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L161— 0-1096
Weeds of the North Central States
North Central Regional Research Publication No. 281
toSSK
ffHE LIBRARY OF THE
Bulletin 772 University of Illinois at Urbana-Champaign
College of Agriculture Agricultural Experiment Station
TO RENEW PHONE 338-8400
L161-0-1096
Weeds of the North Centred States
Agricultural Experiment Stations of Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin, and the U.S. Department of Agriculture cooperating
Urbana, Illinois April, 1981
Sponsored by the Agricultural Experiment Stations of Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, Oklahoma, South Dakota, and Wisconsin, and by the U.S. Depart- ment of Agriculture, Science and Education Administration — Agricultural Research and Cooperative Research.
North Central Regional Technical Committee NC-121 (Integrating Crop Culture, Chemicals and Life Cycles to Control Persistent Weeds) was re- sponsible for this publication. Members of the committee include the follow- ing representatives of the State Agricultural Experiment Stations and the U.S. Department of Agriculture, Science and Education Administration:
State Agricultural Experiment Stations
Loyd M. Wax — Illinois
Richard S. Fawcett — Iowa
Loren J. Moshier — Kansas
William F. Meggitt — Michigan
Donald L. Wyse — Minnesota
Lloyd C. Haderlie — Nebraska
Calvin G. Messersmith — North Dakota
Leo E. Bendixen — Ohio
W. E. Arnold — South Dakota
Jerry Doll — Wisconsin
U.S. Department of Agriculture, SEA
Melvin K. McCarty — Agricultural Research Kenneth P. Dorschner — Cooperative Research
Administrative Advisor H. R. Lund — North Dakota
The publication was prepared by a subcommittee that included Loyd M. Wax, University of Illinois and U.S. Department of Agriculture, SEA (Chair- man) and Richard S. Fawcett and Duane Isely, Iowa State University.
The participating Agricultural Experiment Stations and government agencies provide equal opportunities in programs and employment.
no. "772
FOREWORD
Weeds of the North Central States was originally published in 1954 as North Central Regional Publication 36 and Illinois Agricultural Ex- periment Station Circular 718. Members of the Regional Technical Committee of Project NC-10, including representatives of the Agricul- tural Experiment Stations of the twelve North Central states and Oklahoma, contributed to the original edition. The editorial subcommittee that prepared the material for publication was made up of K. P. Buch- holtz, Wisconsin (Chairman) ; B. H. Grigsby, Michigan; O. C. Lee, Indiana; F. W. Slife, Illinois; C. J. Willard, Ohio; and N. J. Volk, Indiana, Administrative Advisor.
A revised, enlarged edition was published in 1960. The editorial subcommittee that prepared the revision consisted of Professors Slife (Chairman) and Buchholtz from the initial subcommittee, together with Thor Kommedahl, Minnesota.
The present edition was prepared by the editorial subcommittee of the North Central Regional Technical Committee NC-121. Members of the subcommittee are: Loyd M. Wax, University of Illinois and U.S. Department of Agriculture, Science and Education Administration (Chairman) ; and Richard S. Fawcett and Duane Isely, Iowa State University.
This edition includes all the weeds that were in the 1960 edition, with some changes in nomenclature, updating of distribution maps, and minor revisions of the descriptions. In addition, 19 weeds have been added, the original keys have been expanded, and a new key for com- mon weed seedlings in corn and soybean fields has been included.
CONTENTS
INTRODUCTION 5-8
WEED DESCRIPTIONS 11 -240
KEYS FOR IDENTIFYING WEEDS 243-290
Key 1. Plants with yellow, orange, or cream flowers 247-257
Key 2. Plants with white flowers 257-266
Key 3. Plants with red, pink, blue, lavender, or purple flowers 267-273
Key 4. Plants with greenish flowers, grosses or grasslike 274-279
Key 5. Plants with greenish flowers, not grasses 280-285
Key 6. Plants woody 286-288
Common weed seedlings of corn and soybeans 289-290
GLOSSARY 291-294
INDEX TO SPECIES 295-302
INDEX TO FAMILIES. . ..303
ACKNOWLEDGMENTS
Illustrations were obtained from many sources. Credit for illustrations that appeared in the first two editions of this publication, as well as in the present edition, is due the following institutions: California State Depart- ment of Agriculture (Weeds of California), Iowa State Department of Agriculture (Bul.N81-A), Michigan Agricultural Experiment Station (Bui. 267 and Spec. Bui. 304), University of Minnesota (illustrations prepared under W.P.A. project 65-1-71-140), Missouri Agricultural Experiment Station (Bui. 433), Nebraska State Department of Agriculture (Bui. 101), South Dakota State Weed Board (Publication No. 5), U.S. Department of Agriculture (Misc. Pub. 200).
The editorial subcommittee that prepared the present edition appreciates the suggestions and guidance given by members of the Project NC-121 Regional Technical Committee. Special thanks for texts, drawings, and maps for species added in 1981 are given to personnel from the following institutions: University of Minnesota, South Dakota State University, Kansas State University, University of Wisconsin, University of Nebraska, North Dakota State University, and University of Illinois.
Ax THE WEEDS commonly found in the North Central Region, as well as a good many that are less common, are illustrated and de- scribed in this book. Detailed pictures have been given for most of the weeds, and wherever possible in the descriptions common terms have been substituted for technical ones. People with a minimum of botanical knowledge should therefore be able to identify almost every weed they are likely to find.
What is a weed? Although we all have a general concept as to what a weed is, it is sometimes hard to determine whether a particular plant is a weed or not. Some crop plants, for example, can become weeds when they appear where they are not wanted. On the other hand, a number of plants usually thought of as weeds may actually be useful under some conditions or in some areas. They may help to control soil erosion or may serve as foods for wild animals and birds. Sometimes certain weeds are used as forages for farm animals.
With these points in mind, we can define a weed as a plant not in- tentionally sown, whose undesirable qualities outweigh its good points. This definition eliminates the many plants — often native — that grow uncultivated in every locality but seldom have weedy tendencies. They are not aggressive enough to be troublesome in cropland or pastures. Since they do not interfere with agricultural production they should be allowed to grow undisturbed. In fact, many of these plants have such colorful flowers and interesting habits that they are well worth preserving.
How weeds are troublesome. Weeds reduce crop yields by depriving the crops of the water, light, and soil nutrients they need. Weeds may also produce allelopathic substances that are toxic to crop plants. The work of controlling weeds in crops and pastures increases production costs. If weeds are present at crop maturity, they may cause harvesting problems.
Weeds often serve as hosts for crop diseases; and they may provide a place for insects attacking crop plants to overwinter. Some weeds detract from the quality of crops and of animal products; wild garlic, for example, reduces the value of wheat and taints the milk of cows that graze it.
The harmful effects of some common weeds on the health of animals and people are well known. Farm animals become ill and sometimes die from eating poisonous weeds. Thousands of people who suffer from hay fever can attest to the annoyance caused by the pollen from many plants, especially ragweed.
Control is difficult. The seeds of many weeds remain dormant in the soil for years and then germinate when conditions are favorable. Some weeds have extensive root systems and underground stems that help the weed to spread and persist. Perennial weeds store reserve foods in their root systems and continue to sprout again and again after the tops are destroyed. These characteristics of weeds make control a problem.
Even though control is often difficult, the proper selection and use of herbicides can give excellent results with most of the common weeds. For best results, however, it is necessary to identify the weed problem correctly before selecting herbicides. Many herbicides are rather specific in their action and may control only one or a few species of weeds. The same thing is often true of other control measures. If control measures are applied haphazardly, they may not only fail to control weeds, but they may also injure the crop.
Recommendations for the control of weeds vary from locality to locality, and may change fairly rapidly as new herbicides and new combinations become available. Thus no attempt is made in this publica- tion to describe control measures. Precise, up-to-date recommendations for your situation are best obtained locally. This type of information is available from agricultural experiment stations, county agents or ex- tension advisors, agricultural teachers, and other agricultural leaders.
How to identify weeds. A particular weed may be identified in sev- eral ways. Always, however, you need a reasonably good specimen. Identification will be easier if you have the entire plant with leaves, roots, and flowers. Fresh plants are always more easily identified than wilted or dried ones.
If you believe the unidentified weed belongs to a particular family, such as the grass or mustard family, you have a head start in identifying it. Since plants are arranged by families in this bulletin, you can com- pare your plant with the different illustrations and descriptions in the family until you find what you're looking for. (A special index to fami- lies is given on page 303.) Check the flower color, flower shape, leaf arrangement and shape, type of growth, and other characteristics, to make sure the identification is correct.
Sometimes several closely related weeds are grouped together on a page, with only one being described in detail. If the weed you are trying to identify is in such a group, it may not correspond exactly with the one described. It may differ in size, leaf shape, leaf color, and other minor characteristics. However, the description usually mentions if these related forms of a weed are likely to be found.
If the weed is entirely unfamiliar to you, you may have to compare the specimen with the various illustrations in the bulletin until you find
the correct one. However, this may be a long process. A better way is usually to go to the key at the back of the bulletin. Directions for using the key are given on page 243. Some practice is needed to use it rapidly, but it usually offers the quickest way of identifying an unknown plant.
At times it is necessary to make a tentative identification of weeds while they are still in the seedling stage. For this purpose, beginning on page 289, we have included vegetative keys that will help in identifying young seedlings of the most common grass and broadleaf weeds found in corn and soybean fields in the North Central region. While it is difficult to identify these young seedlings positively, practice with these keys can result in a correct identification much of the time.
Many plants that are occasionally found in the region are not illus- trated in this publication. These may be identified by consulting local or state authorities or botanical manuals.
Maps show distribution. With each weed illustration there is a small outline map that indicates the general prevalence of the weed. The maps are based on a study of herbarium samples and, perhaps more impor- tantly, on the opinions of weed scientists from throughout the region. Changes are required from time to time as species advance to new areas or decline in others as the result of changes in cropping practices, tillage methods, and herbicide use. The following illustration gives the signif- icance of the shadings used on the maps.
Rare or absent -
Found occasionally to frequently — »• ~ M± „
•^ — General and common
Names of weeds vary. Common names of weeds vary considerably in different localities. One weed may have several different names, or several weeds may be known by the same name. The names used in this bulletin have been selected because they seem to be the ones in most general use and because they avoid unnecessary duplication. For the most part, these common names are based on the Composite List of Weeds that was published in Weed Science 19:435-476, 1971.
Scientific names of plants are more uniform than common names, but they sometimes vary according to the authority. Moreover, the names of some plants may be changed as the result of continuing taxo- nomic studies. In general, the scientific names used in this book follow those used in the Composite List of Weeds mentioned above, as well as in the following publications.
Manual of the Grasses of the United States, by A. S. Hitchcock, revised by Agnes Chase. U.S. Department of Agriculture, Mis- cellaneous Publication 200. 1950.
Gray's Manual of Botany, eighth edition, revised by M. L. Fernald. American Book Company. 1950.
Manual of Vascular Plants of Northeastern United States and Adjacent Canada, by H. A. Gleason and A. Cronquist. D. Van Nostrand Co., Inc. 1963.
Atlas of the Flora of the Great Plains, edited by T. M. Barkley. Iowa State University Press. 1977.
In some instances, if authorities differed or if recent taxonomic studies indicated the need for a changed name, decisions were made to use different scientific names than those given in previous editions of Weeds of the North Central States.
Suggestions will be welcome. The subcommittee responsible for this publication would appreciate comments and suggestions, so that they may be considered for future editions. New weed problems are con- tinuously developing in the region while others seem to diminish. Thus information about needed changes in distribution maps would be especially helpful. We would also welcome suggestions as to possible changes in names of plants.
Weed Descriptions
HORSETAIL FAMILY, Equisetaceae
FIELD HORSETAIL, Equisetum orvense L. 1, fertile or reproductive shoots; 2, sterile or vegetative shoots; 3, rhizomes. Perennial, reproducing by spores instead of seeds, and by rhizomes, to which are attached small tubers. Stems tough and wiry, hollow, jointed, and of two types: fertile, producing fruiting heads and having large, easily separable joints, not branched; sterile or vegetative, having much smaller joints, with lateral branches in whorls around the main stem. Leaves on sterile stems only, in the form of cup- shaped toothed sheaths at the joints. Fruiting heads contain masses of tiny pale greenish spores in small pine-cone-like structure. Found mostly on wet, sandy, or gravelly soil. It is poisonous to livestock when eaten in large quantities. There are several species of Equisetum in the area, all of which can be recognized as horsetails from this illustration.
11
FERN FAMILY, Polypodiaceae
BRACKEN, Pteridium aquilinum (L.) Kuhn. 1, plant showing leaves and rhi- zomes; 2, segmented leaflet; 3, undersurface of leaflet showing spore-bear- ing margin. Perennial, growing 1 to 4 feet (0.3 to 1.2 m) tall. Reproduces by spores or by shoots from a thick, black, scaly rhizome that may grow to a length of 20 feet (6 m). Leaves or fronds arise directly from the rhi- zome, with many branches, each branch being made up of numerous leaflets which in turn are segmented. Spores are borne on the underside of each leaflet in a narrow, brownish marginal band. Found in open pastures, wood- lands, and hillsides, particularly on acid soils. The plant is poisonous if consumed over time, but is not usually eaten unless feed is very short.
12
GRASS FAMILY, Gram/necre
JOINTED GOATGRASS, Aeg/'/ops cy/indr/co Host. 1, lower part of plant showing fibrous roots; 2, upper portion with spike; 3, seeds. Winter annual, reproducing by seeds. Root system fibrous. Stems erect, branching at base. Leaves alternate, simple, with auricles at the base of the blade, smooth or, in one variety, hairy. Spikes with spikelets arranged in a compact cylinder, bearded, longest beards at top of head. Seeds ripening ahead of wheat, shattering easily. Found principally in wheat fields, from which it spreads to roadsides and waste places. Very difficult to control where wheat is grown continuously.
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GRASS FAMILY, Gramineae
QUACKGRASS, Agropyron repens (L.) Beauv. 1, spike; 2, stems, leaves, and inflorescence; 3, auricle and ligule; 4, seed; 5, spikelets; 6, buds on rhi- zome; 7, new shoots; 8, origin of new shoots; 9, rhizomes and roots. Per- ennial, reproducing by seed and underground rhizomes. Rhizomes vary from 2 to 8 inches (5 to 20 cm) in depth, depending on soil type and soil treatment. Individual rhizomes live only two summers and one winter but new ones develop from buds in the axils of reduced leaves. Roots arise only at nodes. Stems IVi to 3 feet (45 to 90 cm) tall, with smooth culms and 3 to 6 joints. Leaves have auricles, ligule 1/32 inch (0.8 mm) long, hairy lower sheaths, upper sheaths smooth or nearly so. Spike has 3 to 7 short-awned florets in a spikelet. Found in open waste places, pastures, and most cropped areas. It requires special control methods because of its weedy habits. Al- though it is considered a primary noxious weed in most states, it can often be used for pasture or hay.
14
GRASS FAMILY, Gram/neae
BROOMSEDGE, Andropogon yirginicus 1. 1, stems and root system; 2, part of inflorescence; 3, single spikelet and rachis segment. Perennial, growing in small erect clumps or bunches, reddish-brown when dry. Roots densely fibrous. Stems several in a tuft, slightly flattened, 1 to 3 feet (30 to 90 cm) tall, upper part branched. Leaves 6 to 12 inches (15 to 30 cm) long, flat or folded, very hairy on upper surface where attached to stem. Panicle con- sists of 2 to 4 fingerlike clusters, each % to V/2 inches (1.9 to 3.8 cm) long, bearing tufts of conspicuous white hairs, enclosed by reddish-brown leaves. Seeds about l/g inch (3 mm) long, brown, bearded. Found mostly on poor run-down pastures and open meadows. A serious problem in pastures on marginal lands, it disappears under fertilization and adequate grazing.
