Europe; cos-
mopolitan. ;
Extermination.—The seeds are produced abundantly, but young
as well as older plants are easily killed by cultivation.
Vig. 170. Speedwell (Veronica peregrina). Common in gardens and fields in
early spring.
(Photographed by Quade.)
PLANTAGINACEAE, PLANTAIN FAMILY.
The family contains few plants of economic importance. The
seeds of a few species are used as medicine.
DESCRIPTIVE MANUAL - 297
Fig. 170-A. Distribution of Speedwell.
Common Plantain (Plantago major L.).
- Description. —A smooth, glabrous perennial with short root-
stocks; leaves with a long channeled petiole, ovate, oblong or oval;
spike long, linear, cylindrical, capsule circumscissile near the mid-
dle; flowers proterogynous; seed smooth, angled, reticulated : tri-
chomes short, several-celled, from a broad base..
- Distribution—Common plantain is widely distributed in North
America from the Atlantic to the Pacific. Perhaps native far
northward; probably naturalized in Iowa, It is found in every
county in the state; frequent in dooryards, fields and pastures.
Extermination.—Usually not a difficult weed to exterminate in
cultivated fields.
Clark and Fletcher recommend the following treatment: ‘‘Hoed
crops every four years will keep this weed in ‘check. Working
with a broad-shared cultivator, followed by a. harrow, to drag the
plants with their fibrous roots to the surface, is recommended for
spring cultivation. Plantain in lawns may be weeded out when
the soil is firm by forcing a small implement like a chisel, with
a half-round blade having a point like the tip of a spoon, between
the soil and the fleshy crown of the weed to a depth sufficient ‘to
break the plant away from its fibrous roots without disfiguring the
turf. northwestern and western Iowa.
(Photographed by Pammel.)
Extermination —Correspondents sending this weed frequently
refer it to Canada thistle. It occurs not only in pastures and mead-
376 WEED FLORA OF IOWA
ows, but also in corn and grain fields. It grows in patches like the
Canada thistle. These patches increase in size from year to year.
It was described as a doubtful perennial by early botanical writers
and so far as I have been able to determine, it is a perennial. It
may be exterminated by thorough cultivation, plowing well and
then following with the cultivator.
Prairie Thistle (Cirsium discolor (Muhl.) Spreng.).
Description.—Tall, branching, leafy biennial, 5-7 ft. high, with
heads larger than in Canada thistle; stem striate, slightly hirsute;
leaves radical, 12-14 in. long, deeply pinnatifid, the divisions fre-
quently divided, prickly-toothed, the upper surface smoothish, and
the lower white ; woolly single heads terminating the branches, with
Fie, 221. Prairie or Wood Thistle (Cirsiwm discolor). Common border of
woods, ete.
(Photographed by Colburn.)
DESCRIPTIVE MANUAL 377
Fig. 221A Figure 221B
Fig, 221-A. Trichomes or plant hairs of wood thistle.
Fic. 221-B. Distribution of Prairie Thistle.
purple flowers; heads 1-11% in. long: bracts of the globose involucre
somewhat suppressed, slightly arachnoid, lower bracts ovate with a
broad base and a weak prickly recurved bristle, slight dorsal ‘gland,
inner linear-lanceolate with a nearly colorless entire appendage;
flowers purple, tube of the corolla 11-12 lines long, lobes of the
corolla terminating in clavate tips; anther tips acute, filaments
pubescent; bristles of pappus plumose; achene 22 lines long,
‘smooth, upper part yellow. ee
Distribution—Common in many portions of Iowa; Marshall,
Johnson, Winnebago, Lee, Winneshiek, Allamakee, Greene, and
Emmet counties; at Keokuk, Muscatine, Ames, Cedar Rapids, Car-
roll; Des Moines, Polk City, Steamboat Rock, Mason: City, Belle
Plaine and Iowa City.
Extermination.—This field thistle should be treated like all other
biennial weeds. The flattened masses in the spring should be cut
off below the ground and none of the plants allowed to go to seed.
We have received numerous inquiries in regard to this weed from
western and northwestern Lowa.
Iowa Thistle (Curstwm towense (Pammel) Fernald).
Description.—Biennial with downy, branching stem; leaves
roughly hairy above but white-woolly beneath, oblong-ovate to nar-
rowly lanceolate, sinuate-toothed, or somewhat pinnatifid, lobes or
378 WEED FLORA OF IOWA
Fig. 222. Iowa Thistle (Cirsium iowense). Common in pastures and meadows.
(Photographed by Colburn.)
Fic. 222-A. Distribution of Iowa Thistle.
DESCRIPTIVE MANUAL 379
teeth with weak prickles; rather large heads; involucre 1-114 in.
long; bracts with broad glandular back, the inner with a some-
what attenuated colorless tip.
Distribution—Common in borders of woods and in fields. From
Iowa to South Dakota and Kansas. In Story, Emmet, Kossuth,
Marshall, Boone, Linn, Clinton, Webster and Carroll counties in
prairie meadows.
Extermination.—This biennial is readily destroyed by cutting
the plants off below the surface of the ground. When left to
flower it dies but in meadows where cut off above the surface of the
ground it acts like a perennial.
Canada Thistle (Cirsium arvense (li.) Scop.).
Description.—Smooth perennial, spreading by roots and root-
stocks, 1-3 ft. high, corymbosely branched at the top; stem smooth ;
leaves lanceolate, sessile, and deeply pinnatifid, lobes and margins
of leaf with spiny teeth; heads small, 34-1 in. high, bracts ap-
pressed, the outer with a broad base, inner narrow, all with an
acute, never spiny, tip; somewhat arachnoid flowers purple, di-
oecious; in staminate plant, flowers exserted with abortive pistils,
in pistillate less so, scarcely exceeding the bracts; tube of the
corolla 6 lines long; stamens with abortive anthers, anther tips
acute, filaments minutely pubescent; young achene pubescent; all
of the bristles of the pappus plumose; trichomes simple, long,
floccose.
Distribution —This European weed is widely distributed in Can-
ada to the Pacific coast; found in Jowa in many counties, more
common in northern counties than in the southern. It is more or
less abundant in Hardin, Pocahontas, Clinton, and Worth coun-
ties, frequently in clover meadows and in pastures.
Extermination.—The Canada thistle can be treated with sodium
arsenite. No other chemicals, so far as our experiments extend,
will entirely destroy this weed. Carbolic acid only partially de-
stroys the roots and the plants shoot up again from below the point
of injury, but by repeating the process the Canada thistle can ulti-
mately be exterminated. A good method of eradicating the weed
is to plow shallow and cultivate frequently during the summer.
The roots of the Canada thistle extend deeply down into the soil,
hence for this reason deep cultivation will be of no avail. After
380 WEED FLORA OF IOWA
Fig, 223. Canada Thistle (Cirsium arvense). Common and widely distributed
in Iowa.
(After Clark and Fletcher.)
DESCRIPTIVE MANUAL 381
Figure 223A Figure 223B
Fic. 223- A. Trichome or plant hair from leaf of Canada Thistle.
-(Drawing by Charlotte M. King.)
Fic. 223-B. Distribution of Canada Thistle.
plowing, the soil should be dragged and the roots exposed to the
sun and removed, when possible. It may be necessary to run
over the field with a hoe to cut off the stray plants which appear.
This method was tried on a patch several years ago and no
Canada thistles have since made their appearance in this place.
Various crops, such as clover and sorghum, are said to be ef-
fective in subduing the thistles.
Of the various chemicals which have been used to exterminate
Canada thistles none are more effective than sodium arsenite. It
is apphed at the rate of 114-2 pounds to 52 gallows of water.
Carbolic acid at the rate of one part to one part water destroys
the root when it comes in contact with the mixture, and for a little
distance beyond. This is not an effective method, as the roots
sprout out from below.
In response to circulars of inquiry sent out by the Iowa Experi-
ment Station, the majority of correspondents recommend shallow
plowing, disking, and harrowing; and continuing cultivation and
hoeing as long as the thistles make their appearance. Some report
successful treatment with galt when scattered thickly about the
thistles, especially if cattle or sheep are given access to it. Some
report success with carbolic acid when it is applied directly to the
stem. Tarred paper in a few cases gave success, as did also the
method where the thistle was covered thickly with straw or ma-
nure. The depth of covering was not, however, given.
382 WEED FLORA OF IOWA
Clark and Fletcher recommend the following treatment:
‘“The chief safeguard against the Canada thistle and all similar
deep-rooted perennials is undoubtedly a regular short rotation. A
three-year rotation, including two cuttings of early red clover for
the first year, followed by a deep fall plowing for hoed crops with
clean cultivation, and a cereal crop for the third year, will sup-
press it.”’
A correspondent in The Prairie Farmer on the resisting quali-
ties of Canada thistle says: ‘‘I have been debating in my mind
and endeavoring to determine whether or not root-stocks or por-
tions thereof have to some extent the hibernating qualities of the
seed. For instance, take two seeds of the cocklebur—one hiber-
nates for one season and the other for two seasons, with growth
always present. Now the question is may not a Canada thistle
with its root-stock or a portion of it lie dormant for a season or
more? If this be true, then some of the best known methods of
extermination are useless.’’
To this Prof. R. A. Moore says: ‘‘In regard to Canada thistle
roots hibernating and retaining their vitality for several years,
will say, that I think your correspondent’s version seems reason-
able, and it is quite conclusive from this fact that the eradication
of the pest is all the more difficult. It seems that many of the
seeds and plants are given this power of remaining dormant when
subjected to adverse conditions. In the lower order of plants,
many of the species of bacteria when subjected to adverse environ-
ments are transformed into resistant spores and will not vegetate
until the conditions are favorable.’’
Wallace’s Farmer says concerning its eradication: ‘‘We
believe if we had a quarter of an acre of Canada thistles
we would let them alone until August, when the thistle will put
forth its utmost efforts to produce seed. While the thistles are in
full blossom we would mow them, rake them up and burn them,
and then plow the ground about eight inches deep, throwing the
furrow flat. Letting them put forth their full strength to produce
seed and thwarting that by mowing and burning would weaken the
roots materially. Then by plowing them under eight inches deep,
if possible, you would attack them at their weakest point.
DESCRIPTIVE MANUAL 383
Knapweed (Centaurea solstitcalis L.).
Description.—Annual erect, branched, cottony stem; lower leaves’
lyrate, deeply pinnatifid, upper leaves, linear, entire or nearly so,
decurrent wings on the stem; outer bracts, with long spreading
spines, those at base few and smaller; flowers yellow, with soft
pappus.
Itc. 224. Knapweed, Star Thistle (Centaurea solstitialis). Im alfalfa fields.
; (Mich. Agr. Exp. Sta.)
384 WEED FLORA OF IOWA
Fic. 224-A., Distribution of Knapweed.
Distribution —Massachusetts to Ontario and Iowa; introduced
with alfalfa seed into other western states.
Extermination.—This annual weed has been introduced largely
with alfalfa seed. Sow clean seed. Use seed coming from the
Rocky mountains or Kansas where the weed is not common. It is
an extremely objectionable weed because of ane spiny heads. It
is easily killed by cultivation.
Chicory or Succory (Cichoriwm intybus L.).
Description—aA branching perennial with deep roots, alternate
leaves; blue flowers, or sometimes pink or purple; basal leaves
spreading on the ground; stem leaves oblong or lanceolate,
partly clasping.
Distribution.—It is common along roadsides in fields and waste
places from New England to Canada to Nebraska, especially com-
mon where chicory has been cultivated; it has become a trouble-
some weed in Wisconsin and Minnesota. It is allied to endive, cul-
tivated as a salad plant.
Extermination.—Chicory is not difficult to destroy where ro-
tation of crops is practiced. Though a perennial, the roots are
easily killed by repeated cultivation.
Clark and Fletcher recommend the following treatment:
‘‘A short rotation of crops will soon suppress it. Chicory is not
often seen in good farming districts except as a wayside weed.
Individual plants may be destroyed by close cutting and applying
salt to the root in hot, dry weather.’’
DESCRIPTIVE MANUAL | 385,
Piate 64 ’
CHIGORY - ay
(Cichoriam infybus- 4)
Fic. 225. Chicory (Cichorium intybus). Im clover and alfalfa fields, some-
times in waste places.
(After Clark and Fletcher.)
25
386 WEED FLORA OF IOWA
WoC a owe
TER SE,
EEE RS, SSR N
VT STS SRS sy ae
UU hkl RSS
Fic. 225-A. Distribution of Chicory.
Dandelion (Taraxacum officinale Weber).
Description.—A smooth, or at first pubescent, biennial or per-
ennial; the many-flowered head borne on a slender hollow scape;
root leaves pinnatifid or runcinate; involucre double, the outer of
Fic. 226. Dandelion (Taraxacum officinale). Long root, sometimes to a depth
of three and one-half feet in the soil.
(Photographed by Gardner.)
DESCRIPTIVE MANUAL tues 387
Fig. 226-A. Distribution of Dandelion.
short scales, the inner of long, linear, erect scales in a single row;
after flowering the inner involucre closes, the fruit is ripened
close to the ground, and when ripe the hollow scape elongates and
the whole involucre is reflexed permitting the wind to scatter the
“seeds ;’’ “‘seeds’’ oblong, long-beaked, the beak being 2 or 3 times
as long as the remainder of the achene, bearing at the end the
pappus. j
Fig. 226-B. A patch of Dandelion in a lawn, early in June.
(Photographed by Charlotte M. King.)
388 WEED FLORA OF IOWA
Distribution—The dandelion is cosmopolitan. It is quite as
common in Europe as in the United States, being common and
abundant at high elevations, as in the Rocky mountains. Found
everywhere in lowa on lawns and pastures.
Fic. 227. Common Dandelion (Taraxacum officinale). A weed common in
lawns, pastures, etc.
(Photographed by Colburn.)
Extermination.—The dandelions are not difficult to exterminate
in cultivated fields but in garden crops it is more difficult to do
so, especially in strawberry beds. As the dandelions are perennial
herbs, seed formation should be prevented. Where they occur in
small patches a spud may be used successfully. Where they are
abundant in lawns it is only necessary to keep the lawn closely
cropped and dig them up with a small spud to prevent seeding.
Blue grass and clover, especially the latter, will crowd them out.
It is rare that dandelions give trouble after the middle of June.
DESCRIPTIVE MANUAL 389
W
RAN 7
Oi?
S NS Ne
ny AR
Fie. 227-A. Common Dandelion (Taraxacum officinale). 1, head; 2, single
flower; 3, achene; 4, receptacle and seed with pappus.
Experiments have been made with herbicides and the one most
commonly used is iron sulphate which is usually applied at the
rate of 100 pounds to one barrel of water. The weed where prop-
erly sprayed will be destroyed, but owing to the fact that the dan-
delion possesses a long perennial root, sometimes 4 feet long, it
will sprout again. The spraying must be kept up until fall.
Chemical Composition.—According to the report of the Bussey
Institution the chemical composition of the dandelion is as follows:
FRESH OR AIR DRY MATERIAL.
. Z Nitrogen free
Water | Ash | Protein | Fiber | Extract Fat
85.54 | 1.99 | 2.81 | 1.52 745 | 0.69
WATER FREE SUBSTANCE.
| 13.8 | 19.4 | 10.5 51.5 4.8
*Bull. 1877. Compiled by Jenkins and Winton; Bull. 11, Off. Exp. Sta., U. S.
Dept. Agr.
390 WEED FLORA OF IOWA
Red-seeded Dandelion (Taraxacum erythrospermum Andyz.).
Description—A perennial weed with long root; leaves deeply
runcinate-pinnatifid or pinnately divided into narrow segments;
heads somewhat smaller than in common dandelion, sulphur yel-
low; involucre glaucous, the inner bracts corniculate, appendaged
at tip; the outer short, spreading or ascending; achene reddish,
tuberculate above.
Distribution.—Red-seeded dandelion is a much more recent in-
troduction than common dandelion. It occurs from Maine to
Kansas. Naturalized from Europe, in similar situations to com-
mon dandelion in Iowa; sometimes less abundant and sometimes
more abundant than the latter.
Extermination—May be exterminated in the same way as the
common dandelion.
Fic. 228. Red-seeded dandelion (Taraxacum erythrospermum). Common in
lawns.
(Photographed by Colburn.)
Clark and Fletcher recommend the following treatment:
‘‘It is important to prevent dandelions from seeding in lands
adjacent to lawns. Though entailing much labor, the most satis-
factory way to deal with them, when deeply rooted in lawns, is to
loosen the soil with a digging fork and pull them up. The use of
DESCRIPTIVE MANUAL 391
the fork may not be necessary in some wet and soft soils. The ap-
plication of kerosene to the crown of the plant, in the centre of
the rosette of leaves, is recommended. Sulphate of ammonia or
sulphate of iron in excess is also recommended. A small table-
spoonful of salt applied in the morning of a hot day, when the soil
is dry, will kill them.
Annual Sow-thistle (Sonchus oleraceus L.).
Description.—Annual, succulent herb with leafy, smooth stems,
and pale yellow flowers in corymbose or umbellate clusters; leaves
of stem dentate, runcinate-pinnatifid, terminal with a large seg-
ment; heads numerous; blossoms in late summer and fall.
Distribution.—This weed is common in fields and waste places
throughout North America, especially in the north. It is common
in Europe and also occurs in Mexico and South America.
Extermination.—Sow thistle is easily exterminated by cultiva-
tion. It can also be exterminated by the use of iron sulphate at the
rate of 100 pounds to a barrel of water; where it is abundant it
may be necessary to make two or three applications.
Clark and Fletcher recommend as follows: ‘‘Prevent them
from seeding in waste places by cleaning them up and seeding them
to permanent, vigorous grasses. This annual weed, with its rela-
tively small, pale yellow flowers, when compared with perennial
species is not difficult to control by ordinary methods of cultivation
and alternation of crops. Sheep, if sufficient in numbers, will pre-
vent sow thistles from seeding in pasture lands.’’
The Iowa Homestead says concerning its eradication: ‘‘We
have seen the sow thistle take complete possession of a soil,
growing so thickly that other crops were entirely choked out. Nec-
essarily the best way to destroy it is to cultivate freely. If it
makes its appearance in stubble ground we would advise plowing
as early as possible after harvest and the cultivation of surface at
intervals during the late summer and fall in order to keep the
thistles below the ground.
392 WEED FLORA OF IOWA
Fic. 229. Common Sow Thistle (Sonchus oleraceus). Waste places.
(After Clark and Fletcher.)
DESCRIPTIVE MANUAL 393
Fic. 229-A. Distribution of Annual Sow Thistle.
Sow Thistle (Sonchus asper (.) Hill). :
Description.—Like the preceding species except that stem leaves
are less divided and more spiny-toothed, with auricles of the
Fic, 230. Sow Thistle (Sonchus aspen), Waste places, yellow flowers and milky
juice.
(Photographed by Colburn.)
394 WEED FLORA OF IOWA
oo
asi aes
Fic. 230-A. Distribution of Sow Thistle.
clasping base rounded; achenes 3-nerved on each side and
margined, smooth.
Distribution—Common with the preceding species, in waste
places.
Extermination—This annual is not difficult to exterminate by
giving thorough cultivation.
Perennial Sow Thistle (Sonchus arvensis L.).
Description.—A perennial with creeping root-stock, and milky
juice; leaves runcinate, pinnatifid and spiny toothed, heart-shaped
base; flowers yellow; peduncle and involucre bristly; achenes ob-
compressed, wrinkled on the ribs.
Distribution—Common from Nova Scotia west to Saskatchewan,
North Dakota, Minnesota, occasional in Iowa to New Jersey and
New England. :
Extermination.—A most difficult weed to exterminate and should
be treated like the Canada thistle. Summer fallow with frequent
cultivation is the only successful method. Clark and Fletcher of
Canada, recommend the following:
“Small patches may be eradicated by digging out the roots as
thoroughly as possible and destroying them. This may have to be
done several times during a season. Great care must be taken not
to distribute pieces of the rootstocks over the fields by harrows or
other implements. To exterminate Perennial Sow Thistle, some
system must be adopted which will prevent the development: of
leaves for a period sufficiently long to kill the roots by smothering
DESCRIPTIVE MANUAL 395
Fic. 231. Perennial Sow Thistle (Sonchus arvensis). Plants with bright yel-
low flowers, milky juice. Not common in Iowa. A difficult weed to exter-
minate.
(Photographed by Colburn.)
Fic. 231-A. Distribution of Perennial Sow Thistle.
396 WEED FLORA OF IOWA
them. When a field is badly infested it requires special treatment
for a season and close’ attention for a number of years. One of
the most effective methods is to plow lightly immediately after
the hay or grain crop is removed and follow with frequent use of
a broad-shared cultivator. Late in the fall plow again, somewhat
deeper. In the spring give frequent cultivation, so as to prevent
the development of any leaves and thus weaken the roots to the
greatest possible extent. About the middle of June or first of
July sow rape in drills at the rate of about 114 lbs. per acre.
Cultivate between the drills as soon as possible and repeat at short
intervals until the rape completely covers the ground. Some hand
hoeing may be necessary to keep all the thistles down. This should
pretty well exterminate the pest but if some plants still remain
when the rape is cut or pastured off, the field may be fall plowed
and put into hoed crop the next season, when special attention can
be given to any small patches that may appear. Buckwheat is
sometimes used instead of rape for a smothering crop.’’
Prickly Lettuce (Lactuca scariola L. var. integrata Gren. & Godr.).
Description.—Tall, erect herbs, glaucous, green, 2-5 ft. high,
simple or branched except the lower part of stem which has stiff
bristles; leaves glaucous, green, smooth except the midrib which
is beset with weak prickles lanceolate to oblong in outline, with
spinulose, denticulate margins, occasionally sinuate-toothed; flow-
ers pale yellow. The leaves of ZL. scariola are pinnatifid and more
prickly ; trichomes multicellular.
Distribution.—Prickly lettuce was introduced into Massachu-
setts about 1863 from Europe. It is quite widely distributed in
northern Africa and Europe and has become frequent throughout
the northern Mississippi valley to the Pacific coast. It is com-
mon everywhere in Iowa particularly along roadsides, highways
and in gardens. The ZL. scartola is becoming more frequent in
Iowa, in Ames, Des Moines, Boone, etc.
Extermination—The weed is easily exterminated from culti-
vated fields and in waste places by cutting off young plants below
the ground. Where the stem is cut off below the surface of the
ground it will give no trouble, but in meadows and lawns where
the plants are cut off above the ground the weed will continually
reappear, producing from 3-6 branches. The following excellent
suggestions are made by L. H. Dewey:
DESCRIPTIVE MANUAL 397
a PRICKLY LETTUCE
fuCR SEGMIGI G fier rica:
A Ge
Fic. 232. Prickly Lettuce (Lactuca scariola var. integrata). Common road-
sides and gardens.
(After Clark and Fletcher.)
398 WEED FLORA OF IOWA
SetMERMneS
e BUYS
ee iM
ase NE Ane
= aa
‘et
Figure 232A Figure 232B
Fic. 232-A. Bristles on Prickly Lettuce (integrata).
(Drawing by Charlotte M. King.)
Fic, 232-B. Distribution of Prickly Lettuce.
‘“Sheep and sometimes cattle will eat the young prickly lettuce,
and in some localities their services have been found very effective
in keeping it down, especially in recently cleared land where culti-
vation is impossible. Repeatedly mowing the plants as they first
begin to blossom will prevent seeding and eventually subdue them.
Thorough cultivation with a hoed crop, by means of which the
seed in the soil may be induced to germinate, will be found most
effective. The plowing should be shallow so as not to bury the
seeds too deep. Under no circumstances should the mature seed-
bearing plants be plowed under, as that would only fill the soil
Fic. 232-C. Distribution of Prickly Lettuce (Lactuca scariola).
DESCRIPTIVE MANUAL 399
with seeds buried at different depths to be brought under condi-
tions favorable for germination at intervals for several years. Ma-
ture plants should be mowed and burned before plowing. The
seed appears as an impurity in clover, millet and the heavier grass
seeds, and the plant is doubtless most frequently introduced by
this means. As the seeds may be carried a long distance by the
wind, the plants must be cleared out of the fence rows, waste land
and roadsides.”’
Clark and Fletcher recommend as follows: ‘‘The seed is
short-lived and if the plant is kept closely cut and prevented
from seeding in waste places for two or three years it will soon
disappear from cultivated areas. Clean waste lands and seed
to permanent vigorous grasses. Ordinary methods of cultiva-
tion will suppress it in the fields.’’
Wild Lettuce (Lactuca canadensis L.).
DescriptionStem leafy, glabrous or nearly so, glaucous; lower
leaves sinuate, pinnatifid, upper entire; heads numerous, in a
rather long, open panicle; flowers yellow.
Distribution.—Nova Scotia to Ontario, Ohio and westward; fre-
quently found in Iowa. ;
Extermination This perennial is not difficult to destroy by
cultivation. .
400 WEED FLORA OF IOWA
Fic. 233. Wild or Canadian Lettuce (Lactuca canadensis). Fields, roadsides
and meadows.
(Photographed by Quade.)
DESCRIPTIVE MANUAL 401
Fic, 233-A. Wild or Canadian Lettuce (Lactuca canadensis). Plant with milky
juice and yellow flowers.
(Photographed by Quade. )
Fic. 233-B. Distribution of Wild Lettuce.
26
402 WEED FLORA OF IOWA
Blue Lettuce (Hactuca pulchella (Pursh.) DC.).
Description.—Perennial plant, deep-rooted, pale or glaucous;
stem simple, about 1 foot high; leaves sessile, oblong or linear-
lanceolate, glabrous, entire, or lower leaves somewhat pinnatifid;
racemose heads large, erect; peduncles with scaly bracts; bracts
of involucre imbricated in 3-4 ranks; flowers blue.
Distribution.—Northern Michigan and Ontario southward; re-
ported from several localities in Iowa.
Extermination.—Prevent from distributing seed by continued
cutting before flowering. If it becomes established in a field, try
thorough summer fallow with deep cultivation so as to check
growth of long rootstocks.
Fig. 234. Blue Lettuce (Lactuca pulchella). Blue flowered lettuce. Plant with
milky juice. Common in western Iowa.
(Photographed by Quade.)
DESCRIPTIVE MANUAL 403
Fic. 234-A. Distribution of Blue Lettuce.
Rushlike Lygodesmia (Lygodesmia juncea (Pursh.) D. Don.).
Description —A tufted, smooth, frequently glaucous perennial a
foot or more high, coming from a thick woody root, with copious
Fic. 235. Lygodesmia or Skeleton Weed (Lygodesmia juncea). A deep rooted
perennial with a yellowish milky juice.
(Photographed by Colburn.)
404 WEED FLORA OF IOWA
Fie. 235-A. Distribution of Lygodesmia.
yellowish juice; lower leaves rigid, linear-lanceolate, small, entire,
the upper scalelike; flowers purple in erect heads; achenes nar-
row-ribbed, pappus light brown. This weed is sometimes called
skeleton weed.
Distribution.—This weed is common from Missouri river to west-
ern Montana and east to St. Croix river in Wisconsin. A some-
what troublesome weed in northwestern Iowa; easily recognized by
the yellowish juice and rushlike stems.
Lixtermination.—This plant produces a long root which enables
the plant to spread rapidly. It also produces a large number of
““seeds.’? Where the weed is common, plough the field after
harvest and disk the plants. It is a good plan to follow up with
a hoe, cutting off the plants.
CHAPTER II.
THE GENERAL CHARACTERS
OF SEEDS
By
L. H. PAMMEL
and
CHARLOTTE M. KING
CHAPTER II.
CYPERACEAE, SEDGE FAMILY.
Sedge (Carex vulpinoidea Mx.).
Achene enclosed by an utricle called the perigynium, hardly 3-
angled, somewhat flattened, tipped by lanceolate 2-toothed beak,
the persistent base of the flower-style; achene flask-shaped, about
Figure 236A
Figure 236B
Fic. 236. Forms of Sedges. a, Hleocharis palustris; b, Carex vulpinoidea.
(After Gray.)
one-sixteenth of an inch in length, light brown; surface incon-
spicuously nerved; whitish, projecting scar.
Spike Rush (Eleocharis palustris R. Br.).
Achenes slightly flattened, somewhat lenticular, with 2 or 3 ob-
tuse angles one-twelfth to one-tenth in. long, brown, smooth, shin-
ing, minutely cross-striated ; seed with persistent tubercle from tip ;
tubercle conical, triangular, constricted; bristles pale, longer than
408 WEED FLORA OF IOWA
Fic. 237. Achenes, “seeds,’’ of common forms of Sedges (Carer).
(After Hillman, Bull. Nevada Agr. Exp. Sta.)
achene; seed may appear with or without tubercle and bristles.
Seed occasionally found in seed of alsike and red clover from wet
erounds.
GRAMINEAH, GRASS FAMILY.
Johnson Grass (Sorghum halepense (li.) Pers.).
Sessile spikelet broadly lanceolate, acute, 4-6 mm.* long, be-
coming dark at maturity ; callus small, obtuse, shortly and sparsely
barbate; first glume coriaceous, slightly pubescent on the flattened
back, 5-7 nerved; second similar, equal to first, with hyaline, ciliate,
Fic. 238. Spikelet of Johnson Grass (Sorghum halepense).
(Drawn by Charlotte M. King.)
inflexed margins; the third glume shorter, membranous, faintly
2-nerved, with ciliate, infolded margins; fourth glume broad, ob-
tuse, shorter than second, 2-lobed at apex, ciliate, awned; awn
10-16 mm. long; palea shorter than glumes, without nerves, ciliate.
Smooth Crab Grass (Digitaria humifusa Pers.).
Spikelets lanceolate or elliptical, one-twelfth in. in length, acut-
ish; glumes usually present, first glume wanting, sometimes rudi-
mentary, 3-nerved; the first and second, hairy on the margins;
*1 mm. = 0.0394 inch, or nearly one-twenty-fifth inch.
THE GHNHRAL CHARACTERS OF SEEDS 409
Fig. 239. Seeds of Smooth Crab Grass (Digitaria humifusa). A and B, spike-
lets; A showing the second glume, B showing the third glume. C, D and #,
florets; D, bearing a portion of the second glume, H, the inner face, showing
the edges of the flowering glume. F, a spikelet of Digitaria filiformis, show-
ing the shorter second glume. G, the natural size of both of these species.
(After Hillman, Bull. Nevada Agr. Exp. Sta.)
the third, 7-nerved; the fourth, dark purplish brown. Occurrence
very frequent in alfalfa clovers and commercial grass seed.
Crab Grass (Digitaria sanguinalis (L.) Scop.).
Spikelets one-seventh in. in length with usually persistent scale-
like glumes, lanceolate, pedicellate; second glume usually ciliate
on margins, short; fourth glume silky-villous along marginal nerves,
5-nerved, color pale. Frequently occurs in red and alsike clover,
as well as in timothy.