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GRASS FAMILY, Grom/neae
PRAIRIE THREEAWN, Aristida oligantha Michx. 1, entire plant showing habit; 2, glumes and floret. Annual, reproducing by seeds. Roots fibrous. Stems branched near surface of ground, wiry, 12 to 26 inches (30 to 65 cm) high, smooth or sometimes slightly rough. Leaves very narrow, flat, smooth, tapering to fine point. Panicle loose, terminal, each containing a few short-pediceled, narrow, 1-flowered spikelets. Seeds bear a triple awn with bristles of nearly equal length. Awns 1 to 3 inches (2.5 to 7.5 cm) long, somewhat spirally curved at base. Found generally on open, dry, sterile soil, especially overgrazed prairies and abandoned land that was formerly cultivated. Awns cause irritation in mouth and nostrils of live- stock. Several other species of threeawn grasses are found and can be recognized as belonging to the genus Aristida from this illustration.
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GRASS FAMILY, Grcrm/necre
WILD OAT, Avena fatua 1. 1, panicle; 2, portion of lower stem, crown, and roots; 3, 4, seeds with hull and enlargement of "sucker-mouth" base; 5, ker- nel without hull. Annual, reproducing by seed. Root system extensive and fibrous. Stems smooth, stout, 1 to 4 feet (0.3 to 1.2 m) high. Leaves 3 to 8 inches (7.5 to 20 cm) long, resembling those of tame oats. Panicle usually more open than that of tame oats. Spikelets distinguished by long, dark awns, the lower parts twisted, the upper parts bent sharply at right angles to twisted parts. Seeds vary from white to yellow, brown, gray, or black; are usually hairy, especially near base. Distinguished from cultivated oats by the round "sucker-mouth" callus at base of the grain. Seeds usually ripen earlier than most cereals and many drop to ground before "time to harvest cultivated cereals. Found especially in fields under continuous crop- ping to small grains and flax. Probably the most harmful annual weed in the hard red spring wheat area. Recently it has become a problem in the southern part of the hard red winter wheat area, where it acts as a winter annual.
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GRASS FAMILY, Grcrm/neae
JAPANESE BROME, Bromus /aponicus Thunb. 1, part of hairy stem; 2, ma- ture spikelet; 3, seed, inner surface; 4, distribution. Winter annual or annual, reproducing by seeds. Stems erect, 10 to 30 inches (25 to 75 cm) tall. Leaves, both blades and sheaths, covered with soft hairs. Inflorescence a panicle. Spikelets about l/2 inch (13 mm) long, somewhat hairy, borne on long, drooping stalks. Seeds mature May-June, have a stiff beard *4 to Vz inch (6 to 13 mm) long, bend conspicuously outward at maturity. Found in grain fields, meadows, wasteland.
CHEAT, Bromus secalinus L 5, lower part of stem; 6, panicle; 7, mature spikelet; 8, seed; 9, distribution. Winter annual or annual, reproducing by seed. Stems erect, 12 to 24 inches (30 to 60 cm) high. Leaves, both blades and sheaths, smooth or slightly hairy. Inflorescence a panicle. Spikelets borne on shorter, more upright stalks than Japanese brome. Seeds bearing a short beard (i/& to 1/4 inch; 3 to 6 mm), or none at all, broader and shorter than Japanese brome. Found in grain fields, meadows, and waste places.
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GRASS FAMILY, Grammeae
DOWNY BROME, Bromus fecforum L. 1, mature plant with fibrous root sys- tem; 2, mature seed; 3, panicle; 4, spikelet. Winter annual or annual re- producing by seeds. Stems erect or spreading, slender, 6 to 24 inches (15 to 60 cm) high. Leaves, both blades and sheaths, light green, covered with long soft hairs. Panicle rather dense, soft, very drooping, often purplish, flowering in April-May. Seeds long and narrow, bearing long beard (]/2 to */4 inch; 12 to 19 mm), maturing in May-June. Found in meadows, pas- tures, small grain, wasteland.
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GRASS FAMILY, Gramineae
LONGSPINE SANDBUR, Cenchrus longispinus (Hack.) Fern. 1, mature plant showing burs in terminal spikes; 2, bur; 3, a single seed from a bur. Annual, reproducing by seed. Roots fibrous. Rooting may occur at the nodes of the stems when they come in contact with the soil. Stems erect, or sometimes spreading and matlike, 6 inches to 2 feet (15 to 60 cm) long. Leaves smooth, twisted, 2 to 5 inches (5 to 12.5 cm) long. Spike short, composed of spikelets enclosed in sharp spiny burs. Burs each contain 1 to 3 seeds, usually 2. Found mostly on sandy soil. Is troublesome in garden crops, lawns, and fields mainly because the spiny burs cause discomfort to persons and livestock.
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GRASS FAMILY, Gramineae
BERMUDAGRASS, Cynodon dactylon (L.) Pers. 1, plant; 2, spikelets; 3, seed. Perennial, reproducing by seed (although rarely in our region), rhizomes, and stolons. Rhizomes hard, scaly, sharp-pointed, forming dense heavy sod. Stolons flat, hairless, extensively creeping, bearing at each joint the dead, bladeless sheaths that make the "dog's teeth" giving the plant its Latin name (Cynodon — dog's tooth). Flowering stems erect or ascending, 6 to 18 inches (15 to 45 cm) tall. Leaf blades Ys inch (3 mm) wide, gray-green, slightly hairy or glabrous except for a fringe of long hair at edge just above collar; sheath sparsely hairy or hairless, strongly flattened, ligule a ring of white hairs. Flowers borne in "finger-branched inflorescence of 3 to 7, usually 5, parts. Spikelets in 2 rows tightly appressed to rachis. Seeds re- semble those of timothy. Found in open places, pastures, and most cropped areas. A very persistent weed when established, it seems to have entered our territory primarily in nursery stock or by being sown as a lawn; is definitely spreading northward.
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GRASS FAMILY, Gramineae
LARGE CRABGRASS, Digitaria sanguinalis (1.) Scop. 1, plant; 2, section of spike showing spikelets; 3, seed; 4, distribution. Annual, reproducing by seed. Stems stout, smooth, up to 3 feet long; when prostrate, rooting at the joints. Leaf blades usually at least somewhat hairy, Y^ to Ys inch (6 to 8 mm) wide; leaf sheaths, especially the lower ones, densely long-hairy. Inflorescence has 3 to 10 segments, in whorls at top of stem. Seeds 3/32 inch (2.4 mm) long, alternate on the branches of the inflorescence. Found in lawns, gardens, and fields. The most troublesome lawn weed in southern part of region. Starts late, when ground is quite warm; grows well under dry, hot conditions; flowers August-September. Also commonly known as hairy crabgrass.
SMOOTH CRABGRASS, Digitaria ischaemum (Schreb.) Muhl. 5, distribution. Similar to above but not so coarse or tall, without hairs, more purplish or bluish. Found in same places as large crabgrass, but most commonly in lawns.
22
GRASS FAMILY, Gram/neoe
BARNYARDGRASS, Echinochloa crusgalli (1.) Beauv. 1, plant; 2, two views of spikelet. Annual with fibrous, rather shallow roots. Stems 1 to 4 feet (0.3 to 1.2 m) tall, thick, coarse, mostly erect, smooth, branching at the base. Leaves, both sheaths and blades, smooth. Blades % to */% inch (9 to 15 mm) wide, light green. Panicle bearing several rather compact side branches, green or purplish in color. Florets covered with conspicuous short stiff bristles, bearded. Seeds tan to brown, oval with longitudinal ridges on the convex surface. Found in most cropped areas in late summer or fall.
23
iRASS FAMILY, Gram/neae
GOOSEGRASS, Eleusine indica (1.) Gaertn. 1, close-up of a tiller showing arrangement of leaf sheaths and blades; 2, entire plant showing fibrous roots and finger-like inflorescence; 3, spikelets; 4, seeds. Annual, repro- ducing by seeds. Roots fibrous. Stems smooth, sometimes upright but usually nearly prostrate, 6 inches to 2 feet (15 to 60 cm) long. Leaves smooth, blades 3 to 12 inches (7.5 to 30 cm) long, sometimes slightly roughened. Inflorescence fingerlike, similar to crabgrass, with 2 to 10 segments 1 to 3 inches (2.5 to 7.5 cm) long. Spikelets 3- to 6-seeded along the edges of the rachis. Seeds very small, reddish-brown, rough, ridged. Found in lawns, gardens, roadsides, and waste places. A common weed, it is sometimes con- fused with crabgrass but is darker green and grows only in tufts.
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GRASS FAMILY, Gram/neoe
STINKGRASS, Eragrostis cilianensis (All.) Lutati. 1, plant; 2, spikelet; 3, seed. Annual with shallow fibrous roots. Stems slender, smooth, 1 to 2 feet (30 to 60 cm) tall, branched at top — several usually arising from root crown. Leaves have smooth sheaths except for hairs on upper portion, and flat, smooth blades, 1/16 to 5/16 inch (1.5 to 7.5 mm) wide. Panicles branched, the branches moderately spreading, bearing numerous spikelets *4 to H inch (6 to 15 mm) long. Spikelets flat, containing 20 to 40 florets or seeds; dark gray-green to purple. Seeds egg-shaped, 1/32 inch (0.8 mm) in diame- ter, orange-red. Found in cultivated fields and waste places. A moderately troublesome weed. Plant has disagreeable odor.
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GRASS FAMILY, Gramineae
WOOLLY CUPGRASS, Erioch/oa v///osa (Thunb.) Kunth. 1, entire plant; 2, portion of stem, leaf, and raceme; 3, spikelet; 4, seed. Annual, reproducing by seed. Root system fibrous. Stems 3 to 5 feet (0.9 to 1.5 m) tall, erect but sometimes decumbent at base, lower portion often purplish, especially in young plants. Leaves dark green, covered with a fine pubescence, one leaf margin often distinctly crinkled. Inflorescence of several racemes, the rachises and pedicels very woolly; rachis narrow, with spikelets in 2 rows on one side. Seed varies in color from tan to brown to green, with bulbous base, large (to 3/16 inch or 4.5 mm long). Found on moist soils in corn, soybean, small grain, and forage crops.
26
GRASS FAMILY, Gram/neae
FOXTAIL BARLEY, Hordeum jubatum L. 1, upper portions of stems with spikes; 2, base of plant; 3, seed with awns; 4, distribution. Perennial, grow- ing in clumps. Roots densely fibrous. Stems usually erect, 1 to 2 feet (30 to 60 cm) high. Leaves alternate, sheaths smooth, blades y& to 1/4 inch (3 to 6 mm) wide, rough on upper surface. Spike 2 to 5 inches (5 to 12.5 cm) long, nodding, with rather soft, yellowish-green or purplish bristles about 2 inches (5 cm) long. Seeds about l/s inch (3 mm) long, yellow, hairy. Found in pastures, where it is especially troublesome, and other noncultivated areas. Bristles may injure mouths of livestock.
LITTLE BARLEY, Hordeum pusillum Nutt. 5, part of whole plant; 6, group of spikelets or seeds; 7, seed; 8, distribution. Winter annual or annual. Roots shallow and fibrous. Stems smooth, 4 to 15 inches (10 to 37.5 cm) tall, bent slightly at each node. Leaves erect, ^ to 2^4 inches (1.9 to 6.9 cm) long, rough on upper surfaces. Spike resembles small dense head of rye, 1*4 to 3V4 inches (3 to 8 cm) long, with short, stiff bristles (5/16 to H mcn or 7.5 to 15 mm). Seed l/s to J4 mcn (3 to 6 mm) long, hairy at apex, yellow. Found in same places as above.
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GRASS FAMILY, Gramineae
DARNEL, Lolium temulentum 1. 1, spike; 2, lower portion of plant; 3, spike- let (note long single outer glume on the right) ; 4, seed. Annual, reproduc- ing by seeds. Roots fibrous. Stems about U/2 to 2 feet (45 to 60 cm) tall. Leaf sheaths smooth, overlapping on one another. Leaf blades l/s to l/\ inch (3 to 6 mm) wide, flat, slightly rough on upper surfaces. Spikes long and narrow with 2 rows of small, flattened spikelets placed edgewise to the stem. Outer glume of spikelet as long as or longer than spikelet, sharp- pointed. Seed y& to *4 mcn (3 to 6 mm) long, narrowly oval, brownish, usually short-bearded at the tip. Found in grain fields, pastures, roadsides, and waste places. Usually not a serious problem.
28
GRASS FAMILY, Gramineae
WIRESTEM MUHLY, Mu/i/enberg/a frondosa (Poir.) Fern. 1, lower part of plant; 2, upper portions of stems with panicles; 3, spikelet. Perennial, reproducing by seeds, rhizome growth, and rhizome fragments. Rhizomes short, creeping, very scaly. Stems erect or decumbent, 2 to 3 feet (60 to 90 cm) tall, smooth below joints, very tough, leafy, freely branched, rooting at lower nodes. Leaves flat, rough, pale green, scattered along the stem and dense near the tip, giving a bushy appearance. Panicles terminal and axillary, barely protruding from the leaf sheaths. Seeds tightly enclosed in the lemma, which may or may not be awned. Found in fence rows and along roadsides; sometimes persists in cultivated fields. Growth starts in late spring.
29
GRASS FAMILY, Gramineae
NIMBLEWILL, Muhlenbergia schreberi J. F. Gmel. 1, plant showing rooting at lower nodes; 2, spikelet. Perennial, reproducing by seed and numerous fine stolons. Stems not hairy, very slender, spreading, branching, decumbent at base and rooting at lower nodes, forming dense patches 1 foot (30 cm) or more in diameter from a single plant. Leaf blades flat, short (l/2 to 2 inches or 1.3 to 5 cm), not hairy except for occasional marginal hairs at the base; ligule short, membranous; collar not hairy, leaf sheath loose, not hairy. Inflorescence a fine slender panicle, 2 to 6 inches (5 to 15 cm) long, appearing in September. Seeds very small, about the size of redtop. Found generally in lawns, fence rows, and noncultivated areas. Often confused with crabgrass and Bermudagrass in lawns.
30
GRASS FAMILY, Gramineae
WITCHGRASS, Pan/cum capillare L. 1, entire plant; 2, panicle; 3, seeds. Annual with fibrous roots, reproducing by seeds. Stems 10 to 30 inches (25 to 75 cm) tall, often spreading and branched. Leaves and especially the leaf sheaths covered with dense soft hairs. Panicle much branched, becom- ing spreading and open at maturity, often breaking from stem and blown about by wind. Seeds 1/16 inch (1.5 mm) long, greenish or grayish, shiny, smooth, readily separated from hulls when ripe. Found in small grain stub- ble, cultivated fields, meadows, gardens, and waste areas. Seed frequently spread in small-seeded crop seeds.
31
GRASS FAMILY, Grom/neoe
FALL PANICUM, Pon/cum d/c/iofom/florum Michx. 1, lower part of plant showing root system; 2, panicle; 3, section of stem; 4, seed; 5, seed with hull. Annual with fibrous roots, reproducing by seeds. Stems 20 to 50 inches (0.5 to 1.3 m) long, smooth, spreading, often partly flat on the ground. Lower nodes swollen, often rooting. Leaves smooth or sparsely hairy. Leaf sheaths heavy, short, smooth, loose, often purplish. Panicle more compact and shorter than that of witchgrass. Seeds about 1/16 inch (1.5 mm) long, yellow, smooth, dull, readily separated from hulls when ripe. Found in gar- dens, cultivated fields, waste places, and low areas. Often common in corn and soybean fields in the fall.
32
GRASS FAMILY, Gramineae
WILD PROSO MILLET, Pan/cum miliaceum L 1, entire plant; 2, enlarged sec- tion of upper stem with panicle; 3, seed; 4, seed with hull. Annual with fibrous roots, reproducing by seeds. Stems 20 to 60 inches (0.5 to 1.5 m) tall, either spreading or erect, branched. Leaves and especially leaf sheaths covered with dense, stiff hairs. Panicle resembling fall panicum but larger. Seeds 3/32 to ]/& inch (2.4 to 3 mm) long, oval, brown to black, shiny, smooth, readily separated from hulls, resembling domestic proso millet or "bird seed" but darker. Found in cultivated fields, particularly field and sweet corn. Grows rapidly; is particularly well adapted to sandy or drouthy soils and hot weather. Large seedling resembles volunteer corn but hairy. Prolific seed producer. Seed shatters easily and is often spread on harvest equipment.
33
GRASS FAMILY, Gram/neae
ANNUAL BLUEGRASS, Poa annua L. 1, entire plant; 2, spikelet; 3, seed. Annual in the North Central states. Grows well in cool weather but is not winter hardy. Roots shallow, easily pulled from the soil. Stems 1 to 12 inches (2.5 to 30 cm) tall, often decumbent at base, sometimes rooting at lower joints. Leaves a soft, light green. Panicles very small in clipped lawns; plants flower during the entire growing season. Prevalent in lawns and gardens, particularly those with moist, rich soils.
34
GRASS FAMILY, Gramineae
GIANT FOXTAIL, Sefcrr/cr foberi Herrm. 1, lower part of plant; 2, stem with panicle; 3, spikelets with bristles attached. Annual, reproducing by seed. Stems 3 to 7 feet (0.9 to 2 m) tall, so weak that plants may lodge unless supported by each other or by other vegetation. Leaves covered with short hairs on upper surface. Panicle dense, 3 to 8 inches (7.5 to 20 cm) long, bending near base so that head is drooping. Three to six bristles extend from base of each spikelet. Seed mostly greenish, about 1/16 inch (1.5 mm) long, intermediate in size between seeds of green and yellow foxtail. Found in cultivated crops, where it is extremely troublesome.
35
GRASS FAMILY, Gramineae
YELLOW FOXTAIL, Sefor/o lutescens (Weigel) Hubb. 1, entire plant; 2, seeds. Annual, reproducing by seeds. Stems erect, 1 to 2 feet (30 to 60 cm) tall. Leaves flat, often having a spiral twist, with many long hairs on the upper surface near the base. Panicle dense, erect. Spikelets with 5 or more bristles. Seed about 1/12 inch (2 mm) long, mostly yellowish but some dark brown. Found in all places except woods. A serious weed. Also commonly known as pigeon grass.
36
GRASS FAMILY, Gram/neae
BRISTLY FOXTAIL, Sefar/a verf/ci//afa (L.) Beauv. 1, lower part of plant; 2, seeds; 3, upper part of stem with panicle. Annual, reproducing by seeds. Stems 1 to 4 feet (0.3 to 1.2 m) tall, erect but branching more than those of other foxtails. Panicle dense, 2 to 4 inches (5 to 10 cm) long, with 1 bristle at the base of each spikelet, rarely 2 or 3. Bristles barbed, causing seed heads to be carried great distances by man and animals. Seed greenish, similar to that of green foxtail in shape and size. Found in gardens, orchards and other noncultivated areas as well as in some cultivated fields. Irritating to humans and animals because of sticky habit.
37
GRASS FAMILY, Gramineae
GREEN FOXTAIL, Sefor/o vine/is (L.) Beauv. 1, entire plant; 2, seeds. Annual, similar to giant foxtail but smaller, usually growing 1 to 3 feet (0.3 to 0.9 m) tall. Stems erect. Leaves hairless. Panicle dense, 1 to 3 inches (2.5 to 7.5 cm) long, erect, except near tip, which bends slightly. One to three bristles below each spikelet. Seed green, about 1/16 inch (1.5 mm) long, but uniformly smaller than that of giant foxtail. Found generally through- out region. One of the most widespread grass weeds. Several types of S. vine/is in the region vary greatly from the above description. They may grow to 6 or 7 feet (1.8 to 2 m) tall and may have panicles as large as or larger than those of giant foxtail. Some types may have purple bristles. The seed, however, is always smaller than that of giant foxtail. Some authors have separated these types of S. viridis into varieties and refer to them by such names as giant green, robust white, and robust purple foxtails.
38
GRASS FAMILY, Gramineae
SHATTERCANE, Sorghum b/co/or (L.) Moench. 1, upper portion of stem with panicle of racemes; 2, group of spikelets. Annual, reproducing by seed. Root system fibrous. Stems erect, smooth, 4 to 8 feet (1.2 to 2.4 m) high; tillers readily produced from crown. Leaves resemble those of forage sor- ghum or sudan. Seeds resemble forage sorghum seed, enclosed in black to red, shiny glumes; seeds shatter very easily and remain viable in soil 2 to 3 years. Found only in cultivated fields, where it reseeds itself.
39
GRASS FAMILY, Gramineae
JOHNSONGRASS, Sorghum halepense (L) Pers. 1, stout stem base, roots, and a young rhizome; 2, panicle; 3, group of spikelets; 4, section of stem showing base of leaf; 5, seed. Perennial, reproducing by large rhizomes and seeds. Root system freely branching, fibrous. Rhizomes stout, creeping, with purple spots, usually with scales at the nodes. Stems erect, stout, from 1^/2 to 6 feet (0.45 to 1.8 m) or more tall. Leaves alternate, simple, smooth, 6 to 20 inches (15 to 50 cm) long, about y2 to V/z inches (1.3 to 3.8 cm) wide. Panicles large, purplish, hairy. Seed nearly l/s inch (3 mm) long, oval, reddish-brown, marked with fine lines on surface, bearing a conspicu- ous awn easily broken off. Found especially on rich soil. Troublesome in corn and soybeans on overflow bottoms. Difficult to control or eradicate. Listed as noxious weed in states where found.
40
GRASS FAMILY, Gram/neae
ANNUAL DROPSEED, Sporobo/us neg/ecfus Nash. 1, plant; 2, spikelets; 3, seed. Annual, reproducing by seeds. Root system fibrous. Stems erect or base prostrate, 6 to 12 inches (15 to 30 cm) high, smooth, slender, branching at base. Leaves very slender, long and tapering, smooth, hairy at base, 1 to 3 inches (2.5 to 7.5 cm) long. Panicles slender, at first more or less hidden in the sheath. Awnless, slender spikelets. Seeds small, nearly transparent with a dark gray or brown spot for the germ, separated easily from white chaffy hull. Found in old alfalfa fields, pastures, lawns, and waste places on dry, sandy soil. It appears late in the season and has little forage value. Becomes objectionable in grassed areas as it leaves bare spots each spring and white spots after fall frosts.
41
GRASS FAMILY, Gram/neoe
FOR CD PIN EGR ASS, Sf/pa sparfea Trin. 1, entire plant; 2, several views of leaf base; 3, glumes; 4, seed. Perennial, reproducing by seeds only. Stems smooth, 2 to 4 feet (0.6 to 1.2 m) high, in clumps. Leaves smooth beneath, rough on top, slightly rolled, 6 to 12 inches (15 to 30 cm) long, tapering to a fine point. Seeds brown, shiny, 14 to Yz inch (6 to 13 mm) long, borne in a panicle 3 to 6 inches (7.5 to 15 cm) long. One end of seed has a sharp point with a ring of soft hairs and the other end, a twisted awn 3 to 5 inches (7.5 to 12.5 cm) in length. Moisture untwists the awn, forcing the sharply pointed end into the ground or into the flesh of animals. A valuable forage grass if properly handled to prevent seed formation. Found in range land and waste places.
42
SEDGE FAMILY, C/peraceae
HOP SEDGE, Carex lupulina Muhl. Perennial, reproducing by seeds and rhi- zomes. Root system shallow and fibrous. Stems smooth, 2 to 2l/2 feet (60 to 75 cm) tall, 3-sided, filled with pith, with few nodes and internodes, ending in a spike. The plant grows in dense mats. Leaves 3-ranked, without hairs but harsh, mostly basal with long blades and short sheaths. The relatively few stem leaves have long, narrow, V-shaped blades, pronounced midribs, closed sheaths, no auricles, and much reduced ligules. Spikes 1 to 3 inches (2.5 to 7.5 cm) long, bearing male and female flowers on the same plant, with male flowers uppermost on inflorescence. Bloom in July and August. Seeds brown, 3-sided, y$ inch (3 mm) thick and 1/2 inch (13 mm) long. Found in swamps, ditches, and other poorly drained areas. Not an impor- tant weed.
43
SEDGE FAMILY, C/peraceae
YELLOW NUTSEDGE, Cyperus esculentus L. 1, whole plant; 2, seed. Peren- nial, reproducing by seed and by tubers produced at the tips of scaly rhi- zomes. Root system fibrous. Stems erect, triangular, yellow-green. Leaves 3-ranked, narrow, grasslike, basal. Flowers yellowish or yellowish-brown, small, arranged in narrow spikelets on umbel-like inflorescence. Seeds yel- lowish-brown, 3-angled, small, about 1/16 inch (1.5 mm) long, with blunt ends. Found primarily on low, damp soils. Often troublesome in cultivated fields and pastures, especially on low land. Usually considered a serious weed.
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RUSH FAMILY, Juncaceae
SLENDER RUSH, Juncus tenuis Willd. 1, entire plant; 2, flower with immature seed pod; 3, seed. Perennial, reproducing by seeds. Roots fibrous, tufted. Stems 6 to 24 inches (15 to 60 cm) tall, slender, round, hollow, wiry, dark green, branching at the top, not jointed. Leaves very narrow, grasslike, mostly at the base of the stems. Flowers small, greenish-brown, with 6 scalelike bracts surrounding the seed pod; borne in clusters of 3 at the tips of the stems. Seed pod nearly egg-shaped, brown, splitting into 3 sections when mature. Seeds brown, small, about l/s inch (3 mm) long, with minute crossline markings. Found along paths, in pastures, roadsides, and waste places.
45
LILY FAMILY, Liliaceae
WILD GARLIC, Allium vineale I. 1, flower cluster; 2, old bulb and bulblets; 3, underground bulblets; 4, entire plant. Perennial, reproducing from seed, aerial bulblets, and underground bulblets. Stems 1 to 3 feet (30 to 90 cm) tall, smooth, and waxy. Leaves slender, hollow, nearly round, attached to lower half of stem. Aerial bulblets form in a cluster at top of stem, are oval and smooth with shiny covering. Flowers greenish-white, small, on short stems above aerial bulblets. Seeds black, flat on one side, about y& inch (3 mm) long; formed only occasionally. Found in grain fields and pastures; serious in the humid winter wheat area of the region.
WILD ONION, A///um ccrnac/ense L. 5, entire plant; 6, flower cluster; 7, old bulb. Similar to above species but does not produce underground bulblets. Stems 1 to 2 feet (30 to 60 cm) tall. Leaves flat, not hollow, arising from base of plant only. The old bulb coat of wild onion is fibrous-matted while in wild garlic it is thin and membranous. Found in same places as above.
46
HEMP FAMILY, Connobaceae
HEMP, Cannabis sativa 1. 1, upper part of female plant; 2, upper part of male plant; 3, root; 4, flower from female plant; 5, seed. Annual, repro- ducing by seed, with much-branched taproot. Stems 2 to 10 feet (0.6 to 3 m) tall, coarse, somewhat grooved, rough, and hairy. Plants usually bushy unless crowded. Hairs on the upper parts exude a sticky resin with a charac- teristic odor. Leaves palmately divided, consisting of 5 to 9 hairy leaflets with notched edges. Flowers of two kinds; male and female flowers borne on separate plants. Pollen-producing flowers have no petals and are borne in clusters from the axils of upper leaves. Male plants turn yellow and die after shedding pollen. Seed-producing flowers are without petals and are located in the axils of the leaves. Female plants are vigorous and dark green until frost. Seed oval, mottled brown, about Ys inch (3 mm) long. Plants are prolific seed and pollen producers. Found along ditches, fences, roadsides, and on wastelands with moist, fertile soil. Cultivated varieties are grown as fiber crop. Also commonly known as marijuana.
47
NETTLE FAMILY, Urf/ccrceae
STINGING NETTLE, Urf/ccr d/oica L. 1, lower part of plant; 2, upper part of plant with flowers; 3, section of stem with hairs; 4, seed. Perennial, re- producing by seeds and underground rootstocks. Stems 2 to 7 feet (0.6 to 2 m) tall, slightly branched near the top, slender, rigid, covered with numer- ous stinging hairs. Leaves dark green, coarse, opposite, 3 to 6 inches (7.5 to 15 cm) long, pointed with saw-toothed margins, sometimes rounded at base, covered with stinging hairs. Flowers are greenish without petals and produced in clusters in the leaf axils. Male and female flowers borne separately but on the same plant. Seed pod 1-seeded. Seeds small, egg- shaped, slightly rough, yellow to grayish-tan. Found in barnyards, fence rows, thickets, waste places, and roadsides; generally in damp rich soil. When this plant comes in contact with the skin it causes welts or inflam- mation.
48
BUCKWHEAT FAMILY, Polygonaceae
PROSTRATE KNOTWEED, Po/ygonum av/cu/crre L. 1, entire plant; 2, seeds; 3, portion of stem and leaves; 4, single leaf; 5, distribution. Annual, repro- ducing by seed. Stems bluish-green, leafy, wiry, extending 4 to 24 inches (10 to 60 cm) in all directions from the small taproot and forming a dense mat. Each joint or node covered with a thin papery sheath. Leaves bluish- green, alternate, oblong, narrowed at base, pointed at tip. Flowers very small, yellow or white, borne in clusters in the leaf axils. Seeds small, slen- der, reddish-brown, triangular. Found in hard trampled areas in yards, lawns, waste places, and along roadways or paths.
ERECT KNOTWEED, Po/ygonum erecfum L 6, branch of plant; 7, portion of stem and leaf; 8, leaf; 9, distribution. Annual, reproducing by seed. Stem erect, 8 to 24 inches (20 to 60 cm) high, branched near top, smooth, yellowish-green, slightly rigid. Leaves light green, oval, alternate, Y^ to 1 inch (0.6 to 2.5 cm) long, sometimes covered with mildew. Flowers and seed similar to those above. Found in same areas as prostrate knotweed.
49
BUCKWHEAT FAMILY, Po/ygonocecre
SWAMP SMART WEED, Po/ygonum cocc/neum Muhl. 1, upper part of plant; 2, portion of rhizome; 3, seed. Perennial, reproducing by long, creeping, tough, woody, horizontal rhizomes and by seed. Stems erect, 1 to 3 feet (0.3 to 0.9 m) long, enlarged at nodes, usually unbranched; may produce roots at nodes. Leaves alternate, oblong, 2l/z to 8 inches (6.3 to 20 cm) long, pointed at tip, rounded at base with prominent veins. A sheath at base of each leaf surrounds stem. Flowers rose in color and produced in compact erect spike 1 to 3 inches (2.5 to 7.5 cm) long. Seeds oval, flattened on one side, black, shiny, and slightly rough; however, not usually pro- duced in northern areas. Found usually in low, wet places in fields, gardens, or roadsides, but may be present elsewhere. The extensive root system makes it a strong competitor with other plants and difficult to kill. Also commonly known as tanweed and devil's shoestring.
50
BUCKWHEAT FAMILY, Po//gonaceae
WILD BUCKWHEAT, Po/ygonum convolvulus L. 1, entire plant; 2, mature seed; 3, vine entwined around stem of grass. Annual, reproducing by seed. Stems smooth, slender, twining or creeping, branched at base. Leaves alter- nate, heart-shaped, pointed with smooth edges. Flowers small, greenish- white, borne in clusters in leaf axils. Seeds triangular, somewhat shiny, black; often covered with a dull brown, rough hull. Found in noncultivated areas and under most cropping systems. It is often mistaken for field bind- weed (page 139), but the annual habit, black, shiny 3-cornered seeds, heart- shaped leaf, and minute flowers set it apart. It is a serious weed and often reduces crop yields and quality; its seeds are difficult to remove from crop seeds.
51
BUCKWHEAT FAMILY, Polygonaceae
PENNSYLVANIA SMARTWEED, Polygonum pensylvanicum L. 1, lower part of plant; 2, upper part of plant; 3, section of stem, leaf, and leaf sheath; 4, flower; 5, seed. Annual, reproducing by seeds. Stems smooth, swollen at nodes, branching, 1 to 4 feet (0.3 to 1.2 m) tall. Leaves smooth, pointed, alternate, 2 to 6 inches (5 to 15 cm) long, with a sheath at the base extend- ing around the stem. Flowers bright pink or rose, 5-parted, arranged in a short spike. Seeds shiny, black, smooth, flattened, almost circular. Found in cultivated ground and waste places, and along ditches.