FF
a
co fe He
Fig. 240B Figure 240C
Fic. 240. Common Crab Grass (Digitaria sanguinalis). A, an enlarged view
of Crab Grass. B, with small glume attached. C. A, spikelets showing
the second glume, floret, and edges of the third glume. B, the opposite
face, showing the minute first glume and third glume. D and H, the two
faces of the floret. F, seeds, natural size.
(A and B, Drawings by C. M. King; C, after Hillman, Bull. Nevada Agr.
Exp. Sta.)
410 WEED FLORA OF IOWA
Tickle or Hair Grass (Panicum capillare L.).
Spikelets small, ovate or acute, one-fifteenth to one-twelfth in.
long, acuminate-pointed, smooth, shining; sterile glumes usually
absent, when present not shining; first glume 1-3-nerved, obtuse to
Figure 241A Figure 241A Figure 241B
Fic. 241. A. Tickle or Hair Grass (Panicum capillare)., At the left a spikelet
opened, at the right various views.
Fig. 365A
i!
1
\
.
Fig. 3650
Fic. 365. Achenial hairs of Beggar-ticks. A. Bidens frondosa. B. Bidens
cernua. C. Bidens aristosa.
(Drawings by Mary A. Nichols.)
Sneezeweed (Helenium autumnale L.).
Achenes straw-colored, with several longitudinal ribs, length 1
mm., breadth 0.3 mm. at apex, toward which the achene widens;
surface bears scattered appressed hairs; pappus several chaffy
points on margin of truncate apex.
Fetid Marigold (Dyssodia papposa (Vent.) Hitche.).
Achene slender, 4-angled; length 3 mm., width at truncate apex
.75 ram.; black, with numerous, scattered, appressed black hairs;
pappus a row of chaffy scales, dividing into numerous, rough,
bristly hairs; 3 mm. long. According to Mr. Fracker, the achenial
hairs are simple and duplex, the tip in duplex hairs deeply cleft.
THE GENERAL CHARACTERS OF SEEDS 491
Fig. 366A Fig. 366B Fig. 366C
Fic. 366. Seeds and achenial hairs of Sneezeweed and Fetid Marigold.’ A.
Sneezeweed (Helenium autumnale). B. Fetid Marigold (Dyssodia papposa).
C. Achenial hairs of Fetid Marigold.
(A and B, drawings by Charlotte M. King; C, from drawing by Mary A. Nichols.)
Yarrow (Achillea millefolium L.).
Achenes one-twelfth to one-tenth in. long, oblong to obovate,
somewhat compressed; light on the margin, the remainder some-
what brownish; sometimes slightly curved, base with prominent scar
with slightly raised border; apex larger with a notch in the center
‘and a projecting knob; surface of the achene marked with fine
lines ; pappus absent.
A
Fig. 367A Fig. 367B
Fic. 367. Seeds of Yarrow and Mayweed.! A, Yarrow (Achillea millefolium) ; a
seeds (achenes) in side view, the two at the left showing the minute, cir-
cular sear; b, group showing the natural size.
B. Mayweed (Anthemis cotula); a, a group of seeds showing the prevailing
forms; b, a group showing the natural size.
(After Hillman, Bull. Nev. Agr. Exp. Sta.)
Mayweed (Anthemis cotula L.).
Achenes one-twentieth to one-sixteenth in. long, oblong with
preminent tubercled ribs, or occasionally smoothish curved, the base
tipped with smooth nipple-like projections; pappus absent; straw-
colored to light brown; bearing a projection scar; base with round,
light-colored sear. Common in clover and grass seeds.
492 WEED FLORA OF IOWA
Ox-eye Daisy (Chrysanthemum leucanthemum L.).
Achenes flattened, club-shaped, straight or slightly curved, one-
twentieth to one-tenth in. long, oblong; angles white, with brown
interstices ; 5-10-ribbed ; small scar at basal end; pappus wanting.
Fic. 368. Seeds of Ox-eye Daisy (Chrysanthemum leucanthemum). A, pre-
vailing forms of seeds (achenes); B, one in cross section; C, a group
showing the natural size. ‘
(After Hillman, Bull. Nev. Agr. Exp. Sta.)
Wormwood (Artemisia biennis Willd.).
Achenes brown, smooth, from 3-4 flattened faces, angled between
longitudinally ; length .£8 mm., width .3 mm., broader at apex than
at base.
2 x a
. oe ~
~ ~ eo 4 =
.
. a 4
b b
Fig. 369A Fig. 369B
Fic. 369. Seeds of Wormwood and Fireweed. A. Wormwood (Artemisia
biennis) ; a, achenes, b, natural size.
B. Fireweed (Hrechtites hieracifolia) ; a, achenes, b, natural size.
(After Hillman, Bull. Ney. Agr. Exp. Sta.)
Fireweed (Hrechtites hieractfolia (L.) Raf.).
Achene linear-oblong, straight, or curved, prominently striate,
pubescent, beakless, one-sixth in. in length; upper end with a white
ring, within the ring a slight depression; scar at the lower end with
whitish ring, and a small depressed opening; pappus of numerous
white soft, capillary bristles.
THE GENERAL CHARACTERS OF SEEDS 493
Indian Plantain (Cacalia tuberosa Nutt.).
Achenes oblong, straight, or slightly curved, one-fifth in. in
length; brown; prominently ribbed, the ribs minutely roughened ;
the apex of the seed with a slightly projecting rim or border to
which the pappus is attached; the base with a circular ring; pappus
with numerous fine, white, capillary bristles.
Fig. 370A Fig. 370B
Fic. 370. Seeds of Indian Plantain and Groundsel. A. Indian Plantain (Cacalia
tuberosa). B. Groundsel (Senecio vulgaris).
(Drawings by Charlotte M. King.)
Groundsel (Senecio vulgaris L.).
Achenes teretish or those of marginal flowers compressed, narrow,
eylindrical; 5 or 10-ribbed, pubescent; one-half in. long; upper
part expanded, extending beyond narrow portion of upper part of
achene; lower portion with a depression; color reddish; pappus of
fine, white, capillary bristles.
Burdock (Arctium lappa L.).
Achenes 3-5-ridged, upper portion truncate, one-fifth to one-
fourth in. long, compressed or oblong, nearly straight to slightly
eurved, 3-angled; surface mottled in appearance, due to the small
serrulate scales with projecting tips of ridges beyond the border;
scar surrounded by a circular lighter colored area; scar at base
lighter in color; pappus of numerous short scales. In commercial
seeds, occasionally.
494 WEED FLORA OF IOWA
74
Fic. 871. Seeds of Burdock (Arctium lappa). a, a side view of one of the inner
achenes of a bur; b, showing the inner surface of a curved, outer achene,
and exhibiting the character of the apex, both enlarged; c, a group show-
ing natural size.
(After Hillman, Bull. Nev. Agr. Exp. Sta.)
Tall Thistle (Cirsium altissimum Willd.).
Achenes lanceolate-obovate, tapering toward lower end, and some-
what narrowed toward the apex, wider in the middle, one-eighth in.
in length; width one-twelfth in.; dull brown or grayish excepting
light colored ring at upper end; numerous fine ridges; apex con-
cave, with the remnant of corolla tube projecting from the center;
color uniform; not marked by light and dark areas as the bull
thistle.
Fig. 372A Fig. 373B
Fic. 372, Seeds of Thistles. A. Different views of Canada Thistle (Cirsium
arvense). B. Bull Thistle (Cirsium lanceolatum).
(Drawings by Charlotte M. King.)
Canada Thistle (Cirsium arvense (L.) Scop.).
Achene lanceolate, narrowed at lower end, tapering from some-
what thickened top, one-twelfth to one-eighth in. long; the eup-
shaped top with a projecting conical portion, straight or slightly
curved; marked with longitudinal dark lines or furrows; apex
with a light colored border, giving appearance of a ring. Found in
seed of small grains, clovers and grasses.
THE GENERAL CHARACTERS OF SEEDS 495
Field Thistle (Oirsiwm discolor (Muhl.) Spreng.).
Achenes obovate, inner edge nearly straight, outer curved, convex ;
one-seventh to one-sixth in. long, tapering from narrowed base
to apex, upper part longitudinally striated, slightly pigmented ;
Fic. 373. Seeds of Thistle. 3. Cirsium altissimum. 4. Cirsium discolor. 5.
Cirsium undulatum. 6. Cirsium ioense.
(Drawing by Charlotte M. King.)
grayish, upper part yellowish for one-third length of the achene.
Found in seed of alfalfa and red clover.
Towa Thistle (Cirsium ioense (Pammel) Fernald).
Achenes obovate, lanceolate, one side of seed straight, outer side
slightly convex, one-fifth to one-fourth in. long, one-twelfth to, one-
sixteenth in. in width, gradually tapering from lower end toward
upper end, prominently widened just below the apex, marked by
longitudinal striations and dark areas, upper part yellowish, promi-
nent rim glossy; apex concave, with the prominent projecting rem-
nant of flower center.
Bull Thistle (Cirsium lanceolatum (.) Hill).
Achene lanceolate, curved, tapering, in many cases somewhat
angular, one-eighth to one-sixth in. long; brownish, not darkly
striated, marked with definite grooves, upper part lighter, ringed,
also showing at center of concave apex; apex with projecting point.
Found in red clover and in alfalfa seed.
Waivy-leaved Thistle (Cirsium undulatum (Nutt.) Spreng.).
Achene in general outline lanceolate, tapering from base, inner
edge slightly convex, several prominent ridges, light brown, not
pigmented; upper part yellowish; apex with prominent rim and
prominent remnant of corolla tube; achene slightly thicker than
that of C. discolor. Found in seeds of red clover and alfalfia.
496 WEED FLORA OF IOWA
Chicory (Cichorium intybus L.). -
Achenes oblong, ribbed, 5-angled, spotted, grayish or straw-
colored, with darker spots, one-twelfth to one-eighth in. in length
apex with the base of the pappus scales extending beyond the scar;
Fic. 374. Chicory (Cichorium intybus). A, B, two views of seeds; C, seeds,
natural size.
(After Hillman, Bull. Mich. Agr. Exp. Sta.)
minutely, transversely roughened ; base of seed lighter in color, with
small depressed scar; achenes from the inner part of the flower more
slender and straight than from outer part. Found with various
commercial seeds.
Corn-flower (Centaurea cyanus L.).
Achene oblong or obovoid, compressed, one-sixth to one-fifth in.
long; smooth, shining; with inconspicuous veins or nerves; lower
part of achene oblique; ivory-white; the elliptical or somewhat cir-
cular scar at base with whitish rimmed border, depressed, made up
of soft tissue; pappus of several series of scaly bristles; brownish
in color. The achenial trichomes, according to Mr. Fracker, are
long and simple.
Barnaby’s Thistle (Centaurea solstitialis L.). -
Involucre ovoid, 1.5 cm. in diameter, with stout straw-colored
spines, widely spreading ; achene cream or pale brown after matted;
length 2 mm., scar of attachment in a notch above rounded base;
apex truncate, bearing tubercle in the center.
THE GENERAL CHARACTERS OF SEEDS 497
Fig. 375A Fig. 375B é Fig. 375C
Wie. 375. Seeds of Corn-flower and Knapweed. A. SBarnaby’s Thistle or
Knapweed (Centaurea solstitialis); a, achene with pappus, ¢c, pappus re-
moved, b and d, achenes, natural size.
B. Corn-flower (Centaurea cyanus). C. Achenial hairs of Corn-flower.
(A, after Hillman, Bull. Nev. Agr. Exp. Sta.; B, after Nobbe; C, drawing by
S. B. Fracker.)
Bristly Ox-tongue (Picris echioides L.).
Achene elliptical, narrowed at base, with projection at tip ; one-
tenth in. in length; light brownish red; wrinkled transversely, espe-
cially toward apical end. Found in seed of alfalfa and clover.
Oyster Plant, Salsify (Tragopogon porrifolius L.).
Achenes linear, terete, beaked or long, covered with scalelike
tubercles on the ribs, or merely roughened, light straw-colored or
darker pappus of numerous plumose bristles; small scar at apex,
whitish with a depression scar at base with an oval depression.
Reported as a “‘weed of alfalfa meadows.”’
Meadow Salsify (Tragopogon pratensis L.).
Achenes linear, terete, one-half in. or little more long, exclusive
of beak; scar at base, whitish, with an oval depression; beak one-
third in. long; scar at end of beak whitish, with a depression,
striate, smooth or slightly roughened, light straw-colored or darker ;
pappus of numerous soft, brownish, plumose bristles.
: 382
498 WEED FLORA OF IOWA
es. —
SS
===
SOR
ae Eo
ee ee .
aos
St
Cant saa
x
ENS
et
a
Raabe
eit
Fig. 376A Fig. 376A1 Fig. 376B Fig. 376C
Fic. 376. Seeds of Picris and Tragopogon. A and Al. Bristly Ox-tongue
(Picris echioides). B. Oyster Plant (Tragopogon porrifolius) ; a, achenes
enlarged, b, achenes natural size.
C. Meadow Salsify (Tragopogon pratensis).
(A, drawings by L. R. Collins; B, after Hillman, Bull. Mich. Agr. Exp. Sta. ;
C, drawing by C. M. King.)
Dark-seeded Dandelion (Taraxacum erythrospermum Andrz.).
Achenes one-sixth to one-fifth in. long; lance-shaped, or spindle-
shaped, 5 longitudinal ridges, upper end with rough tubercles, per-
sistent long beak about two-fifths in. long, brownish, somewhat
pointed, prominently ribbed; pappus of numerous capillary, fragile,
white bristles ; color reddish ; toothed at apex; beak and pappus both
shorter; achenes more prominently tubercled than in 7’. officinale.
Sor >,
=<
i
Fig. 377A Fig. 377B
Fic. 377. Dandelion seeds. A. Red Seeded Dandelion (Taraxacum erythros-
permum) ; a, seed enlarged, b and c, seed, natural size, c, with pappus.
B. Common Dandelion (Taraxacum officinale).- A, an enlarged view of one
of the two similar faces of an achene, in which no attempt is made to show
the minute surface-scales which are not evident under the ordinary lens.
B, a group of seeds, natural size. b, one bearing the beak and pappus. C,
a group showing common variation in the form of the achenes.
(After Hillman: A, Bull. Mich. Agr. Exp. Sta.; B, Bull. Nev. Agr. Exp. Sta.)
THE GENERAL CHARACTERS OF SHEDS 499
Dandelion (Taraxacum officinale Weber).
Achenes two-fifths in. long including persistent beak, fusiform in
shape, prominent ribs, and projecting teeth at ribs, especially at
upper end; beak four-fifths to one in. in length; achenes light gray in
color, otherwise like preceding; pappus capillary, whitish, fragile.
With grass seeds.
Field Sow Thistle (Sonchus arvensis L.).
Achenes dark reddish brown, dull, ends slightly truncate, length
2.5-3 mm., width 0.8 mm., somewhat flattened, with 4 strong ribs or
angles, between which lie smaller ridges ; numerous transverse ridges
on the ribs.
Fig. 378C
Fic. 378. Seeds of Sow Thistles. A. Field or Perennial Sow Thistle (Sonchus
arvensis) ; B, natural size, showing pappus on one achene,
B. Sonchus oleraceus, different views of achenes.
C. Sonchus asper, A and B, different views of achenes, C, achenes, natural size.
(After Hillman, Bull. Mich. Agr. Exp. Sta.)
Spiny Sow Thistle (Sonchus asper Vill.).
Achenes broadly oblong or lance-shaped, similar faces, many-
ribbed, one-tenth in. long, slightly pubescent, prominent ridges
minutely roughened; base with a minute sear, brownish; the apex
with projecting point and fine, capillary, white, bristles. Found
with grass seeds.
500 WEED FLORA OF IOWA
Sow Thistle (Sonchus oleraceus L.).
Achenes light brown, flattened, ribbed, the prominent ribs rough-
ened; one-eighth in: long; pappus of white capillary bristles, much
like the preceding. ‘‘Apt to occur among grass seeds.’’
Wild Lettuce (Lactuca canadensis L.).
Achene three-twentieths in. in length, straight or curved, sides
somewhat unequal, transversely wrinkled, blackish brown, beak one-
twentieth in. long, shorter than in L. floridana; one faint rib on each
side of prominent midrib; decidedly convex on each side of midrib
to the flattened margin ; scar with whitish ring and small depression ;
pappus white, capillary. Much like ZL. floridana, beak smaller and
shorter. With commercial seed.
Fig. 379A Fig. 379B
Fic. 379. Seeds of Lettuce. A. Lactuca canadensis; a, enlarged achene, b,
natural size. B. Lactuca floridana.
(A, after Hillman, Bull. Mich. Agr. Exp. Sta.; B, drawing by Charlotte M. King.)
False Lettuce (Lactuca floridana (l.) Gaertn.).
Achene brown, transversely wrinkled, three-twentieths to seven-
fortieths in. in length, straight or slightly curved; beak light
brown, about one-fifth in. long, generally persistent, convex; ribs
rather faint, 1 on each side of prominent midrib, strongly convex
on each side of midrib, margin flattened; pappus white, capillary.
Prickly Lettuce (Lactuca scariola var. integrata Gren. & Godr.).
Achenes brownish, margin somewhat lighter, surface roughened,
one-ninth to one-sixth in. long; beak one-tenth to one-eighth in. long,
lance-shaped, straight or slightly curved, upper end tapering
THE GENERAL CHARACTERS OF SEEDS fe 501
v
BS
Dp
~
(
Fig. 380A Fig. 380B
Fic. 380. Lettuce Seeds. A. Lactuca scariola; A, side view of an achene, en-
larged. B, a group of the same, natural size. C, an achene bearing its
beak and fragile pappus.
B. Prickly Lettuce (Lactuca scariola var. integrata.)
(A, after Hillman, Bull. Nev. Agr. Exp. Sta.; B, drawing by L. R. Collins.)
toward the beak, somewhat flattened, on one side margined, faces
convex, with 5-7 longitudinal nerves; scar circular, with a small
depression.
Rattlesnake Root (Prenanthes alba L.). .
Achene oblong or columnar, truncate, somewhat flattened, 4-5
angled, brownish; upper part with a projecting ring to which the
bristles of pappus are attached; scar at the base whitish, not prom-
inent; one-eighth in. in length; pappus tawny.
Fig. 381A Fig. 381B
Fic. 381. Seeds of Rattlesnake Weed and False Calais. A. Rattlesnake Weed
(Prenanthes alba). B. False Calais (Agoseris cuspidata).
(Drawings by Charlotte M. King.)
502 WEED FLORA OF IOWA
False Calais (Agoseris cuspidata (Pursh.) Steud.).
Achenes fusiform, slightly contracted at the apex, with 10
prominent ribs; one-half in. long, or little longer; pappus of soft,
white, capillary bristles; scar at base, whitish, with a small opening.
Orange Hawkweed (Hieraciwm aurantiacum L.).
Achene oblong, columnar, one-tenth in. long; blackish or dark
brown, marked with prominent longitudinal ridges, minutely
roughened; base of achene with small circular raised border, lighter
than remainder of achene; pappus of numerous somewhat brown-
ish bristles, frequently breaking away near the top of the achene,
then showing short bristles.
Fig. 382A Fig. 382A1 Fig. 382B
Fic. 382. Seeds of Hawkweeds. A and Al, Orange Hawkweed (Hieracium
aurantiacum). B, Hawkweed (Hieracium canadense).
(A, after Hillman, Bull. Mich. Agr. Exp. Sta.; Al, drawing by L. R. Collins;
B, drawing by Charlotte M. King.)
Hawkweed (Hieracium canadense Mx.).
Acheres one-tenth to one-eighth in. long, oblong, columnar,
10-15-ribbed; blackish or reddish; base with prominent disklike
area marked by circular ring; apex with somewhat fine tawny-
colored capillary bristles; below point of attachment is an area
bulging outward; capillary bristles have tendency to break.
CHAPTER III.
MICROSCOPIC STRUCTURE OF
SOME WEED SEEDS
By
L. H. PAMMEL
and
CHARLOTTE M. KING
CHAPTER II.
-GRAMINEAE,* GRASS FAMILY.
Smooth Crab Grass (Digitaria humifusa Pers.).
A cross section of seed shows but slight development of the
pericarp and testa. The epidermal cells of the former are smaller
than the underlying rows of cells of the wall of the ovary. The
testa is reduced to a single layer of cells, longer than broad. The
aleurone layer is filled with protein grains. The starch cells of
the endosperm are larger and densely packed with polygonal
grains.
Fic. 383. Structure of the grain fruits of some Grasses (Gramineae).
I. Wild Barley (Hordeum jubatum). II. Timothy (Phleum pratense). III.
Smooth Crab Grass (Digitaria humifusa). IV. Sandbur (Cenchrus tribu-
loides). V. Millet (Setaria italica). VI. Corn (Zea mays). VII. Barn-
yard Grass (Echinochloa crusgalli).
t=testa. al=aleurone. en=endosperm. n=nucellus.
(Drawings by L. H. Pammel.)
ae,
*The material for this family has been taken from the accounts by Pammel
and Winton.
506 WEED FLORA OF IOWA
Broomecorn Millet (Panicum miliaceum L.).
The walls of the ovary are similar to those of Digitaria humifusa
except that they are wider. The testa is much compressed and
consists of several layers of small cells. The cells of the aleurone
layer are small, somewhat longer than broad. The cells of the
starch layer are similar to those of D. humrfusa.
Barnyard Grass (Echinochloa crusgalli (l.) Beauv.).
The adherent glumes in this species consist of several rows of
parenchyma cells, the inner portion, of one row of thick-walled
sclerotic cells with pore canals. The cells of the pericarp and testa
are much as in the other species, thin-walled and compressed. The
protective features are preserved in the coriaceous glumes. The
starch and aleurone layers are similar to those of Digitaria
humifusa.
Hungarian Grass or Millet (Setaria italica (L.) Beauv.).
The colorless smooth pericarp is but slightly thickened and con-
sists of three or four rows of elongated cells. These in colored
seeds contain the pigment. The testa is but slightly developed.
The cells of the aleurone layer are not much longer than broad,
and are densely filled with protein grains.
Green Foxtail (Setaria viridis (L.) Beauyv.).
Dr. A. L. Winton describes the microscopic structure as follows: ~
Empty Glumes and Glume of Sterile Flower. The lower empty
glume is three-nerved and less than 1 mm. long; the upper empty
glume and the glume of the staminate flower are five-nerved and
2 mm. long. In microscopic structure the three are practically
identical. 1. Outer Epidermts. Characteristic of this layer are
the elongated cells with sinuous side walls and longitudinal rows
of pits so arranged that one pit occurs in each concave bend of
the wall. On the middle portion of the mature glume each of
these pits is so large that it fills completely the bend of the wall,
and in addition has a thickened border, half of which coincides with
the cell wall, thus giving the tissue a lacelike appearance. This
structure is optically delusive, the pit borders often appearing to
be the cell walls, but is resolved by careful focusing and comparison
with the tissue in earlier stages of growth. In addition to these
MICROSCOPIC STRUCTURE OF WEED SEEDS 507
Fic. 384. Green Foxtail (Setaria viridis). I, spikelet with ripe fruit. g', lower
empty glume; g%, upper empty glume; gf, glume, and p', palet of the
staminate flower; ef?, glume, and p?, palet of fertile flower; c, caryopsis; b,
bristles. II and III. caryopsis enclosed by flowering glume and palet. X 8.
(After Winton, Conn. Agr. Exp. Sta.)
elongated cells, pairs of short cells, one isodiametric, probably a
hair-scar, the other more or less crescent-shaped, occur here and
there, and less frequently stomata and thin-walled one to three-
jointed hairs. 2. Mesophyl. Only about the nerves and the basal
Fig. 385A. Fig. 385B
Fic. 385. Green Foxtail. A. Outer epidermis of the staminate flower; I, at
the edge; II, in the middle. X 300.
B. Outer epidermis of the glume of the fertile flower, showing the wrinkled
central portion and the smooth edge.
(After Winton, Conn, Agr. Exp. Sta.)
508 WEED FLORA OF IOWA
portions of the glumes is this coat evident. It has no diagnostic
importance. 3. The Inner Epidermis is composed of elongated cells
with straight walls.
Palet of Staminate Flower. Within the glume of the staminate
flower is the palet, a hyaline scale only 1 mm. or less long with
a notch at the end. In general structure, it is much the same
as the other thin envelopes, but the cell walls are thinner.
1. Outer Epiderms. The narrow, elongated cells are wavy in out-
line, but pits are lacking or are indistinct. Isodiametric cells are
thin-walled; jointed hairs also occur. 2. Inner Epidermis. Except
at the base, where traces of mesophyl are sometimes evident, the
inner epidermis immediately underlies the outer epidermis.
Glumes and Palet of Perfect Flower. Both the glume and the
palet of the fertile flower closely envelop the grain at maturity,
the former being strongly convex, the latter flat except on the
edges, which clasp about the caryopsis. At the time of flowering
these envelopes are thin and of a green color, but at maturity they
are coriaceous, silicified and of a brown or mottled color. Under
the lens, numerous transverse wrinkles are evident on the glume
and on the middle or flat portion of the palet, the lateral portions
of the latter which clasp the caryopsis being smooth and shining.
1. Outer Epidermis. Throughout the glume and on the middle
portion of the palet, the cells are isodiametric or moderately elon-
gated and are arranged not only in longitudinal rows but also in
irregular transverse rows, the wrinkles being formed by the out-
bending of the cells at the end walls and the inward bending
half way between. At the time of flowering, it may be seen that
at the outer surface the end walls are sinuous and the side walls
are compoundly sinuous, but farther inward the end walls are
nearly straight and the side walls are simply, not compoundly
sinuous. At the end of each cell nearest the apex of the envelope,
a cuticular wart bearing a group of pits is usually evident, par-
ticularly on the palet. About these warts the adjoining end walls
are more or less curved and the side walls are not so deeply sinuous.
At maturity the cell cavity beneath the wart is conspicuous (on
the palet nearly circular), but at the other end of the cell is nar-
row or not evident at all owing to the encroachment of the strongly
thickened walls. The cell contents during the early stages of devel-
opment are colorless, but later on usually become dark brown. The
epidermal cells on the lateral or smooth portions of the palet which
MICROSCOPIC STRUCTURE OF WEED SEEDS 509
Fic. 386. Green Foxtail. Outer epidermis from the middle of the glume of the
fertile flower. I, outer surface, and II, inner surface soon after blooming.
III, outer surface when in fruit. X 300.
(After Winton, Conn. Agr. Exp. Sta.)
elasp about the caryopsis are longer, narrower, and less complex
than those already described. At maturity the wrinkles are usually
from 0.03 to 0.06 mm. apart. 2. The Hypodermal Fibers may be
readily isolated by treatment on the slide with caustic alkali. They
vary in length up to 0.6 mm. and are often toothed at margin.
3. Mesophyl. Rectangular parenchyma cells without intercellular
spaces make up this layer. Numerous chlorophyl granules are
present at the time of flowering. 4. The Inner Epidermis is com-
510 WEED FLORA OF IOWA
posed of rectangular cells resembling those of the mesophyl. Both
of these layers become more or less obliterated at maturity and are
of no diagnostic importance.
Pericarp. The ventral side is flat and has a darker colored spot,
the remains of the hilum, near the base. Extending half way from
the base to the apex on the dorsal side is a groove, which marks
the position of the embryo. Vogl describes minutely the histology
of the caryopsis of common millet (Panicum miliacewm L.) and
Fic. 387. Green Foxtail. Outer epidermis from the edge of the glume of the
fertile flower. X 300.
(After Winton, Conn. Agr. Exp. Sta.)
states that German millet (Setaria panis Jessen) has practically
the same structure. I find that his description applies also to the
caryopsis of both green and yellow foxtail. 1. Epidermis. As in
the outer epidermal layers of the floral envelopes the cells are
elongated and wavy in outline. On the dark colored spot already
referred to, the epidermal cells are more or less rectangular.
2. The Cross-Cells are similar to the tube-cells in form but are
usually shorter, broader, and more irregular in shape. 3. Tube-
Cells. These are 0.002 to 0.004 mm. wide and often reach the
length of 0.3 mm. a. Nucellar or Hyaline Layer. After treatment
with alkali, this layer is clearly seen in surface view. The cells
are of large size and have beaded walls. b. Endosperm. 1. Alewrone
Layer. The cells vary in diameter from 0.01 to 0.02 mm.
MICROSCOPIC STRUCTURE OF WEED SEEDS 511
2. Starch-Cells. Polygonal starch granules with conspicuous hilums
fill the parenchyma cells of the endosperm. In the outer layers
they are from 0.004 to 0.008 mm. in diameter but farther inward
they reach the maximum diameter of 0.018 mm. After dissolving
the starch with potash, there remains a network of threads con-
taining conspicuous granules. In this respect, however, this fruit
cannot be distinguished from the fruits of S. glauca Beauv.,
S. panis Jessen, Panicum miliaceum L. (see Vogl) and all the
other species of Panicum which I have examined. Detection m
Powder Form. The membranous glumes with pores in the bends of
Fic. 388. Green Foxtail. Transverse section of caryopsis. F, pericarp con-
sisting of the epidermis ep and the tube-cells sch; N, nucellar layer; H,
endosperm consisting of the aleurone-cells al and the starch cells s. X 300.
(After Winton, Conn. Agr. Exp. Sta.)
the walls and the coriaceous, transversely wrinkled, more or less
spotted, envelopes of the fertile flower with compoundly sinuous,
thickened cell walls are highly characteristic of both green and
yellow foxtail. These tissues are usually present in all stages of
development. The fruit elements are like those of common millet
and German millet. Treatment with caustic alkali brings out the
structure of the fruit coats and nucellar layer, and serves to dis-
tinguish this fruit from the common cereals. The starch is hardly
distinguishable from the starch of bindweed.
Dr. A. L. Winton describes the microscopic character of yellow
foxtail (Setarta glauca Beauv.) as follows:
The fruit of this species is larger than that of green foxtail, the
envelopes are also proportionately larger (with the’ exception of
the upper empty glume which is but half the length of the
512 WEED FLORA OF IOWA
spikelet) and the wrinkles on the glume of the fertile flower are
more pronounced. In microscopic structure the fruits of the two
species are identical. The floral envelopes are also much alike,
the only distinction being in the distance apart of the wrinkles on
the mature flowering glumes. In green foxtail this distance is
usually from 0.03 to 0.06 mm., but in yellow foxtail it is often
from 0.08 to 0.12 mm. Since this distinction does not apply to
the mature glumes and since the wrinkles on the palets of the two
species are practically the same, it is often difficult to identify the
species in ground mixtures. Fortunately, identification of the
genus is all that is usually required.
Fic. 389. Green Foxtail. Caryopsis in surface view. Significance of letters.
same as in Fig. 388.
(After Winton, Conn. Agr. Exp. Sta.)
Broom Corn (Andropogon sorghum var. technicus Koern).
Dr. A. L. Winton describes the microscopic structure of the
pericarp and testa of broom corn as follows: “As
Empty Glumes.—Both glumes are from 4 to 6 mm. long, equal-
ing and closely enveloping the fruit. They vary in color from
yellow-brown to red-brown. The soft hairs, which nearly cover
the outer surface, are loosely attached and most of them are re-
moved during the threshing and cleaning of the seed, leaving the
glumes smooth and shining. 1. The Outer Epidermis consists of
strongly sclerenchymatized cells several times as long as they are
broad, with wavy contour, interspersed here and there with iso-
diametric hair-scars, each accompanied by a crescent-shaped cell
MICROSCOPIC STRUCTURE OF WEED SEEDS 513
Fig. 390. Broom-corn. Fruit with chaff. r, two staminate spikelets; g1, lower
empty glume; g2, upper empty glume; g%, glume of rudimentary flower; gf,
flowering glume with awn; p, palet; ec, caryopsis. X 4.
(After Winton, Conn. Agr. Exp. Sta.)
with granular contents. The hairs, which are almost invariably
detached in preparing the mount, if not in cleaning the seed, are
often 1.0 mm. long and 0.012 mm. broad in the middle but taper
toward both ends. Invariably the lumen is much broader than
the walls. 2. The Hypoderm Fibers, of which there are several
layers, have thick walls and narrow cavities. They vary in length
Kaan pry ADwe™
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Fic. 391. Broom-corn. Transverse section of caryopsis and an empty glume.
Sp, empty glume, consisting of the outer epidermis aep, the fiber layer f,
the spongy parenchyma p, and the inner epidermis iep; g, bundle; sto,
stoma; Fs, pericarp, consisting of the epidermis ep with the cuticle ec, the
hypoderm hy, the starchy mesocarp mes, the cross-cells q, and the tube-cells
sch; N, nucellar or hyaline layer with swollen inner walls s; H, endosperm,
consisting of the aleurone layer al and the starch-cells with starch
granules st and proteid network a. X 160. :
(After Winton, Conn. Agr. Exp. Sta.)
33
514 WEED FLORA OF IOWA
up to 0.5 mm. or more. 3. Spongy Parenchyma. As seen in sur-
face view, the cells of this layer are more or less rectangular with
circular intercellular spaces and resemble those of rice and barley
glumes. 4. Inner Epidermis. In cross section this layer is not
readily studied since the radial walls are usually collapsed; but
in surface preparations, the large elongated cells, often 0.15 mm.
long and 0.05 mm. wide, interspersed with stomata and hairs, are
clearly displayed.
Thin Glume.—Within the lower or first glume and nearly equal-
ing it in length, is the third or thin glume, the remnant of an
abortive flower. This glume is exceedingly thin and membranous
and bears numerous hairs, particularly in the margin. 1. Outer
Epidermis. In general form the cells are similar to those of the
outer epidermis of the thick glumes, but are narrower and much
thinner-walled. The marginal hairs are long (often 0.5 mm.)
single-celled and pointed; but on the surface shorter hairs, with
two or three joints and blunt ends, also occur. Both of these
Fig, 392A Fig. 392B
Fic. 392. Broom-corn. A. aep, outer epidermis and f, fiber of an empty glume
in surface view. X 300.
B. p, spongy parenchyma and iep, inner epidermis of an empty glume in surface
view; sto, stoma; h, hair. X 300.
(After Winton, Conn. Agr. Exp. Sta.)
MICROSCOPIC STRUCTURE OF WEED SEEDS 515
forms have exceedingly thin walls. 2. The Inner Epidermis is dis-
tinguished from the outer by the straight walls and almost entire
absence of hairs.
Flowering Glume.—The fourth or flowering glume, situated be-
tween the upper or second glume and the grain, is also mem-
branous and bears an upwardly barbed awn 5 to 7 mm. long. This
awn, with the larger part of the flowering glume, being readily de-
tached by threshing, it is seldom found in the grain on the market.
Fic. 393. Broom-corn. Glume of rudimentary flower in surface view. aep,
outer epidermis with h, one-celled hair and h, two-celled hair; iep, inner
epidermis. X 300.
(After Winton, Conn. Agr. Exp. Sta.)
Palet—tThis is membranous and hairy like the third or ite
glume, but is much smaller.
Pericarp.—The grain or caryopsis is about 5 mm. long and from
2 to 3 mm. wide, tapering to a blunt point at both ends. It varies
in color from yellow-brown to red-brown.
Harz, Hassack and particularly Mittlacher have described so
fully the histological elements of the caryopsis, that only a brief
description, essential for a clear understanding, need here be given.
1. Eyidermis. The cells are longitudinally extended and have
thick wavy side walls, with more or less distinct pores. Hassack
has noted that the cuticle is of uneven thickness, due to minute
granules or crystals, which may be seen in either section or sur-
516 WEED FLORA OF IOWA
FIG. 394. Broom-corn. Layers of the pericarp in surface view. Significance
of letters same as in Fig. 391. X 160.
(After Winton, Conn. Agr. Exp. Sta.)
face view. 2. The Hypoderm consists of from one to three layers
of cells, with walls somewhat thinner than those of the epidermis.
3. Starchy Mesocarp. Several layers of thin-walled parenchyma
cells, filled usually with small round or rounded polygonal starch
granules seldom over 0.006 mm. in diameter, make up this coat.
In all the varieties here described the starch appears during the
early stages of growth and persists until the fruit nearly or quite -
reaches full maturity. As the caryopsis, even when nearly mature,
is intensely green owing to chlorophyll grains in the outermost
layers of the mesocarp,. it may be inferred that this starch is a
direct product of photosynthesis in the pericarp. So far as I have
observed, the presence or absence of a starchy mesocarp in the
erain at the time of harvest is not a definite varietal peculiarity,
but is dependent on the ripeness of the fruit or other conditions.
Some kernels of the same variety may possess it, while others show
only empty, obliterated cells. Whether or not the starch is present
in a given seed may often be determined by careful scraping and
observation with the naked eye. 4. Cross-Cells. These cells are
usually long and narrow, being distinguished from the tube-cells
only by their transverse arrangement. Near the extremities of
the seed they are, however, shorter and of more irregular shape.
5. Tube-Cells (sch). The cells of this layer lie at right angles to the
_ eross-cells. They are about 0.005 mm. wide and often reach a
length of 0.20 mm. a. Nucellar or Hyaline Layer. This layer is
frequently 0.05 mm. thick. The outer radial walls are thin, but
the inner wall is greatly swollen. In surface view the large cells
MICROSCOPIC STRUCTURE OF WHED SEEDS 517
are conspicuous, not only because of their size, but because of their
yellow or brown color. b. Endosperm. 1. Aleurone Layer (al).
The individual cells of this layer are characterized by their
great variation in size (0.01 to 0.04 mm. in diameter) and form.
2. Starch-Cells (st). In the outer layers the starch granules, if
present, are much smaller than in the interior of the seed, where
they sometimes reach a diameter of 0.083 mm. They are usually
sharply polygonal, with a distinct hilum and radiating fissures.
The starch is surrounded by small protein granules, forming a
network which is especially evident after removing the starch by
reagents. In some specimens, one or more of the outer cell layers
are filled with these protein granules to the complete exclusion of
the starch. )
Sandbur (Cenchrus tribuloides L.).
The pericarp is divided into two portions. The cells of the
outer portion are thick-walled and short; of the inner portion,
elongated, thick-walled and fusiform. The testa consists of one to
two rows of thin-walled cells, much compressed. The aleurone
cells are much larger than in Panicum and Setaria, thick-walled,
densely filled with protein grains. Walls of the starch cells thick-
ened; starch grains larger and loosely arranged.
Timothy (Phlewm pratense L.).
The testa and pericarp are dark colored. The epidermal cells
are thin-walled, elongated, sometimes slightly irregular. The
testa consists of several rows of thick-walled dark brown cells
much longer than broad. The aleurone layer consists of a single
row of cells relatively thin-walled, somewhat variable in size,
solidly packed with aleurone grains. The nucellus is very evident
as a remnant in some places. The cells of this layer are thick-
walled, clear and colorless. The starch cells are much larger than
the aleurone, and contain angular starch grains.
Cheat or Chess (Bromus secalinus L.).
Dr. A. L. Winton describes the microscopic structure as follows:
Flowering Glume.—The structure throughout is much the same
as in darnel, but the cells of the outer epidermis are much more
conspicuously thick-walled, and the wavy-walled cells throughout
much longer than broad. The circular cells also have wavy walls.
The cells on the margins, interspersed with lance-shaped hairs, are
the same as in darnel.
518 WEED FLORA OF IOWA
Fic. 395. Chess (Bromus secalinus). Outer epidermis of flowering glume in
surface view. X 160.
(After Winton, Conn. Agr. Exp. Sta.)
Palet—The flowering glume and palet of chess are very similar
in structure, but the outer epidermis of the latter is barbed on the
keel, the stiff hairs often reaching 45“ in length.
Pericarp (F).—The pericarp consists of two layers with rudi-
ments of another layer in parts. 1. The Epidermal Cells (ep) are
large, elongated-polygonal, and have thin, non-porous walls.
2. Mesocarp. As a rule, the cross-cells immediately underlie the
Fic. 396. Chess. Transverse section of fruit. F, pericarp consisting of
epidermis ep, and cross-cells q; S, testa; N, perisperm; H, endosperm con-
sisting of aleurone layer al, and starch-parenchyma st. X 160.
(After Winton, Conn. Agr. Exp. Sta.)
epidermis, but occasionally traces of the mesocarp are evident.
3. Cross-Cells (q). Whether this layer corresponds with the cross-
cells of the tube-cells of other grasses, I have been unable to decide.
MICROSCOPIC STRUCTURE OF WEED SEEDS 519
The tissue is made up of irregular spongy-parenchyma cells,
usually transversely elongated with large, round or elongated inter-
cellular spaces.
The Testa (S).—Consists of one layer of elongated brown cells
10-20 wide.
Perisperm (N).—This layer is enormously developed. As may be
seen in cross section, the cells are 40“ thick, but the walls are so
swollen as to almost entirely obliterate the cavity. After soaking
for some time in 1 per cent soda solution they are evident in sur-
face view.
Endosperm.—l1. The Alewrone Layer (al) is not of especial in-
terest. 2. The Starch-Parenchyma (st) is remarkable for the thick-
ness of the cell walls (often 10 thick) and the elliptical starch
grains 3-204 in diameter. With proper illumination each grain
may be seen to have an elliptical hilum.
Fic. 397. Chess. Elements of fruit in surface view. Significance of letters same
as in Fig. 396.
(After Winton, Conn. Agr. Exp. Sta.)
Wild Barley or Squirrel-tail Grass (Hordeum jubatum L.).
The grain is adherent to the palet. The epidermis consists of
thick-walled, tangentially elongated ‘cells, most of which are longer
than broad. In part the cells are developed into short conical
trichomes. The underlying cells are thick-walled with prominent
pore canals. The remainder of the adhering palet consists of thin-
walled cells much larger than broad. The pericarp as well as the
520 WEED FLORA OF IOWA
testa is but slightly developed. In some cases the underlying
parenchyma cells are not clearly defined. The blackish pigment is
found in the internal part of the palet; some also occurs in peri-
carps and the aleurone layer. The pericarp consists of one or
two rows of rather thin-walled, tangentially elongated cells. The
testa is reduced to a single layer of cells longer than broad. The
nucellus is nearly absent except in the groove. It consists of a
single row of thin-walled, colorless, compressed cells. In the groove
several rows of cells occur. The aleurone in the specimens studied
is made up of a single row of cells. The cells of the starch layer
are larger than those of the aleurone.
Darnel (Lolium temulentum L.).
Dr. A. L. Winton describes its microscopic structure as follows:
The Flowering Glume is 6-8 mm. long, equaling or exceeding
the caryopsis. It is obscurely five-nerved, lobed at the end, and
bears an upwardly barbed awn often 15 mm. long. Like the glumes
of barley, oats, and other cereals, it consists of four coats, some of
which, however, are lacking on the margins and at the end. 1. The
Outer Epidermis differs greatly in structure in different parts of
the glume. At the margins (as is clearly shown in Fig. 1 by
Moeller*), it consists of straight-walled, elongated cells inter-
spersed here and there with short lance-shaped hairs. On the
ereater part of the surface, however, the cells, as in barley and
some other cereals, are of three kinds: first, cells of wavy outline,
lic. 398. Darnel (Lolium temulentwm). Margin of flowering glume showing
lance-shaped hairs. X 300.
(After Winton, Conn. Agr. Exp. Sta.)
MICROSCOPIC STRUCTURE OF WEED SEEDS 521
into which the straight-walled cells at the margin pass; second,
circular cells corresponding to the conical hair-cell of barley ; third,
exceedingly short, more or less crescent-shaped cells. Near the
‘ margins and on the veins, where they alternate with stomata, the
cells of wavy outline are elongated; but in other parts they are
very short, often being broader than long. Although thick-walled,
the walls are transparent, whereas the middle lamella is con-
spicuous, giving the impression of thin-walled cells. Pores are few
and inconspicuous. Near the margin the circular cells are small
and are usually accompanied by crescent-shaped cells which often
exceed them in size. On the greater part of the glume, however,
the circular cells are much larger, often being 70# in diameter.
Numerous pores are conspicuous, both in the radial and tangential
walls. Often one, sometimes two, crescent-shaped cells accompany
a circular cell. Characteristic of this coat are the short, wavy
Fic. 399. Darnel. Middle portion of flowering glume. X 160.
(After Winton, Conn. Agr. Exp. Sta.)
cells and the numerous circular cells, the latter frequently exceed-
ing in area the former. 2. Hypoderm. The fibers in this layer
are much the same as in cereals. Fibers of similar structure also
make up the ground-tissue of the awn. 3. Spongy-Parenchyma.
The elements are more or less rectangular in shape, like those of
the corresponding layer of barley, and are readily distinguished
from the star-shaped elements of oats. 4. Inner Epidermis. This
layer is made up of thin-walled cells and stomata, and is of no
diagnostic importance.
522 WEED FLORA OF IOWA
Palet.—The two-keeled palet is about the same size as the flower-
ing glume, but is of a thinner texture, owing to the absence of a
well developed hypoderm layer. The Outer Epidermis is much the
same as that of the flowering glume, except that it is barbed on ~
the keels with rigid thornlike hairs 150“ or less in length, as is
shown in Fig. 3 by Moeller.
Fie. 400. Darnel. Keel of palet showing outer epidermis with hair h, and
hypoderm fibers f. X 160.
(After Winton, Conn. Agr. Exp. Sta.)
The Pericarp (F').—Consists of four coats, of which only two, the
epidermis and cross-cells, are fully developed. 1. Epidermis (ep).
Cross sections of the mature seed show that this layer consists of
collapsed, moderately thick-walled cells, which are best studied
after heating with potash. Seen in surface view, the cells at the
apex of the seed are nearly isodiametric, but at other parts are
elongated. The walls are indistinctly beaded. 2. The Mesocarp (m)
is not developed on all parts of the seed, but is conspicuous on the
angles. The cells vary greatly in shape and size, some being ir-
regularly isodiametric, others transversely elongated, resembling the
cells of the next layer. 3. Cross-Cells (q). Especially striking are
the cells of this layer, which resemble the cross-cells of barley. As
has been noted by Moeller, the radial walls appear indistinctly
beaded, but this is evident only under favorable conditions.
4. Tube-Cells, spongy-parenchyma, and various intermediate forms,
make up the interrupted inner layer of the pericarp.
Testa (S).—The cells are for the most part elongated and are
often diagonally arranged with reference to the axis of the fruit. In
MICROSCOPIC STRUCTURE OF WEED SEEDS 523
42m” 4
Fic. 401. Darnel. Transverse section of fruit. F, pericarp consisting of
epidermis ep, mesocarp m, cross-cells q, and tube-cells sch; S, testa con-
sisting of outer layer a. and inner layer i; N, perisperm; f, fungus layer;
HE, endosperm consisting of aleurone layer al, and starch-parenchyma st.
x 160.
(After Winton, Conn, Agr. Exp. Sta.)
transverse sections this coat often separates from the pericarp on
the one hand and the perisperm on the other. Examined in water,
only one cell layer (the inner) is evident; but successive treat-
ments with 5 per cent potash, dilute acetic acid and chlorzine
iodine, bring out two layers. 1. The Outer Layer (a) is made up
of thin-walled cells with cuticularized outer walls. Treated as
above described, the cuticle is colored yellow-brown, the radial and
inner walls, blue. 2. The Inner Layer (1) is not only thicker than
the outer, but the cells are thicker-walled and, in addition, swell
greatly with potash. These swollen walls are stained deep blue by
chlorzine iodine, thus differentiating them from the yellow-brown
cuticle on the inner wall.
Perisperm (N).—Characteristic of this seed is the nucellar-coat,
consisting usually of two cell layers. In cross section these cells
are rectangular with swollen walls; in surface view, as maybe
seen after soaking for a long time in dilute potash, they are:ir-
regularly polygonal or more or less elongated. Shines
Fungus Layer (F').—In most specimens a layer of fungus-threads
20 thick is present between the perisperm and the aleurone layer.
So commonly is this fungus present in darnel grown in Europe,
that it is of no little value in identifying the grain; but it remains
to be determined whether in California, where the plant is a pest
524 WEED FLORA OF IOWA
in wheat fields, the fungus is also a common accompaniment. After
treatment with potash this layer is stained bright yellow by zine
chloride of iodine.
Endosperm.—1. The Aleurone Cells (al) vary from less than 20
to 40“ in diameter. 2. Starch-Parenchyma (st). The thin-walled
cells contain small polygonal grains 3 to 7# in diameter. The in-
dividual starch grains are not distinguishable from the grains of
rice and oats, and like the latter, often occur in aggregates of
various sizes.
:
Nez
Ps ne :
Fic. 402. Darnel. Elements of fruit in surface view. Significance of letters
same as in Fig. 401. X 160.
(After Winton, Conn. Agr. Exp. Sta.)
URTICACEAE, NETTLE FAMILY.
Hemp (Cannabis sativa L.).
The smooth crustaceous achene consists of an outer epidermal
layer of thick-walled cells with wavy outline, the thickness of the
radial walls varying somewhat. This is followed by a layer of
loosely arranged parenchyma cells, and a layer of cells with brown
contents. A layer of small cells spoken of as the dwarf cells by
Winton, may also be made out in some sections. The palisade
layer consists of thick-walled cells with pore canals, the walls
having a wavy outline. The cell cavity is very much reduced.
The testa is very thin and consists of thin-walled elongated paren-
chyma cells, the second layer of spongy parenchyma. The com-
MICROSCOPIC STRUCTURE OF WEED SEEDS 525
pressed nucellus follows. The endosperm consists mostly of a
single layer of cells, the embryo of small epidermal cells and the
elongated palisade parenchyma on the upper face of the cotyledon;
cells of embryo and endosperm contain fat and protein.
Nettle (Urtica gracilis Ait.).
The pericarp of the small achenes consists of an outer epidermal
layer of rather large cells with exterior walls thickened, and
underneath several layers of loosely arranged parenchyma cells.
The testa and nucellus are compressed; cells of the embryo squarish,
containing fat and protein grains.
Fic. 403. Microscopic structure of the seeds of the Nettle family. (Urticaceae).
I. Hemp (Cannabis sativa). II. Common nettle (Urtica gracilis).
ep=epidermis, thick-walled short cells, underneath followed by a pigment layer,
thinner-walled parenchyma cells and a layer of thick-walled cells. pal=
palisade cells. p=parenchyma cells with the pigment. t=testa. n=
nucellus. em=embryo.
(Drawings by L. H. Pammel and Charlotte M. King.)
POLYGONACEAH,* BUCKWHEAT FAMILY.
Miss E. Sirrine finds, ‘‘In the seed coats of the family, the
palisade portion constitutes the outer part of the achenium; this is
followed in most cases by the testa consisting of several layers of
eells varying, however, in some cases; they are quite regular in
form and in some instances are of a dark color. In the mature
palisade cell, the cavity is present; this varies greatly in the dif-
ferent genera; in some cases occupying nearly the entire cell, in
others small and irregular.’’
*A study of the microscopic structure of the achenes is largely based on Miss
Emma Sirrine’s work and upon that of Dr. Winton.
526 WEED FLORA OF IOWA
Sorrel or Sour Clover (Rumesx acetosa L.).
This species has very small palisade cells, rectangular in shape
and with a small cell cavity which occupies only a small portion
of the lower end of the palisade cell. No canals or irregularities
of cell cavity.. The cell is light in color while canal is darker.
The sub-palisade portion is composed of small round cells of a
variable number. The endosperm is composed of irregularly ar-
ranged cells. Measurements: whole seed coats, 38.34; palisade
cells, 23"; sub-palisade, 13.2.
HULL ee rt
mat OE
=| unum: UNE
} TUM
pee
twin mM mn
Fic. 408. Black Bindweed. Seed in surface view. Significance of letters same
as in Fig. 406.
(After Winton, Conn. Agr. Exp. Sta.)
Detection in Powder Form.—Characteristic of this fruit are
the papillae on the outer epidermis of the calyx and the epicarp
with sinuous cell walls and rows of warts. The outer epidermal
cells of the testa are sinuous in outline, like those of buckwheat,
but, unlike the latter, are commonly elongated. Although the cross-
cells are morphologically the same as the spongy parenchyma of
buckwheat, they resemble more nearly in structure the tube-cells
of the cereals.. The starch granules are not characteristic and the
network obtained after treatment with caustic alkali serves merely
as an indication that the seed belongs to a Polygonaceous plant.
Buckwheat (Fagopyrum esculentum Moench.).
The achenium consists of elongated epidermal cells with thick-
ened walls, underneath similarly elongated thick-walled sclerotic
parenchyma cells with pore canals. This layer contains the pig-
ment. The testa follows the pericarp and is differentiated into
an epidermal layer of yellowish brown walls, followed by smaller
thin-walled, parenchyma cells. The testa is much compressed; the
albumen consists of an outer aleurone layer of small cells followed
by larger cells. The albumen cells contain compound starch
grains.
532 WEED FLORA OF IOWA
4)
b)
Fic. 409. Black Bindweed. Surface view of the pericarp from below. X 160.
Significance of letters same as in Fig. 406.
(After Winton, Conn. Agr. Exp. Sta.)
CHENOPODIACHAH, GOOSEFOOT FAMILY.
Goosefoot or Lamb’s Quarters (Chenopodium album L.).
Harz has given an account of the structure of Beta and Spinacia.
The structure of the seed of lamb’s quarters is somewhat different.
The thin utricle consists of an epidermal layer of somewhat wavy
eells and an indistinct layer underneath. The testa contains the
brownish pigment. The cells are thick-walled; the nucellus is com-
pressed. The cells of the endosperm are large and contain an
abundance of small starch grains.
Russian Thistle (Salsola kali (.) var. tenutfolia G. W. F. Meyer).
The seed is without endosperm; the embryo fills the seed, and
is coiled in a conical spiral. The seed coat consists of two parts,
a layer of three rows of elongated cells followed by a layer of
three rows of irregular parenchyma cells. One side of the seed
coat is wider than the other and these cells contain an abundance
of calcium oxalate crystals. The cells of the outer layer of the
MICROSCOPIC STRUCTURE OF WHEHD SEEDS 533
embryo are somewhat elongated; the remainder are nearly as broad
as long; these contain no starch but albuminoids and fat.
Fic. 410. Microscopic structure of seeds of the Chenopod family. (Chenopodia-
ceae). I. Russian Thistle (Salsola kali var. tenwifolia). II. Lamb’s Quar-
ters (Chenopodium album). us
ep=epidermis. p=parenchyma cells. t=testa. n=nucellus. en=endosperm.
(Drawings by L. H. Pammel and Charlotte M. King.)
NYCTAGINACEAE, FOUR-O’CLOCK FAMILY.
Wild Four-o’clock or Umbrella Plant (Oxybaphus nyctagineus
(Mx.) Sweet).
The nutlike fruit of the wild four-o’clock or umbrella plant is
somewhat hairy; the outer portion of the pericarp is made up of
thick black-brownish cells from 6 to 9 rows. The epidermal cells
are smaller, some of the cells elongated into one-celled thick-walled
trichomes. Adjacent to the testa are bundles of thick-walled,
sclerotic cells, the outer layer of cells of the testa consisting of
mucilaginous cells with colorless walls. This is followed by a
second layer of thin-walled parenchyma cells. The nucellus con-
sists of an indefinite granular mass, followed by the endosperm,
and the thin-walled cells of the embryo. |
CARYOPHYLLACHAH, PINK FAMILY.
Soapwort or Bouncing Bet (Saponaria officinalis L.).
The kidney-shaped, black, roughish seeds consist of tangentially
elongated, thick, black, rough cells, the outer layer being brownish
colored, while the cell cavity is red or blackish brown. . The inner
walls of the testa are thinner, the cells are elongated and the inner
seed coat is much compressed. The nucellus is indistinguishable
from the inner seed coat. This is followed by the endosperm,
534 WEED FLORA OF IOWA
Fig. 411. Wild Four-o’clock (Oxybaphus nyctagineus). The sclerotic paren-
chyma, parenchyma and epidermis belong to the pericarp.
ep=epidermis. p=parenchyma. scl=sclerotic parenchyma. t=testa. t=tri-
chome. en=endosperm. r=ribs.
(Drawing by L. H. Pammel and Charlotte M. King.)
consisting of an outer tangential layer with granular contents.
The aleurone layer and remaining portion of the endosperm cells
consist of large rather thin-walled cells with compound starch
grains and protein.
Slender Catchfly (Silene antirrhina L.).
The small kidney-shaped seeds are rough and brownish in color.
The outer epidermal walls are thick, brownish black in color. The
underlying parenchyma cells are tangentially elongated with near-
ly colorless walls, This is followed by an indefinite layer con-
MICROSCOPIC STRUCTURE OF WEED SEEDS 535
sisting of an inner seed coat and a nucellus. The endosperm con-
sists of thin-walled parenchyma cells with granular contents con-
sisting of starch grains and protein.
Zi
Fic. 412. Microscopic structure of some seeds of the Pink family (Cary-
ophyllaceae).
I. Bouncing Bet (Saponaria officinalis). II. Catchfly (Silene antirrhina). III.
Virginia Catchfly (Silene virginica).
ep=epidermis. p=parenchyma. n=nucellus. h=hypoderm cells. en=endo-
sperm.
(Drawings by L. H. Pammel.)
The seeds of Virginia Catchfly (Silene virginica) are irregular.
The outer walls are greatly thickened, irregular, the underlying
parenchyma cells being slightly elongated. This layer is followed
by the nucellus and the aleurone layer and remaining endosperm
cells containing starch grains and protein material.
Silene inflata is described and figured by Harz*.
*Samenkunde 2 :10-79.
536 WEED FLORA OF IOWA
RANUNCULACEAE, CROWFOOT FAMILY.
Common Buttercup (Ranunculus abortivus L.).
The greenish achenes of the buttercup consist of three distinct
layers. The outer epidermal is of elongated, thickish black cells.
The cells containing the brown pigment are yellowish brown.
The underlying layers of three or four rows of seeds are similar
but larger and paler in color. This layer is followed by a thick-
walled sclerotic layer containing three or four layers of thick-
walled cells with pore canals. The testa consists of an outer layer
of thin-walled parenchyma cells; the inner layer consisting of
sclerotic parenchyma cells filled with pore canals. The endosperm
cells are large or thin-walled and contain protein material. Harz
has given an account of the structure of R. arvensis*.
ic. 413. Microscopic structure of the seed of Buttercup (Ranunculus aborti-
VUS).
ep=epidermis. p=parenchyma. scl=sclerotic parenchyma. en=endosperm.
(Drawing by L. H. Pammel and Charlotte M. King.)
PAPAVERACEAE, POPPY FAMILY.
Common Poppy (Papaver somniferum L.).
Prof. A. L. Winton describes the seeds of this plant as follows:
Testa (S).—Cross sections are prepared after soaking the seed
in water that may be cleared with chloral or alkali. After soaking
the whole seed for about twenty-four hours in 1 per cent sodium
hydrate solution, the first four layers readily separate from the
*Landw. Samekunde 2 :10-64.
MICROSCOPIC STRUCTURE OF WEED SEEDS 537
fifth. Subsequent treatment with hydrochloric acid dissolves out
the calcium oxalate, and staining with chlorzine iodine or safranin
renders the outer layers more distinct. 1. The Hpidermal Cells
(ep) are polygonal and of enormous size, corresponding to the net-
work on the seed. As appears in cross section, the cells are col-
lapsed except in the neighborhood of the radial walls. In surface
view the radial walls are sinuous and thin, what are often con-
sidered the thick dark walls of this layer being not the walls at all,
but the ribs formed by the thickening of the second and third
layers. This conclusion is consistent with Meyer’s and Hanausek’s
figures of cross sections, also with Meyer’s drawings and Mach’s
photomicrographs of surface preparations. The statement of
Tschirch and Oesterle that the epidermis consists of elongated cells
situated over the ribs, with large polygonal cells between, has since
been corrected by the authors themselves. Doubtless they mistook
some of the cells of the second layer for epidermis. Hanausek’s
surface view, on the other hand, might convey the impression that
the ribs were the cell walls, but his description and cross section
clearly show their true nature. 2. Crystal Layer (k). On the
Fic. 414. Poppy Seed (Papaver somniferum). Transverse section. s, testa
consisting of epidermis ep, crystal layer k, fiber layer f, cross-cells q and
netted-cells n; e, endosperm containing aleurone grains al. X 160.
(After Winton, Conn. Agr. Exp. Sta.)
ribs, the cells of this layer are more or less tangentially elongated,
but between the ribs are isodiametric and polygonal, the elongated
cells having longer radial walls than the others, thus contributing
to the formation of the ribs. They contain fine, granular crystals
‘of calcium oxalate. Meyer has demonstrated that the blue color
of the poppy seed is due, not to a blue pigment, but to the inter-
ference of light by the crystals over the brown cells in the back-
ground, and is the same phenomenon that causes the apparent
blue color of the sky and the iris of the eye. As soon as these
erystals are dissolved in hydrochloric acid, the seed appears brown.
538 WEED FLORA OF IOWA
3. Fiber Layer (£). The fibers of this layer are 15-40" broad
and are parallel to the curved axis of the seed. Seen in cross
section, this layer is thickest in the ribs, the walls throughout
being distinctly thickened and stratified. In surface view they
are rendered more distinct by chlorzine iodine. 4. Cross-Cells (q).