LADYSTHUMB, Polygonum persicaria I. 6, upper part of plant; 7, section of stem, leaf, and leaf sheath; 8, seed. Annual, reproducing by seeds. Stems smooth, sometimes hairy, much-branched, 6 inches to 3 feet (15 to 90 cm) tall. Leaves alternate, pointed at both ends, 1 to 6 inches (2.5 to 15 cm) long, with smooth edges and usually a dark spot in the middle. Sheath at base of the leaf fringed with short bristles. Flowers pink or purplish. Seeds almost circular, flattened or 3-sided, smooth, black, shiny. Found in same areas as above.
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BUCKWHEAT FAMILY, Po//gonaceae
RED SORREL, Rumex acetosella 1. 1, young plant; 2, seed; 3, entire plant. Perennial, reproducing by creeping rootstocks and seeds. Roots and root- stocks extensive but rather shallow. Stems 6 to 18 inches (15 to 45 cm) high, slender, upright, branched at top. Several stems may arise from 1 crown. Leaves are arrow-shaped, 1 to 3 inches (2.5 to 7.5 cm) long, thick, smooth, acid to the taste. Early growth consists of a rosette of basal leaves. Flowers yellow to red, borne on a raceme near top of plant. Male and female flowers borne on different plants. Seeds 3-sided, reddish-brown, shiny. Hull reddish-brown, rough, often adhering to the seed. Found mainly in pastures and meadows, sometimes in lawns. Persists in areas of poor drainage, low soil fertility, and little competition.
53
BUCKWHEAT FAMILY, Po/ygonaceae
PALE DOCK, Rumex altissimus Wood. 1, lower part of plant; 2, upper part of plant with seed head. Perennial, with large taproot, reproducing by seed. Stems 2 to 4 feet (0.6 to 1.2 m) tall, erect or ascending, smooth, branched, arising singly or in groups from a fleshy crown. Leaves at first in a dense rosette, 6 to 12 inches (15 to 30 cm) long, flat, ovate, with smooth margins. Leaves on stem smaller, alternate, with heavy midribs, smooth margins, and short petioles bearing papery sheaths surrounding the stem. Flowers in clusters on branches at tip of stem, without petals, small, greenish, be- coming brown at maturity. Seeds 3-sided, brown, shiny, surrounded by 3 heart-shaped bracts with smooth edges. Found along roadsides, in pastures and new hayfields, especially in places with moist rich soil. Also commonly known as smooth dock.
54
BUCKWHEAT FAMILY, Po/ygonoceae
CURLY DOCK, Rumex cr/spus L. 1, lower part of plant; 2, upper part of plant; 3, seed; 4, distribution. Perennial, with large, yellow, somewhat branched taproot, reproducing by seed. Stems smooth, erect, 1 to 4 feet (0.3 to 1.2 m) tall, single or in groups from the root crown. Leaves mostly basal, smooth, 6 to 12 inches (15 to 30 cm) long, lanceolate, with wavy- curled edges. Upper leaves alternate, the base of the short petiole having a papery sheath surrounding the stem. Flowers in dense clusters on branches at tip of stem, without petals, small, greenish, becoming reddish-brown at maturity. Seeds brown, shiny, triangular, and sharp-edged, surrounded with 3 heart-shaped bracts with smooth edges. Found in pastures, roadsides, new hay fields, and waste areas.
BROADLEAF DOCK, Rumex obtusifolius I. 5, seed; 6, leaf; 7, distribution. Similar to curly dock. Leaves broad and flat with a heart-shaped base. Bracts surrounding seed with toothed edges.
55
GOOSEFOOT FAMILY, Chenopocf/'aceae
SPREADING ORACH, Afr/p/ex pafu/o L. 1, flowering branch; 2, female flower. Annual, reproducing by seed. Stem smooth, slender, 1 to 4 feet (0.3 to 1.2 m) long, with numerous spreading branches. Leaves petioled, fleshy, triangular, lanceolate or linear, mostly opposite, usually mealy, especially on lower surface. Flowers small without petals; male and female flowers borne separately on the same plant in scattered spikes at ends of branches and in axils of upper leaves. Seed round, gray, borne between 2 triangular green bracts. Found in damp saline soil. Seldom a troublesome weed.
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GOOSEFOOT FAMILY, Chenopocf/oceae
COMMON LAMBSQUARTERS, C/ienopod/um album L 1, roots; 2, leaves and flowers; 3, flower; 4, seed; 5, distribution. Annual, reproducing by seeds. Taproot short and much branched. Stems 3 to 4 feet (0.9 to 1.2 m) tall, smooth, grooved, often with red or light green striations. Branching varies from little to much, depending on competition. Leaves alternate, 1 to 3 inches (2.5 to 7.5 cm) long, smooth, usually white mealy-coated, especially on underside and in early stages, and with edges more or less toothed. Flow- ers small, green, without petals, borne at the ends of branches and in the axils of leaves. Seed shiny, black, disk-shaped, 1/16 inch (1.5 mm) in diame- ter, with a gray hull. Found in cultivated crops.
MEXICANTEA, Chenopod/um ambrosioides L 6, roots; 7, leaves and flowers; 8, seed; 9, distribution. Somewhat similar to above with longer, narrower, wavy-edged leaves, not mealy, and with unpleasant, pungent, aromatic odor. Widely distributed but almost uncommon compared to lambsquarters.
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GOOSEFOOT FAMILY, Chenopod/acecre
MAPLELEAF GOOSEFOOT, Chenopod/um hybridum L 1, root; 2, upper por- tion of stem with flowers; 3, seed. Annual. Stem ridged, upright, widely branched, as much as 5 feet (1.5 m) tall. Leaves alternate, thin, light green, long-petioled, as broad as wide, with 1 to 4 large teeth on margins, free of mealiness on lower surface, easily detached from stem. Flowers greenish, inconspicuous, in a loose terminal panicle. Seeds dull black, lens-shaped, 1/16 inch (1.5 mm) or more in diameter, and covered with thin tissue that rubs off. Found in fence rows and waste areas.
58
GOOSEFOOT FAMILY, Chenopod/aceae
WINGED PIGWEED, Cyc/o/oma atriplicifolium (Spreng.) Coult. 1, upper por- tion of stem with flowers; 2, seed. Annual, bushy, much-branched plant. Stems l/2 to 2 feet (15 to 60 cm) tall, smooth, without hairs after seedling stage, often turning red during the fall. Leaves alternate, l/2 to 2 inches (1.3 to 5 cm) long, with scalloped edges, falling early. Flowers numerous, sessile, greenish, borne singly on the nearly leafless upper branches. Seeds flat, round, about i/g to 3/16 inch (3 to 4.5 mm) in diameter, with a prom- inent circular wing, often red or purple in the fall. Found in cultivated fields and in row crops. Often prevalent in sandy soils.
59
GOOSEFOOT FAMILY, Chenopod/aceae
KOCHIA, Koch/a scopar/a (L.) Schrad. 1, entire plant; 2, individual flower; 3, seeds. Annual, reproducing from seeds. Stems smooth, green, much branched, from a few inches to over 6 feet (1.8 m) high, growing from a taproot. Leaves alternate, simple, hairy, 1 to 2 inches (2.5 to 5 cm) long, pointed, without petioles. Flowers small, greenish, without petals, in axils of upper leaves and in terminal panicles. Seeds about 1/16 inch (1.5 mm) long, oval, flattened with groove on each side, finely granular, surface dull, brown with yellow markings. Fragile star-shaped hull may enclose seed. Found in cropland, dry pastures, and rangeland, where it is a serious weed. Also commonly known as Mexican fireweed.
60
GOOSEFOOT FAMILY, Chenopod/aceae
RUSSIAN THISTLE, Sa/so/a kali L var. tenuifolia Tausch. 1, branch; 2, root; 3, portion of older branch; 4, seed in hull; 5, seed, hull removed. Annual, reproducing by seed. Stem profusely branched, 1 to 3 feet (30 to 90 cm) high, forming typical ball-like tumbleweed at maturity. Young plants soft, succulent; mature plants stiff and woody. Leaves cylindrical or awl-shaped. Young leaves long, soft. Later leaves short, stiff, prickle-pointed. Flowers numerous, small, without petals, axillary on upper branches. At maturity, entire plant may be splashed with red color; stem breaks from root and moves freely across open fields with winds scattering the seed. Found in spring grain and legume seedings. An important annual weed, it is most troublesome in dry years.
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PIGWEED FAMILY, Amaranfhaceae
TUMBLE PIGWEED, Amaranthus a/bus L 1, fruiting branch; 2, seed. Annual, reproducing by seed. Stem pale green, with numerous ascending branches making more or less globular plant, 1 to 3 feet (30 to 90 cm) tall. Breaks off at ground at maturity and is rolled over open fields by wind, distributing the seeds. Leaves spatulate, short-petioled, 1/2 to 1 inch (1.3 to 2.5 cm) long. Flowers small, greenish, in axillary clusters. Seed small, round, shiny, black, each contained in a bladderlike hull. Found in cultivated and fallow land. Dried plants often observed in piles against fences and hedge rows after windstorms.
62
PIGWEED FAMILY, Amoranfhaceae
PROSTRATE PIGWEED, Amaranf/ius blitoides S. Wats. 1, lower portion of plant showing spreading habit; 2, upper part of plant with flowers; 3, seed; 4, distribution. Annual, reproducing by seeds. Stems 1 to 3 feet (30 to 90 cm) long, nearly smooth, reddish, spreading flat over the ground, mostly erect at the tips. Leaves small, alternate, simple, egg-shaped, broadest near tip. Flowers without petals, small, inconspicuous in axils of leaves. Seeds flat- tened, shiny, black, nearly circular, 1/16 inch (1.5 mm) in diameter. Found in fields, gardens, unused yards, and similar places.
63
PIGWEED FAMILY, Amaranfhaceoe
SMOOTH PIGWEED, Amaranfhus hybridus 1. 1, upper stem with leaves and flower clusters; 2, flower; 3, seed. Annual, reproducing by seeds. Taproot shallow, reddish. Stems erect, up to 8 feet (2.4 m) tall, branching freely if not crowded. Leaves dull green, usually at least 6 inches (15 cm) long when mature, ovate to lanceolate. Flowers green, small, in slender, lax, panicle- like spikes with many short, crowded lateral branches. Bracts and sepals slightly longer than utricles. Sepals straight and acute. Seeds shiny black, lens-shaped, ovate, notched at narrow end, about 1 mm in diameter. Found in cultivated fields, yards, fence rows, and other waste places. Other species such as redroot pigweed (page 65) and Powell amaranth (Amaranthus powellii S. Wats) are similar to smooth pigweed in morphology and weedy habits, and may often be found in the same area. Powell amaranth has longer floral bracts than smooth pigweed; has straight, acute sepals that are longer than the utricle; has a stiff terminal inflorescence that either is simple or has a few widely spaced, long lateral branches; and is found mainly in northern part of region.
64
PIGWEED FAMILY, Amaronthaceae
REDROOT PIGWEED, Amaranthus refroflexus L. 1, lower stem and roots; 2, upper stem with leaves and flower clusters; 3, flower; 4, seed. Annual, reproducing by seeds. Taproot shallow, reddish. Stems erect, up to 6 feet (1.8 m) high, rough, branching freely if not crowded. Leaves dull green, usually at least 6 inches (15 cm) long when mature, ovate to lanceolate. Flowers green, small, in thick, stiff, paniclelike terminal spikes with many short, crowded lateral branches. Bracts much longer than sepals and utricles. Sepals longer than utricle, curved, rounded, often with small notch at end. Seeds shiny black, lens-shaped, ovate, notched at the narrow end, about 1 mm in diameter. Found in cultivated fields, yards, fence rows, and other waste places. Other species, such as smooth pigweed and Powell amaranth (page 64), are similar to redroot pigweed in morphology and weedy habits, and may often be found in the same area. Redroot pigweed is also commonly known as rough pigweed.
65
PIGWEED FAMILY, Amaranthaceae
SPINY AMARANTH, Amaranthus spinosus 1. 1, upper portion of plant show- ing leaves, spines, and flowers; 2, flower; 3, seed. Annual, reproducing by seeds. Stems upright, branched, up to 3 feet (0.9 m) tall, reddish, bearing spines at the bases of the leaf stalks. Leaves alternate, simple, dull green, ovate-lanceolate to ovate. Flowers small, green, in numerous long spikes. Terminal spike often wholly or chiefly staminate; axillary flower clusters mostly pistillate. Seeds egg-shaped, shiny black, notched at one end, about 0.7 to 1 mm wide. Found in fields, gardens, unused yards, and similar places.
66
PIGWEED FAMILY, Amaronfhaceoe
TALL WATERHEMP, Amaranthus tuberculatus (Moq.) Sauer. 1, top of plant in flower; 2, seed in the hull and dehulled. Annual, reproducing by seed. Stem smooth, erect, ascending or somewhat prostrate, stout or slender, 3 feet (0.9 m) up to 8 feet (2.4 m) tall. Leaves narrowly ovate to lanceolate, long-petioled, alternate, 3 to 6 inches (7.6 to 15 cm) long. Flowers small, greenish, surrounded by small bracts, in loose terminal and axillary spikes; male and female flowers borne on separate plants. Seeds oval, reddish-black, each contained in a bladderlike hull. Found chiefly in cultivated crops or waste areas, especially on low ground. Other very similar species, Amaran- thus tamariscinus (Nutt.) Wood and Amoranfhus aren/co/o I. M. Johnston, also occur in the region. Some waterhemp in the region is probably a hybrid complex among these various species.
67
FOUR-O'CLOCK FAMILY, Nyctaginaceae
WILD FOUR-O'CLOCK, Mirabilis nyctaginea (Michx.) MacM. 1, upper part of plant in flower; 2, fleshy taproot; 3, leaf; 4, flower; 5, seed. Perennial, with large, tough taproot. Reproduces by seeds. Stems smooth, bushy, often 4- sided, 1 to 3 feet (30 to 90 cm) tall. Leaves heart-shaped, 2 to 4 inches (5 to 10 cm) long by 1 to 3 inches (2.5 to 7.5 cm) wide, smooth, opposite, with smooth margins. Flowers bloom from June to October; are red, small, with 1 to 5 in a cluster. Seeds hairy, oblong, grayish-brown, with 5 ridges. Found rather generally along roadsides, in gardens, meadows, pastures, and waste places. Not usually troublesome in cultivated land.
68
POKEWEED FAMILY, Phyfo/accoceae
COMMON POKEWEED, Phyfo/acca crmer/cana L. I, part of fleshy taproot; 2, branch with flower raceme and berries; 3, flower; 4, upper surface of berry; 5, seed. Perennial, from a very large, poisonous taproot, often 6 inches (15 cm) across in older plants. Stems stout, erect, 3 to 9 feet (0.9 to 2.7 m) high, smooth, branching above, often reddish, dying to the ground each winter. Leaves alternate, large but smaller toward top of plant, with short to long petioles. Flowers small, white, in long, rather narrow, un- branched racemes from ends of stems and from upper branches. Fruit a dark purple, many-seeded berry with red juice. Seeds small, flattened, round in outline, shiny black, about Vs inch (3 mm) in diameter. Found in rich, low- ground pastures, roadsides, borders of fields, and similar places. The root is the most poisonous part of the plant. Poisoning from leaves and berries is occasional.
69
CARPETWEED FAMILY, Aizoaceae
CARPETWEED, Mollugo verticillata L 1, small plant, showing habit of growth; 2, flower; 3, young seed pod in calyx; 4, seed. Annual, reproduc- ing by seed, with little-branched taproot. Stems green, smooth, branching along the ground in all directions from the root, making flat circular mats on the soil surface. Leaves in circles of 5 or 6 at each joint of the stems, smooth, tonguelike. Flowers small, white, several at each joint. Seeds very small, orange-red, somewhat kidney-shaped. Found in gardens, tilled crops, lawns, and wasteland. A late-starting, quick-growing summer annual, it will quickly cover any fertile bare soil where it starts.
70
PURSLANE FAMILY, Portulacaceae
PURSLANE, Porfu/aca o/erocea L. 1, entire plant showing fleshy stems, pros- trate growth habit; 2, flower; 3, pods; 4, seed. Annual, reproducing by seed. Root system fibrous. Stems juicy, smooth, often reddish, either com- pletely prostrate or turned up at the ends, sometimes forming mats 1 foot (30 cm) or more in diameter. Leaves alternate or clustered, simple, juicy, and smooth. Flowers small, yellow, in axils of leaves and branches. Seeds small, flattened, broadly oval, glossy black. Seeds require warm soil to germinate. Found in fields and waste places. Especially troublesome in gar- dens and truck crops. The fleshy stems and leaves make this plant drouth- resistant, difficult to kill.