The fourth layer consists of moderately thick-walled, transversely
elongated, pointed cells arranged side by side in rows. The walls
_ are impregnated with brown material. 5. Netted-Cells (n). Ow-
ing to the netted-veined, colorless walls and the presence of deep
brown contents, these cells are particularly striking. They are
arranged transversely and often side by side in rows. The cell
contents are insoluble in alkali and do not give the tannin re-
action. Some authors designate the cells of this layer ‘‘Pigment
cells,’ notwithstanding the fact that in the white poppy they do
not contain pigment. Meyer, Tschirch and Oesterle, Vogl, and
Hanausek describe an inner layer of thin-walled cells, but I am
unable to find such a layer except in the vicinity of the hilum.
Fic. 415. Poppy seed. Testa in surface view. Significance of letters same as
in Fig 414. pig, pigment. X 160.
(After Winton, Conn. Agr. Exp. Sta.)
The Endosperm (E) contains aleurone grains up to 34 in
the outer layers and 7 in the inner layers, each grain containing
several globoids and crystaloids.
Embryo.—In the cotyledons there is only one layer of palisade-
cells and these cells are only slightly elongated. The aleurone
grains are like those of the endosperm.
MICROSCOPIC STRUCTURE OF WEED SHEDS 539
Prickly Poppy (Argemone intermedia Sweet).
The blackish pitted seeds are difficult to study. They consist
of nearly colorless epidermal cells, with thick outer walls and
cuticle. The cells of the underlying layer are thick-walled, walls
and contents blackish, difficult to make out on account of dense
Fic. 416. Rocky Mountain Poppy (Argemone intermedia).
ep=epidermis with thick outer walls. pi=pigment layer, n=nucellus, en=en-
dosperm. :
(Drawing by L. H. Pammel and Charlotte M. King.)
pigment. The nucellus is compressed, colorless. The endosperm
of large cells contains oil in large amounts, and protein. The
structure seems to differ in a marked degree from Papaver as
described by Harz and G. Kraus..
CRUCIFERAH, MUSTARD FAMILY.
Virginia Peppergrass (Lepidium virginicum L.).
The seed coats consist of three well defined layers. The outer
or epidermal cells are tabulated, somewhat compressed. The cuticle
forms a continuous layer over these. On the addition of water the
epidermal cells elongate and form a mucilaginous mass, showing
stratified layers. These are not difficult to make out when the
specimen is mounted in water. The cell cavity is very much re-
duced; that portion of the cell wall in contact with the cell cavity
is differentiated from the outer cell wall substance. Long con-
tinued addition of water causes the cuticle to break and the exterior
becomes very irregular.
The second layer is colored brown, the cell walls are considerably
thickened laterally and project upwardly in the shape of cones.
A section made through the ends of these seeds shows that the
second layer is considerably more developed and there are evidences
540 WEED FLORA OF IOWA
here of an indistinct layer between the first and second. The
layer following this consists of thin-walled parenchyma cells, in
some cases considerably elongated but in others short.
The third layer is followed by the endosperm which consists of
a layer of rather thick-walled parenchyma cells. These carry
granular protein grains. This is followed by one or more layers
of elongated cells, in which the cell cavity is very much reduced.
These cells reach their highest development between the folds of
the caulicle and cotyledon.
The cells of the first layer of the embryo are smaller, quite uni-
form in size and filled with protein grains and oil.
Small Peppergrass (Lepidium apetalum Willd.).
The cuticle forms a continuous layer over the epidermal cells,
which are larger than in LD. virginicwm. On the addition of water
the cell wall rapidly elongates, emitting a copious mucilage. The
cell cavity is very much reduced but longer than in L. vwirginicum.
It is surrounded by a denser, more or less differentiated part of
the cell wall which is more yellow in color than the remainder of
the cell wall. The second layer is of a yellow straw color and
consists of very minute cells with small cell cavities.
The cell walls of the third layer are strongly thickened, brown,
and serve the same purpose as in the other species. The endosperm
consists of thick-walled parenchyma cells.
In the first layer of cells, the cell walls are very much larger
and packed with protein grains. The other layers of endosperm
consist of smal] elongated thick-walled cells with a small cell cavity.
These attain their greatest development between the caulicle and
cotyledon. In the embryo, the cells of the first row are isodiametric
filled with protein grains and oil. The outer cells are elongated
larger, and also densely packed with the same material.
Shepherd’s Purse (Capsella bursa-pastoris (L.) Medic.).
The seed coats attain their maximum development in the region
of the caulicle. Cuticle covers the epidermal cells, the latter
tabular, compressed but in the addition of water elongating, be-
coming mucilaginous and showing stratification.
The second and third layers are brown with thick cell walls.
Fourth layer consists of endosperm, one layer of isodiametric cells
filled with protein grains, followed by thick-walled cells reaching
MICROSCOPIC STRUCTURE OF WHED SEEDS 541
Fic. 417. Microscopic structure of seeds of Mustard family (Cruciferae).
I. Hedge Mustard (Sisymbriwm canescens). II. Small Peppergrass (Lepidium
apetalum). To the right an enlarged epidermal cell with mucilaginous walls.
ep=epidermis. p=parenchyma. em embryo.
(Drawing by L. H. Pammel.)
their greatest development between the cotyledon and caulicle.
First row of cells of embryo. nearly isodiametric, filled with oil
and protein grains. Others somewhat larger contain the same
substances. Cotyledons incumbent. Central part of caulicle sepa-
rated from the rest. Cells of caulicle very much larger than cells
of cotyledons.
Black Mustard (Brassica nigra Koch.).
The cuticle covers the epidermal cells as a continuous layer;
when mounted in alcohol the outer layer is very much compressed
and shows very slight stratification; the cell walls expand and
after it has been moist for a considerable time the cuticle breaks.
Stratification is very evident on the addition of water. The second
layer consists of rather thin-walled parenchyma. The cells of
542 WEED FLORA OF IOWA
Fic. 418. Microscopic structure of some Cruciferous seeds (Cruciferae).
I. False Flax (Cameélina sativa). II. Black Mustard (Brassica nigra). III.
Common Mustard (B. arvense). IV. Winter Cress (Barbarea vulgaris).
V. jPeppergrass (Lepidium virginicum). VI. Tumbling Mustard (Sisym-
brium altissimum). VII. Shepherd’s Purse (Capsella bursa-pastoris).
t=testa. p=parenchyma cells. n=nucellus. em=embryo.
I, II, III, and IV. Hlongated palisade cells below the epidermal layer and
parenchyma cells. To the right of I, epidermal cells after the addition
of water.
(Drawings by L. H. Pammel.)
this layer differ greatly with reference to their size, being scarcely
at all developed in places, in others nearly as large as the cells
of the outer layer.
MICROSCOPIC STRUCTURE OF WEED SEEDS 543
The third layer consists of thick-walled parenchyma cells, densely
packed, radially elongated, sides presenting a cone-shaped appear-
ance. Underneath this is a layer of thick-walled parenchyma cells
which contain some coloring matter. The endosperm follows this
layer. The first layer consists of thick-walled cells, densely packed
with albuminous matter. The remaining cells vary in number,
are much elongated, thick-walled with a small cavity; these cells
extend down between the contiguous portions of the cotyledon or
caulicle.
The Embryo—tThe cells of the first layer surrounding the
cotyledon or caulicle are smaller, filled with fat and protein grains.
The remaining cells are larger, also filled with fat and protein
grains. The central part of the caulicle shows a differentiation of
the embryonic vascular portion, consisting of small cells.
Charlock or Common Mustard (Brassica arvensis (L.) Ktze.).
The outer layer of cells is compressed, tabular, with stratification
not evident, and cuticle well developed, and forms a continuous
layer over the outer cells; on the addition of water, the cell walls
become mucilaginous, elongate, stratification becomes evident, the
cuticle breaks, and an irregular surface is formed. The second
layer is but slightly developed, made up of thin-walled parenchyma
cells. The cells of the third layer are elongated and thickened
laterally. These cells are much longer than in B. nigra and brown
in color. The fourth layer consists of one to two rows of rather
thin-walled cells carrying pigment. Endosperm consists of several
rows of cells; first row nearly isodiametric, filled with protein
erains. The three or four layers of cells following are thick-walled
with a small cell cavity.
Embryo.—First layer of cells nearly isodiametric, those follow-
ing somewhat larger, filled with protein and fat grains.
Fiedge Mustard (Sisymbrium. officinale Scop.).
Cuticle covering the epidermal cells, the latter tabular, much
compressed. On the addition of water the cell walls become
mucilaginous with evident stratification. The cells of the second
layer are brown and thin-walled, much compressed. On addition
of choloral hydrate they expand. Third layer much darker than
the second, thick-walled, followed by endosperm, cells elongated,
filled with protein grains, followed by elongated thick-walled cells
544 WEED FLORA OF IOWA
with a small cavity. These reach their highest development between
cotyledons and caulicle. First row of cells of the embryo nearly
isodiametric, filled with protein grains and oil.
Tumbling Mustard (Stsymbrium altissimum L.).
On the addition of water the cell wall of the outer seed coat
becomes mucilaginous. Outer epidermal layer covered with cuticle,
cells elongated, on the addition of water, walls become mucilaginous
and show stratification. Cell walls of second layer thick, light
brown, followed by endosperm of two layers of cells, first elongated,
thick-walled. Cells of embryo as in S. officinale.
Hairy Hedge Mustard (Sisymbriwm canescens Nutt.).
The testa of the small brownish cells consists of an outer
epidermal layer with thick walls. These cell walls become mucil-
aginous on the addition of water. This is followed by a layer of
several rows of brownish cells and a compressed layer, the nucellus.
The cells of the outer row of the embryo are smaller than the
underlying cells.
Common Winter Cress or Yellow Rocket (Barbarea vulgaris R. Br.).
First layer of outer seed coat not well developed, cells elongated
in the direction of the seed. Cuticle covers the epidermal cells.
On the addition of water a slight mucilaginous modification takes
place. Second layer with thick lateral walls and quite large cell
cavities, colored brown. Third layer of rather thick-walled
parenchyma cells also colored brown, followed by endosperm as is
usual in cruciferous seeds.
False Flax (Camelina sativa (Li.) Crantz.).
Seed coats consisting of four layers. The outer epidermal cells
not much longer than wide, on the addition of water become
mucilaginous and well stratified. On the addition of chloral hydrate
stratification is more evident. The cell walls are differentiated
into several layers. The second layer is not always developed.
Cells of third layer with thick walls and brown pigment, followed
by a narrow layer of thick-walled brown cells. The first row of
cells of endosperm, rather thick-walled, filled with protein grains,
the other layers of unequal development, cells elongated, thick-
walled; followed by cells of embryo; these contain protein grains
and fat.
MICROSCOPIC STRUCTURE OF WEED SEEDS 545
ROSACHAH, ROSH FAMILY.
White Avens (Geum canadense Jacq.).
A greater part of the so-called seed is made up of the pericarp
consisting of a layer of small epidermal cells with trichomes. The
underlying parenchyma cells are large with numerous intercellular
spaces. -The testa is thin, consisting of an outer pigment layer
followed by several rows of thick-walled, colorless cells.
Fic. 419. Microscopic structure of fruit of Avens (Geum canadense).
ep=epidermis. p=parenchyma. per=pericarp. t=trichome. t'!=testa.
(Drawing by L. H. Pammel and Charlotte M. King.)
LEGUMINOSAE,* PULSE FAMILY.
Rattlebox (Crotalaria sagittalts L.).
The testa not strongly developed; endosperm 196” in thickness.
From Nadelmann’s studies it appears that in Crotalaria verrucosa
the horny endosperm is well developed, being four and one-half
times as wide as the testa. The aleurone layer contains fat. and
aleurone grains. The cells of the embryo contain protein and fat
but no starch.
*The descriptions here given are taken for the most part from a paper by
L. H. Pammel, Trans. Acad. Sci. St. Louis, 9.
30
546 WEED FLORA OF IOWA
Malpighian.—The cells are prismatic in surface view, 9.84
across, with five to six canals. In cross sections they are 84# long.
The cuticle forms a continuous layer, with longitudinal canals pro-
jecting into the cells; these extend down through the upper part
of the cell wall and the cuticularized substance; this layer is lighter
in color than the rest of the cell wall, and separates from the re-
mainder of the cell in the form of a band. The narrow light line
occurs close under the cuticularized layer. The cell cavity is
narrow and gradually tapers upward; it contains some protein
matter. The cell wall consists of cellulose.
Osteosclerid.—The walls are thickened. Cells wide in the lower
part and narrowing upwards, with large intercellular spaces. Cells
contain protein.
Nutrient— Consists of radially elongated cells, which are slightly
compressed. Walls of medium ‘thickness, shghtly colored.
Fic. 420. Microscopic structure of the testa of Rattle-box (Crotalaria sagittalis).
ll=light line. m=malpighian cells. n=nutrient layer. o=osteosclerid.
(Drawing by L. H. Pammel.)
‘Endosperm—Not strongly developed. The cells of the aleurone
layer large, containing protein. Two layers follow this, the cells
very much compressed, and somewhat radially elongated, of thick-
walled cells. All of the cells contain protein and fat.
Embryo.—Cells of outer row smaller; those adjoining the en-
dosperm thicker walled, the inner part with thinner walls. The re-
maining cells of the embryo larger. All of the cells filled with
protein. Starch is absent.
Black Medick (Medicago lupulina L.).
Testa and endosperm well developed, 245“ in thickness on sides.
More than half of this thickness consists of endosperm.
MICROSCOPIC STRUCTURE OF WEED SEEDS 547
Malpighian.—Cells 40-424 in length. Cuticle slightly irregular;
underneath the cuticle a light colored area with conical projec-
tions, as in Melilotus, but somewhat more prominent. With chlor-
iodide of zine this rapidly colors blue. It corresponds to the
mucilaginous ‘‘membrana interna’’ of Mattirolo and Buscalioni,
and, as shown by Schips, is chemically differentiated from the
cuticle and remainder of the cell wall. The conical layer is highly
refractive. The light line occurs below the conical layer and colors
blue soon after the addition of chlor-iodide of zine. The cell cavity
is broadest at the base, gradually tapering upward. A large
chromatophore occurs at the base or near the middle of the cell
cavity. In colored seed some pigment occurs in the cavity as well
as considerable amounts in the walls. Small pore-canals occur in
the upper part of the cell wall. The cell walls color blue more
slowly with chlor-iodide of zine than the cuticularized layer.
Osteosclerid—Cells broad at the base, with conspicuous longi-
tudinal pores; intercellular spaces below the Malpighian cells tri-
angular; walls colored brownish; cells containing pigment and
tannin. ri ;
Nutrient.—This layer is much compressed, and differentiated
into two parts; cells elongated, rather thin-walled; those in the
lower portion carry a great deal of pigment, and are much more
compressed than the upper portion.
Endosperm.—The endosperm is of unequal development, later-
ally as much as 150% in thickness. Harz gives the thickness as
250". Cells of the aleurone layer rectangular, thick-walled, and
filled with fat and protein grains. This layer is followed by re-
serve cellulose. The primary wall persists when treated with weak
solvents. The walls, except the primary, color blue with chlor-
iodide of zinc. The inner portion of the endosperm consists of
. thick-walled, elongated cells.
Embryo.—Cells of the first row smaller than those below; ex-
terior walls thickened more than the lateral; all of the cell walls
consist of cellulose. Cells contain fat and protein grains; starch
grains do not occur, though Harz says they are usually abundant.
In several specimens examined starch was not found even when
potassium hydrate or weak sulphuric acid was used with the iodine.
548 WEED FLORA OF IOWA
Fe
Fic. 421. Microscopic structures of seeds of some leguminous weeds.
I. and V. Yellow Sweet Clover (Melilotus officinalis). 1. White Sweet
Clover (Melilotus alba). III. Black Medick (Medicago lupulina). IV.
Bur Clover (Medicago denticulata).
m=malpighian cells. ll=light line of the same. o=osteosclerid. em=embrya
t=testa. en=endosperm. p=parenchyma. n=nucellus,
.(Drawings by L. H. Pammel.)
MICROSCOPIC STRUCTURE OF WEED SEEDS 549
Bur Clover (Medicago denticulata Willd.).
The seeds of this species agree with those of M. lupulina.
Malpighian cells 35-384 long; the narrow light line occurs be-
low the conical layer; the chromatophores are absent.
Osteosclerids 16-184 long; longitudinal striae well marked.
Cross sections show beyond a doubt that these striae are canals.
The nutrient layer is much compressed.
Aleurone layer of endosperm as in M. lupulina. The mucil-
aginous reserve cellulose not so strongly developed as in the last
species. Treatment with iodine gives no reaction for starch; nor
do blue grains appear when treated with weak sulphurie acid and
iodine, or potash and iodine. An abundance of fat and protein
grains occurs in the cells. Walls of the reserve cellulose color
light blue. Malpighian cells a darker blue.
Sweet Clover (Melilotus alba Lam.).
Testa and endosperm vary in thickness, average 75". Malpighian
cells as long as the thickness of the endosperm and remainder of
testa. :
Malpighian.—Cuticle wavy and well developed; the cuticularized
layer below with small, conical projections, those of two adjoining
cells meeting at the middle lamella of the lateral walls, giving the
layer the appearance of consisting of conelike projections. These
cones are also connected with the small pore-canals. This cuticular-
ized layer is highly refractive. The lhght line consists of a nar-
row but distinct refractive zone below the conical layer. The
refractive zone colors blue with chlor-iodide of zinc. The whole
upper part is more or less refractive. The remainder of the cell
wall contains pigment and is colored blue with chlor-iodide of
zine; the cuticularized layer as well as the conical layer colors
blue. Small canals project into the walls, and in some cases extend
beyond the light line. The chromatophores are irregularly dis-
tributed in the cell cavity, some near the base, others in the center.
Osteosclerid.—Cells with a broad base and a small triangular
intercellular space above; longitudinal pore-canals in the upper -
part of the cell, but these do not extend its entire length.
Nutrient—This layer is much compressed; consists of thin-
walled cells, divided into two parts; cell walls of lower part
thicker. Both layers contain pigment and tannin, the upper more
than the lower. Cell walls consist of cellulose.
550 WEED FLORA OF IOWA -
Endosperm.—The aleurone layer is quite distinct; the cells are
rectangular; cell walls made up of cellulose. The walls of the re-
mainder of the endosperm, except where it joins the embryo, are
thick, consisting of mucilaginous reserve cellulose. Cells of the
internal layer of the endosperm thick-walled, clon sey containing
some protein grains and fat.
Embryo.—Cells of the exterior walls of first row thickened;
smaller than those below. All of the cells contain fat, protein
grains, and small starch grains. Procambial vessels well developed.
Yellow Sweet Clover (Melilotus officinalis Lam.).
Testa with endosperm varying from 260-300 in thickness. The
Malpighian cells of this species are longer than in WM. alba, and
also more abundantly supplied with pigment. The conical pro-
jections are longer. The osteosclerids are longer and nearly as
wide above as below. The longitudinal canals are as conspicuous
and well developed as in that species. Cells of the nutrient layer,
especially in the lower part, are abundantly supplied with pig-
ment and some tannin. The walls of the aleurone cells are thick;
the mucilaginous reserve cellulose and the thick-walled, elongated
cells are not essentially different from the last species. It also
agrees with it with respect to the embryo.
Hairy Prairie Clover (Dalea alopecuroides Willd.) (Parosela
dalea (l.) Britt.).
Testa and endosperm from 150-265 in thickness. Variation is
mostly due to endosperm, which reaches its greatest development
laterally.
Malpighian.—Cells are 36.4" in length. Cuticle prominent;
cuticularized layer not conspicuous; narrow light line near the
cuticle; pores prominent, extending into the walls beyond the
light line. Cell cavity broad at the base, containing protein
erains.
Osteosclerid.—Cells thick-walled, lighter in color than the Mal-
pighian layer. They contain pigment, tannin and protein.
Nutrient—This layer is compressed and the cells are elongated.
Walls color blue with chlor-iodide of zinc. Brown pigment
abundant in the vascular region.
Endosperm.—Aleurone cells nearly isodiametric, containing fat,
and protein; most of the endosperm consisting of reserve cellulose
MICROSCOPIC STRUCTURE OF WEED SEEDS 551
Fie. 422. Microscopic structure of leguminous seeds (Leguminosae).
I. Silky Sophora (Sophora sericea). II. Parosela (Dalea alopecuroides). III.
Common Vetch (Vicia sativa). IV. Stemless Locoweed (Oxvytropis lam-
verti). V. Wild Liquorice (Glycyrrhiza lepidota).
m=malpighian cells. l=light line. em=embryo. o=osteosclerid. p=parenchy-
ma. al=aleurone layer. en=endosperm. en=endosperm reserve cellulose
cells. tr=tracheae.
(Drawings by L. H. Pammel.)
552 WEED FLORA OF IOWA
with prominent pore-canals; the internal layer consisting of
elongated thick-walled cells, with cell cavity much reduced.
Embryo—First row of cells of embryo smaller than underlying,
with thickened outer walls. Cells below with small intercellular
spaces. Reserve material consists of fat and protein grains;
starch is absent.
Stemless Loco Weed (Oxytropis lamberti Pursh.).
Testa and endosperm 170-1754. This, the so-called loco weed, is
said to cause disturbances in animals, but alkaloids have not been
found in the seed or any other part of the plant.
Malpighian.—Cells 40-424 long. Cuticle somewhat uneven; the
narrow well marked cuticularized layer colors blue with chlor-
iodide of zinc; the light line occurs below the cuticularized layer,
and this also colors blue; the remainder of the cell wall takes on
a darker blue color. Cells contain an abundance of pigment,
tannin, and some plastic material.
Osteosclerid.—Cell walls thickened, not prominently I-shaped,
but with an elongated intercellular space.
Nutrient.—Layer consists of thin-walled elongated cells from
ten to twelve rows. Pigment more abundant in lower than in
upper part. Walls color blue with chlor-iodide of zine.
Endosperm.—The aleurone layer consists of thick-walled cells;
the underlying thick-walled ‘cells of the reserve cellulose become
mucilaginous on the addition of water. The internal part consists
of thick-walled, elongated cells. The cells contain protein.
Embryo.—Cells of the first row smaller, with thick exterior
walls; cells below not so compact atid with thinner walls. Cell
walls color blue with chlor-iodide of zine. Starch is absent but
cells contain fat and protein.
Bush Clover (Lespedeza capitata Mx.).
Testa and endosperm 90-100 thick. Light line occurs close
under the cuticle. A large spherical chromatophore occurs in the
pigmented Malphigian cells which is variable as to its position in the
cell. The long pores extend to the middle of the cell. The os-
teosclerids are short. The nutrient layer is compressed, containing
much pigment. Endosperm as in D. stuvei; the aleurone cells are
thick-walled, and the reserve cellulose is mucilaginous. Embryo
as in the other species containing fat and protein but no starch.
MICROSCOPIC STRUCTURE OF WHED SEEDS 553°
Common Vetch (Vicia sativa L.).
This species has been studied by Harz, Tschirch and Oesterle,
Beck, and Sempolowski. Testa irregular, with small projections,
126 thick. Endosperm reduced to a single layer. The presence
of endosperm has been indicated by the above writers. Beck
speaks of an aleurone spot: (Aleurone fleck) in the epidermal cells
of the cotyledons of this and other species of the genus Vicia.
Malpighian.Cells 72-75" long, pointed at the upper end;
cuticle very irregular because of the projections; cuticularized
layer most prominent in the depressions; pores project into the
walls below the light line, and partly connect with the cell cavity;
_the upper part of the cell is not pigmented, or very little. The
light line oceurs just above the pigmented part of the cell. Cell
cavity is large at the base, narrows upward, becoming much con-
stricted below the light line, and above widens again. Small
lateral projections or pores extend into the wall at right angles to
the cavity. A large chromatophore, some pigment, and small
granules occur in the cavity. The walls in lower part of cell are
colored bluish brown.
Osteosclerid.—Cells are thick-walled, 13-16.8- long, longitudinally
striated. Upper and lower ecross-bars nearly equal; the inter-
cellular spaces elongated. Tschirch and Oesterle state that this
layer is not very strongly developed, but in specimens which I
have examined it is well developed. These cells are more or less
variable, as indicated by Harz, who states that they are from
11-13" long.
Nutrient —This layer is differentiated into two parts; the upper
consists of thin-walled, elongated cells with a yellowish pigment;
the cells of the lower part are larger, thin-walled and elongated,
containing a brown pigment.
Nucellus.——This consists of a narrow zone of compressed cells.
Endosperm.—Ocecurs in the form of thick-walled elongated cells
with a narrow eell cavity. Usually only one or two rows of cells.
_ Hmbryo.—The outer row of cells of the cotyledon is continuous.
The exterior walls are thickened; cells below are more loosely ar-
ranged; small intercellular spaces in the angles of the cells; the
epidermal cells contain fat and protein, the others in addition an
abundance of spherical or elliptical starch grains measuring 25
x22.5" to 50x25". Palisade cells wanting.
554 WEED FLORA OF IOWA
Wild Liquorice (Glycyrrhiza lemdota (Nutt.) Pursh.).
Testa and endosperm 490-500" thick. Endosperm variable in
different parts of the seed, but usually well developed.
Malpighian—Cells 70-75" long. Cuticle somewhat irregular;
the light colored cuticularized layer is followed by a narrow but
sharply marked zone, the light line; cell cavity is large at the base,
gradually tapering upward. Pore-canals extend into wall beyond
the ight line. Cells contain pigment and some plastic material.
Osteosclerid.—The I-shaped cells are thick-walled, with small
projections somewhat similar to those shown for Ervuwm lens by
Mattirolo and Buscalioni. The intercellular space is elongated.
The cells attain their greatest development in the hilar region.
All of the cells carry some pigment and plastic material.
Nutrient.—This layer is much compressed and thin-walled; cells
number from four to six rows. Pigment is most abundant in the
lower part of the layer.
Endosperm.—Aleurone layer consists of nearly isodiametric
thick-walled cells. The mucilaginous reserve cellulose is variable
in quantity. Cell walls differentiated into primary, secondary and
tertiary. Internal part of the endosperm consists of thick-walled,
elongated cells. All of the cells contain protein grains.
Embryo.—Cells of the outer row smaller than those within; ex-
terior walls thickened, those below more loosely arranged than the
-epidermal; more compact and with thicker walls than those of
Astragalus meaxicanus. Cells contain fat and protein grains but
no starch.
LINACEAE, FLAX FAMILY.
Common Flax (Linwm usitatissimum L.).
The shining, brownish seeds consist of an outer epidermal layer
of thick-walled cells; walls colorless and stratified; these become
mucilaginous on the addition of water. The cell cavity is very
small, the underlying layer consists of yellowish parenchyma cells.
The third, called the fiber layer by Winton, consists of sclerotic
parenchyma cells with pore-canals, the sclerotic parenchyma fol-
lowed by a layer of colorless cross-cells with thin walls. The
parenchyma cells of the pigment layer follow; these cells are
squarish, pigment yellowish brown. The endosperm follows the
MICROSCOPIC STRUCTURE OF WEED SEEDS 555
Fic. 428. Microscopic structure of the seed of common Flax (Linum usitatis-
simum). :
ep=epidermis. p=parenchyma, underneath thick-walled sclerenchyma cells and
the pigment layer. pi=pigment layer. en=endosperm.
(Drawing by L. H. Pammel and Charlotte M. King.)
pigment layer and consists of 2-6 layers of cells, the walls being
thicker than those of the embryo, and containing fat and aleurone
grains. The epidermal cells of the embryo are squarish, the cells”
underneath on the upper face of the cotyledon are palisade-like.
All of the cells contain fat and protein.
' GERANIACEAE, GHRANIUM FAMILY.
Carolina Cranesbill (Geranium carolinianum L.).
The testa of the smooth small seeds consists of an outer epider-
mal layer, the cell walls not greatly thickened; underlying it
is a single row of elongated parenchyma cells followed by the Mal-
phigian cells; the light line is narrow and occurs in the middle of
the cell; this is followed by a layer of much larger cells with
thick walls. The inner seed coat is much compressed and consists
of several rows of small cells and a single row of large cells. The
walls in both cases are not greatly thickened. The nucellus is
much compressed. The cells of the endosperm are not much longer
than broad. The cells of the outer row or the aleurone layer are
much smaller than those of the second layer.
556 WEED FLORA OF IOWA
pal
Fe wes Se ee
€ 9Gn.
A Z ee en
aa
3Be
Fic. 424. Microscopic structure of the seed of common Geranium (Geranium
carolinianum).
p=parenchyma, malpighian cells below. ll=light line of mal-
ep=epidermis.
pal=palisade cells. it=inner testa. n=nucellus. en=en-
pighian cells.
dosperm.
(Drawing by L. H. Pammel and Charlotte M. King.)
EUPHORBICEAH,* SPURGH FAMILY.
Flowering Spurge (Huphorbia corollata L.).
The outer layer of the seed coat is mucilaginous; the walls of
the cells are thickened and colorless; showing stratification upon
addition of water; the cell contents are dark in color. The granu-
lar layer beneath the mucilaginous cells is well developed; the con-
tents give a blue reaction to iodine. Underneath the granular
layer is a row of slightly elongated thin-walled parenchyma cells;
beneath these are the long palisade-like cells, in which are pores
of less prominence than in HL. marginata and others. Next lie two
compressed layers of thin-walled parenchyma cells.
Spotted Spurge (Huphorbia preslii Guss.).
The outer layer of cells are darkened; these cells are not
mucilaginous. The palisade-like cells are present, as in all the
species.
*The descriptions here given are from a paper by L. H. Pammel, Trans.
Acad. Sci. St. Louis. 5:543. The literature will be found in this paper.
MICROSCOPIC STRUCTURE OF WEED SEEDS 557
Prostrate Spurge (Huphorbia maculata L.).
The walls of the outer cells are dark in color; these cells are
but slightly mucilaginous. The granular layer is not pronounced.
The palisade-like cells resemble those of the other species.
Fie. 425. Microscopic structure of the seeds of the Spurge family (Huphor-
: biaceae).
I. Cypress Spurge (Huphorbia cyparissias). II. Flowering Spurge (Huphor-
bia corollata).
ep=epidermis, in figure II cell-walls mucilaginous. pal=palisade cells. p=
parenchyma cells. ;
(Drawing by L. H. Pammel.)
Yellow Spurge (Huphorbia cyparisstas L.).
The seed shows the usual palisade-like cells with the overlying
and underlying thin-walled parenchyma cells.
MALYVACEAH, MALLOW FAMILY.
Velvet Weed, Butterprint (Abutilon theophrasti Medic.).*
The outer layer a, of the first integument is transformed into a
strongly refractive layer. The second layer is composed of radially
elongated cells. The seed hairs arise from a single cell and are
large and conspicuous. The hairs are spindle-shaped and thin-
walled; they occur mostly at the ends of the seed and are more or
less pressed to it. There is little or no coloring matter in this in-
*From Rolfs, P. H., Bot. Gaz. 1892 :33-39.
558 WEED FLORA OF IOWA
tegument excepting in the base of the hair cells. The palisade
cells, c, are narrow for their length. The cell cavity is not promi-
nent and the nodosity is inconspicuous. The light line is narrow
and occurs near the outer end of the palisade layer. The sub-
palisade portion, d, is made up of two layers of light brown cells.
They are symmetrical and elongated tangentially.
Measurements, seed coats, 1474; outer integument, 134; palisade
layer, 96"; subpalisade, 38.
Shoo-fly (Hibiscus trionum L.).
P. H. Rolfs has made a study of H. militaris, the microscopic
structure of which species closely resembles that:of H. trionwm.
The dark grayish seeds are roughened with tubercular processes,
which contain the ‘‘seed hairs.’? The seed hairs consist of cells
somewhat longer than broad beginning with a broad base, ex-
tending into a several-celled trichome, the terminal portion larger
than remainder of cell. These hairs contain a yellow pigment.
The Malpighian cells occupy about one-half the thickness of the
testa, the cuticle is well developed, the hght line is near the upper
portion of the cell. The cell cavity is spindle-shaped and near
the middle of the cell. The remainder of the testa consists of a
subpalisade portion of parenchyma cells carrying a brownish pig-
ment; underneath it, larger thin-walled cells; walls brownish, a
compressed narrow, brownish layer, the nucellus, n. This is fol-
lowed by the squarish cells of the endosperm.
Common Mallow (Malva sylvestris L.).
The surface of M. sylvestris is rough in appearance. The second
layer, b, of the outer integument, a, has been compressed into a
thin layer and seems to have no definite arrangement. The outer
layer, a, has been elongated radially. In places, these elongated
‘eells have divided forming a double layer of cells. There is no
brown coloring matter in this integument nor is there any between
the integuments. The palisade cells, c, are clear; the walls thick.
The cell cavity occupies about one-third the length of the cells,
the lower end reaching to the middle. The nodosity is promi-
nent. Below the cavity the cells are clear, almost transparent.
The subpalisade portion, d, is usually made up of two layers, at
some places only one, of large dark brown eells.
MICROSCOPIC STRUCTURE OF WEED SEEDS 559
Measurements, seed coats, 122”; outer integument, 274; outer
layer of same, 22”; inner layer of same, 5“; palisade layer, 70#;
subpalisade, 254. (P. H. Rolfs.)
Fie. 426. Microscopic structure of the seeds of some Malvaceous weeds.
I. Shoo-fly (Hibiscus trionum). II. Indian Mallow or Butterprint (Abutilon
theophrasti). III. Mallow (Malva sylvestris). IV. Sida (Sida spinosa).
V. Cheeses or common Mallow (Malva rotundifolia).
ep=epidermal cells. m=malpighian cells. ll=light line. pi=pigment layer. D=
parenchyma cells. pal=palisade or malpighian cells. n=nucellus. en=en-
dosperm. h=trichome. t=plant hair or trichome surface view
(Drawings by P. H. Rolfs.)
Cheeses or Mallow (Malva rotundifolia L.).
The roughened, somewhat velvety, dark grayish seeds consist
of an outer row of rather large, rather thick-walled cells, walls
colorless. This layer is followed by the very long Malpighian
‘cells, which are longer than the cells of the rest of the testa, light
line near the upper part of the cell, lower portion of cell slightly
yellowish. Cavity spindle-shaped near the middle. The dark
560 WEED FLORA OF IOWA
brownish pigment cells of two or three rows. Adjacent to the
pigment layer is the colorless compressed nucellus and the squarish
endosperm cells.
Sida (Sida spinosa L.).
The brownish seeds are minutely roughened. The Malpighian
cells occupy more than one-half of the thickness of the testa, the
cuticle is well developed, the light line occurs near the upper end
of the cells. The cell cavity is spindle-shaped near the lower end
of the cell. The subepidermal layer contains the brownish pig-
ment, the walls of these cells are thickened; the parenchyma cells
of the layer underneath are colorless, the walls are less thickened;
a narrow pigment layer follows. The cells of the endosperm are
thick-walled containing protein grains.
ONAGRACHAH, EVENING PRIMROSE FAMILY.
Evening Primrose (Oenothera biennis L.).
The small, irregular, winged seeds are rough. The epidermal
cells, ep, of the testa are small, thick-walled with minute pore
canals; the underlying parenchyma cells, p, are large, thick-walled
and with small pore canals; these cells reach their greatest develop-
ment where the wings occur. The remaining portion of the testa
consists of four or five layers of cells more or less rectangular.
The nucellus and the endosperm much compressed, outer epidermal
cells of the embryo, em, thin-walled, a little longer than wide.
Bez
Fic. 427. Microscopic structure of the aie. of Evening Primrose (Oenothera
biennis).
ep=epidermis of thick-walled cells. p=thick-walled parenchyma underneath
thinner-walled parenchyma. n=nucellus and below a few layers of cells of
the endosperm.
(Drawing by Charlotte M. King and L. H. Pammel.)
MICROSCOPIC STRUCTURE OF WEED SEEDS 561
UMBELLIFERAH, PARSLEY FAMILY.
Sweet Cicely (Osmorrhiza longistylis (Torr.) D.C.).
The epidermal cells are longer than broad, the outer walls are
thickened, five to six rows of thin-walled parenchyma cells occur
underneath the epidermal layer; the ribs contain the vascular ele-
ments, thick-walled sclerenchyma cells; the testa consists of a
layer of thin-walled. parenchyma eells, p, followed by a layer tan-
gentially elongated and-another of large parenchyma cells, p*, and
the compressed nucellus, n.. The endosperm consists of large thin-
walled cells.
Fic. 428. Microscopic structure of some Umbelliferous weeds.
I. Sweet Cicely (Osmorhiza longistylis). II. Cow Parsnip (Heracleum lana-
tum). III. Wild Carrot (Daucus carota). Underneath, parenchyma cells,
thick-walled sclerotic parenchyma, sectional view to the right.
n=nucellus. p=parenchyma. t=testa. en=endosperm. ep=epidermis. o=oil
duct.
(Drawings by L. H. Pammel.)
36
562 WEED FLORA OF IOWA
Wild Carrot (Daucus carota L.).
The cremocarp consists of an outer epidermis of cells some-
what longer than broad; the underlying cells are of similar struc-
ture except the cells near the inner epidermis, which are much
longer than wide; a large oil duct occurs in each rib. The testa
consists of a single layer of parenchyma cells and a few rows of
compressed elements, probably the nucellus. The endosperm of
thin-walled parenchyma cells contains protein.
Cow Parsnip (Heraclewm lanatum).
An outer epidermis with outer walls thickened. The underlying
parenchyma cells similar, followed by a layer of thick-walled
sclerenchyma cells. The testa of single layer of cells. The en-
dosperm cells contain protein.
ASCLEPIADACEAE, MILKWEED FAMILY.
Milkweed (Asclepias syriaca L.).
The flattened reddish brown seeds consist of an epidermis of
isodiametric cells; the outer walls wavy, and thickened; each cell
with a projecting point, outer walls colorless, contents brownish;
the epidermis is followed by 10-14 rows of thin-walled parenchyma
cells containing a brownish pigment. This layer is followed by
oP
Fic. 429. Microscopie structure of the seed of Milkweed (Asclepias syriaca).
ep=epidermis. p=parenchyma. n=nucellus. em=embryo.
(Drawing by L. H. Pammel and Charlotte M. King.)
MICROSCOPIC STRUCTURE OF WEED SEEDS 563
the compressed perisperm, brownish yellow in color. The endo-
sperm consists of thickish-walled, colorless parenchyma cells, the
outer row smaller than the underlying, the inner layer of smaller
elongated cells. The contents consist of protein and fat. The
inner epidermal cells of the embryo are smaller than the endo-
sperm cells; they contain protein and fat.
CONVOLVULACHAE, CONVOLVULUS FAMILY.
European Bindweed (Convolvulus arvensis L.).
The testa consists of an outer row of short or elongated cells p
with thick walls and brownish contents. This is followed by a
layer of small cells with colorless walls. Contents brownish. The
Malphighian cells m are situated underneath. This is followed by
a layer of parenchyma cells consisting of 8-12 rows of cells. The
endosperm consists of thick-walled colorless cells. The walls in
part mucilaginous.
Fic. 430. Microscopic structure of the seeds of Convolvulaceae.
I. Morning-glory (Convolvulus sepium). II. Cultivated Morning-glory (Ipomoea
purpurea). III. Dodder (Cuscuta epithymum). IV. Bindweed (Convol-
vulus arvensis).
ep=epidermis. m=malpighian cells. ll=light line. p=parenchyma. n=nucellus.
en=endosperm. a8
(Drawings by L. H. Pammel and Charlotte M. King.)
564 WEED FLORA OF IOWA
Wild Morning Glory (Convolvulus sepium L.).
The testa of the seed of the common morning glory consists of
an outer layer of elongated cells containing the blackish pigment
followed by the Malpighian cells with small cell cavity and promi-
nent light line. The colorless parenchyma cells are thick-walled
followed by a compressed indistinct layer, the compressed nucellus
and the endosperm cells.
Cultivated Morning Glory (Ipomoea purpurea (.) Roth.).
The black-brownish seeds are rough. The testa. consists of a
superficial layer of cells with granular brownish contents. The
Malpighian cells m occur underneath; the light line is near the
upper part of the cell, cell cavity small. The cells of the paren-
chyma layer are compressed. The cells of the endosperm are thick-
walled and somewhat mucilaginous.
Dodder (Cuscuta epithymum Maurr.).
The small seeds are minutely roughened and velvety. The outer
layer of the testa consists of large cells with yellowish contents,
the following layer consists of thick-walled cubical or prismatic
cells p, the colorless Malpighian cells m follow. They are elongated
with a small cell cavity. The layer following consists of com-
pressed cells, tangentially elongated. The endosperm layer con-
sists of an outer aleurone layer of nearly square cells. The cells
below are irregular. The endosperm cells contain compound or
simple starch grains and protein.
BORAGINACHAEH, BORAGE FAMILY.
Wild Comfrey (Cynoglossum virginianum L.).
The rough fruits are covered with hooked appendages, the sides
roughened with small colorless points; the epidermal layer is ir-
regular and prominent, in some cells developed into short trichomes,
whose walls are greatly thickened. The epidermal walls and con-
tents are blackish, the underlying sclerotic parenchyma cells have.
thick walls and are blackish. The parenchyma cells of the testa
are thinner walled and colorless, followed by the compressed layer
of the nucellus n. The endosperm cells are longer than broad,
colorless, contain protein and fat.
MICROSCOPIC STRUCTURE OF WEED SEEDS 565
Fic. 431. Microscopic structure of some fruits of the Borage Family (Boragin-
aceae).
I. Stickseed (Lappula echinata) part of fruit or bur. II. Stickseed (Lap-
pula echinata). Enlarged view of epidermal cells showing irregularities in
cell wall and cavity. III. Wild Comfrey (Cynoglossum virginianum).
ep=epidermal cells. n=nucellus. pi=pigment layer. en=endosperm. t=tri-
chomes. ;
(Drawings by L. H. Pammel and C. M. King.)
Stickseed (Lappula echinata Gilibert).
The fruits are rough and provided with hooked appendages,
the cells of the appendages are elongated, thick-walled, the walls
colorless; the cells of the epidermis toward the exterior are very .
irregular with projecting rounded or sharp points, walls colorless.
The epidermal cells are elongated with central cell cavity and
prominent pore canals at right angles with the cell cavity, these
having the appearance of a series of cells one above the other.
The epidermal cells contain a brownish pigment, the underlying
parenchyma cells are thinner walled and also contain a brownish
566 WEED FI.ORA OF IOWA
pigment. The testa is thin, consisting of thin-walled parenchyma
cells with granular contents.
VERBENACEAE, VERVAIN FAMILY.
Hoary Vervain (Verbena stricta Vent.).
Epidermal cells thick-walled; ‘outer cells colorless. Underneath
this lie several layers of pigmented cells, slightly longer than broad.
This layer is followed by rather thick-walled, colorless cells, with
small cell cavity; one or two rows toward the middle are thick-
walled and smaller. Next follow the cells of the embryo.
Fic. 432. Miscroscopic structure of seed and fruit of Vervain (Verbena stricta).
ep=epidermis, thick-walled. p=parenchyma layer. pi=pigment layer of small
parenchyma cells. The two inner layers of cells of the testa.
(Drawings by L. H. Pammel and Charlotte M. King.)
LABIATAE, MINT FAMILY.
Catnip (Nepeta cataria L.).
The small dull brown seeds are finely roughened. The pericarp
consists of an epidermal layer with thin cuticle, on the addition
of water becoming mucilaginous. This layer is followed by under-
lying parenchyma cells, then the Malpighian cells with conspicuous
light line. The cells are colored yellowish brown; underlying this,
MICROSCOPIC STRUCTURE OF WEED SEEDS 567
the testa, consisting of a single layer of cells, thin-walled. The
nucellus of whitish, elongated, rather thick-walled cells, the en-
dosperm differentiated into an outer layer of larger parenchyma
and a compressed inner layer of thick-walled cells. The epidermal
cells of the embryo nearly isodiametric, contain protein and fat.
The epidermal cells of the upper epidermis nearly like the lower,
palisade parenchyma underneath.
Fic. 433. Microscopie structure of seeds of the Mint Family (Labiatae).
I. Catnip (Nepeta cataria). II. Giant Hyssop (Agastache scrophulariaefolia).
ep=epidermis, underneath, parenchyma cells in I and sclerotic parenchyma in
II, the epidermal cells irregular showing some trichomes. scl=sclerotic
parenchyma. en=endosperm. m=malpighian cells. n=nucellus. ll=light
line. p=parenchyma. em=embryo.
(Drawings by L. H. Pammel and C. M. King.)
Giant Hyssop (Agastache scrophulariaefolia (Willd.) Ktze.).
The small pubescent nutlet consists of the epidermal cells of
the pericarp with small unicellular thickened trichomes; cells con-
tain a brownish pigment; the cells of: the layer underneath are
thick-walled, cell wall and cavity contain a brownish pigment.
The Malpighian layer follows, the cells being longer than wide,
the light line near the upper part of the cell. These cells are
yellowish. The testa is compressed and consists of elongated cells,
brownish in color. The endosperm varies in thickness, the cells
are in some cases elongated, in others squarish, and contain fat
and protein material.
568 WEED FLORA OF IOWA
SOLANACHAE, NIGHTSHADE FAMILY.
Horse Nettle (Solanum carolinense L.).
The testa consists of an outer row of cells whose walls are
mucilaginous ; the underlying cells are thick-walled with interven-
ing air spaces broad below and narrow above. The cells of this
layer contain the yellow pigment. The underlying parenchyma
layer is compressed, composed of colorless cells which are longer
than wide; the layer adjacent to the endosperm is compressed
and not clearly defined. The cells of the inner portion of the
endosperm are smaller and contain protein. Cells of embryo are
small and contain protein.
Fig. 434. Microscopic structure of the seeds of some Solanaceous weeds.
I. Jimson Weed (Datura stramoniwm). II. Black Nightshade (Solanum ni-
grum). III. Buffalo Bur (Solanwm rostratum). IV. Horse Nettle (Sola-
num carolinense). V. Ground Cherry (Physalis pubescens).
ep=epidermis. en=endosperm. pal=palisade cells. em=embryo. p=parenchyma. p!=
elongated parenchyma cells.
(Drawings by L. H. Pammel and C. M. King.)
MICROSCOPIC STRUCTURE OF WEED SEEDS | 569
Buffalo Bur or Spiny Nightshade (Solanum rostratuwm Dunal).
The black seeds are irregular on the surface, which is mucil-
aginous; the underlying layer consists of thick-walled cells with
large cavities into which thickened processes extend; the third
layer is also pigmented and consists of squarish cells or elongated,
compressed elements. The endosperm is composed of thick-walled
cells, the outer nearly square, the others elongated. Starch ab-
sent; protein present. The cells of the embryo are smaller, thin-
walled and contain protein and fat.
Black Nightshade (Solanum nigrum L.).
The surface of the yellowish seeds is slightly irregular. The
superficial layers consist of mucilaginous, parenchyma, cells, fol-
lowed by large parenchyma cells with thickened folds. These cells
are, however, variable as to structure and are sometimes short
with folds not evident. The elongated, thick-walled portion of
the testa contains the yellowish pigment. The cell cavity is tri-
angular. The second layer of parenchyma cells is compressed.
Jimson Weed (Datura stramonum L.).
The blackish seeds are rough, surface irregular, cells and walls
of epidermis ep thick; the underlying thinner-walled cells » are
small, longer than broad, followed by an indistinct layer p’, whose
walls are not clearly defined. The layer adjacent to the endosperm
consists of somewhat larger cells also thin-walled. The endosperm
cells e are large, containing protein.
Ground Cherry (Physalis pubescens L.).
The epidermal cells are thick-walled, the outer walls colorless.
These cells contain the pigment. The parenchyma cells of the
second layer are elongated; an indistinct compressed layer follows.
The outer row of the endosperm cells are smaller, containing
protein.
A discussion of the seed coats of this family is to be found in Harz, Samen-
kunde, 2 996-1025.
570 WEED FLORA OF IOWA
SCROPHULARIACEAE, FIGWORT FAMILY.
Mullein (Verbascum thapsus L.).
The minute, roughened seeds are irregular. The epidermal cells
are dark colored, longer than broad and thick-walled. The epider-
mal layer is followed by one or more layers of parenchyma eells,
more numerous in the micropilar region; an indistinct and com-
pressed layer with large intercellular spaces follows, these corre-
sponding to the irregularities on the surface, smaller intercellular
Fic. 435. Microscopic structure of the seeds of the Figwort family (Scrophul-
ariaceae).
I. Moth Mullein (Verbascum blattaria). II. Common Mullein (Verbascum
thapsus).
ep=epidermis. p=parenchyma. al=aleurone layer. en=endosperm. em=em-
bryo.
(Drawings by L. H. Pammel and Charlotte M. King.)
spaces occurring between the larger. The nucellus is compressed,
showing remnants of cell walls. The endosperm consists of an
outer aleurone layer, the walls with pore canals; this is followed .
by cells of the same character. The cells of the embryo are
smaller. The testa of Verbascum blattaria in an undeveloped seed
consists of the epidermal cells with chlorophyll and the SEES
much larger cells also with chlorophyll.
MICROSCOPIC STRUCTURE OF WEED SEEDS 571
PLANTAGINACEAH, PLANTAIN FAMILY.
Common Plantain (Plantago major 1.).
The small, yellowish brown seeds consist of an epidermal layer
of thick black-brownish seeds. The walls on the addition of water
become mucilaginous and expand. The cell cavity is small. The
epidermal layer is followed by several layers and small parenchyma
cells. These cells are usually somewhat compressed and brownish
in color. The pigment layer and endosperm consist of an outer
layer of aleurone cells smaller than the underlying eells. These
cells contain protein grains and starch; the walls have small: pore
canals.
Bre
en
'
t
'
1
wn
:
Fig. 486. Microscopic structure of the seeds of Plantain family.
I. Bracted Plantain (Plantago aristata). II. Common Plantain (Plantago
major). III. Buckhorn (Plantago lanceolata).
1l=epidermal cells showing stratification. c=cell cavity. ep=epidermis. pi=un-
derlying parenchyma cells. 2=underlying parenchyma cells of the testa.
em=embryo. n=nucellus. p=parenchyma cells. en=endosperm.
(Drawings by L. H. Pammel and C. M. King.)
572 WEED FLORA OF IOWA
_ Buckhorn (Plantago lanceolata L.).
The smooth, brownish, elongated seeds consist of epidermal cells
with a small cavity and thick walls; the outer walls become mucil-
aginous on the addition of water. The underlying cells are thin,
blackish, elongated, followed by a brown pigment layer as in the
last species. The aleurone cells and remaining endosperm cells
are of about the same shape and size; the walls are provided with
small pore canals.
Bracted Plantain (Plantago aristata Mx.).
The seeds of this are similar in structure to those of P. lance-
olata. The walls of the epidermal cells are mucilaginous. The
underlying parenchyma cells and the underlying pigment layer
are followed by the endosperm and embryo. The cells of the
nucellus are narrow, elongated, and thick-walled. The eells of
the embryo are isodiametric and are thin-walled. Several species of
the genus have been studied by Harz*. Numerous earlier papers
and references will be found in Pammel’s article in Transactions
St. Louis Academy of Science, 9:91.
RUBIACHAH, MADDER FAMILY.
Bedstraw (Galium aparine L.).
The dry fruit of the common bedstraw is provided with hooked
prickles. The epidermal cells are somewhat elongated, brownish.
The trichomes consist of single hooked cells with pitted walls. The
underlying thin-walled parenchyma cells are elongated. Harz ob-
served mucilaginous cells in this portion of the- pericarp. The
testa is very much reduced, consisting of several layers of thin-
walled cells with granular contents. The endosperm consists of
an aleurone layer, thick-walled cells followed by a thick-walled
irregular layer of cells with pore canals. Contents consist of pro-
tein grains.
*Samenkunde 2; 983.
MICROSCOPIC STRUCTURE OF WEED SEEDS 573
Fic. 437. Microscopic structure of fruit of Bedstraw (Galium aparine).
ep=epidermis. t=testa. t! =trichome. en=endosperm.
(Drawing by L. H. Pammel and Charlotte M. King.)
CUCURBITACEAE, GOURD FAMILY.
Wild Cucumber (Sicyos angulatus L.).
The testa of the brownish seeds consists of elongated epidermal
cells with narrow cell cavities; walls thickened, with pore canals.
The underlying portion consists of a layer of one or two rows of
cells with thin walls, and protein contents; the remaining portion
of the testa is composed of thin-walled cells with large inter-
cellular spaces. The related species, Echinocystis lobata, contains
a thick, pigment layer of brownish sclerotic parenchyma followed
by a thinner layer of thick-walled cells with blackish brown pig-
ment. In this species, as in Sicyos angulatus, frequently portions
of the fruit adhere to the surface. The seed coats of this family
have been described-by Harz.
574 WEED FLORA OF IOWA
Fic. 438. Microscopic structure of seeds of some cultivated weeds.
I. Wild Cucumber or Wild Balsam Apple (Echinocystis lobata). II. Bur
Cucumber (Sicyos angulatus). f
ep=epidermis. ll=light line. p=parenchyma. m=malpighian layer. scl=scler-
otic cells.
(Drawings by L. H. Pammel and C. M. King.)
COMPOSITAE, COMPOSITE FAMILY.
Large Ragweed (Ambrosia trifida IL.).
The so-called ‘‘seed’’ consists of an inyolucre of rather thick-
walled sclerotic parenchyma cells, occurring underneath the
epidermis; some of these cells are radially elongated, others are
spherical in cross section, showing numerous pore canals. The
internal layer of the involucre is composed of nearly isodiametric,
thick-walled, sclerotic cells. The testa consists of a layer of brown-
ish colored cells followed by a layer containing black pigment.
Next within lies a layer of thick-walled, small, nearly colorless
cells, then the compressed layer of the nucellus, followed by the
nearly square cells of the embryo.
MICROSCOPIC STRUCTURE OF WEED SEEDS > 575
Common Sunflower (Helianthus annuus L.).
The microscopic structure of the fruit and seed has been studied
by Hanausek, Harz, Winton and Moeller. The obovoid achenes
are more or less four-sided. The pericarp in some varieties is
nearly black, in others it is striped with white and black. The
pericarp consists of thin porous walls which are dark colored in
the black seeded varieties, although in the varieties with striped
seeds only a part of the cells are colored. Some of the cells are
elongated, forming duplex hairs, which are attached to what
Hanausek called the ‘‘foot cell.’? The underlymg hypodermal
cells of 4-6 rows of cells are thick-walled and porous, the cells ar-
ranged in rows. These contain the blackish pigment, pitchlike in
character. The third layer consists of thick-walled sclerotic
parenchyma cells. These cells are more or less isodiametric. This
layer contains the fibrovascular bundles which occur adjacent to
the thin-walled parenchyma eells. Extending into the sclerotic
parenchyma are radial rows of thinner-walled parenchyma cells.
This layer is followed by large thin-walled parenchyma cells. The
testa consists of thin-walled loose parenchyma cells. The outer or
epidermal cells are roundish and have obscurely beaded walls;
the spongy parenchyma follows and contains the fibrovascular
bundles. The spongy parenchyma is followed by the rectangular
cells of the inner epidermis. The endosperm consists of one or
two rows of aleurone cells. The epidermal layer of the embryo
consists of small, rather thin-walled cells of the cotyledons and
underneath! this on the upper surface are several rows of palisade
cells. These cells contain irregular spherical aleurone grains larg-
er than those in the epidermal cells.
Crownbeard, (Verbesina helianthoides Mx.).
The microscopic structure of the achene includes a series of small,
rather thick-walled epidermal cells, followed by elongated or short,
rather thick-walled parenchyma cells. The pigment layer is com-
posed of thick-walled cells, whose walls contain a blackish pigment.
The testa consists of two layers; an outer of elongated, thick-walled
cells and an inner layer of shorter cells also colorless. The cells
of the embryo are much larger and contain protein grains.
Boot-jack, Spanish Needle (Bidens discoidea (T. & G.) Britton).
The pericarp consists of an outer epidermal layer underlaid by
a similar layer of elongated, thick-walled cells; between which are
576 WEED FLORA OF IOWA
thinner-walled parenchyma cells. The outer layer of the testa
is composed of nearly isodiametric cells, followed by larger thick-
walled parenchyma cells; cells of the lower portion compressed. The
endosperm is much reduced, of elongated cells; embryo with row
of outer cells longer than broad.
cK
J
>
Z ‘
o> 7. AWA ) A
haces (i
Bra \e
<
Ay
Wy
ry Co
1 .
é
/
Fig. 439A Fig. 439 B
Fic. 439. Sunflower (Helianthus annuus).
A. Cross section of outer layers of pericarp. 0, epicarp with h, .hairs; K,
hypoderm; H, fiber bundles separated by m, parenchyma; p, parenchyma
with g, fibro-vascular bundles. X 160.
B. Epicarp with h, twin hairs, in surface view.
After Winton.
Burdock (Arctium lappa L.).
The brownish mottled fruits consist of a thick-walled pericarp,
the outer epidermal layer of thick-walled cells, walls colorless or
but slightly colored; the underlying layer of six or eight rows of
thick-walled cells, not as thick, however, as the epidermal cells.
The first layer carries the brownish or blackish brown pigment.
MICROSCOPIC STRUCTURE OF WEED SEEDS 577
7? OG= rar
par c yo)
em,
SIS®
SEY
Fic. 439A. Miscroscopic structure of some weeds of the Sunflower family
(Compositae).
I. Small Ragweed (Ambrosia artemisiaefolia). II. Verbesina (Verbesina hel-
ianthoides). III. Spanish Needle (Bidens discoidea). IV. Burdock
(Arctium lappa).
ep=epidermis. scl=sclerotic parenchyma, t=testa. n=nucellus. en=endosperm.
em=embryo. pal=palisade cells.
(Drawings by L. H. Pammel and Charlotte M. King.)
The pigment layer is followed by elongated sclerotic parenchyma
with a narrow cell cavity; cells with granular contents. The testa
is thin, cells elongated, cell wall thickened slightly, tinged with
yellow. The testa is followed by remnants of the nucellus. The
parenchyma cells of embryo follow the nucellus.
Wood or Field Thistle (Cirstum discolor (Muhl.) Spreng.).
The microscopic structure of the yellowish gray seeds shows a
elear relationship to Arcttwm; the outer epidermal layer of the
pericarp consists of thick-walled colorless cells, the walls bright
and lustrous; the pigment layer underneath the walls, not nearly
37
578 WEED FLORA OF IOWA
as thick-walled as the epidermal, pigment yellowish. The elong-
ated sclerotic parenchyma cells are yellowish white or nearly color-
less; this layer is followed by the parenchyma cells of the testa and
remnants of the nucellus. The parenchyma cells of the embryo
with numerous small intercellular spaces contain protein and fat.
The fibrovascular bundles are located one at each end of the achene.
Fic. 440. Microscopic structure of the seeds of Thistles (Cirsiwm).
I. and II. Common Wood Thistle (Cirsiwm discolor). III. Iowa Thistle (Cir-
sium iense).
ep=thick-walled epidermal cells. pi=pigment layer. scl=sclerotic palisade cells
with narrow cell-cavity. p=parenchyma cells of testa. t=testa. n=nucellus.
em=embryo. fv=fibro-vascular bundles.
(Drawings by L. H. Pammel and Charlotte M. King.)
Iowa Thistle (Cirstum ioense (Pammel) Fernald).
The microscopic structure of the seeds is similar to that of pre-
ceding, comprising a thick-walled epidermal layer with bright
colored walls and underlying pigment layer, an elongated sclerotic
parenchyma and the testa of small parenchyma cells.
MICROSCOPIC STRUCTURE OF WEED SEEDS 579
Chicory (Cichorium intybus L.).
The microscopic structure of the pericarp and seed of chicory
has been given by Harz and Lavialle. The pericarp consists of
epidermal cells whose outer walls are irregular and cuticularized.
This is followed by a variable number of rows, usually 10-15, of
sclerotic parenchyma, some of the cells of which as observed by
eee e 7
Broce Iria
xt, oa
Bay (fer
Fic. 441. Microscopie structure of the seed of Chicory (Cichorium intybus).
ep=epidermis. scl=sclerotic parenchyma. per=pericarp. t=testa. al=aleu-
, rone layer. en=endosperm.
(Drawing by Charlotte M. King and L. H. Pammel.)
Kraus, contain crystals of calcium oxalate. Beneath are 6-8 rows
of thin-walled, elongated parenchyma. The testa consists of a layer
of large epidermal cells, followed by smaller thin-walled parenchy-
ma, the inner portion much compressed. The aleurone layer is
of elongated cells containing aleurone grains.
Dandelion (Taraxacum officinale Weber). -
Harz has given an account of the structure of the pericarp and
seed. The epidermal cells are irregular, many of the cells pro-
longed into one-celled trichomes, the ribs forming tubercular
processes. The underlying portion containing the thinner-walled
parenchyma and the sclerotic parenchyma cells of the ribs. This
is followed by several rows of compressed, elongated, thin-walled
parenchyma cells. The testa consists of the epidermal layer of
elongated, spirally thickened walls, followed by a compressed layer
of parenchyma cells. The endosperm of one or two rows of
aleurone cells. .
WEED FLORA OF IOWA
580
Saag, Rees
Sam
SSN x,
ile C
nN
()
Dandelion (Taraxacum officinale).
Fic. 442.
BIBLIOGRAPHY.
ANATOMICAL STUDY OF SEED COATS.
GENERAL. »
Buscaloni, L. Contribuzione allo studio della membrana cellulare.