71
PINK FAMILY, Coryop/iy//aceae
CORN COCKLE, Agrostemma githago L. 1, plant in flower; 2, seed pod en- closed by the ribbed calyx; 3, seed. Winter annual, reproducing by seed. Taprooted, shallow. Stems rough, hairy, erect, 2 to 3 feet (60 to 90 cm) tall, swollen at joints, branching slightly. Leaves opposite and joined at base, slender, hairy. Flowers large, purple, with narrow, green sepals longer than colored petals. Seed pod holding several seeds, enclosed in a 10-ribbed urn- like calyx. Seeds black, about ]/& inch (3 mm) in diameter, triangular, cov- ered with rows of sharp tubercles. Seeds poisonous and therefore highly objectionable in grain used for milling or feed. Found especially on culti- vated land and in association with fall-sown grain crops.
72
PINK FAMILY, Car/ophy//aceae
MOUSE-EAR CHICKWEED, Cerasf/um vu/gafum L. 1, plant; 2, flower; 3, seed pod enclosed in calyx; 4, seed. Perennial, reproducing by seeds, occasionally by root development on lower branches. Roots shallow, branched, fibrous. Stems hairy, slender, partly spreading to erect. Leaves small, very hairy, opposite, attached directly to the stem. Flowers small, with 5 white petals notched at the tips, surrounded by an equal number of hairy sepals. Seed pods very small, cylinder-like, located at tips of the stems, containing many seeds. Seeds brown, very small, circular, flattened with a rounded back bear- ing irregular knobs. Seeds long-lived, often remaining dormant in the soil over several seasons. Found in lawns, pastures, and abandoned cultivated land.
73
PINK FAMILY, Caryophyllaceae
WHITE COCKLE, Lychnis alba Mill. 1, seed; 2, entire plant; 3, new plant from portion of root; 4, seed capsule. Biennial, or short-lived perennial. Re- production largely by seeds. Rootstocks thick, sending up a few short bar- ren shoots and long, branching, flowering stems. Stems erect, branched, stout, quite hairy and sticky, 1 to 2^2 feet (30 to 75 cm) tall. Leaves oppo- site, long and narrow, not petioled, covered with short hair, pointed at the tip and rather light green. Flowers fragrant, white to pink, about y<\ inch (1.9 cm) in diameter with 5 notched petals; borne on erect stems in leaf axils or loose panicles; open in evening. Male and female flowers on sepa- rate plants. Seed pod swollen, ovoid with 10 short teeth at top, in hairy inflated calyx. Seeds numerous, flat, nearly round, pale gray, covered with small knobs, and about 1/16 inch (1.5 mm) in diameter. Found along road- sides, borders of fields, and in waste places; may become troublesome in grain and legume fields.
74
PINK FAMILY, Caryophyllaceae
BOUNCINGBET, Scrponcrr/a officinalis L 1, lower part of plant; 2, flowering stems; 3, flower; 4, mature seed pod with part of calyx removed; 5, seed. Perennial, reproducing by seeds and short rhizomes. Stems stout, jointed, erect, 12 to 24 inches (30 to 60 cm) tall, clustered, smooth, and usually un- branched. Leaves opposite, smooth, entire, 2 to 3 inches (5 to 7.5 cm) long, about 1 inch (2.5 cm) wide, without petioles. Flowers in conspicuous clus- ters at the tops of the stems; about 1 inch (2.5 cm) across with 5 pink or white petals, and with base enclosed in a tubular calyx about % inch (1.9 cm) long. Seed pod narrowly egg-shaped, pointed, containing numerous seeds, enclosed by calyx. Seeds flattened, dull black, kidney-shaped, about 1/16 inch (1.5 mm) long, surface covered by curved rows of minute knobs. Found along roadsides, in waste places, and on ditch banks. Originally grown in gardens as an ornamental, from which it has spread. In pioneer days, used as a soap substitute, the stems and rhizomes making a foamy solution when bruised in water.
75
PINK FAMILY, Caryophyllaceae
SLEEPY CATCHFLY, Si/ene antirrhina 1. 1, plant; 2, flower with pod; 3, upper portion of stem; 4, flower enclosed by calyx; 5, seed. Annual, reproduced by seeds only. Stem slender, erect, 1 to 2^/2 feet (30 to 75 cm) high, sparingly branched, upper part often of darker color and sticky. Leaves opposite, not petioled, linear, although those at base are somewhat broader. Flowers small, Ys inch (3 mm) across, pink with 5 petals, enclosed at base by ovoid calyx. Seeds kidney-shaped, very small, lead-colored, covered with knobs. Found especially on dry, light soil. Important weed in clover seed fields, because seeds are difficult to remove from the clover seed.
76
PINK FAMILY, CaryophyJ/acecre
BLADDER CAMPION, Si/ene cucuba/us Wibel. 1, upper part of plant in bloom; 2, root and base of plant; 3, seed pod; 4, seed. Perennial, propa- gated by seeds and creeping rhizomes. Stems 1 to l*/2 feet (30 to 45 cm) tall, smooth, decumbent from base. Leaves opposite, elliptical, smooth- edged, not hairy. Flowers white, 1 inch (2.5 cm) wide with 5 notched petals, borne in loose panicles, often drooping. Seed pod enclosed by a thin, in- flated, 5-toothed calyx. Seeds blackish, round and flattened, covered with knobs, about 1/16 inch (1.5 mm) in diameter. Found in waste places and fields.
77
PINK FAMILY, Caryophyllaceae
NIGHT-FLOWERING CATCHFLY, Si/ene nocfiflora L. 1, plant in bloom; 2, flower; 3, seed pod; 4, seed; 5, seedling. Annual, reproducing by seed. Stems 1 to 3 feet (30 to 90 cm) high, erect, densely covered with sticky hairs. Leaves oblong, 2 to 5 inches (5 to 12.5 cm) long, smooth-edged. Flowers white, shading into pink, about */\ inch (1.9 cm) across with 5 petals. Seed pod enclosed by calyx with 5 teeth. Seeds rounded, 1/16 inch (1.5 mm) in diame- ter, gray, with knobs covering surface. Seed is common impurity in clover seed. Found in Reids and waste places.
78
PINK FAMILY, Car/op/iy//aceae
CORN SPURRY, Spergu/a arvensis L. 1, plant in bloom; 2, seeds. Annual, reproducing by seeds. Stems erect or ascending, 6 to 18 inches (15 to 45 cm) high, not hairy or only slightly so, slender, branching. Leaves bright green, threadlike, 1/2 to 1 inch (1.3 to 2.5 cm) long, in whorls around each joint of the stem. Flowers small, white, with 5 petals, in terminal clusters. Seed pod round, breaking into 5 sections, containing many seeds. Seeds lens-shaped, dull black with a conspicuous white wing. Found locally in small grains and other annual crops.
79
PINK FAMILY, Caryophyllaceae
COMMON CHICKWEED, Sfe//ar/a media (1.) Cyrillo. 1, plant in flower; 2, flower; 3, seed pod; 4, seed. Winter annual or annual, reproducing by seed and creeping stems, rooting at the nodes. Root system fibrous, shallow. Stem is much branched, creeping or ascending, resulting in low spreading plant 4 to 12 inches (10 to 30 cm) high. Leaves small, opposite, simple, broadly ovate, pointed at the tips, smooth; petioles have a line of hairs on one side. Flowers small, white, with 5 deeply notched petals. Seed pod cylindrical, breaking into 5 segments at maturity, containing many seeds. Seed small, dull reddish-brown, somewhat heart-shaped but nearly round, roughened by curved rows of minute tubercules. Found in lawns, gardens, alfalfa, straw- berry beds, nurseries.
80
PINK FAMILY, Car/op/i///aceae
COW COCKLE, Vaccar/a segetalis (Neck.) Garcke. 1, plant in flower; 2, root and basal portion of stem; 3, seedling plant; 4, flower; 5, pod; 6, seed. Annual, reproducing by seed. Stem erect, branched, smooth, whitish, 1 to 3 feet (30 to 90 cm) high. Leaves opposite, not petioled, ovate to lanceolate, smooth-edged. Flowers deep pink, about ^2 inch (13 mm) across, with 5 petals. Seed pod a capsule with many seeds, enclosed by an angular calyx. Seeds globular, about 1/16 inch (1.5 mm) in diameter, dull black, covered with minute tubercles, and having circular whitish seed scar. Found in wheat and other crops, feedlots, and waste places, mainly in spring wheat area. Seeds are poisonous to animals and if concentrated in screenings make such feed unsafe to use.
81
CROWFOOT FAMILY, Ranuncu/aceae
SMALLFLOWER BUTTERCUP, Ranunculus abortivus L 1, young plant; 2, plant in bloom; 3, mature receptacle bearing seeds; 4, seeds. Annual or biennial, reproducing by seeds. Stems slightly hairy, slender, branched from base, 6 to 20 inches (15 to 50 cm) tall. Lower leaves round, bright green with round-toothed margins, borne on long petioles coming from base of plant. Upper leaves on shorter petioles, divided into 3 to 5 leaflets with somewhat toothed margins. Flowers small, yellow, with small oblong petals. Seeds produced in round heads, numerous, flattened with very small curved beak, dull, wrinkled, yellowish-brown. Found in lowland meadows, pastures, and fields. The plant has no forage value and may poison livestock.
82
CROWFOOT FAMILY, Kanuncu/aceae
TALL BUTTERCUP, Ranunculus acris L. 1, plant in bloom; 2, seed head; 3, seeds. Perennial, reproducing by seeds. Stems erect, branched above, hairy, 1 to 3l/z feet (30 to 106 cm) tall. Leaves alternate, hairy, palmately divided into narrow segments. Flowers usually bright yellow but sometimes cream- colored, with 5 to 7 petals. Seeds numerous, dark brown, about Y& inch (3 mm) long, minutely pitted, flattened, with hooked beak; formed in a rounded head. Found in pastures; does not persist in cultivated crops. This plant contains an acrid juice which is somewhat poisonous if eaten by live- stock, often blistering the mouth and intestinal tract.
83
POPPY FAMILY, Papaveraceae
BLUEST EM PRICKLEPOPPY, Argemone intermedia Sweet. 1, plant in flower; 2, root system; 3, seed pod. Annual, reproducing by seed. Stems stout, prickly, not branched, 1 to 2 feet (30 to 60 cm) high. Leaves bluish-green with spiny margins and prickly surfaces, alternate, clasping the stem. Sap in stems and leaves orange-colored. Flowers large, white, 2 to 3 inches (5 to 7.5 cm) across, petals dropping off quickly. Seed pod oblong, about 1 inch (2.5 cm) in length, spiny, containing many seeds. Seeds globular, about 1/16 inch (1.5 mm) in diameter, dark brown, rough with narrow ridge along one side, short pointed tip on one end. Found on prairies and uncul- tivated areas. Plant is poisonous to cattle but they don't eat it because of its prickliness.
84
CAPER FAMILY, Capparaceae
ROCKY MOUNTAIN BEEPLANT, C/eome serrulata Pursh. 1, upper part of plant; 2, lower part of plant; 3, seed. Annual, reproducing by seeds. Stems 2 to 8 feet (0.6 to 2.4 m) tall, pale, smooth, branched at summit. Leaves alternate, compound, with 3 pointed leaflets per leaf; surface and margins smooth, with strong fetid odor. Flowers in terminal racemes, 4 white or pink petals per flower, each petal about ^ inch (9 mm) long and separate, some petals notched. Seeds in pods (capsules) which are 1 to 2 inches (2.5 to 5 cm) long and have projections at the base that are as long as the pedicels; each seed is y& inch (3 mm) long, rough, dull, grayish-brown, grooved on each side. Found in pastures, prairies, ranges, fields, and waste places, often on sandy soils.
85
MUSTARD FAMILY, Croc/ferae
YELLOW ROCKET, Bcrrbarea vulgaris R. Br. 1, upper part of plant; 2, lower part of plant; 3, pods; 4, flower; 5, seed; 6, root. Winter annual, biennial, or perennial, reproducing by seed, taprooted. Stems numerous, growing from a crown, upright, 1 to 2 feet (30 to 60 cm) tall, branched near top, smooth, and angular or ridged. Leaves pinnately divided; basal leaves have a large terminal lobe, are 2 to 8 inches (5 to 20 cm) long, and form a dense rosette; stem leaves become progressively shorter with top leaves about 1 inch (2.5 cm) long and less deeply lobed. Flowers bright lemon-yellow, 4- petaled (typical mustard flower), borne in spikelike racemes on end of each branch. Bloom in late April and early May. Pods about 1 inch (2.5 cm) long, about 3/32 inch (2.4 mm) in diameter, nearly square in cross section. Seeds light yellow to yellowish-brown, 1/32 inch (0.8 mm) long, ripening in May and early June. Found along roadsides, in pastures, and in timothy, clover, and alfalfa fields, where it matures before the crop is cut. Seeds live several years in the soil. Also known as winter cress.
86
MUSTARD FAMILY, Cruci ferae
HOARY ALYSSUM, Berferoo mcano (L.) DC. 1,2, seed; 3, seed pod; 4, seed pod split open; 5, upper part of flowering plant; 6, flower; 7, stem; 8, lower part of plant. Annual, biennial, or perennial, reproducing by seeds. The name "hoary" indicates many rough hairs on stems, leaves, and seed pods. Stems gray-green, hairy, 1 to 3 feet (30 to 90 cm) tall, with many branches near the top. Leaves gray-green, hairy, alternate, oblong, narrow, l/2 to 3 inches (1.3 to 7.5 cm) long, with smooth edges. Flowers white, with 4 deeply divided petals, produced in long raceme. Seed pods hairy, swollen, oblong with short beak on the end. Seeds oblong, rough, dull gray-brown. Found in meadows, pastures, and waste places. Emerges early in the year, continues to grow throughout season, producing seeds until frost.
87
MUSTARD FAMILY, Cruc/ferae
INDIAN MUSTARD, Brassica /uncea (L.) Coss. 1, seed pod; 2, lower leaf; 3, upper part of plant. Annual or winter annual with taproot. Stems smooth, erect, usually growing 2 to 3 feet (60 to 90 cm) tall. Leaves: upper ones short-petioled, lance-shaped, tapering gradually from a broad base; lower ones petioled, deeply lobed, leaf margins coarsely toothed. Flowers yellow, with 4 petals. Seed pods 1 to 2 inches long, tips conical. Seeds rounded, reddish-brown, surface pitted. Found in small grain and legume fields.
BLACK MUSTARD, Brassica nigra (L.) Koch. 4, seed pod; 5, lower leaf; 6, upper part of plant. Annual, with taproot. Stems erect, branched, growing commonly between 3 and 6 feet (0.9 and 1.8 m) tall; lower parts somewhat hairy. Leaves also somewhat hairy. Upper leaves narrow with elongated petiolelike base. Lower leaves petioled, divided, with large terminal lobe, leaf margins fine-toothed. Flowers yellow, with 4 petals. Seed pods Vz to y$ inch (1.3 to 1.9 cm) long, lying along stem. Seeds somewhat oval, dark red- dish-brown, their surface pitted. Found commonly in waste areas and fields.
88
MUSTARD FAMILY, Cruc/ferae
WILD MUSTARD, Brassica kaber (DC.) Wheeler. 1, lower part of plant; 2, upper part of plant; 3, leaf from upper part of stem; 4, flower cluster; 5, seed pods; 6, seed. Annual or winter annual, reproducing by seeds. Stems erect, branched near top, with a few bristly hairs. Leaves: lower ones irreg- ularly lobed, toothed, with petioles and with bristly hairs; upper leaves smaller, often not lobed, alternate, with no petioles or short ones. Flowers conspicuous, with 4 yellow petals, in clusters at the ends of branches. Seed pod slender, on a spreading stalk; 1 inch (2.5 cm) or more long, about V2 of length being an angular beak at the tip. Seeds round, black, bluish, or brown, smooth and hard, about 1/16 inch (1.5 mm) in diameter. Found commonly in grain Reids and occasionally in other cultivated crops. A troublesome weed in many areas. Seeds live in the soil for many years. Also commonly known as charlock.