Malpighia 6 :3-40, 217-228; pl. 1-2. 7:105-162; pl. 1-2. 8:3-13;
pl. 1-3. 1875.
Anatomisch-physiologisch Untersuchung tber d.
Dahmen, Max.
Funiculus d. Samen. Prings. Jahrb. f. wiss. Bot. 23 :441-478;
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Fluckiger, F. A., and Hanbury, D. Pharmacographia: a history
of the principal drugs of vegetable origin met with in Great
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Frank, A. B. Ueber die anatomische Bedeutung und die Entste-
hung der vegetabilischen Schleime. Pringsh. Jhrb. f. wiss.
Bot. 5:161; pl. 15-16. 1886.
MICROSCOPIC STRUCTURE OF WEED SEEDS 581
Godfrin, H. Etude histologique sur les téguments sémineaux des
angiosperms. Bull. Soc. des Sci. de Nancy. 5:109-219.
Godfrin, J. Recherches sur l’anatomie comparée des cotylédons
et de l’albumen. Ann. Sci. Nat. Bot. Soc. des Sci. de Nancy.
59:109-219; pl. 1-5. 1880.
Guignard, L. Recherches sur Je développement de la graine et en
particulier du tégument séminal. Jour. de Bot. 7:1-14, 21-34,
57-66, 97-106, 114-1538, 205-214, 214-250, 282-296, 303-331.
Hanausek, T. F. Die Nahrungs-und Genussmittel aus dem
Pflanzenreiche. 485, 100 f.
Harz, C. D. lLandwirthschaftliche Samenkunde. 1:552; f. 1-14.
2 :093-1362; f. 15-201. Berlin, 1885.
ios Oe Verholzungen die hoheren Pflanzen, speciell uber
das Vorkommen von Lignin in Samenschalen. Bot. Centrbl.
24 :21-31, 59-61. 1885.
Hofmeister, W. Ueber die zu Gallerte aufquellenden Zellem der
Aussenflache von Samen und Perikarpien. Ber. d. Kon. Sachs
Gesell. D. Wiss. Sitz. 18-37. Feb. 20, 1853.
Jenkins, T. E. H., & Winton, A. F. American feeding stuffs.
Bull U. S: Dept. Acer) Ot Expy Sta. 112155) 1892.
Joxe, A. Sur l’ouverture des fruits indehiscents 4 la germination.
Ann. de Sci. Nat. [X. 15 :257-375.
Junowiez, R. Die Lichtlinie in den Prisemnzellen der Samen-
schalen. Sitzb. d. k. Akad. d. Wissensch. Wien. 76 :335-352;
2 pl.
Mattirilo, O. la linea lucida nelle cellule Malpighiane degli in-
tegumente seminali. Mem. della R. Accad. delle Sci. I, 37:30;
1 pl. 1885.
Mattirilo, O., and Buscalioni, L. Letture sulla funzione della linea
lucida nelle cellule Malphigiane. Nota preventiva. Atti R.
Ace. delle Sci. di Torino. 25:310-315. 1890.
Moeller, Josef. Muikroskopie der Nahrungs-und Genuss-mittel aus
dem Pflanzenreiche. 394; f. 308. Berlin, 1886.
Pammel, L. H. Some methods in the study of mature seeds.
Jour. Appl. Micro. 1:37-89; 6 f. 1898.
Sempolowski. A. Beitrige zur Kenntniss des Baues der Samen-
schale. Inaug. Dis. Leipsig. 1874. 60; pl. 1-3.
5 2 Oo ae ee Ueber den Bau der schale landwirtschaftliche
wichtiger Samen. Landw. Jahrb. 3:824-866; pl. 7-8.
Winton, A. L. Anatomy of weed seeds. Rept. Conn. Agr. Exp.
Sta. 1902 :345-358.
582 WEED FLORA OF IOWA
AMARANTACEAE.
Gravis, A., and Constantinesco, Mlle. A. Contribution 4 l’anatomie
des Amarantacées. Arch. Inst. Bot. Univ. Liege. IV :1-146.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2:1101.
ASCLEPIADACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2:963-966.
BERBERIDACEAE.
Pammel, L. H., Burnip, J. R., and Thomas, H. Some studies on
the seeds and fruits of Berberidaceae. Proc. Ia. Acad. Sci.
5) LIS),
BORAGINACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2:870.
CARYOPHYLLACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2:1075-1089.
Winton, A. L. Anatomy of Cockle seeds. Winton’s Microscopy
of vegetable products. 148; Cowherb, p. 151, Soapwort, p. 151.
CHENOPODIACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2:1092-1039.
Pammel, L. H. Bull. Ia. Agrl. Exp. Sta. 26 :20.
COMPOSITAE.
Gerdts, C. L. Bau und Entwickelung der Kompositenfrucht mit
besonderer Berucksichtigung der offizinellen arten. Thése
Inaug. Leipzig, 1905.
Goldflus, Mathilda. Sur la structure et les fonctions de 1’assise
epitheliale et des antipodes chez les Composées. Journ. de
Bot. Morot. 1898-1899.
Hanausek, T. F. Ueber das Perikarp und Perikarpsekret der
Gattung Carthamus. Ber. d. deutsch. Bot. Gesellsch. 29 :13-18;
pl. 1.
Ske Sapa ennai Zar entwickelungsgeschichte des Perikarps von
Helianthus annuus. Ber. d. deutsch Bot. Gesellsch. 20 :449;
pl. 21.
Harz, C. D. See Landwirtschaftliche Samenkunde. 2 :841-866.
Lavialle, P. -Ovaire des Composées Ann. d. Sci. Nat. IX, 15:
(No. 2.) 65-149; 97 f.
Nichols, Mary A. Achenial hairs of Compositae. Bot. Gaz. 18 :378;
(Dig Ook
MICROSCOPIC STRUCTURE OF WHED SEEDS 583
Prister. Oelliefernde Compositernfruchte. Landw. Versuch.
Stat. 43.
Rosenthaler and Stadler. Ein Beitrag zur Anatomie von Cnicus
benedictus. Arch d. Pharm. 246:486.
Schwere. Zur Entwicklungseeschichte der frucht von Taraxacum
officinale. Flora 82. 1896.
Winton, A. L. Anatomy of the seed of the Sunflower (H. annuus).
See Winton’s Microscopy of vegetable products. 194-197.
CONVOLVULACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2 :751-767.
Guttenberg, H. von. Ueber die anatomischen Unterscheidung der
Samen einiger Cuscuta—Arten. Naturwiss. Zeitschs. Forst.
u. Landw. 7:32-43. 1909. Abs. in Bot. Centr. 111:578.
CRUCIFERAE.
Burchard, O. Ueber der Bau der Samenschale einiger Brassica—
und Sinapis Arten. Journ. Fiir Landw. 42:125; 44:377.
Cordemoy, J. de. Recherches anatomiques sur les genres Brassica
et Sinapis. 190; 45 f. Paris, 1907.
Fournier, Eug. Recherches anatomiques et taxonomiques sur la
famille des Cruciferes et particuliérement sur le genre Sisym-
brium. 154; pl 1-2. Paris.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2 :914-916.
Pammel, L. H. On the seeds and testa of some Cruciferae. Cont.
Bot. Dept. Ia. Agr. Coll. 6:25. Reprint from Am. Mo. Mic.
Jour.
Pieters, A. J., and Charles, V. K. The seed coats of certain species
of the genus Brassica. Bull. U. S. Dept. Agr. 29:19. |
Schroder. Untersuchung der Samen der Brassica—Arten und
Varietaten. Landw. Versuchs—Station. 14. 1871.
Uloth, W. Ueber Pflanzenschlerme und seine Entstehung in der
Samen epidermis von Plantago maritima und Lepidium
satiwwum. Flora. 58 :173-200, 209-216; pl. 6.
Winton, A. L. Anatomy of oil seeds among Cruciferae. Microscopy
of vegetable products. 174-193.
EUPHORBIACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2:825-841.
Pammel, L. H. On the seed coats of the genus Euphorbia. Contr.
Shaw School of Bot. 8:5438-568. Trans. St. Louis Acad. Sci.
5 :543-568.
584 WEED FLORA OF IOWA
GENTIANACEAE.
Guerin, . Développement et structure anatomique du tégument
séminal des Gentianées. Compt. Ren. Acad. des Sci. de Paris.
vi: 136.
GRAMINEAE.
Bessey, C. EK. Structure of the wheat grain. Bull. Neb. Agr. Exp.
Sta. 32
Hanausek, T. F. Vorlaufige Mittheilung tber der von Vogl. in
der Frucht von Lolium temulentwm entdeckten Pilz. Ber.
Deutsch. Bot. Ges. 16:203. 1898.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2:1145-1349.
Hillman, F. H. The seeds of fescue grass and chess. Bull. U. S.
Dept. Agr., Bur. Pl. Ind. 25:4.
Holm, Theo. A study of some anatomical characters of N. A.
Graminee. Bot. Gaz. 16 :166-171, 219-225, 275-281. 17 :358-363.
20 :362-365. 21 :357-360. 22 :403-406.
Jumelle. Sur le constitution des fruit des Graminées. Compt. Rend.
107 :285. 1888.
Krutizky. On some peculiarities in the structure of the caryopsis
of wheat. Just’s Bot. Jahresb. 21: (Abt. I) 571. 1893.
Moeller, J. Die Mikroskopie der Cerealien. Pharm. Centralh. 25:
507. 1884.
Pammel, L. H. Comparative anatomy of the corn caryopsis. Trans.
Ja. Acad. Sei. 1897. 5.
The histology of the caryopsis and endosperm of some
grasses. Trans. St. Louis Acad. Sei. 1898 :199-220.
Pammel, L. H., Weems, J. B., and Lamson Scribner, F. The
Grasses of Iowa. Bul. Ia. Geol. Survey. 1:525.
Winton, A. L. The anatomy and microscopic identification of the
fruits of darnel and chess. Rept. Conn. Agr. Exp. Sta. 1903.
165-174.
Anatomy of the seed of green foxtail. Rept. Conn. Agr. Exp.
Sta. 1902. 352-358.
Anatomy of seed of yellow foxtail. Ibid. 1902: 358.
Ueber amerikanische Weizenausreuter. Ztschr. Unters.
Nahr-Genussm. 6:433.
LABIATAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2 :866-870.
MICROSCOPIC STRUCTURE OF WHED SEEDS 585
LEGUMINOSAE.
Beck, G. Die Samenkunde einiger Leguminosen. Sitzb. K. K.
Akad. Zu. Wien. 1878. 79. :
Vergleichende Anatomie d. Samen von Vicia und Ervum.
Sitz. d. k. Akad. d. Vissench. Wien. 76 :335-352; 2 pl.
Chalon, J. La graine des légumineuses. I. Cellule de la carapace.
II. Albumen. Soc. des Arts, et des lettres du Hainaut. 1875.
66; pl. 1-3.
Haberlandt, G. Ueber die Entwicklungsgeschichte und den Bau d.
Samenschule bei der Gattung Phaseolus. Sitz. d. k. Akad. d.
Wissensch. Wien. 75:33-47; 2 pl. 1877.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2; 562-736.
Mattirolo, O. Ricerche anatomo-fisiologische sui tegumenti seminali
delle Papilianacee. Nota preventiva. Atti. R. Accad. delle
sei. di Toniro. 24. 1889.
Ricerche anatomo-fisiologische sui tegumenti seminali
delle Papilionacee. I. Anatomia. II. Stor ia di sviluppo dei
tegumenti seminali. JII. Contribuzioni allo studio della fisiol-
ogia del seminali. IV. Bibliographia. Reale Accad. delle Sci.
di. Torino II, 42 :223-318, 359, 445; pl. 1-5. 1892. |
Nadelmann, Hugo. Ueber d. Schleimendosperme d. Leguminosen.
Prings. Jahrb. Wisensch. Bot. 21:609-691; pl. 16-78. 1890.
Pammel, L. H. Anatomical character of seeds of Leguminose.
Trans. St. Louis Acad. Sci. 9:91-263; Tables A-G; pl. 7-35.
The seed coats of Crotalaria sagitalis and Astragalus mollis-
simus. Bienn. Rept. Ia. St. Agr. Coll. and Farm. 13 :17-24;
pl. 59-58. |
On the structure of the testa of several leguminous seeds.
Bull. Torr. Bot. Club. 13 :17-24; pl. 52-58.
Schips, K. Ueber die Cuticula und die Auskleidung der Intereel-
lularen in den Samenschalen der Papilionaceen. Ber. Deutsche.
Bot. Ges. 11:311. 1893.
Schively, Adeline F. Contributions to the life history of Amphi-
carpaea monoica. Cont. Bot. Lab. Univ. Penn. 1:270-363; pl.
19-36.
Schleiden, M. J. Beitrage zur Entwickelungsgeschichte d. Bluthen-
theile bei d. Leguminosen. Nov.-Oct. K. Leopold-Carol. Akad.
Naturf. 19 :59-84; pl. 9-11. p
Winton, A. L. Anatomy of the seeds of Vicia sativa. Winton’s
Microscopy of vegetable products. 251-252.
586 WEED FLORA OF IOWA
MALVACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2:736-750.
Rolfs, P. H. The seed coats of Malvacex. Bot. Gaz. 17 :33-39.
ONAGRACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2 :875-878.
PHYTOLACCACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2:1088-1031.
PLANTAGINACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2 :982-987.
Winton, A. L. Anatomy of plantain seeds. Microscopy of vegeta-
ble products. 163.
Uloth, W. Ueber Pflanzenschleime und seine Entstehung in der
Samenepidermis von Plantago maritima und Lepidum sativum.
Flora. 58 :193-200, 209-216; pl. 6. 1885.
POLYGONACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2:1101-1113.
Sirrine, Emma. Structure of the seed coats of Polygonacez. Proc.
la. Acad. Sei. 2:128-134; pl. 7-9.
Winton, A. L. Anatomy of seed of black bindweed. Rept. Conn.
Agr. Exp. Sta. 1902 :340-352. Winton’s Microscopy of vege-
table products. 157-158.
RANUNCULACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2 :1063-1074.
Winton, A. L. Anatomy of Ranwnculus arvensis. Microscopy of
vegetable products. 152-154.
SAPINDACEAE.
Guérin, M. P. Développement de la graine et in particulier du
tégument séminal de quelques Sapindacées. Jour. de Bot. 15;
336-348.
SCROPHULARIACEAE.
Bachmann, E. Die Entwicklungsgeschichte und der Bau der
., Samenschalen der Scrophularinéen. 179. Halle, 1880.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2 :966-973.
SOLANANCEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2 :997-1025.
MICROSCOPIC STRUCTURE OF WEED SEEDS 587
UMBELLIFERAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2:1030-1063.
Winton, A. L. Anatomy of the seeds of wild carrot. Microscopy
of vegetable products. 158-159.
URTICACEAE.
Harz, C. D. See Landwirthschaftliche Samenkunde. 2:978-982.
Winton, A. L. The anatomy of certain oil seeds with especial
reference to the microscopic examination of cattle foods. Conn.
Agr. Exp. Sta. 1903. 175-180.
Microscopy of vegetable products. 212-217.
CHAPTER IV.
MORPHOLOGY OF LEAVES
AND FLOWERS
By
J. N. MARTIN
CHAPTER IV.
LEAVES.
INTRODUCTORY STATEMENT.
Leaves are distinguishable into primary and secondary. The pri-
mary leaves arise directly from the first cells produced by the
division of the fertilized egg and in seed plants are called cotyle-
dons. They are usually transient, and not rarely are so distorted by
acting as storage places for reserve food that they do not function
as foliage leaves at all. The secondary leaves arise upon the sides
of the stem and are the ordinary foliage leaves of the plant. They
are very important organs in connection with the work of nutrition.
PARTS OF A LEAF.
In the typical foliage leaf there are three parts—the expanded
portion which is called blade or lamina, the leaf stalk (petiole),
and a pair of appendages at the base of the petiole known as
stipules.
Fic. 443. Apple leaf; b, blade; p, petiole; s, stipules.
(After Thomé.)
592 WEED FLORA OF IOWA
In some cases, as in the Hare’s-ear mustard, (Conringia orient-
alis) and in the upper leaves of Canada thistle (Cirsium arvense)
the petiole is absent and the blade is directly attached to the stem.
Such leaves are designated as sessile.
Fie. 444. Sessile leaf of Thistle.
(After Thomé.)
The stipules are small leaf-like structures which appear at the
place where the leaf is attached to the stem. They are very often
absent but are conspicuous in the cinquefoils, vetches and other
members of the rose and pulse families.
VEINING.
The blade of the leaf is traversed by a frame work of fibro-
vascular bundles known as veins. In the leaves of grasses, sedges,
and rushes, the veins run more or less parallel from the base to
the tip of the leaf. These leaves are the parallel-veined type. In
the leaves of most of our common weeds, the veins are branched so
as to form a network. These are the netted-veined type.
Palmate and pinnate veining.—Netted-veined leaves are palmately
veined when the primary ribs radiate from the base of the petiole
as in the great ragweed. If there is only one midrib from which
smaller ribs extend both ways, as in dandelion, dock, goldenrod,
etc., the veining is said to be pinnate (meaning featherlike).
LEAF ARRANGEMENT.
Sometimes as in dandelion and evening primrose, the stem does
not appear above ground or is late in appearing and the leaves at
the surface of the ground are called radical leaves in distinction
to the stem or cauline leaves.
MORPHOLOGY OF LEAVES AND FLOWERS 593
Fig. 4451 Fig. 44511
Fic, 445. I. Vetch. (Lathyrus aphaca), showing opposite leaves; r, tendril; b,
flower; f, fruit. Stipules performing the function of leaves.
II. Grass type of leaf; L, leaf blade; G, leaf sheath; Lig, ligule.
‘ (After Thomé.)
Leaves are usually arranged so as to secure the best exposure to
the light. In the milkweed there is a pair of leaves at each node
and the two leaves are on opposite sides of the stem. Here the
leaves are said to be opposite.
Fig. 446. The clinging stem of the Bindweed, showing the alternate leaves.
(After Thomé.)
38
594 WEED FLORA OF IOWA
In the asters, ironweed, goldenrods, lamb’s quarter, ete., there
is only one leaf at each node, and they are spoken of as alternate.
In some cases several leaves appear at each node in a whorl. Such
examples of whorled or verticillate leaves are found in the bed-
straws and Joe Pye weed.
BRANCHING.
The outline of a blade is extremely various. When the general
outline is completely filled out and the margin represents an even
line, the leaf is said to be entire. Examples of such leaves are
found in water pepper (Polygonum hydropiper), mild water pepper
(P. hydropiperoides), Pennsylvania smartweed (P. pennsylvani-
cum), ete. : |
Fic. 447. Leaf of the Privet plant showing entire margin.
To designate the amount and character of the branching, the
following terms are used:
Fig. 4481 Fig. 44811 Fig. 448'II Fig. 4481V
Fic. 448. I. Triangular, lobed leaf of the Notch-weed. II. The reniform or
kidney-shaped leaf of Ground Ivy, illustrating wavy margin. III. Arrow-
shaped leaf of Bindweed. IV. Spear-shaped leaf of Sorrel.
(After Thomé.)
MORPHOLOGY OF LEAVES AND FLOWERS 595
Wavy margin, when the margin forms a wavy line bending
slightly inward and outward in succession, as in the bitter dock
(Rumex obtusifolius).
Fig. 449 T Fig. 449 II Fig. 449 III Fig. 449 1V Fig. 449 V
- Fic. 449. I. Leaf of Daisy, spatulate in shape with a serrate margin. San
Spiny-pointed, serrulate leaflet of alfalfa. III. Wavy-margined leaf of
Pigweed (Amaranthus). IV. Ovate, dentate leaf of Snowball. V. Serrate
leaf of Hen-bit. ;
(After Thomé.)
Toothed or dentate, when the margin is cut into sharp teeth and
the teeth point out, as in the lower leaves of the daisy fleabane
(Erigeron annuus).
Fic. 450. Cleft and pinnatifid leaves of Wild Lettuce.
(After Thomé.)
596 WEED FLORA OF IOWA
Serrate, when the teeth point forward, as in the common sun-
flower (Helianthus annuus).
Serrulate, when the margin is finely serrate as in milk purslane
(Euphorbia maculata).
Crenate, when the teeth are broad and rounded as in the common
mallow (Malva rotundifolia).
100
ONONN
HHH
Fig. 451 1 Fig. 451 II Fig. 451 It
Fic. 451. Compound leaves. I. Leaf of Clover with three leaflets. I1.
Pedately divided leaf of Dragon Root. III. Pinnate leaf of Locust with
19 leaflets.
(After Thomé.)
Lobed, when the leaf is deeply cut, as in the great ragweed. The
projecting portions are then called lobes. When the incisions are
sharp the term cleft is often used; the leaf is pinnatifid when the
incision extends almost to the midrib, as in the prickly lettuce
(Lactuca scariola) ; it is pinnate when the incisions have extended
to the midrib and each separated portion takes the character of a
leaf. Each of the smaller portions is a leaflet, and the leaf is now
considered compound. The spotted cowbane (Cicuta maculata),
spring vetch (Vicia sativa) and cinquefoil (Potentiula monspelien-
sis) are good examples.
MORPHOLOGY OF LEAVES AND FLOWERS 597
Fig. 452 I Fig. 452 II
Fig. 452. I. Wedge-shaped leaflet of Horse Chestnut. II. Pointed leaf of
the Wall Pellitory.
(After Thomé.)
All of the above marginal characters may characterize the lobes
of a simple leaf or the leaflets of a compound leaf.
LEAF STRUCTURE.
Before considering the work of the leaf it will be necessary to
become acquainted with its structure.
The leaf is covered with an epidermis which is composed of com-
pact layers of cells, so modified as to protect the more delicate
inner parts. The epidermis may be peeled off as a delicate trans-
parent skin. A microscope shows that this transparent skin is
made up of many cells, so closely fitted together as to make a contin-
uous sheet or covering. Many slitlike openings between two cres-
cent-shaped cells (guard cells) appear quite evenly distributed in
the epidermis. The opening and guard cells constitute the stoma
(plural stomata) which really means mouth. These numerous
openings are passage ways into the interior of the leaf and per-
mit interchange of gases between outside air and the air in the
leaf interior. The guard cells can change their shape and so vary
the size of the opening. In horizontal leaves the stomata are chiefly
and sometimes exclusively on the lower surface, a fair average
number being about 62,500 to the square inch. .
598 WEED FLORA OF IOWA
O)
pOwCOEDS f
aSnases
avaly
d
p
Fic. 453. I. A cross section of a leaf of Peppergrass (Lepidium) showing
the upper epidermis (e), the lower epidermis (é), stoma (s), the chlor-
enchyma (c) consisting of closely placed palisade cells (p) and more
loosely placed spongy tissue (f), and a vascular or conductive tract (v)
With bundle sheath (b), hadrome or xylem (h), and leptome or phloem (1).
II. Surface view of stoma from Haster Lily; g, the kidney-shaped guard cells en-
closing the stomatal aperture (Ss); b, the subsidiary cells.
III. Cross section of stoma; g, guard cell; s, central slit; 0, outer slit; i,
inner vestibule; c, stomatal cavity ; b, subsidiary cell.
IV. Surface view of a grass stoma (Poa pratensis) showing the guard cells
(g), With their dumb-bell-shaped lumina; b, subsidiary cells with prominent
nucellus (n).
V. Median cross section and cross section through end of stoma of Poa annua;
g, guard cell lumina; b, lumina of subsidiary cells.
VI. | ee
Yellow foxtail .. £22 2 0|Se 28 22u)_ 2 ceo eee ee
Green: foxtall: 5a ae a eee 098) |e 1785
Pennsylvania
smartweed _~--------- 15 38 65 49° De See eee
Mustard) 222222 93° Niue S ee ee ee
‘Horseweed: ] 2 eeeeesases| 222 a/b 9 10 11
Secribner’s panic grass_|_-_-_--_|-----_-- +4 |. =-2-- |. eee
Tansy mustard —__--~-_|_-------|-------- Fae -Yanens emer fete SS |e
Ny Cteleay- Sesame 6 as 2 Sree | Se eee § _|-23 eae
Yellow dodke2222)). | |h eae ———E—E————ee +158
Large spottedtspurce..|22 = Se ee eee eee 129
Old: witchworasse: 2-2) 22 ee ee ee ee 2
Wild fourocloelk 22.222) ee ee 12
Selif-he ail eee | ee ee 2
*In sheltered place on the south side of the railroad grade. Weeds were
not all counted on April 27th, but there were hundreds of small ragweeds and
smartweeds, and probably more than a thousand green foxtail plants.
++Winter annual.
+Perennial.
These tables reveal some interesting facts. The first weeds to
appear in March were the winter annuals, like peppergrass and
shepherd’s purse, certain perennial weeds, and in one ease horse-
weed (Erigeron canadensis) in a timothy meadow. Two weeks
later smartweed (Polygonum) was abundant. Spurge (Huphor-
bia), an annual, was abundant in the latter part of April and
early May. Foxtails in some cases surpassed all other weeds in
abundance early in May. The smartweeds (Polygonum) and
spurges increased enormously. These weeds were entirely removed
from the plots. Fall plowing and clean cultivation certainly in-
dicate a smaller number of weeds.
Long, who measured off a square yard of ground in* Great
Britain, roughly grouping its plant life therein into species, found
on this square yard 1,050 seedlings or 5,082,000 per acre. There
were 654 buttercup seedlings, 107 of annual meadow grass, 60 of
dock, 26 of goosefoot, 25 of groundsel, 15 of shepherd’s purse, 14 of
*Trans. of Highland Agri. Soc. Scotland V. 28: 52.
NUMBER AND KINDS OF WEEDS ON DIFFERENT SOILS 661
Fic. 515. A weedy cornfield, mostly Foxtail and Smartweeds.
(Photographed by Colburn.)
annual sow thistle, and 10 of chickweed, besides 139 of other
species. He states that Korsmo’s investigation revealed the pres-
ence of an even larger number of seeds having the power of ger-
mination, the seeds per square yard to a depth of 9.8 inches being
as follows: Fallow field, 8,682 weed seeds (over 42,000,000 per
acre) ; field for spring grain bearing the same crop for four suc-
cessive years, 28,213 weed seeds (over 136,000,000 per acre) ; fallow
field, 1,474 weed seeds (over 7,000,000 per acre).
Mr. Long gives the following species of weeds found in Great
Britain within an area 100 feet square:
662
Fic. 516.
WEED FLORA OF IOWA
ChE we ay ay,
N WY "
SING 2
ny’ V ¢
gy.
S|
\V a i
Shepherd’s Purse, a common winter annual.
(After Vasey, U. S. Dept. Agr.)
NUMBER AND KINDS OF WEEDS ON DIFFERENT SOILS 663
Fig. 517. A cornfield from which Quack Grass was removed by hoeing and
cultivation. In adjacent check it formed a sod. The check was given the
ordinary methods of cultivation.
(Photographed by Colburn. )
*Convolvulus arvensis (Euro-
pean bindweed.)
*Polygonum convolvulus (Black
bindweed )
*Polygonum aviculare (Knot-
grass)
*Rumex sp. (Dock)
*Tussilago farfara ‘(Coltsfoot)
*Mentha arvensis (Pepper-
mint)
*Sinapis arvensis (Common
mustard )
*Sonchus arvensis (Field sow
thistle)
*Stellaria media (Chickweed)
Papaver sp. (Poppy)
*Ranunculus arvensis (Corn
crowfoot)
*Viola sp. (Violet)
Potentilla anserina (Silver
weed)
Aethusa cynapium (Fool’s
parsley) ;
Scandia pecten-veneris (Ven-
us’ comb)
Senecio vulgaris (Groundsel)
*Galium aparine (Cleavers)
Victa sativa (Vetch)
664 WEED FLORA OF IOWA
*Matricaria wmodora (Wild *Agrostis sp. (Bent grass)
chamomile) Agropyron repens (Quack
Plantago major (Common grass)
plantain) Poa annua (Low spear grass)
Lychnis alba (White cam- *Veronica sp. (Speedwell)
pion) , | Myosotis sp. (Forget-me-not)
“Euphorbia exigua (Spurge) Alchemilla arvensis (Parsley-
“Alopecurus agrestis (Foxtail piert)
erass)
Most of these species are troublesome weeds, and it may be added
that those marked with * were abundant.
For an Iowa cultivated field on June 2, 1903, the following
weeds were found in one square rod.
Name of weed. No. per sq. rod.
Smartweed (Polygonum pennsylvanicum) ........0..0.e ee eeeeee 40,324
Hedge mustard (Sisymbrium officinale)..............5++-+- to 3,060
Black beggar-ticks (Bidens frondosd)...............0ceceee cere 476
Prickly lettuce (Lactuca scariola var. integrata)..........+--- os 204
Pigweed \(Ohewepon1un .al 1m) sane yee eee ee 340
Horseweed (Hrigeron CANAdENSIS) .... sce eee e ween cere cece ceneee 7,412
Dandelion (Tarawacum Officinale) .......e cece reece eee eee eceeee 68
Moxtail (CS€t@rig) sce c2 cdiemacaies oe Satie olgae oda aier gees mee eine 136,000
WEEDS AND CONTINUOUS CROPPING.
Everyone has observed that continuous cropping increases the
number of weeds; not only is this true for many. parts of Iowa but
it is equally true for the older sections of the United States and of
Europe. A. D. Hall who reported on the crops grown in grain
land at Rothannstad* said:
After continuous cropping for forty-seven years uel weeds of all
descriptions occupy considerably more space after continuous crop-
ping than before. The relative proportion they bear to the grasses
and clover has increased from year to year. Such weeds as barnet,
hawkbit and black knapweed became abundant.
Mr. Long gives the following list of worst weeds made by four
expert Scotch agriculturists :
Arable Land.—Charlock, runch, chickweed, spurrey, docks,
thistle, groundsel, coltsfoot, day nettle, red-shank, annual meadow
grass, bulbous oat grass (pearl grass), couch grass, fine bent grass
or black couch, and wild oats.
*Jour. Roy Agr. Soc. 64:-88.
NUMBER AND KINDS OF WEEDS ON DIFFERENT SOILS 665
Fic. 518. Green Foxtail (Setaria viridis). Common in gardens and fields.
‘ (Photographed by Colburn.) '
Grass Land.—Buttercups, self-heal, docks, ragwort, daisy, thistles,
ribwort, plantain, creeping soft grass, common bent grass, York-
shire fog or woolly soft grass, moss.
There are, however, many other weeds which are given by him
which are serious pests to the agriculturist of that country. Of the
weeds of the arable land he lists buttercups, poppies, fumitory,
charlock (Brassica arvensis), runch (Raphanus raphamstrum) , shep-
herd’s purse, corn cockle, spurrey, silver weed, cleavers, thistle
(Canada thistle), sow thistle, coltsfoot, groundsel, bindweeds (Poly-
gonum convolvulus), (Convoluulus arvensis), dodder, buckhorn,
plantain, broom rape, corn or field mint, hemp and dead nettle,
smartweed, or red-shank (Plygonum persicaria), knotweed, docks,
goosefoot, quack grass, fine bent grass, pearl grass (Arrenatherum
avenaceum), slender foxtail (Alopecurus agrestis), wild oats and
666 WEED FLORA OF IOWA
Fic. 519. Needle Grass (Stipa spartea). In pastures.
(Photographed by Charlotte M. King.)
Fie. 520. Purple Cone Flower (Brauneria purpurea). In a prairie pasture.
(Photographed by Pammel.)
NUMBER AND KINDS OF WEEDS ON DIFFERENT SOILS 667
horsetail. Of grass land weeds there are listed (Colchicum autum-
nale), buttercups, leguminous weeds, gorse (Ulex) broom, rest har-
row (Ononts spinosa), dyer’s green weed (Gemsta tinctoria), wild
carrot, burdock, knapweed (Centaurea nigra), thistles (Cirsiwm
arvense, C. acaule, C. lanceolatum, C. palustris), cotton thistle
(Onopordum acanthium), daisy (Bellis perennis), ox-eye daisy, rag-
wort (Senecio jacobaea), plantains, yellow rattle, self-heal (Pru-
nella vulgaris), docks, sorrel (Rumex acetosa, R. acetosella), sting-
ing nettle (Urtica dioica) ; grasses: bent grass (Agrostis alba) tus-
sock grass (Aira caespitosa), Yorkshire fog (Holcus lanatus),
creeping soft grass (H. mollis), quaking grass (Briza media), bar-
ley grass (Hordeum pratense), and the bracken (Pieris aquilina),
horsetail, and mosses.
\
Fic. 521. Common Porcupine or Needle Grass (Stipa spartea). A weed native
to gravel soil, soon succumbs to cropping. a, single spikelet; b, fruit with
sharp pointed callus.
(Lamson-Scribner, U. S. Dept. Agr.)
CHAPTER VIII.
INJURIOUSNESS OF WEEDS
CHAPTER VIII.
INJURIOUSNESS OF WEEDS.
Weeds are injurious to man in the following ways:
1. They crowd out the growing crop.
2. They consume the moisture necessary for a crop.
3. They consume the mineral or other food elements essential
to a crop.
4, They pull down the crop.
5. They are injurious because the seeds are difficult to remove.
6. They are injurious because they harbor insects.
7. They are injurious because they harbor parasitic fungi.
8. They prevent the proper cultivation of the soil.
9. They may cause conditions which breed disease.
10. They may poison the soil.
11. They stop drains.
12. They poison animals and man.
1. WEEDS CROWD OUT GROWING CROPS.
When weeds are abundant they crowd out growing crops. Every
plant requires a certain amount of space to bring forth a bountiful
erop. Two plants cannot grow together in the same place; sooner
or later, one plant will crowd out the other. If the weed is a more
vigorous grower, like the greater ragweed, it will prevent the oat
plant from maturing a crop. It prevents the proper amount of
light coming to the plant, and so the food neecssary for a crop can-
not be made.
2. WEEDS CONSUME THE MOISTURE.
To produce a crop all weeds need moisture, which should go to a
more desirable crop. They transpire water just as cultivated plants
do. Long, in ‘‘Common Weeds of the Farm and Garden,’’ says:
29
Weeds also absorb from the soil and ‘‘transpire,’’ or pass off into
the atmosphere, large quantities of moisture which would be of
great service to the growing crop. For example, a maize plant has
been observed to transpire in the 16 weeks between May 22d and
September 4th as much as 36 times its own weight. A large oak
672 WEED FLORA OF IOWA
Fic. 522. Ragweeds (Ambrosia trifida) consume an enormous amount of mois-
ture.
INJURIOUSNESS OF WEEDS . 673
tree is also stated to transpire 10 to 20 gallons of water in a day;
while barley, beans, and clover were found to transpire, during
five months of their growth, over 200 times their dry weight of
water. Experiments conducted at the agricultural experiment sta-
tion of Cornell university showed that during the growth of a 60-
bushel crop of maize the plants pumped from the soil, and tran-
spired into the air through the leaves, upwards of 900 tons of
water. A 25-bushel crop of wheat similarly disposed of 500 tons of
water. Weeds also transpire, and if the ground be covered with
weeds it is certain that much of the moisture which would be of
value to the crop will be lost in the manner indicated. Weeds are
especially harmful in this way in a hot summer, and the loss is
most felt by the cultivated crop on light sandy soils.
3. WEEDS CONSUME MINERAL AND FOOD ELEMENTS.
A weed needs not only the carbon dioxide of the air to make
food, but the nitrogenous and mineral elements of the soil to make
plant food, all of which should go to the crop. Long gives the fol-
lowing in his book, ‘‘Common Weeds of the Farm and Garden’’:
Some analyses made at Konigsberg, and lately reported by Profes-
sor Stutzer and L. Seidler, show that the amounts of nitrogen, phos-
phorie acid, potash, and lime which are removed are deserving of
serious consideration. A number of weeds without their roots were
collected from oat fields, the soil of which was fairly heavy and
poor in humus. In the case of the Wild Radish or White Char-
lock the plants had already formed many seed-pods, but the other
weeds were in full bloom. The table following shows the percentage
of ingredients in the dry matter. These figures indicate in a gen-
eral way the amount of the chief plant foods required by weeds. The
nitrogren in the Persicaria nearly equaled 20 per cent, and that in
the Sow Thistle nearly 15 per cent of albuminoids in the dry mat-
ter. Phosphoric acid was chiefly taken up by Spurrey and Persi-
earia; potash by the Sow Thistle and Spurrey; and lime by Per-
sicaria, Yarrow, and Cornflower.
43
674 WEED FLORA OF IOWA
PERCENTAGE CONTENTS OF DRY MATTER.
1
]
f=) (oho)
e ee Zz ° E 34
= 2 © 2 iE za
GZ ce ou = nN io)
Sow thistle (Sonchus oler-
ACCUS) 0 MSE eR ai there ans eek 2.39 0.88 4.77 1.94 2.16 14.95
Cornflower (Centaurea cy-
CNUS) A Vda oe eich eee 2.30 0.78 1.94 3.13 1.07 8.12
Spurrey (Spergula arven-
SUS)! Sasa Oe Ress oe eee 2.36 1.08 4.21 1.52 1.91 10.12
Wild Radish (Raphanus
raphanistrum) .......... 1.85 0.78 1.30 1.81 0.71 5.22
Persicaria or red-shank
(Polygonum persicaria).'| 3.12 1.16 3.12 4.93 2.53 10.58
Yarrow (Achillea millefol-
AULT) ©. ctsisec ee ROOT ue 2.30 0.93 3.15 3.84 ali 9.61
Average of six weeds..... 2.38 0.93 3.08 2.86 1.59 9.76
4. WEEDS PULL DOWN THE CROPS.
Weeds like morning-glory, bindweed, wild buckwheat, and others,
pull down a cultivated plant and then prevent the formation of a
good erop.
5. WEEDS ARE INJURIOUS BECAUSE IT IS DIFFICULT TO RE-
MOVE THE SEEDS.
It is difficult in many cases to remove weed seeds from seed of
various kinds. Buckhorn can be removed with difficulty from
clover seed; peppergrass with difficulty from timothy seed; greater
ragweed from wheat; wild oats from oats; quack grass from brome
grass; cockle from wheat. These impurities often greatly reduce
the quality of the grain or seed.
6. WEEDS HARBOR INSECTS.
Long gives the following insects found on weeds:
Uf ZA ENGIN LAWS
Ez . .
i)
Fic. 523. Morning-glory pulls down the corn and other crops.
(After Vasey, U. S. Dept. of Agriculture. )
676 WEED FLORA OF IOWA
SS
Fic. 524. Impurities found in Red Clover: 1, Bull Thistle; 2, Canada Thistle;
3, Green Foxtail (Setaria viridis) ; 4, common Plantain (Plantago rugelit) ;
5, Peppergrass (also found in Timothy); 6, Chicory; 7, Pigeon Grass
(Setaria glauca) ; 8, Crabgrass (Digitaria sanguinalis) ; 9, Old Witch Grass ;
10, Timothy; 11, Wild Carrot; 12, Pigweed (Amaranthus retroflexus) ; 13,
Smartweed (Polygonum persicaria) ; 14, Lamb’s quarters; 15, Dropseed
Grass (Muhlenbergia).
(Drawings by Charlotte M. King.)
Weed “host.” Insect.
Turnip Flea Beetle or “Fly” (Phyl-
Charlock (Sinapis arvensis) and lotreta (Haltica) nemorum)
similar Crucifers Cabbage and Turnip Gall Weevil -
(Ceutorhynchus sutlcicollis)
Goosefoot (Chenopodium album)
Thistles (Cirsium sp)
Sow Thistle (Sonchus) . Mangold Fly (Pegomyia betae)
Dandelion (Taraxacum) and appar-
ently Docks (Rumez)
INJURIOUSNESS OF WEEDS 677
Charlock and other Crucifers Diamond-Back Moth (Plutella mac-
Prickly saltwort (Salsola kali) ulipennis)
Thistles, and the Cotton Thistle
(Onopordon Acanthium) } Celery Fly (Acidia heraclei)
Hops, Yorkshire Fog, Poa annua, aN
Daisy, Shepherd’s Purse, Spurrey, :
Buttercup, Cornflower, Sow This- + See Merete devas
tle, Black Bindweed (Polygonum
Convolvulus) and Plantain
Nightshades, Henbane, Hedge, cana Colorado Beetle (Doryphora decem-
tard, Thistles, Goosefoot, and lineata)
many other plants
Shepherd’s Purse, Winter Cress, | Cabbage Root Fly (Phorbia bras-
Hedge Mustard sicae)
Various Grasses } Frit Fly (Oscinis frit)
Docks, Goosefoot, and some ee
weeds Bean Aphis (Aphis rumicis)
Ghost or Otter Moth (Hepialus
Docks, Thistles, Burdock lupuli)
7. WEEDS ARE INJURIOUS BECAUSE THEY HARBOR PARA-
SITIC FUNGI.
' Long and Percival, in ‘‘Common Weeds of the Farm and Gar-
den,’’ have the following table of fungus diseases that affect va-
rious weeds:
Weed “host.” Disease.
Finger-and-toe of turnips (Plasmodio-
phora brassicae Wor.)
Peronospora parasitica De Bary
Charlock and other Crucifers
White Root-rot (Rosellinia necatria
Prill.)
Sclerotium Disease (Sclerotinia scleroti-
orum Mass.)
Many species
inum) sporium gramineum ESSE)
Shepherd’s Purse and other
Crucifers
White Rust of Cabbages (Cystopus can-
didus Lev.)
Many species a. Root-rot (Rhizoctonia violacea
Agrostis canina L., and other
grasses
Reed-mace Fungus (EHpichloe typhina
Wild Barley (Hordeum mur: u Blindness in Barley and Oats (Helmintho-
i
} Tul.)
678 WEED FLORA OF IOWA
Barberry { Rust of wheat (Puccinia graminis Pers.)
Aakers Gooseberry-leaf Cluster-cup (Puccinia
Sedges (Carex) \ pringsheimiana Kleb.)
Goosefoot t Peronospora effusa Rab., on spinach.
Docks, Sorrel, and many) Rosellinia radiciperda Mass. A white
others Root-rot in New Zealand.
\ Chrysanthemum Rust (Puccinia hieracii
Hawkweed (Hieracium) Mart.)
Groundsel, Ragwort, and) Pine Cluster-cups (Peridermium pini
other species of Senecio Waillr.)
Many wild grasses t Ergot of rye (Claviceps purpurea Tul.)
SOD :
(Sexes
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(EE Ce
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D0. Solavacedow Nie Mismadesmamily 55 2. Seams eiee es 5 ee: 9
NE NUNLO CLO Cracmmam leven almiliy so... 5. ln me eran rq eee ows. a aa ae alt
Benes UTULCOCEUe wNGtUleMU aM Yin 020. ct le cnt ge) Meee etch ses + oom « 5)
jon. Valeranacedos Valerian Wamily.. 5 i205 ee oon Sens oe i
pia, Verbenaceaeverbenaub amily : 022 2-38 leis sare oie e'o es it
Dm) a ViLOLACCRC MNO ley MCA eh es «Sie ike «aw date ty Apricorn cte «14 il
The weeds of the Pacific coast are somewhat different from those
of the Atlantic coast. Eugene Hilgard, in a series of interesting
articles in Garden and Forest, some years ago, S. B. Parish, J.
Burtt Davy and other California botanists, have contributed notes
on the introduction of these weeds of the coast. They enumerated
the more important weeds, among which mention may be made of
black mustard: (Brassica nigra), catchfly (Silene gallica), storksbill
(Erodium cicutariwm), musk erodium (Hrodium moschatum),
small-flowered mallow (Malva borealis), black medick (Medicago
lupulina), bur clover (M. denticulata), white sweet clover (Meli-
lotus alba), and yellow sweet clover (M. officinalis), star thistle
(Centaurea cyanus), knapweed (C. solstitialis), brown knapweed
(C. jacea), black knapweed (C. nigra), wild carrot (Daucus car-
ota), beet (Beta vulgaris), spinach (Spinacia oleracea), lady’s
thistle (Silybum marianum), cotton thistle (Onopordon acanthiwm),
dodder (Cuscuta epithymum).
The writer recently noted the following weeds in the San Fran-
cisco Bay region, Oakland, and Sacramento, many of our eastern
weeds being common among them: Hedge mustard (Sisymbrium
officinale), Raphanus sativus, Marrubium vulgare, dock (Rumex
crispus), cheeses (Malva rotundifolia), mallow (M. crispa), bull
thistle (Cirsium lanceolatum), sow thistle (Sonchus oleraceus),
eat’s-ear (Hypochaeris radicata), knotweed (Polygonum erectum),
black medick (Medicago lupulina), Brassica campestris, lamb’s
quarters (Chenosodium album), chickweed (Stellaria media), Poa
annua, Alfilaria (Hrodwm cicutaria), pineapple weed (Matricaria
suaveolens), common groundsel (Senecio vulgarts), burdock (Arc-
tium lappa), Silybum marianum, Centaurea melitensis, prickly let-
tuce (Lactuca scariola), mustard (Brassica campestris), also such
native weeds as Amsinckia and Escholtzia.
726 WEED FLORA OF IOWA
Fig. 549A 1
Fig. 549A IT
Fig. 549A III
Fie. 549-A. Seeds of weeds scattered with agricultural seeds. I. Dodder in
clover and alfalfa seed. II. White Sweet Clover in alfalfa seed. III.
Bitter Dock (Rumex obtusifolius) in red clover seed.
Many of these weeds have made their way into California by
way of South America. Others are indigenous and widely scat-
tered on the Pacfiic coast. The Pacific northwest has in common
with the rest of the Pacific coast many European weeds, but also
many that are indigenous to the country. Many years ago Cusick
called attention to the predominance of the Northern fireweed
(Epilobium angustifolium), which, after the removal of the forest
and the burning of the slashings, comes up in great abundance.
The writer in another connection* discussed the weeds commonly
*The Problem of Weeds in the West; Proc. Ia. Acad. Se. 15: 34.
WEED MIGRATION 727
Fie. 550. Curled Dock (Rumex crispus). .A common European weed now
occurring across the continent.
(After Chesnut, U. S. Dept. Agr.)
found in the northwest. A few of the abundant species may be
mentioned. Russian thistle (Salsola kali var. tenutfolia) is abun-
dant in the drier regions, especially east of the Cascades. In the
Puget Sound country are found such common European weeds as
Canada thistle (Cirsium arvense), bull thistle (C. lanceolatum),
batchelor’s button (Centaurea cyanus), chicory (Cichorium inty-
bus), common mustard (Brassica arvensis), mullein (Verbascum
thapsus) and also V. blattaria, and toadflax (Linaria vulgaris).
It is not uncommon to find in clearings of the forest the small
Kenilworth ivy (Linaria cymbalaria), the common pansy (Viola
tricolor), the petunia (Petunia grandiflora), the dead nettles (La-
mum amplexicaule and L. album), ox-eye daisy (Chrysanthemum
leucanthemum), hemp nettle (Galeopsis tetrahit), foxglove (Digi-
talis purpurea), European bindweed (Convolvulus arvensis). The
728 WEED FLORA OF IOWA
eats’-ear (Hypochaeris radicata) is one of the most common weeds
in lawns. There is a common belief that it was introduced from
Chile.
In the Great Basin country, especially in Utah, a large number
of the weeds are of Huropean origin. Of the most common of
these mention may be made of the brome grasses (Bromus brizae-
formis and B. tectorum), bouncing Betty (Saponaria vaccaria),
black medick (Medicago lupulina), dodders (Cuscuta arvensis and
C. epithymum), poison hemlock (Coniwm maculatum), moth mul-
lein (Verbascum blattaria), mint (Mentha viridis), Russian thistle
(Salsola kali var. tenuifolia), horehound (Marrubium vulgare),
Fie. 551. Awned Brome Grass (Bromus tectorum).. Common in the Great
Basin country and California, occasionally in Iowa.
WEED MIGRATION 729
prickly lettuce (Lactuca scariola) and storksbill (Hrodiwm cicu-
tartwm). There are also such native weeds as bee-plant (Cleome
serrulata), wild liquorice (Glycyrrhiza lepidota), the squirrel-tail
grasses (Hordeum jubatum and H. caespitosum), prickly lettuce
_(Lactuca pulchella), pine-apple weed (Matricaria suaveolens) and
prickly poppy (Argemone platyceras). In the Rocky mountain re-
gion, especially Colorado, many of the more recent introductions
are from Europe. Among these are the sweet clovers (Melilotus
alba and M. officinalis), black medick (Medicago denticulata),
purslane (Portulaca oleracea), dodder (Cuscuta arvensis and C.
2: b
Fig. 551A I Fig. 551A IL
G @
oy 92
Fig. 551A IIL : Fig. 551A IV
Fic. 551-A. Seeds scattered with agricultural seeds... I. Barnyard Grass
(Echinochloa crusgalli). 11. Medicago denticulata, common in alfalfa
seed. II. Horehound (Marrubium vulgare), a weed commonly scattered
with alfalfa seed. Common in the Great Basin country. IV. Wild Buck-
wheat or Bindweed (Polygonum convolvulus), commonly scattered with
grain seed.
(All after Hillman.)
epithymum), foxtail (Setaria viridis), storksbill (Erodiwm cicu-
tarium), Russian thistle (Salsola kali var. tenuifolia), vegetable
oyster (Tragopogon porrifolius), goat’s beard (T. pratensis) and
lamb’s quarters (Chenopodium album). A large number of native
plants have become weedy, such as marsh elder (Iva xanthifolia),
730 WEED FLORA OF IOWA
(Franseria discolor), the two annual sunflowers (Helianthus an-
nuus, H. petiolaris), small ragweed (Ambrosia artemisiaefolia),
buffalo bur (Solanum rostratum), Rocky Mountain bee plant
(Cleome serrulata), gumweed (Grindelia squarrosa) and squirrel-
tail grass (Hordewm jubatum).
Fig. 551B IIT Fig. 551B IV
Fic. 551-B. Seeds of immigrant weeds. I. Squirreltail (Hordeum jubatum) ;
widely scattered with hay and stock trains from the western plains. II.
Spinage (Spinacia oleracea) ; a common weed of the Great Basin country.
Seattered from cultivated plants. III. Russian Thistle (Salsola kali var.
tenuifolia) ; brought to Dakota with flax seed and grain seed; now scat-
tered in Iowa with alfalfa seed. IV. Winged Pigweed (Cycloma atri-
plicifolium).
(II, drawing, L. R. Collins; the others after Hillman.)
Cosmopolitan Weeds.—A great many weeds, originally, had a
very wide distribution, although many of these so-called weeds
were probably introduced by man. In many eases it is almost
impossible to tell how and whence they came to the places in
which they occur. . ;
Who can trace the immigration of such weeds as common purs-
lane, or charlock, or barnyard grass? In the first: place, these
WEED MIGRATION So tetod
plants immigrated when little was known about the species of
plants. What was said about them by the early botanical writers
was often very indefinite. In the second place, many of the early
writers did not take pains to leave statistics concerning the intro-
duction of the plants. The future records, however, will be more
accurate as the adventive plants are being recorded by a host of
botanical writers the world over. The notes in such floras as
Britton’s Manual, Robinson and Fernald-Gray’s Manual, Bentham
and Hooker’s Handbook of the British Flora, Garcke’s Flora of
Germany, Acloque’s Flora of France, Moore’s Handbook of the
Flora of New South Wales, Arcangeli’s Flora of Italy, Baron Fer-
dinand von Mueller’s Systematic Census of Australian Plants,
Grisebach’s Flora of the British West Indies, Millspaugh’s Flora
of Yucatan, Hemsley’s Botany of Central America, Urban’s papers
on the Flora of the West Indies give more or less detailed infor-
mation on introduced weeds.
Fie. 552. Crabgrass (Digitaria sanguinalis). A cosmopolitan weed.
The following weeds are more or less cosmopolitan: crab grass
(Digitaria sanguinalis), found in North and South America, Eu-
rope, Asia, Africa, Australia and New Zealand; barnyard grass
(Echinochloa crusgallt), in Europe, Asia, Africa, North and South
America and Australia; green foxtail (Setaria viridis), in Europe,
732 WEED FLORA OF IOWA
Fig. 553. Foxtail Grass (Alopecurus geniculatus). Widely distributed. Cos-
mopolitan grass.
(U. S. Dept. of Agr.)
Asia, Africa, Australia, North and South America; pigeon grass
(Setaria glauca), in Europe, Asia, Africa, North and South Amer-
ica; whorled millet (Setaria verticillata), in Europe, Asia, Africa,
North and South America; Johnson grass (Sorghum halepense),
in Europe, Asia, Australia and North America; foxtail grass
(Alopecurus genculatus), im Asia, New Zealand, Australia, North
America; hair grass (Agrostis hyemalis), in Australia, New
Zealand, North America; Bermuda grass (Cynodon dactylon), a
valuable forage plant, but, in cultivated fields, a weed, Europe,
Asia, Africa, Australia, New Zealand, North and South America;
southern spear grass (Hragrostis pilosa), Europe, Asia, Africa,
Australia, New Zealand, North and South America; crowfoot grass
WHED MIGRATION 733
(Eleusine indica), Europe, Asia, Africa, Australia, New Zealand,
North and South America; cheat (Bromus secalinus), Europe,
Asia, North America, a weed; brome grass (Bromus tectorum),
Europe, Asia, Africa, North America; soft chess (Bromus arven-
sis), Europe, Asia, Africa, North America... It is singular that
only one species of Bromus is given by Moore and Ferdinand von
Mueller, the Bromus arenarius. Reed (Phragmites communis),
though not regarded as a weed in the United States, is a cosmo-
politan plant-found in Europe, Asia, Africa, Australia, New
Zealand, Papua, North America (Canada, United States and
Mexico).
Yy
if
\
y
f \\ J
7
Fic. 554. Tumbling Mustard (Sisymbrium altissimum). Introduced with grain
in the Dakctas.
(Dewey, U. S. Dept. Agr.)
Cress (Barbarea vulgaris) occurs in Europe, Asia, Australia,
New Zealand and North America. None of the most common
North American weeds among the remaining members of the mus-
734 WEED FLORA OF IOWA
tard family occur in Australia or New Zealand, although shep-
herd’s purse (Capsella bursa-pastoris), common mustard (Brassica
arvensis), the hedge mustards (Sisymbrium officinale and S. altis-
stmum) and peppergrass (Lepidiwm apetalum) are common in
Europe and Asia.
Of the pulse family the bird’s-foot trefoil (Lotus corniculatus) —
occurs in Europe, Asia, Africa and Australia; the indigo plant
(Indigofera hirsuta) in Africa, Australia, Papua and Asia. The
absence of black medick (Medicago lupulina) and hop clover (Tri-
folium agrartum) from Australia is striking.
Of the geranium family the common European, African and
Asiatic species of storksbill (Hrodium cicutariwm) are absent in
Australia and New Zealand and the little yellow flowered sorrel
(Oxalis cormculata) is the only representative in New Zealand,
Australia and Papua. This species also occurs in Europe, Asia,
Africa and America. The only malvaceous weeds in Australia
common also to the United States are sida (Sida spinosa) and
butter-print (Abutilon theophrasti), both of tropical origin. The
former occurs in Europe, Asia, Africa, North and South America,
Australia and Papua. The pigweed (Amaranthus retroflexus) of
southern North America is common in Europe but has not reached
Australia. None of our troublesome weedy species of dock, which
are cosmopolitan, occurs in Australia. Of the smartweeds there
are two species, the water pepper (Polygonum hydropiper)
(Europe, Asia, North and South America) and slender smartweed
(P. lapathifolium) of Europe, Asia, North ‘and South America.
Silky cinquefoil (Potentilla anserina), of the rose family, is com-
mon in the west and here and there in northern Iowa; it is found
in Europe, Asia, Africa, Australia, New Zealand and North
America. Feverfew (Agrimonia striata) is found in Europe,
Africa and North America. None of our Oenotheras is cosmo-
politan; however the primrose willow (Jussiaea suffruticosa), a
sub-tropical plant, is widely distributed in Asia, Africa, America
and Papua. Very few of the Umbelliferae are cosmopolitan.
Moore and Mueller record water parsnip (Siwm latefolwm) for
New Zealand and Australia.
The Mexican Ageratum conyzoides of the sunflower family, found
in Africa, Asia, Europe, North and South America, is often weedy.
The Spanish needle (Bidens bipinnata) is found in Asia, Europe,
North and South America. The small number of plants of this
family found in Australia.and New Zealand is remarkable. None
WEED MIGRATION "735
of our plantains is of common occurrence. There is no morning-
glory.
It may be of interest to compare the noxious weeds of Ger-
many with those of the United States. Dr. A. Thaer of the Uni-
versity of Giessen in 1881 published a small book on the agricul-
tural weeds of that country listing the following: (Those printed
in small capitals are also weedy in Iowa.) Corn poppy (Papaver
rhoeas), mustard (BRASSICA ARVENSIS), charlock (RAPHANUS
RAPHANISTRUM), Canada thistle (CiRstUM ARVENSE), corn cockle
(AGROSTEMMA GITHAGO), chickweed (STELLARIA MEDIA), sheep sorrel
(Rumex acetosella), vetch (Vicia hirsuta), colt’s-foot (Tussilago
farfara), corn chamomile (Anthemis arvensis), corn marigold
Fic. 555. Cypress Spurge (Euphorbia cyparissias). Common in Europe and
waste places in Iowa. In many cases started in the vicinity of cemeteries.
(After Strasburger, Noll, Schenck and Karsten.)
(Chrysanthemum segetum), groundsel (Senecio vernalis), corn-
flower (Centaurea cyanus), sow thistle (SoNCHUS OLERACEUS),
small bindweed (CoONVOLVULUS ARVENSIS), clover dodder (CuSCUTA
EPITHYMUM), broom rape (Orobanche ramosa), garden orach
736 WEED FLORA OF IOWA
(Atriplex hortense), cock’s comb (Rhinanthus crista-galli major
and minor), smartweed (PoLYGONUM PERSICARIA), cypress spurge
( EUPHORBIA CYPARISSIAS) , meadow saffron ( Colchicum autumnale),
silky bent-grass (Agrostis spica-ventr), wild oats (AVENA FATUA),
chess (BROMUS SECATINUS), quack grass (AGROPYRON REPENS),
horse-tail (EQUISETUM ARVENSE).
L. Danger in his work on weeds and parasites of Germany, pub-
lished in 1887, divides the weeds of Germany into two classes:
A. Root weeds, B. Seed weeds.
A. Root weeds—Quack grass (Agropyron repens), reed grass
(Phragmites communis), bindweed (Convolvulus arvensis), deadly
nightshade (Atropa belladonna), goatweed (Aegopodium roda-
graria), sheep sorrel (Rumex acetosella), sour dock (R. crispus),
meadow saffron Colchicum autumnale), marsh marigold (Caltha
palustris), mint (Mentha arvensis), thistle (Cirsium arvense, C.
alteraceum, C. acaule, C. heterophyllum, C. palustre, C. lan-
ceolatum), (Carduus crispus, C. lanceolatus, C. natams), (Onopor-
don acanthium), sow thistle (Sonchus arvensis, 8. palustre, S. asper,
S. oleraceus), colt’s-foot (Tussilago farfara, T. hybrida, T. peta-
sites), yarrow (Achillea millefolium), (Leontodon autumnalis)
dandelion (Taraxacum officinale), plantain (Plantago coronopus,
P. arenaria, P. major, P. media, P. maritima, P. lanceolata), horse-
tails (Hquisetum arvense, E. palustre).
B. Seed weeds—Chess (Bromus secalinus), (Alopecurus
agrestis), wild oats (Avena fatua), (Agrostis spica-venti), darnel
(Lolium temulentum), black nightshade (Solanum nigrum), black
henbane (Hyoscyamus niger), Jimson weed (Datura stramonium),
fool’s parsley (Aethusa cynapium), hemlock (Coniwm maculatum),
cowbane (Crcuta virosa), Venus’ comb (Scandia pecten-veneris),
buckwheat (Fagopyrum esculentum), smartweed (Polygonum
persicaria), dooryard knotweed (Polygonum aviculare), corn cockle
(Agrostemma githago), buttercups (Ranunculus septentrionalis,
k. flammula, R. arvensis), nettle (Lamtum), charlock (Raphanus
raphamstrum), foxglove (Digitalis purpurea), mustard (Brassica
arvensis), mayweed (Anthemis arvensis and A. cotula), groundsel
(Senecio vulgaris), horseweed (Erigeron canadensis), field mari-
gold (Chrysanthemum segetum), Frenchweed (Galinsoga parvi-
flora), spurge (Euphorbia cyparissias), orach (Atriplex hortense),
nettles (Urtica wrens, U. dioica).
WHED MIGRATION 737
AMERICAN WEEDS INTRODUCED INTO EUROPE.
Every year more weeds are introduced into Europe from Amer-
ica; however, it is very noticeable that the more abundant of these
are from the warmer regions of America, rather than from the
colder regions. A good many of these are weeds of the open
country of North America. I have looked rather hastily through a
few of the floras of Great Britain, Italy, Austria and Germany, in
addition to a number of recent references on the adventive flora
of Europe, from which these data have been compiled.
Apple of Peru (Nicandra physaloides) Germany (Garcke).
Aster (Aster novi-belau) Italy (Arcangeli), Germany (Garcke),
France (Acloque).
Aster (Aster parviflorus) Germany (Garcke).
Aster (Aster salicifolius) Germany (Garcke).
Bug seed (Corispermum hyssopifolium) Germany (Garcke),
Italy (Arcangeli).