89
MUSTARD FAMILY, Cruc/ferae
LARGESEED FALSEFLAX, Come//na saf/va (L) Crantz. 1, roots; 2, upper stem with seed pods and flowers; 3, flowers; 4, seeds. Annual or winter annual, reproducing by seeds. Stems 1 to 3 feet (30 to 90 cm) tall, smooth or hairy, branched, becoming woody at maturity. Leaves arrow-shaped, sharp-pointed, 2 to 3 inches (5 to 7.5 cm) long, with smooth edges. Flowers small, pale yellow or greenish-yellow with 4 petals. Seed pods l/\ to 1/2 inch (6 to 13 mm) long, pear-shaped, slightly flattened. Seeds small, pale yellow-brown, oblong, rough, with ridged surface. Found chiefly in flax-growing areas.
SMALLSEED FALSEFLAX, Camelina microcarpa Andrz. Similar to the above but smaller. Stems 1 to 2 feet (30 to 60 cm) tall. Pods V% to 1/4 inch (3 to 6 mm) long. Found in flax-growing areas.
90
MUSTARD FAMILY, Cruc/ferae
SHEPHERD'S PURSE, Capsella bursa-pastor/s (L) Medic. 1, entire plant; 2, root; 3, flower; 4, pods; 5, seeds. Annual and winter annual, reproducing by seed, with a branched taproot. Stems erect, 1 to ll/2 feet (30 to 45 cm) tall, covered with gray hairs. Leaves in rosette at base are coarsely lobed; those clasping stem have pointed lobes, are coarsely serrate, and 2 to 4 inches (5 to 10 cm) long. Flowers are small, white, 4-petaled (typical mus- tard), borne in elongated racemes at ends of branches. Seed pod triangular, 2-parted, about V4 inch (6 mm) long. Seeds small, yellowish, shiny. Found widely in practically all crops as well as in noncultivated areas. Seeds are long-lived in the soil.
91
MUSTARD FAMILY, (True/ferae
HOARY CRESS, Cardcrr/cr draba (1.) Desv. 1, flower; 2, mature pod; 3, seed; 4, new shoot; 5, plant in bloom; 6, root system. Perennial, reproducing by seeds and rootstocks. Roots deep, penetrating, slender, extending horizon- tally and vertically as much as 10 feet (3 m). Stems 1 to iy2 feet (30 to 45 cm) tall, branching little except at top, covered with whitish hairs. Leaves on lower stem spatulate, tapering to a slender base; upper leaves sessile, clasping stem. Leaf margins wavy with shallow indentations. Leaves cov- ered with whitish pubescence. Flowers white, 4-petaled, borne in flat-topped clusters. Seed pods 2-parted, heart-shaped, borne on racemes 2 to 4 inches (5 to 10 cm) long. Seeds oval, rough, about 1/16 inch (1.5 mm) long, red- dish-brown, seed coat marked by many small netlike depressions. Found in dry areas, in all crops where established, especially pastures and meadows, and on sandy ridges. It is very persistent and hard to eradicate. There is another species of Care/aria similar to the above plant.
92
MUSTARD FAMILY, Cruc/ferae
HARE'S EAR MUSTARD, Conr/ngia oriental'* (1.) Dumort. 1, open seed pod; 2, seed; 3, entire plant. Annual or winter annual, with taproots, reproducing by seed. Stem erect, growing from 1 to 3 feet (30 to 90 cm) tall, branching little if at all, becoming stiff and wiry with age. Leaves smooth, alternate, elliptic in shape, 1 to 3 inches (2.5 to 7.5 cm) long, base clasping the stem with heart-shaped lobes. Flowers small, pale yellow, 4-petaled. Pods erect, narrow, 2 to 4 inches (5 to 10 cm) long. Seeds dark mahogany, oblong, circular in cross section, surface roughened with minute shallow pits. Found in small-grain and legume fields.
93
MUSTARD FAMILY, Cruci ferae
TANSY MUSTARD, Descurcr/n/cr p/nncrfcr (Walt.) Britt. 1, stem; 2, upper por- tion of flowering plant; 3, young plant; 4, lower stem and roots; 5, seed; 6, seed pod; 7, flower. Annual or biennial, reproducing by seeds. Stems erect, slightly hairy, 1 to 3 feet (30 to 90 cm) high, much branched above. Leaves light green, alternate, 2 to 4 inches (5 to 10 cm) long, finely divided, almost fernlike. Flowers small, pale yellow, produced on elongated racemes. Seed pods narrow, smooth, slightly curved, */£ to % inch (1.3 to 1.9 cm) long, 2-celled, many-seeded. Seeds small, oblong to 3-angled with a groove on one side, dull red or light brown. Found in cultivated fields, pastures, meadows, waste places, and roadsides. The plant can produce a rank growth, crowding out grain and reducing crop yields. A similar species, flixweed (Descurainia sophia), is also found in abundance in much of the same area.
94
MUSTARD FAMILY, Cruc/ferae
WORMSEED MUSTARD, Erysimum cheiranthoides L. 1, plant; 2, flower; 3, seed pod; 4, seed. Annual or winter annual, reproducing by seed. Stem erect, simple or sparingly branched, 1 to 2 feet (30 to 60 cm) tall, green or slightly grayish. Leaves numerous, alternate, lanceolate, tapering to the base, slightly toothed, finely pubescent. Flowers bright yellow, small, 4- petaled. Seed pods somewhat 4-angled, elongate, pedicels spreading at 45° angle from stem. Seeds small, oblong, brownish. Found on moist soils in corn, soybeans, small grains, or noncultivated areas.
95
MUSTARD FAMILY, Cruci ferae
FIELD PEPPERWEED, Lep/d/um campesfre (L.) R. Br. 1, upper portion of stem; 2, seed; 3, basal leaf. Winter annual (south) or biennial (north), repro- ducing by seed. Stems hoary-pubescent or, rarely, hairless, 6 to 24 inches (15 to 60 cm) high, very leafy. Leaves on stem alternate, covered with soft hairs, arrow-shaped, bases clasping the stem; basal leaves lyrate, deeply cut at base. Flowers inconspicuous, white or greenish with 4 petals, borne in rather dense racemes at top of plant. Seed pods boat-shaped, containing 2 seeds. Seeds dark brown, rough-coated, pointed at tip, shaped like grape seeds, often an impurity in winter wheat. Found in winter wheat, first-year meadows, wasteland.
96
MUSTARD FAMILY, Cruc/ferae
GREENFLOWER PEPPERWEED, Lepidium densiflorum Schrad. 1, plant with flower pods; 2, seeds. Annual or winter annual, reproducing by seed. Root a short, straight taproot. Stems erect, 4 to 15 inches (10 to 38 cm) high, without branches on lower part but with several spreading flowering branches on upper part. Leaves oblong, 1 to 2 inches (2.5 to 5 cm) long, with short sharp teeth or sometimes deeply cut. Flowers greenish. Seed pod round to oblong, somewhat flattened. Seeds small, reddish, oblong, twice as long as wide. Found in fields, pastures, roadsides.
97
MUSTARD FAMILY, Cruc/ferae
VIRGINIA PEPPER WEED, Lepidium virginicum 1. 1, top of plant; 2,3, leaves; 4, seed; 5, flower. Annual or winter annual, reproducing by seed. Stems much branched, 6 to 18 inches (15 to 45 cm) high, not hairy, or with very fine hairs. Leaves on stem lanceolate to linear, coarsely toothed, usually without petioles; basal leaves obovate, with one large terminal lobe and several smaller dentate lateral ones, hairless. Flowers small, white, 4-petaled, borne in racemes which grow for considerable periods, so that there are often ripe seeds below and flowers at the tip of the raceme. Seed pod round, about l/s' inch (3 mm) across, containing 2 reddish-yellow seeds. Found in fields, roadsides, waste areas. A common, but readily controlled, weed. Other similar but less common species are found in the region.
98
MUSTARD FAMILY, Cruc/ferae
BALL MUSTARD, Neslia paniculate (L.) Desv. 1, plant with flowers and fruit; 2, stem and leaves; 3, taproot and lower leaves; 4, flower. Annual or bien- nial, reproducing by seed. Stems branched above, slender, hairy, yellow- green, erect, 1 to 2 feet (30 to 60 cm) tall. Leaves on stems alternate, 1 to 21/2 inches (2.5 to 6.3 cm) long, hairy, arrow-shaped. The leaf base nearly encloses the stem and the tip is blunt to pointed. Lower leaves broad, nar- rowed at the base with a round tip. Flowers yellow, 4-petaled, produced on racemes 2 to 10 inches (5 to 25 cm) long. Seed pods round, about ]/z inch (3 mm) in diameter, gray-brown with definite netlike surface markings. Each pod contains 1 seed, which is hard to separate from pod. Seeds yellow, about the size of white clover seeds. Found especially in grain fields and waste places.
99
MUSTARD FAMILY, Cruc/ferae
WILD RADISH, Raphanus raphanistrum L. 1, upper part of plant with pods and flowers; 2, lower part of plant; 3, flower; 4, seedling plant; 5, pod with section. Annual or winter annual, reproducing by seeds. Stems erect, branching above, 1 to 3 feet (30 to 90 cm) tall, sparsely pubescent with stiff hairs, especially on lower parts. Leaves on lower stem with same type of pubescence, pinnately divided with a large rounded terminal segment. Up- per leaves mostly undivided but with a few small segments. Flowers light yellow, shading into a whitish or purplish color, 1/2 inch (1.3 cm) in diam- eter, with 4 petals. Seed pods pithy and solid, ll/z to 3 inches (3.8 to 7.5 cm) long, y% inch (3 mm) in diameter, at maturity breaking into segments containing seeds. Lower pods usually small and seedless. Seeds vary in size and shape but are usually oval, slightly flattened, light reddish-brown, and 3/16 inch (4.5 mm) in diameter. Found in small grain and flax crops, where it is serious; also common in wastelands. Pod segments containing seeds are hard to remove from seed grain.
100
MUSTARD FAMILY, Cruc/ferae
AUSTRIAN FIELDCRESS, Ror/ppa austriaca (Crantz) Bess. 1, plant in bloom; 2, root and base of plant; 3, flower; 4, seed pod; 5, seed. Perennial, repro- ducing by rhizomes and occasionally by seeds. Stems erect or ascending, branching at the top, smooth, 1 to 3 feet (30 to 90 cm) tall. Leaves alternate. Upper leaves clasping the stem; lowermost leaves larger, with petioles, and more distinctly toothed than those on upper part of plant. Flowers with 4 small yellow petals, in loose clusters at tips of branches. Seed pods small, nearly spherical or oblong, with a distinct beak at the tip. Seeds small, brown to black, rough or warty, usually do not develop in northern regions. Found rarely in pastures, cropland, and waste areas, but regarded as a troublesome weed because it is very persistent. Spread chiefly by rhizome fragments.
101
MUSTARD FAMILY, Cruc/ferae
TUMBLE MUSTARD, S/'symfar/um altissimum L 1, lower leaf; 2, root; 3, upper part of plant; 4, seed; 5, seed pod. Annual or winter annual, reproducing by seed, taprooted. Stem erect, 2 to 5 feet (0.6 to 1.5 m) tall, bushy, branch- ing. Stem and branches smooth above, somewhat hairy below, pithy. Leaves pale green. Lower leaves are large and divided; upper leaves have smaller narrow segments. Flowers yellowish-white, Y^ to Yz inch (6 to 13 mm) in diameter, 4-petaled, growing in numerous but short racemes. Seed pods stiff, narrow, 2 to 4 inches (5 to 10 cm) long, divided into 2 parts; look like long stems rather than seed pods. Seeds oblong, about 1/16 inch (1.5 mm) long, dark reddish-brown. Found in small grains and waste places. Stem often breaks off at maturity causing plant to be blown about by wind.
102
MUSTARD FAMILY, Cruc/ferae
HEDGE MUSTARD, Sisymbrium offic/no/e (L.) Scop. 1, erect appressed pods; 2, lower leaf; 3, upper part of plant. Annual or winter annual, reproducing by seeds. Stems 1 to 4 feet (0.3 to 1.2 m) tall, erect, stiff, with a few branches above. Leaves divided, with coarse, pointed teeth. Lower leaves 4 to 10 inches (10 to 25 cm) long, often in form of a rosette; upper leaves much smaller. Flowers yellow, about l/s inch (3 mm) in diameter, 4-petaled, in small clusters at the tips of the elongated pod-bearing branches. Pods erect, following the stem, sharp pointed, about 1/2 inch (13 mm) long, somewhat hairy. Seeds greenish-brown, about 1/16 inch (1.5 mm) long, irregularly oval with a roughened surface. Found in grain fields and waste places.
103
MUSTARD FAMILY, Cruc/ferae
FIELD PENNYCRESS, Thlaspi arvense L. 1, seed; 2, seed pod; 3, upper part of plant; 4, lower part of plant. Annual or winter annual, reproducing by seed. Stems erect, 4 to 20 inches (10 to 50 cm) tall, simple or sometimes branched above, smooth throughout. Leaves alternate, simple, toothed, 1/2 to 2 inches (1.3 to 5 cm) long, clasping stem with earlike projections. Flowers white with 4 petals, in racemes which lengthen greatly at maturity. Seed pod flat, circular, about Vz inch (1.3 cm) in diameter, 2-valved, broadly winged, with a deep, blunt notch at the top. Each pod contains several seeds. Seed dark reddish-brown to black, ovate in outline, flattened, about 1/16 inch (1.5 mm) long with about 10 curved, granular ridges on each side. Found in small grains, legumes, and noncultivated areas. This weed imparts a bitter, garlicky flavor and odor to milk.
104
ROSE FAMILY, Rosoceae
SILVERY CINQUEFOIL, Pofenf///a crrgenfea L. 1, entire plant; 2, seed. Peren- nial, spreading by seed. Stems as long as 2 feet (60 cm), prostrate or with only the tips ascending. Leaves palmate, with 5 to 7 sharply toothed leaflets; lower surface densely covered with short hairs, giving a silvery color, petiole length variable. Flowers about 1/2 inch (1.3 cm) across; on short stalk, from the axils of the leaves, petals yellow. Seeds yellowish, kidney-shaped, nu- merous, 1/32 inch (0.8 mm) long. Found in lawns, pastures, and meadows, especially on sandy soils.
105
ROSE FAMILY, Rosaceae
ROUGH CINQUEFOIL, Potentilla norvegica 1. 1, base of plant, with roots; 2, top of plant, in bloom; 3, flower; 4, seed; 5, distribution. Annual, winter annual, or biennial, reproducing by seed. Stems rough, hairy, semierect or spreading, 1 to 3 feet (30 to 90 cm) tall. Leaves palmately divided like straw- berry, with 3 leaflets; alternate, usually hairy, coarsely toothed. Flowers small, inconspicuous, yellow, in clusters at tips of branches. Seeds 1/32 inch (0.8 mm) long, light brown, conspicuously marked. Found in fields, meadows, pastures, roadsides, and wasteland.
SULPHUR CINQUEFOIL, Potentilla recta I. 6, lower part of plant; 7, top of plant, in bloom; 8, flower; 9, seed; 10, distribution. Perennial, reproducing by seed. Stems rough, stiffly erect, 1 to 3 feet (30 to 90 cm) tall, hairy. Leaves alternate, palmately divided with 5 to 7 coarsely toothed leaflets; hairy, pale beneath. Flowers conspicuous, sulphur yellow, 1 inch (2.5 cm) across, in terminal clusters. Seeds dark brown, with minute ridges. Found in same kinds of places as above.
106
ROSE FAMILY, Rosaceae
ARKANSAS ROSE, Rosa arlcansana Porter. 1, growth habit showing spiny stems, buds, flowers, and fruits; 2, seeds. Perennial, reproducing by seed and deep underground rootstocks. Stems erect, 1 to 2!/2 feet (30 to 75 cm) high, densely prickly. Leaves compound with 7 to 11 oval leaflets seldom over 1 inch (2.5 cm) long, sharply serrated or toothed, smooth on both sides. Flowers about 2 inches (5 cm) broad, fragrant, light to dark pink, usually in groups at ends of branches. Fruit a round applelike structure about l/s to l/2 inch (8 to 13 mm) in diameter, smooth or sometimes bristly. Seeds hard, hairy, brown, irregularly shaped, Vs to V4 inch (3 to 6 mm) long. Seeds are often contained in oats, wheat, barley, rye, and sweet clover seed. Found in pastures, prairies, fields, roadsides, and fence rows. Many other species of Rosa similar to the above grow in the region.
107
LEGUME FAMILY, Legum/nosae
WILD LICORICE, G/ycyrrh/'za /ep/dofa (Nutt.) Pursh. 1, entire plant; 2, roots; 3, flower; 4, seed pods with seed. Perennial, reproducing by underground rootstocks and by seeds. Roots deep and spreading, with a sweet taste. Stems 1 to 3 feet (30 to 90 cm) tall, smooth, erect, and branched. Leaves alternate, compound with 11 to 19 deeply veined leaflets, smooth-edged. Flowers yellowish-white, resembling those of alfalfa in shape, in a crowded terminal spike. Seed pod l/z to 1 inch (1.3 to 2.5 cm) long, brown, burlike, covered with hooked spines. Seeds green to reddish-brown, smooth, dull, bean-shaped. Found in pastures, meadows, and waste places. Plant does not persist in cultivated land.
108
LEGUME FAMILY, Legum/nosae
BLACK MEDIC, Med/cago /upu/ina L. 1, part of plant in bloom; 2, pod and seed. Annual, biennial, or perennial, reproducing by seed, with shallow taproot. Stems slender, branched, spreading, 1 to 2 feet (30 to 60 cm) long. Leaves have 3 leaflets, the center one on a short stalk. Flowers are 1/16 inch (1.5 mm) long, yellow, in dense, globular spikes borne on short branches from the stem. Seed pods black, coiled, with thick walls, each pod containing 1 seed. Seeds yellowish-green, kidney-shaped. Found in lawns, pastures and meadows. Common and objectionable as an impurity in alsike clover seed, sometimes in other legume seeds. Grown for forage, but is small-yielding. Will inoculate soil for alfalfa.
109
LEGUME FAMILY, Legum/nosae
NARROWLEAF VETCH, Vida angustifolia L 1, plant; 2, seed pods; 3, seed. Annual, reproducing by seed. Stems smooth, 1 to 3 feet (30 to 90 cm) long, upright but weak, clinging to support by means of tendrils at tips of leaves. Leaves pinnately compound with 8 to 12 leaflets. Leaflets on lower leaves oblong, on upper leaves linear, all with smooth margins. Flowers purple, in racemes containing 2 to 9 flowers. Pods smooth, 1 to ll/2 inches (2.5 to 3.8 cm) long, with 4 to 7 seeds. Seeds spherical, brown-black or olive brown, mottled with fine black spots. Found in fields and waste places. Has forage value but is objectionable in wheat fields because the vetch seed contaminates the threshed grain.
110
WOODSORREL FAMILY, Oxalidaceae
COMMON YELLOW WOODSORREL, Oxalis stricta 1. 1, plant in flower; 2, flower; 3, flower bud; 4, leaves; 5, seed. Perennial or annual, reproducing by seed. Plants low, bushy, 4 to 18 inches (10 to 45 cm) tall. Stems weak, branched at the base, hairy; may root at the joints. Leaves with long peti- oles, sour-tasting, divided into 3 heart-shaped leaflets. Flowers yellow, 5- petaled, occurring in clusters. Seed pods l/2 to 1 inch (1.3 to 2.5 cm) long, slender, 5-ridged, pointed. Seeds small, flat, brown, thrown from the parent plant when seed pods burst. Found in pastures, lawns, and waste places, often becoming a troublesome lawn and garden pest. Several other species of Oxalis, differing in detail from this, are readily recognized as woodsorrels from this figure.
Ill
GERANIUM FAMILY, Geran/aceae
CAROLINA GERANIUM, Geranium carolinianum 1. 1, part of plant showing habit; 2, flower; 3, seed pod enclosed by calyx; 4, seed. Annual or biennial, reproducing by seeds. Root system fibrous. Stems erect, branching near base, 4 to 20 inches (10 to 50 cm) high. Leaves 1 to 3 inches (2.5 to 7.5 cm) broad, alternate, deeply cut into 5 to 8 fingerlike, toothed divisions. Flowers small, 5-petaled, pale pink to lavender, found singly or in loose clusters at tips of stems and branches. Seed pod long, pointed, splitting at maturity into 5 curled sections. Seeds dark brown, 1/16 inch (1.5 mm) long, oval to slightly oblong, surface pitted. Found in woods, pastures, lawns, waste places, and along highways. Usually not troublesome in cultivated fields.
112
CALTROP FAMILY, Zygophy/foceae
PUNCTUREVINE, Tribulus terrestris 1. 1, plant; 2, seed pod showing burs. Annual, reproducing by seeds. Root system simple taproot. Stems hairy, prostrate, branching from base to form dense mats of slender trailing branches 6 to 8 feet (1.8 to 2.4 m) long. Leaves oblong, opposite, hairy, divided into pinnate leaflets. Flowers small, yellow, 5-petaled, produced in axils of leaves. Seed pods contain 5 burs, each having 2 sharp, long, stout, rough spines, strong enough to penetrate shoe soles or bicycle tires. Burs separate as they mature and often lie in the soil for years before germinating. Found in pastures, roadsides, and waste places, along railroad tracks, and sometimes in cultivated fields. A serious weed, listed as noxious in some states. Cattle do not graze areas infested with puncturevine.
113
SPURGE FAMILY, Euphorbiaceae
VIRGINIA COPPERLEAF, Acalypha virginica L 1, plant in flower; 2, section of stem with flowers; 3, flower surrounded at base by deeply notched leaf- like structure; 4, seed. Annual, reproducing by seed. Taproot shallow. Stems hairy, 1 to 2 feet (30 to 60 cm) tall, frequently branched at base and spread- ing over the ground. Leaves egg-shaped, on long petioles; the lower leaves arranged in pairs on stems, the upper ones alternate. Flowers in clusters, small, borne in leaf axils in upper portion of stems and branches. Male and female flowers separate but borne together. Seed pod containing 3 seeds, surrounded with deeply cut leaflike structure. Seeds egg-shaped, small, dull reddish-brown to gray with reddish-brown spots. Found in wasteland, grassland, and cultivated fields. Seed occasionally mixed in crop seeds.
114
SPURGE FAMILY, Euphorb/aceae
WOOLLY CROTON, Crofon capitatus Michx. 1, part of lower stem and roots; 2, upper portion of plant; 3, flower clusters with deeply cut, hairy, leaf-like structure; 4, seeds. Annual, reproducing by seeds. Taproot shallow. Stems 1 to 2 feet (30 to 60 cm) tall, extensively branched, densely hairy. Leaves narrow, woolly with short hairs, smooth-edged, borne on long petioles, usually alternate. Flowers in small, dense clusters at ends of stems and branches, surrounded by leafy bract. Seed pod densely hairy, 3-sided, con- taining 3 seeds. Seeds grayish, broadly egg-shaped, about 3/16 inch (4.5 mm) long. Found commonly in old overgrazed pastures.
TROPIC CROTON, Croton glandulosus L. 5, lower and upper leaves; 6, seeds. Similar to the above species. Annual, reproducing by seeds. Stems greenish, rough-hairy but not woolly. Leaves oblong to egg-shaped, with sharply toothed edges, borne on relatively short petioles. Seed ovate, nearly ellipti- cal, about i s inch (3 mm) long. Found in sandy soils, waste areas, and overgrazed pastures.
115
SPURGE FAMILY, Euphorbiaceae
FLOWERING SPURGE, Euphorbia corollala L 1, top of plant; 2, roots; 3, im- mature seed pod and flower; 4, seed and seed pod. Perennial, reproducing by seed and by short rootstocks. Stems 1 to 3 feet (30 to 90 cm) tall, erect, light green, smooth, branched near the top, with a milky juice. Leaves ob- long, narrow, light green; lower ones alternate, upper leaves in whorls on the branches. Flowers small, surrounded by 5 white petallike bracts in the form of a cup. Flowers borne in terminal clusters and in the axils of the upper leaves. Seed pods on short stalks from the cuplike base, smooth, 3- lobed with 3 seeds. Seeds egg-shaped, gray or light brown, mottled, shal- lowly pitted, with a dark line on one side. Found in pastures, roadsides, and waste places, especially in dry or sandy areas.
116
SPURGE FAMILY, Euphorbiaceae
CYPRESS SPURGE, Euphorbia cyparissias L 1, plants arising from old stems and creeping rootstocks; 2, inflorescence; 3, seed; 4, leaf and portion of stem; 5, entire plant. Perennial, usually reproducing by creeping rootstocks but occasionally by seeds. Stems in tufts, forming dense mats if not dis- turbed, usually not exceeding 1 foot (30 cm) in height, somewhat branched, smooth, very leafy, with milky juice. Leaves oblong, narrow, smooth, alter- nate, pale green. Flowers small, greenish, having petals fused in the form of a cup; growing in axils of a terminal whorl of yellowish floral bracts that turn purplish at maturity. Seed pods on short stalk from the cuplike base, smooth, waxy, 3-lobed with 3 seeds. Seeds brownish-gray, smooth. Found in pastures, roadsides, and waste places. Often spreads from gardens where it is used as an ornamental.
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SPURGE FAMILY, Euphorb/aceae
LEAFY SPURGE, Euphorbia esu/cr L. 1, leafy stem; 2, top of stem with flowers; 3, flower with seed pod; 4, seed; 5, root system. Perennial, reproducing from extensive rootstocks and seeds. Roots deep and spreading, woody, very persistent. Stems erect, smooth, branched at top, 1 to 2 feet (30 to 60 cm) tall, with milky juice. Leaves alternate on stems, narrowly strap-shaped, 14 inch (6 mm) wide, usually drooping. Flowers small, greenish, petals fused into a cuplike structure, borne just above the greenish-yellow heart-shaped floral bracts on top of stem. Seed pods on short stalks from the cuplike base, 3-lobed, with 3 seeds. Seeds smooth, light gray, with yellowish or white appendage attached to the tip. Found in pastures, waste areas, along roadsides, and in cultivated fields. A troublesome weed because of its spreading nature and persistence.
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SPURGE FAMILY, Euphorbiaceae
SPOTTED SPURGE, Euphorbia preslii Guss. 1, whole plant; 2, leaf; 3, flower and seed pod; 4, seed; 5, distribution. Annual, with shallow taproot, ger- minating late in the spring or early summer. Stems erect and spreading, 6 inches to 3 feet (15 to 90 cm) in height, with milky juice. Leaves ovate, edges slightly toothed, borne on a short petiole, with a conspicuous reddish spot or blotch. Flowers small, with minute petals in the form of a cup. Seed pods on short stalks from the cuplike base, smooth, 3-lobed, ribbed, with 3 seeds. Seeds 3-sided, oblong, dark brown or black, pitted with ridged surfaces. Found in gardens, fields, and waste areas. Also commonly known as nodding spurge.
PROSTRATE SPURGE, Euphorbia maculata I. 6, whole plant; 7, flower and seed pod; 8, seed; 9, distribution. Stems prostrate, forming a mat. Leaves and seed pods are hairy and much smaller than the above. Leaves spotted like those of spotted spurge. Found chiefly in gardens and open areas; also in lawns and turf. Also commonly known as milk purslane.
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SPURGE FAMILY, Euphorb/aceae
SNOW-ON-THE-MOUNTAIN, Euphorbia marginata Pursh. 1, entire plant; 2, flower, seed pod at left; 3, seed. Annual with milky, sticky sap. Taproot slender. Stems 1 to 3 feet (30 to 90 cm) tall, erect, branched, usually with fine hairs, at least on upper part. Leaves alternate except just below the flower clusters, where they are whorled; ovate or oblong-ovate, edges smooth, bright green except for conspicuous white marginal areas. Flowers small, white, in small clusters, without true petals but with 5 white append- ages on the cuplike structure in which the ovary and stamens are produced. Seed pods hairy, 3-lobed and 3-seeded, elevated above the cup on a slender stalk. Found in dry soil and waste places, sometimes grown as an ornamen- tal. The plant is poisonous to livestock, and the milky sap causes skin irrita- tion on many persons.
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CASHEW FAMILY, Anocard/oceae
POISON IVY, Rhus rod/cans L. 1, root and base of plant; 2, flowering branch; 3, cluster of berries, and single berry; 4, flower. Woody perennial, repro- ducing by seed and rootstocks. The plant may be either a low shrub or a vine climbing high into trees. In climbing it is supported by aerial roots along the stem. Leaves consist of 3 large shiny leaflets each 2 to 4 inches (5 to 10 cm) long, pointed at tip. Leaflet edges either smooth or irregularly toothed. Flowers small, green, 5-petaled, borne in a head 1 to 3 inches (2.5 to 7.5 cm) long. Berries small, white, round, and hard. Found in open woods, fence rows, thickets, orchards, and wasteland. All parts of this plant contain a poisonous material which may cause blistering of the skin. The plant changes from a bright green to a very attractive red or reddish-yellow in the fall, tempting unwary collectors. This is a variable species, not only in habit of growth, but in leaflet shape, rooting habit, pubescence on leaves, petioles, and fruit.
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MALLOW FAMILY, Malvaceae
VELVETLEAF, Abutilon theophrasti Medic. 1, root; 2, upper part of stem with flowers; 3, flower; 4, seed pod; 5, seed. Annual, with strongly developed taproot and stem. Stem smooth, covered with short velvety hairs, often 6 to 8 feet (1.8 to 2.4 m) tall. Leaves large, heart-shaped, pointed, alternate, petioled, and with a soft, velvety, hairy surface. Flowers about % mcrl d-9 cm) in diameter with 5 yellow petals; borne on short stalks attached to leaf axils on upper part of stem. Seed pod cup-shaped, about 1 inch (2.5 cm) in diameter, with ring of prickles about upper edge; contains 5 to 15 seeds. Seeds grayish-brown, flattened, notched, about V6 inch (3 mm) long. Found principally in soybean and corn fields but occasionally in gardens, along fence rows, and in waste places. Also commonly known as buttonweed.
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MALLOW FAMILY, Malvaceae
VENICE MALLOW, Hibiscus frionum L. 1, entire plant; 2, flower; 3, open seed pod with a seed; 4, mature seed pod with sepals. Annual, reproducing by seed. Stems erect or spreading, hairy, 8 to 20 inches (20 to 50 cm) tall. Root system fibrous. Leaves alternate, irregularly shaped, with 3 to 7 parts. Flowers 1 to 2 inches (2.5 to 5 cm) in diameter, with 5 petals, pale yellow or whitish with a purplish-black center. Petals often have a purple margin. Each flower remains open for only a few hours. Seed pod hairy, containing many seeds. Seeds grayish-black, kidney-shaped, rough, about 1/16 inch (1.5 mm) long. Found in gardens, cultivated fields, and waste places. Espe- cially serious in cultivated crops after the last cultivation. Also commonly known as flower-of-an-hour.
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MALLOW FAMILY, Malvaceae
COMMON MALLOW, Matva neglecta Wallr. 1, young plant; 2, flower; 3, seed pod; 4, seed. Annual or biennial with a short straight taproot, repro- ducing by seeds. Stems branching, nearly erect, or spreading on the surface of the ground with tip generally turning up. Leaves large, circular in out- line, simple, toothed or slightly lobed, mostly hairy, on very long slender petioles. Flowers small, with 5 whitish petals, borne singly or in clusters at bases of petioles. Seed pod a flattened disk, when ripe breaking up into 10 to 20 small, hairy, 1-seeded sections. Seed nearly round, flattened, red- dish-brown, about 1/16 inch (1.5 mm) in diameter, notched. Found in culti- vated fields, waste places, gardens, yards, lawns, and roadsides.