Bur cucumber (Sicyos anglinus) Germany (Garcke), Italy
(Areangell).
Clotbur (Xanthiwm spinosum) Italy (Arecangeli), Germany
(Garcke, Bitter, Kiefer), Austria (Neilreich), France (Acloque).
Collomia (Collomia grandiflora) Germany (Garcke).
Cone flower (Rudbeckia hirta) Germany (Garcke).
Cone flower (Rudbeckia lacimata) Germany (Garcke, Bitter;
Lehmann).
Cone flower (Lepachys pinnata) Germany (Bitter).
Kvening primrose (Oenothera sinuata) Germany (Bitter).
Fleabane (Erigeron annwus) France (Acloque), Italy (Ar-
eangeli).
Fleabane horseweed (Hrigeron canadensis) France (Acloque),
Austria (Neilreich), Germany (Garcke, Lehmann), England
(Hooker), Italy (Areangeli).
Galinsoga (Galinsoga parviflora) Italy (Arcangeli), Germany
(Garcke).
Pigweed (Amaranthus retroflexus) Italy (Arcangeli), Germany
(Garcke, Alpers), France (Acloque), Austria (Neilreich).
Goldenrod (Solidago canadensis) Germany (Garcke, Wegelin),
Austria (Neilreich).
- Goldenrod (Solidago lanceolata) Germany (Gareke), England
(Hooker).
47
738 WEED FLORA OF IOWA
Fic. 556. Goldenrod (Solidago rigida). Common in Iowa.
(Photographed by Gardner.)
Goldenrod (Solidago serotina) Italy (Arcangeli), Germany
(Garcke).
Mexican tea (Chenopodium ambrosioides) Germany (Garcke,
Alpers), Italy (Arcangeli).
Nightshade, buffalo bur (Solanum rostratum) Germany (Garcke,
Alpers).
Nightshade, buffalo bur (Solanum heterodoxum) Germany
(Garcke).
Nightshade, Three-flowered (Solanum triflorum) Germany |
(Garcke, Alpers).
Pellitory (Parietaria pennsylvanica) Germany (Garckane
Peppergrass (Lepidiwm virginicum) Germany (Garcke), France
(Tourlet)..
Phacelia (Phacelia tanacetifolia) Gemede (Garcke).
Pigweed, Tumbleweed (Amaranthus graecizans) Italy (Arean-
geli), Germany (Bitter).
Pigweed (Amaranthus retroflexus) Italy (Arecangeli), eine
(Garcke, Alpers), France (Acloque), Austria (Neilreich).
WEED MIGRATION 739
Fig. 557. Rice Cut Grass (Leersia oryzoides). Common in low grounds, Iowa;
not, however, regarded as a weed. Common in Italy.
(Lamson-Scribner, U. S. Dept. of Agr.)
740 Sat WEED FLORA OF IOWA
Pigweed, winged (Cycloloma platyphyllum) Italy (Arcangeli).
Plantain (Plantago aristata) Germany (Bitter).
Ragweed, small (Ambrosia artemisiifolia) Germany (Garcke,
Laubert).
Rice cut-grass (Leersia oryzoides) Italy (Arcangeli), Germany
(Garcke,. Buchenau), France (Acloque), Austria (Neilreich),
England (Hooker).
Sida (Sida spinosa) Germany (Alpers).
Spanish needle (Bidens bipinnata) Italy (Areangeli), Germany
(Garcke, Boute), France (Acloque).
Spanish needle (Bidens frondosa) Italy (Arcangeli).
Spanish needle (Bidens leucanthus) Germany (Garcke).
Speargerass (Hragrostis pilosa) Italy (Arcangeli), Germany
(Garcke), France (Acloque).
Speedwell (Veronica peregrina) Italy (Arcangeli), Austria
(Neilreich).
Sunflower, artichoke (Helianthus tuberosus) Italy (Areangeli),
Germany (Garcke).
Sunflower, common (Helianthus annuus) Germany (Garcke),
Austria (Neilreich).
_ Tickle grass (Panicum capillare) Germany (Alpers, Care
France, Italy (Arecangeli), Austria (Neilreich).
Tickseed (Coreopsis tinctoria) Germany (Bitter).
Waterweed (Elodea canadensis) Germany (Garcke, Scherer,
Weshoff, Bitter), England (Hooker), France (Acloque).
INDIGENOUS WEEDS COMMON TO THE NORTHERN HEMISPHERE.
In all probability a few of the weeds here listed have been intro-
duced, at any rate their origin is in doubt; some occur in Hurope
and North America only; those found in Asia are marked (As.).
Achillea millefolium (yarrow) (As.).
Alopecurus geniculatus (marsh foxtail).
Anagallis arvensis (pimpernel) (As.).
Anaphalis margaritacea (everlasting).
Atriplex patula var. hastata (orach).
Barbarea vulgaris (yellow rocket).
Bidens cernua (sticktight).
Capsella bursa-pastoris (shepherd’s purse).
Cerastiwm arvense (mouse-ear chickweed).
Convolvulus sepium (morning-glory) (As.).
WEHED MIGRATION 741
Sem
CAN
WP
UNAS
Fic. 558. Yarrow (Achillea millefolium). Common in the northern hemis-
phere.
(Drawing by Charlotte M. King.)
Cyperus esculentus (northern nut grass) (As.).
Epilobium angustifolium (fireweed) (As.).
Erigeron acris (fleabane). ©
Erysimum chewranthoides (treacle mustard).
Galwum trifidum (bedstraw) (As.).
Galium aparine (cleavers) (As.).
Gnaphalium uliginosum (cudweed).
Hierochloe borealis (holy grass)...
Juncus tenuis (wire-grass).
Lepidium apetalum (peppergrass).
Mentha arvensis (mint) (As.).
Myosurus minimus (mouse-tail).
Oxalis corniculata (field sorrel).
742 WEED FLORA OF IOWA
Plantago major (common plantain) (As.).
Polygonum aviculare (dooryard knotweed) (As.).
Polygonum hydropiper (smartweed).
Polygonum lapathifolium (smartweed).
Potentilla anserma (silvery cinquefoil).
Potentilla monspeliensis (five-finger) (As.).
Fic. 559. Holy or Vanilla Grass (Hierochloe borealis). Common in the northern
hemisphere, mountain regions. In northern Iowa.
(Lamson-Scribner, U. S. Dept. Agr.)
Prunella vulgaris (self-heal).
Radicula palustris (marsh cress) (As.).
Ranunculus cymbalaria (erowfoot).
Ranunculus pennsylvanicus (crowfoot) (As.).
Ranunculus repens (crowfoot).
Rhinanthus crista-galli (yellow rattle).
WEED MIGRATION 743
Senecio palustris (ragwort).
Stachys palustris (woundwort) (As.).
Taraxacum officinale (dandelion). This species occurs every-
where in the United States and Europe, even on the highest moun-
tains.
Fic. 560. Dandelion (Taraxacum officinale). Common in the northern hemis-
phere, across the continent.
INTRODUCTION OF SOME WEEDS INTO THE UNITED
STATES AND INTO IOWA. ©
CHENOPODIACEAEH, GOOSEFOOT FAMILY.
Russian Thistle (Salsola kali var. tenwifolia).
This plant has long been known as a troublesome weed. Henfrey,
in his work, “‘The Vegetation of Europe, its Condition and Causes,”’
published in 1852, notes its abundance in Russia, east of the Volga.
744 WEED FLORA OF IOWA
Linnaeus, the Swedish botanist, seems to have known the plant as
it occurred in eastern Europe. Prof. L. H. Dewey has given us a
good account of the introduction of this weed in the United States.*
It seems to have been first observed in Scotland, Bonhomme county,
South Dakota, in 1873 or 1874, the seed having been brought in
with flax seed. In 1877, it was reported from Yankton county;
five years later in the counties to the north and west of Bonhomme.
By 1888 it had infested many of the counties east of Missouri river
and two years later practically all of the counties of South Dakota
and southern North Dakota. About the same time it invaded
Fic. 561. Russian Thistle (Salsola kali var. tenuifolia). Common in eastern
Europe. Introduced into the Dakotas, 1873 or 1874. Now common in
northern United States, particularly in the west.
(Drawing by Charlotte M. King.)
*Bull. Div. of Bot., U. S. Dept. of Agr. 15:12. 1894.
WEED MIGRATION 745
northwestern Iowa, northeastern Nebraska and western Minnesota.
In 1898 it was reported from Colorado, Wisconsin, Illinois and
other western states. In 1894 Pammel gave the following account
of its distribution:
Prof. Dewey’s map indicates that the badly infested area extends
from the east bank of the Missouri river at Bismarck to Jamestown
and Moorehead in North Dakota; south to Sioux City, in Iowa, it
also occurs in many isolated places in Minnesota, Wisconsin, Iowa,
and at Denver, Colorado. The localities at which he found it in
Towa are Rock Rapids, Emmetsburg, Spencer and west to the
Missouri river, Council Bluffs, and on the Missouri river opposite
Nebraska City. To these we must add Edna, Ames, Little Rock
(Ball), Calumet (Louthan), Missouri Valley, Mason City, Hagle
Grove, and in all probability it occurs along our great trunk lines
across the state. Last season Mr. G. W. Carver found a small
specimen of what undoubtedly was Russian thistle along the Chi-
cago & Northwestern railroad; the place was revisited this year,
and an abundance of the weed was found.
he saw the importance of making careful examination for the im-
purities of various grass and clover seeds. In 1876 appeared his
classical book, Handbuch der Samenkunde. In addition to this
work he was the author of many other important papers on via-
bility of seeds and other physiological seed problems.
Among other important contributions along this line, we may
mention the papers and work of Kraft, Luhn, and Harz. The work
of Harz summarizes not only the facts pertaining to the anatomy
of seeds but also to many other important topics; the literature
bearing on the subject of seeds is also given.
The work of Burchard on the adulteration of seed with special
reference to their origin is particularly noteworthy. In his book
he has published statistical records showing the origin of clover
seed and the weed seeds found in the same from Middle Europe,
Eastern Europe, Southern Europe and North and South America.
He sometimes missed the important weed species that are found
in our American clover seed, but on the whole it is true that the
character of the weed seeds found in our clover and other seeds
will enable one to tell where they were grown.
Burchard, in his account published in a contribution from the
Seed Control Station of Hamburg, states that a large number of
seeds investigated by him had impurities. Of two hundred and
— eighty seeds tested, one hundred and sixty-seven belonged to the
pulse family, seventy-nine to the grass family, twenty-three to
forest seeds, and eleven were miscellaneous. He found the mini-
mum purity of the clover seed was 54.2 per cent. The highest
percentage of purity was found in timothy, 99.42. The lowest
germinative energy was found in fescue grass, 0.17 per cent, and
*The more important references here given upon the history of seed investi-
gation are taken from bulletins 88, 99 and 105, issued by the Iowa State Agri-
cultural Experiment Station, which are more completely listed in the bibliography.
828 WEED FLORA OF IOWA
the highest in clover, 97.25 per cent. Of the sixty samples of red
clover examined for dodder, twenty-eight were free. The most
common species was clover dodder, although others were also found.
One lot of alfalfa from South America contained the Chilian
dodder. In this investigation as in others, he emphasizes the im-
portance of determining the kinds of weeds found in the seed,
thus: In Australian orchard grass the hairy brome grass was
common, and in North American seed, orchard grass, timothy, blue
grass and tickle grass.
The work of Settegast treats extensively the subject of agricul-
tural seeds and seed testing, especially with reference to vitality
and seed production.
Vandevelde’s work treats of the morphology and physiology of
germination and includes a splendid bibliography.
Attention should be called to the excellent contributions of
Wollny whose reports of his splendid work on seeds and the care
of agricultural crops often give considerable detail on the ger-
mination and viability of various agricultural seeds.
Kienitz gives a detailed account of the methods to be followed
in the study of germination of seeds.
Fruwirth carried out a study on the color and speeie gravity
of clover seeds. He found that the dark violet seeds were heavier
than the light colored ones of the same head, and perhaps had
greater germinative energy.
Samek carried on an experiment, testing seeds for a period of
eleven years, showing the results of germination after the first and
eleventh years.
Hiltner in a somewhat recent paper discusses the limitations of
seed testing and the importance of obtaining pure seed.
H. von Guttenberg gives the description of five species of
Cuscata and a key for their identification. Von Degen notes the
germination of dodder under varying conditions. Kinzel has made
a study of the effect of freezing seed and its bearing upon agri-
cultural weeds. Pieper discusses the method of testing the ger-
mination of seeds and presents a new method of determining the
germination of grass seed. Dorph-Petersen gives a summary of
seed tests carried on by the Danish Seed Control Station, during
which 9,024 samples of clover, grass, and other seeds were analyzed.
The paper gives a list of weed seeds found and includes notes on
germination and purity. F. G. Stebler, of the Zurich Seed Control
Station, Switzerland, gives the results of tests made of 10,335
HISTORY AND BIBLIOGRAPHY 829
seeds examined in 1908, with reference to adulteration, purity,
vitality, and the presence of Cuscuta. Vilke gives an account of
the presence of weed seeds found in Swedish seeds. J. Paczoski
notes the important weeds found in the Cherson Government.
A. Malzew reports on the more important weeds found in Russia;
black bindweed (Polygonum convolvulus) and corn cockle (Agros-
temma githago) were common in wheat; oats had, in addition, wild
oats (Avena fatua, glabrata), and Neshia panculata. In rye, the
black bindweed (Polygonum convolvulus), lamb’s quarters (Cheno-
podium album), stickweed (EHchinospermum lappula), and Neslia
paniculata were found. Lesage made a study upon the effect of
solutions of common salt and alcohol on the germination of garden
eress. O. Munerati and T. V. Zapparoli of Italy have made a
study of weed seeds with hard coats. F. Johnson and R. Hensman
discuss the source of the alien flora of Ireland through weed im-
purities found in agricultural seed. A. J. Ewart made tests of
various grass and garden seeds with reference to the vitality of
seeds after a sea voyage. In a lengthy report on the prolonged
vitality of seeds it was found that quite a per cent of seeds ger-
minated after half a century. Rees made a study of hard seeds
with reference to the cuticular layer. This layer repelled the water,
and for this reason seeds retained their vitality.
A recent paper by E. Lehmann on the temperature and lght
relations and the germination of seeds, gives both an exhaustive
summary of the subject and a great deal of original matter.
It is difficult to say under what conditions seed will germinate.
Older investigators regarded light as having no definite action on
the germination of seeds. Crocker found that the structure of the
seed coats retarded germination in the case of Xanthium. Shull,
Crocker, and others found that oxygen hastened the process. In
a recent paper by H. Lehmann, attention is called to the action of
light and temperature on the germination of seeds, both of which
influence this action. The seeds of Whitlavia grandtflora indicated
that germination is retarded at higher temperatures but not at
lower. He designates some seeds, such as H'pilobium rosewm, E. hir-
sutum (Lehmann), and Veronica peregrina (Heinricher) as light
germinating seeds. Dark germinating seeds are represented by
Phlox drummondii. Tehmann found that 4 per cent germinate in
light and 31 per cent in darkness. Maturity also influences ger-
mination of seed. When wheat is ripened at a lower temperature,
it requires a longer optimum temperature for germination than seed
830 WEED FLORA OF IOWA
ripened at a higher temperature. The seeds of blue grass when
planted soon after maturity did not germinate in darkness but
under the influence of light 88 per cent germinated. In spring,
however, the germination was equally good in darkness and light.
Cieslar found that light influenced germination. It would seem
from this and other investigations that structure, the oxygen, sub-
stratum moisture, temperature, light, in short, the ecology and
structure as well as physiology play an important part in germin-
ation.
There are many other contributions, but most of these papers
will be found recorded in the literature cited by Vandevelde, Harz
and Nobbe.
American work.—Connecticut.—The pioneer work in this coun-
try was done by Profs. E. H. Jenkins and Warneke, of the Con-
necticut Agricultural Experiment Station.
Miss Mary G. Jagger and E. H. Jenkins report the results of
analyses for 1908-1909-1910-1911, and note the character of the im-
purities of seed found in the Connecticut market.
North Carolina——Gerald McCarthy, of the North Carolina Agri-
cultural Experiment Station, published an elaborate paper on the
subject in which he gave the details of an extensive investigation
carried on in North Carolina on germination of seeds.
Michigan.—Some excellent work was done by Prof. W. J. Beal
who reported results of germination of clover seeds furnished by
seedsmen. From seeds grown on moist paper the results of the
germination showed that large red clover had a germination of
88 per cent, medium red clover 88 per cent, white clover 84 per
cent and alsike clover 64 per cent. Prof. Beal called attention to
the difference in germination of seeds when grown in sand and in
blotting paper. From seeds grown in sand the following results
were obtained: Medium clover had a germination of 76 per cent,
white clover 92 per cent, red clover (two separate lots) 70 and 56
per cent. :
A later report of Prof. Beal gives two tests of twelve years old
clover seeds in both of which the germination was 35.8 per cent.
Subsequent reports on the vitality of clover and other seeds were
also made.
Prof. Beal also reports tests on seeds sent by farmers. Fifty-
eight samples ranged from 25 to 97 per cent, seventeen being above
90 per cent. He early called attention to the presence of rib grass
in clover seed. Recently he has published an exhaustive bulletin
on the seeds of Michigan weeds with excellent figures made by
HISTORY AND BIBLIOGRAPHY 831
F. H. Hillman. Dr. R. Zceuw has published the results on the
comparative viability of seeds, fungi, and bacteria, when subjected
to various chemical agents. Ernest Bessey gives the results of seed
analysis for 1911 and 1912 from which it appears that buckhorn
and plantain were frequent. The paper gives the number of weed
seeds in a pound.
Mr. Parsons in 1893 made some interesting tabulations in a
summary of American seed vitality tests. In the results offered
by him we find the following: Alsike 72.7 per cent, crimson clover
59 per cent, red clover 84.8 per cent, mammoth clover 82.5 per
cent, white clover 72.1 per cent, alfalfa 61.6 per cent.
Pennsylvania.—Prof. Butz studied many hundreds of samples
of seeds, chiefly with respect to their germinative power. In many
cases the percentage of germination was very low. Thus we find
recorded the following: Alfalfa 52 per cent, alsike clover 61 per
cent, Japan clover 69 per cent and seradella 13 per cent.
Ohio.—Mr. Devol early recognized and emphasized the im-
portance of the experiment station in studying the viability of
seeds. In tests conducted by him clover showed a germination of
93 per cent. ;
Later Selby and Hicks made a study of fifty-two samples of
clover and alfalfa seeds sold in Ohio. They found not only that
the seeds had a low vitality but that they contained considerable
impurities.
Nevada.—Several very important papers have been published
by Mr. Hillman on clover seeds and their impurities. One of his
earlier bulletins deals with the descriptions of weed seeds and their
distribution, together with an incidental account of the occurrence
of these seeds in commerce. In a later publication he considers
the weed seeds found as impurities in various types of seeds, in-
cluding alfalfa, red clover, white clover, alsike clover, crimson
clover, Japan clover, Bokhara clover, yellow trefoil and esparcette.
In his investigations a large number of samples was examined.
The paper therefore gives a fair estimate of the impurities gen-
erally found in the various clover seeds offered for sale in this
country. ;
Kansas.—Prof. Roberts and Mr. Freeman carried on an extensive
investigation of alfalfa seed, showing adulteration, substitutes
and impurities; and the methods of detecting the latter. They
found some adulteration in alfalfa seed. The yellow trefoil
(Medicago lupulina) was most frequent though there were occa-
832 WEED FLORA OF IOWA
sional instances in which burr clover (Medicago denticulata) and
sweet clover (Melilotus alba) occurred. The most noxious weed
seeds found were the docks and the English plantain. The average
germination of alfalfa seed was 83 per cent. The subject is also
briefly discussed by Ten Eyck.
Prof. Roberts and Mr. Freeman also made quite an exhaustive
study of the grass seeds commonly sold in Kansas. The dodder
may prove to be a destructive clover parasite in the United States.
Mr. Brown, in a paper on legal and customary weights per bushel
of seeds, has also brought together much important matter on the
subject of the weight of commercial seeds.
Maine.—Prof. Harvey and other members of the staff of the
Maine Experiment Station investigated the vitality and the im-
purity found in the agricultural seeds offered for sale in that
state. The results of Prof. Harvey’s investigations disclosed the
advisability of having a law to regulate the sale of seeds. Such
a law was passed by the state of Maine and the work of carrying
on this law was placed in the hands of the director of the Station.
The results of the tests and regulations concerning the seed
testing for Maine were published by Charles D. Woods, director
of the Station. In a subsequent bulletin he discusses seed inspec-
tion and lists 79 kinds of weed seed. With Hammond the require-
ments of the law are given as well as results of seed testing.
Minnesota.—W. L. Oswald, Bulletin 127 of the Minnesota Station
gives the results of purity and germination tests for 1275 samples
of commercial seed.
North Carolina—McCarthy in an early bulletin of the North
Carolina Station reported on the analyses of seed in 1912. O. I.
Tillman reported on the analyses of commercial seed in accordance
with the North Carolina pure seed act.
Kentucky.—Prof. Garman and others, of the Kentucky Experi-
ment Station, have investigated the impurities in grass and other
forage plants sold in Kentucky. It was found that thirty-six of
the five hundred samples examined were adulterated; among these
were red clover, blue grass, timothy and orchard grass. They con-
cluded that the greatest fraud perpetrated is in the sale of certain
varieties under an assumed name. In several publications Prof.
Garman discussed the impurities and adulterations of grass seed
sold in Kentucky and recommended that no field seeds should be
sold in Kentucky containing more than 5 per cent weed seeds.
He also gave a comprehensive account of seed testing apparatus
HISTORY AND BIBLIOGRAPHY 833
and the conditions under which germination tests are made, with
special reference to work in Kentucky.
Kentucky now has-in consequence of this work an admirable
law forbidding adulteration or misbranding of the clovers and
timothy sold for seed in the state. Its effects have been most
salutary and have been studied with profit by other common-
wealths.
Vermont.—Mr. L. W. Barton, under the direction of Profs.
Jones and Orton of the Vermont Experiment Station, made an
examination of thirty-four samples of clover seed in Vermont. He
reports the total percentage of impurities in red clover as being
from .3 to 5.3, with an average of 1.8 per cent; alfalfa as having
a maximum of 7.1 per cent and a minimum of .6 per cent. Sorrel
was found in 60 per cent of the red clover samples and wild carrot
in a few, the rib plantain occurred in 77 per cent, dodder in 5
per cent, and Canada thistle in 5 per cent. Dodder did not occur
in the alfalfa, but in 8 per cent of the samples Canada thistle
was found.
Massachusetts.—G. E. Stone reports on seed tests made in 1908
and 1910. Smith, Chapman, and Stone describe fourteen weed
seeds most commonly found in grass seed and cattle foods, with a
brief account of the weeds of the state.
Maryland.—E. I. Oswald made a series of experiments to deter-
mine the vitality of seeds when placed in manure under different
conditions. It was found that weed seeds when left for six months
in manure had lost their vitality completely. When left there for
one month under conditions usually followed by dairymen, the
seeds of ribgrass, horse nettle, dock, and a few others were still
firm. Mention of weed seeds is made in the treatise by J. B. S.
Norton on Maryland weeds. The same author gives the result of
seed analysis of various commercial seed.
Nebraska.—E. M. Wilcox in a paper on dodder in alfalfa seed
discusses the frequency of the impurities and means of eradicating
the weed.
New Hampshire.—F.. W. Taylor in reports of seed tests for 1910
and 1911 discusses the New Hampshire law giving results of purity
and germination tests.
New York—F. C. Stewart under the head of alfalfa troubles
discussed dodder in alfalfa seed and subsequently gave a method
of screening dodder out of alfalfa seed. In 1910 G. T. French re-
53
834 WEED FLORA OF IOWA
ported on an examination of several hundred samples of seed with
special reference to the occurrence of dodder, Russian thistle, and
Centaurea repens; an earlier report by the same author reported
on seed tests made at the station. Further discussion is found in
the New York Agricultural Experiment Station Circular 8:1-4,
Dodder in Alfalfa, by F. C. Stewart and G. T. French. Mr. M.
T. Munn in Bulletin 362 gives the seed tests made in 1912, giving
results of examinations made for purity of commercial samples.
North Dakota.—H. L. Bolley discussed the pure seed law of
North Dakota and seed work ending December 31, 1909, with an
account of weed seeds found.
Wisconsin.—A. L. Stone in a circular of information discussed
the seed inspection law of the state, adding some general informa-
tion. With G. T. Moore he also discussed the question of the eradi-
cation of farm weeds which have been introduced by means of im-
pure seed.
Mr. George T. Harrington discussed the worst weeds in connec-
tion with grass and clover seeds. D. L. Beach made a study of
commercial feeds with reference to the germination of weed seeds
found in these feeds. Feed subjected to steaming before feeding
contained no germinable weed seeds.
Texas.—According to O. M. Ball alfalfa seed sold in Texas con-
tains the following chief impurities: Russian thistle, ribgrass,
tumbleweed, pigweed, two kinds of dodder, green foxtail, curled
dock, bur clover, and sweet clover. The vitality varied from 49.5
to 96.5 per cent. A subsequent report also on alfalfa seed was
made.
Arizona.—Prof. Thornber made an examination of alfalfa seed
sold in Arizona. This showed a high percentage of germination.
Iowa.—The Iowa Agricultural Experiment Station has produced
several publications relating to weed seeds. Ball discussed im-
purities in grass seed; Pammel, Buchanan and King have pub-
hshed a bulletin covering impurities of commercial seed. Two
bulletins by I. H. Pammel and Charlotte M. King, ‘‘Results
of seed investigations for 1907’’ and ‘‘Results of seed investiga-
tions for 1908 and 1909,’’ give the results of analyses of seed sent
by farmers to the Station. The results of the 1907 investigation
indicated that the weed seeds were different in many cases from
those reported in a previous publication; dropseed grass was
common, occurring in 3.3 per cent of the samples; Canada thistle
seed was also less frequent. The investigations for 1908-1909 in-
HISTORY AND BIBLIOGRAPHY 835
dicated that the seed sold in the state has improved, field tests of
germination were lower than laboratory tests. A method of deter-
mining the vitality is also given. The subject of delayed germina-
tion is discussed by H. S. Fawcett, who found that a relationship
exists between the hardness of the seed coat and the dormant
period. L. H. Pammel states that different conditions influence
the germination of seeds, such as hard coats and freezing of seeds.
The delayed vitality of weed seeds is discussed by L. H. Pammel
and Charlotte M. King. Weed seeds after freezing germinate
more readily when frozen.
Work of the United States Government.—The National Govern-
ment began a serious investigation of agricultural seeds and their
impurities in 1893. Early articles on the subject appeared under
the head of ‘‘Pure Seed Investigations.’’
Mr. Hicks called attention to the abuses in the seed trade. The
matters that were mentioned by him have evidently not been
remedied since 1894. Since then the work of the Department has
been immeasurably increased, especially by such contributions as
have been made by Mr. Duvel on the vitality of buried seeds and
the storage and germination of wild rice; and the paper by Mr.
Pieters on ‘‘The Farmer’s Interest in Good Seed.’’ Among the
notes on seed testing in 1897, Prof. Hicks and Mr. Sothoron Key
published an account of the germination of several forage plants
and flower garden seeds.
A good table on the percentage of germination sanders re-
quired of seeds will be found in a paper by Mr..Pieters. These
seed standards were also published in the Year Book of 1896. Later
Mr. Pieters discussed the presence of clover dodder and other im-
purities in clover seed. In a circular by Prof. Dewey of the same
division the dodders found in clover were discussed.
The quality of the seed, especially its germinative energy, de-
pends somewhat on the manner in which seeds are kept. Two ar-
ticles on this subject are of special interest in this connection, one
by Pieters, ‘‘Agricultural Seeds, Where Grown and How to
Handle,’’ and an article by Pieters and Brown, ‘‘Kentucky Blue
Grass Seed, Harvesting, Curing and Cleaning.’’
The United States Department of Agriculture has published
rules and described apparatus for seed testing. These were adopted
by the standing committee on seed testing of the Association of
American Agricultural Colleges and Experiment Stations.
836 WEED FLORA OF IOWA
In reports of more recent work, A. F. Woods found dodder seed
frequent in alfalfa and red clover seed. The adulteration and mis-
branding of alfalfa, red clover and grain seeds was discussed by
W. A. Taylor and B. T. Galloway. F. H. Hillman in several papers
on the impurities, adulteration, etc., of clover and forage plant
seeds and vetches, presented admirable figures and good descrip-
tions of weed seeds found as impurities. Westgate, McKee, Evans,
and Vinall gave a brief account of impurities found in alfalfa seed
and sweet clover. The subject of low grade clover seed was con-
sidered by Edgar Brown and Miss Crosby.
In a paper by Brown and Hillman, ‘‘The Seed of Red Clover
and its Impurities,’ the more important impurities found in Eu-
ropean and American grown clover seed are given. Attention is
called to the introduction of bad seeds from Chile. In 1905 two
hundred and seventy-five thousand pounds of Chilean red clover
seeds were imported into the United States, and this clover seed
contained Chilean clover dodder seed.
Canadian work.—In 1892 Prof. J. H. Panton called attention to
the importance of making an investigation of seed purity and of
carrying on a campaign for better and cleaner seed. He thought
a large number of the weeds on the Ontario farms were introduced
in clover seed.
He found the number of weed seeds varied greatly, all the way
from one to four thousand five hundred and forty per half ounce.
Among the weed seeds he reported several that have become trouble-
some in the Mississippi valley; these include ribgrass and chicory.
Saunders in several reports of the Experiment Farms has dis-
cussed the vitality of grass and clover seeds. In 1903 there were
tested one hundred and eighty-six samples of clover. The highest
percentage of germination was low, the lowest 17 and the average
76.3. A large number of grass seeds were also tested. The work
has been continued by Saunders and Grisdale (1910) relative to
determining the climatic conditions favorable to high vitality of
seeds.
Since 1903 the Department of Agriculture of the Dominion of
Canada has created a seed division with Mr. G. H. Clark in charge
of the work in purity and vitality tests.
A very notable publication on the subject of weeds and weed
seeds has been contributed by Clark and Fletcher who have given
colored illustrations of the more important impurities found in
clover and other seeds.
HISTORY AND BIBLIOGRAPHY 837
A. B. McCready of the Ontario Agricultural College gives the
results of germination tests of alfalfa and clover in which the
superiority of bright, clean seed is shown.
Australia.—A. J. Ewart made tests of various grass and garden
seeds with reference to the vitality of seeds after a sea voyage. In
a lengthy report on the prolonged vitality of seeds it was found
that quite a per cent of seeds germinated after half a century.
Rees made a study of hard seeds with reference to the cuticular
layer. This layer repelled the water and for the same reason seeds
retain their vitality.
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