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MALLOW FAMILY, Malvaceae
DWARF MALLOW, Malva rotundifolia L 1, entire plant; 2, seeds. Annual, reproducing by seed. Root a short, straight taproot. Stems branching, nearly erect or spreading on surface of ground with tips generally turning up. Leaves rounded, often wider than long, 1 to 3 inches (2.5 to 7.5 cm) long, with 5 to 7 broad, rounded lobes. Flowers pale blue or nearly white, 1/3 to 1/2 inch (8 to 13 mm) wide, borne singly or in clusters at bases of petioles. Seed pod a flattened disk, usually breaking into 10 segments, 1 seed per section. Seed segments generally pie-shaped, dark brown, enclosing a black seed. Found frequently in yards, gardens, and roadsides; occasionally in cultivated fields.
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MALLOW FAMILY, Malvaceae
PRICKLY SIDA, Sida spinosa L. 1, plant; 2, section of stem showing spines; 3, flower; 4, seed pod enclosed by calyx; 5, single section of pod containing seed. Annual, reproducing by seeds. Taproot slender, branching, rather long. Stems erect, branching widely, softly hairy, bearing 2 to 3 short, blunt, spiny projections below each node. Leaves alternate, simple, oblong, with toothed edges. Flowers with 5 pale yellow petals, solitary or clustered in axils of leaves. Seed pod splitting when ripe into 5 one-seeded sections, each with 2 sharp, spreading spines at the top. Seeds about 1/16 inch (1.5 mm) long, 3-angled, egg-shaped, dull dark reddish-brown. Found late in the sea- son in waste places, cultivated fields, gardens, and pastures.
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ST. JOHNS WORT FAMILY, Guff/ferae
ST. JOHNSWORT, Hyper/cum perforafum L. 1, plant in flower; 2, portion of stem with leaves; 3, flower and buds; 4, stamens and ovaries; 5, seed. Per- ennial, reproducing by seeds and rootstocks. Root system branched and extending to considerable depth. Shallow, short rootstocks extend out sev- eral inches from crown. Stems smooth, branched, erect, somewhat 2-edged, 1 to 2 feet (30 to 60 cm) tall, woody at base. Leaves opposite, elliptic to ob- long, covered with small clear dots. Flowers about $4 mcn U.9 cm) in di- ameter, 5-petaled, orange-yellow with occasional black dots along edges of petals. Seed pods rounded, pointed, with 3 parts and many seeds. Seeds about 1/16 inch (1.5 mm) long, cylindrical, blackish, shiny with a rough, pitted, resinous surface. Found in pastures, meadows, rangelands and along roadsides. Not relished by grazing animals; may cause skin irritation and loss of condition in livestock, especially white animals. Also commonly known as Klamath weed.
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CACTUS FAMILY, Cocfoceae
PRICKLYPEAR, Opunf/o spp. Mill. Perennial, reproducing by stems and seeds. Stems flat, fleshy, covered with spines several inches in length, rooting freely at the joints. May be prostrate to erect and 3 feet (90 cm) or more tall. Flowers are several inches across, bright yellow, sometimes with red centers. Fruits somewhat pear-shaped, fleshy to dry and spiny, filled with many hard seeds. Seeds about 3/16 inch (4.5 mm) in diameter, flattened. Found in the drier sandier soils but not generally troublesome except on overgrazed rangelands or pastures. Variable in form; several similar species are found in the area.
128
EVENINGPRIMROSE FAMILY, Onograceae
COMMON EVENINGPRIMROSE, Oenothera biennis L. 1, upper portion of stem showing seed pods, flowers and buds; 2, root; 3, single flower; 4, seeds. Biennial, reproducing by seeds. Produces large rosette of leaves and a fleshy root the first year. Stem the second year erect, leafy, 1 to 5 feet (0.3 to 1.5 m) tall, branching only in upper portion if at all; lower stem often tinged with purple and somewhat hairy. Leaves variable, but usually lanceo- late and without petioles, lower leaves often purplish and hairy like lower stem. Flowers about 1 inch (2.5 cm) across, with 4 yellow petals, opening over a period of several weeks. Seed pods woody, cylindrical, containing many seeds. Seeds 1/16 inch (1.5 mm) long, irregular, angular, brown. Found in wasteland and fields, especially in dry or sandy soil.
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PARSLEY FAMILY, Umbelliferae
SPOTTED WATERHEMLOCK, Cicuta macu/afa L. 1, stems, leaves, and flow- ers; 2, roots; 3, hollow base of stem; 4, flower; 5, seed. Perennial, repro- ducing by seeds and tuberous roots. Stem smooth, 3 to 5 feet (0.9 to 1.5 m) tall, branched at top only, frequently streaked with purplish spots. Leaves compound, 8 to 12 inches (20 to 30 cm) long, alternate, smooth with toothed edges, often spotted; base of petioles clasping stem. Flowers very small, with 5 white petals, borne in compound umbels. Seed flat on one side and rounded on the other, ridged lengthwise with light and dark lines. Found in swamps and lowlands, usually in water or at its edge. Both seed and tubers have a distinct aromatic odor. All parts of the plant, but especially the roots, are poisonous if eaten.
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PARSLEY FAMILY, Umbelliferae
POISON HEMLOCK, Con/urn maculatum L. 1, upper part of plant in bloom; 2, root; 3, flower. Biennial, forming a rosette the first year, reproducing by seed the second year. Root is fleshy, parsniplike taproot. Leaves alternate, large, 4 to 5 times compound, finely divided, and toothed, giving a lacy ap- pearance. Stems smooth, erect, 2 to 7 feet (0.6 to 2 m) tall, much branched, with purplish spots and blotches; hollow between the nodes. Flowers white, produced in large terminal compound umbels that are flattish to slightly convex. Seeds borne in pairs, ovoid, flattened, smooth, prominently ribbed, pale brown. Found in wet sites along streams, in gardens, roadsides, waste areas. Sometimes grown as an ornamental. The entire plant is very poison- ous.
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PARSLEY FAMILY, Umbelliferae
WILD CARROT, Daucus carofa L. 1, entire plant; 2, flower head; 3, head in seed; 4, seed. Biennial, reproducing by seeds. In first year, produces rosette of finely divided leaves and fleshy taproot; in second year blooms and dies. Stem (second year) erect, 1 to 3 feet (30 to 90 cm) tall, hairy, stout, and branched at top. Leaves alternate, finely pinnately divided, hairy, with dis- tinct carrotlike odor. Flowers small, with 5 white petals, borne in umbels at ends of branches. Seeds l/s inch (3 mm) or less long, one side flattened, the other rounded and showing 4 heavy long-bristled ridges with smaller ones between. The outside seed-bearing stalks curve in sharply as they mature. Found in meadows, pastures, and roadsides; not in cultivated fields. Also known as Queen Anne's lace.
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PARSLEY FAMILY, UmbelMerae
WILD PARSNIP, Pastinaca sativa L. 1, top of plant showing leaves, seeds, and flowers; 2, seed; 3, flower; 4, root. Biennial, reproducing by seeds. Pro- duces a rosette of large upright leaves and a large fleshy root the first year. Stem (second year) usually somewhat hairy, grooved, erect, 2 to 5 feet (0.6 to 1.5 m) tall. Leaves alternate, pinnately compound, with coarsely saw- toothed edges, not hairy. Flowers small, with 5 yellow petals, in umbels at the top of stems and branches. Seeds flat, rounded, smooth, straw-colored, with low ribs across them. Found in wastelands and pastures. This is not poisonous but sometimes has been thought to be.
133
DOGBANE FAMILY, Apocynacecre
HEMP DOGBANE, Apocynum cannab/num L. 1, seed pods; 2, section of stems and rootstock; 3, upper part of stem with leaves and flowers; 4, seed. Peren- nial, reproducing by seed and long, horizontal rootstocks. Stems erect, 1 to 2 feet (30 to 60 cm) tall from a woody base, exuding milky juice when broken. Leaves erect, elliptical, narrow, and smooth-edged. Flowers with 5 greenish-white petals which are slightly longer than the green sepals. Seed pod long and slender. Seed thin and flat, with a tuft of soft silky hairs at one end. Found in wasteland and cultivated fields. Another species of dog- bane, Apocynum s/bericum Jacq., is very similar to this one and is found in abundance in much of the same area.
134
MILKWEED FAMILY, Asc/ep/odaceae
HONEYVINE MILKWEED, Ampelamus albidus (Nutt.) Britt. 1, portion of plant; 2, seed pod; 3, seed. Perennial, reproducing by seeds and by long spreading roots. Stems smooth, slender, twining, without milky juice. Leaves smooth, heart-shaped, pointed, with long petioles, in pairs at the nodes on the stem. Flowers small, whitish, borne in clusters on stalks from the axils of the leaves. Seed pod similar to that of common milkweed but smooth and green. Seeds brown, flattened, oval, with a tuft of silky, white hairs at tip. Found in cultivated Reids and fence rows, especially in areas with fertile, moist soil.
135
MILKWEED FAMILY, Asclepiadaceae
SWAMP MILKWEED, Asc/ep/crs incarnate L 1, upper part of plant in flower; 2, seed pods; 3, single flower; 4, hood (5 of which make up the corona). Perennial, reproducing by seeds and weakly creeping rootstocks. Stems single or clustered, 1 to 4 feet (0.3 to 1.2 m) tall, very leafy, branched toward top, with milky juice. Leaves opposite, long, narrow, oblong but tapering toward tip, smooth or hairy, 4 to 7 inches (10 to 17.5 cm) long. Flowers pink to rose-purple or whitish, clustered into several ball-like groups (um- bels). Seed pod erect on short stems, about 3 inches (7.5 cm) long, smooth or slightly hairy. Seeds oval, about Y% inch (9 mm) long, with tuft of hairs at tip. Found in swamps, ditches, and wet prairies, seldom in cultivated fields. Poisonous to livestock.
136
MILKWEED FAMILY, Asclepiadaceae
COMMON MILKWEED, Asclepias syriaca L. 1, lower part of stem and root- stock; 2, upper part of stem with flower clusters and seed pods; 3, single flower; 4, seed. Perennial, reproducing by seed and from rootstocks. Stems stout and erect, 2 to 5 feet (0.6 to 1.5 m) tall, covered with short downy hairs, with milky juice. Leaves opposite, oblong, rounded, 4 to 8 inches (10 to 20 cm) long with prominent veins. Upper surface smooth, lower surfaces covered with short white hairs. Flowers sweet-smelling, pink to white, in large, many-flowered, ball-like clusters at the tips of stems and in the axils of upper leaves. Seed pod grayish, hairy, covered with soft spiny projec- tions. Seed brown, flat, oval, with a tuft of silky, white hairs attached to tip. Found in cultivated fields, pastures, open woods and roadsides.
137
MILKWEED FAMILY, Asclepiadaceae
EASTERN WHORLED MILKWEED, Asc/ep/os veiiicillata 1. 1, base of plant with roots and rootstock; 2, shoot; 3, upper portion of plant with flower clusters; 4, seed. Perennial, reproducing from seed and creeping rootstocks. Stems 1 to 2 feet (0.3 to 0.6 m) tall, slender, smooth, branching at top of plant only, with milky juice. Each crown may produce several stems. Leaves light green, narrow, arranged in groups of 3 to 7 in whorls around stem. Flowers greenish-white, with 5 petals, borne in clusters at top of stem or in the axils of upper leaves. Seed pod 2 to 4 inches (5 to 10 cm) long, slender, smooth, containing numerous seeds. Seeds flat, brown, with a tuft of fine hairs at tip. Found in meadows, pastures, and waste places. Seldom found in cultivated fields. This plant is poisonous to livestock.
138
MORNINGGLORY FAMILY, Convo/vu/aceae
FIELD BINDWEED, Convolvulus arvensis L. 1, plant in flower; 2, seed pod, entire and in cross section; 3, seed; 4, variations in leaf shape. Perennial, reproducing by seeds and rootstocks. Root system extensive; may go down 20 to 30 feet (6 to 9 m). Stems smooth, slender, 2 to 7 feet (0.6 to 2 m) long, twining or spreading over surface of ground. Leaves ovate with spreading basal lobes. Flowers white or pink, funnel-shaped, about 1 inch (2.5 cm) across, usually borne singly in the axils of leaves. Flower stalk has 2 bracts Vi to 2 inches (1.3 to 5 cm) below the flower, which distinguish this weed from hedge bindweed. Seed pod egg-shaped, usually containing 4 seeds. Seeds dark brownish-gray, roughened, about l/s inch (3 mm) long, with 1 rounded and 2 flattened sides. Found in and able to persist and spread in all noncultivated areas and under most cropping systems. One of the most troublesome weeds in the region. Also known as creeping jenny.
139
MORNINGGLORY FAMILY, Convo/vu/aceae
HEDGE BINDWEED, Convolvulus sepium 1. 1, plant in flower; 2, seed; 3, seed pod; 4, variations in leaf shape. Perennial, reproducing by seed and fleshy creeping rootstocks. Roots extensive but relatively shallow. Stems smooth, 3 to 10 feet (0.9 to 3 m) long, twining on plants or trailing on surface of ground. Leaves large, alternate, usually sharp-pointed at tip, basal lobes large. Flowers large, ll/z to 2 inches (3.8 to 5 cm) across, white or pinkish. The flower bud and later the lower part of the flower and seed pod are enclosed in 2 leafy bracts. Seed pod about 3/s inch (9 mm) in diameter, egg-shaped, containing 2 to 4 seeds. Seeds slate-colored to black, dull, usually with 1 rounded and 2 flattened sides. Found in cultivated fields, fence rows and waste areas, especially on bottomlands. Less drouth-endur- ing than field bindweed, but under humid conditions usually a more serious problem.
140
MORNINGGLORY FAMILY, Convo/vu/aceae
DODDER, Cuscufa spp. L. 1, dodder twined on legume plant; 2, flower; 3, seed pod; 4, seed. Annual, reproducing by seed. Dodder is a parasitic plant without chlorophyll. It obtains its food by twining around a host plant and sending rootlike projections into its stem. Stems are stringlike, smooth, yellow or orange, branching extensively, forming dense masses. Leaves ab- sent or reduced to small bracts. Flowers numerous, small, white with 5 lobes, borne in clusters. Seed pod about V6 inch (3 mm) in diameter, with thin papery walls, containing 4 seeds. Seeds triangular in cross section, brown, with a roughened seed coat. Found principally on clovers, alfalfa, and lespedeza, although it can grow on many broad-leaved plants. It is difficult to remove the seeds from clover and alfalfa seeds. A number of similar species growing on various host plants are found in the region.
141
MORNINGGLORY FAMILY, Convo/vu/aceae
IVYLEAF MORNINGGLORY, /pomoea hederacea (L) Jacq. 1, portion of plant; 2, seed pod surrounded by calyx; 3, seed; 4, distribution. Annual, reproducing by seed. Stems hairy, twining or spreading on ground. Leaves usually 3-lobed, alternate, hairy. Plants with entire leaves occur rarely, be- coming more common toward southern part of region. Flowers funnel- shaped, purple or blue varying to white, borne singly on long stalks. Seed pods egg-shaped, partly covered by bristly calyx, usually with 4 to 6 seeds. Sepals lanceolate, narrowed from below the middle into a slender, recurved tip. Seeds about |. 4 inch (6 mm) long, dark brown to black, with 1 round and 2 flattened sides. Found in gardens, fields, and waste places. A trouble- some weed in cultivated fields, especially corn and soybeans, where it ties plants together before harvest.
TALL MORNINGGLORY, /pomoea purpurea (L.) Roth. 5, leaf; 6, distribution. Very similar to the above species. Leaves are larger, heart-shaped, very rarely lobed. Flowers blue, purple, white, or variegated. Sepals lanceolate to oblong, acute to acuminate.
142
MORNINGGLORY FAMILY, Convo/vu/aceae
BIGROOT MORNINGGLORY, /pomoea pandurafa (L) G. F. W. Mey. 1, por- tion of root; 2, portion of vine with flowers; 3, seed pod; 4, seed. Peren- nial, reproducing by seed and from roots. Roots yellowish white, enlarging greatly so that they may weigh many pounds, buried in the soil below the plow line. Stems trailing or twining on plants, 2 to 10 feet (0.6 to 3 m) long, smooth, often purplish. Leaves alternate, heart-shaped, 2 to 6 inches (5 to 15 cm) long, smooth, with long petioles. Flowers funnel-shaped, 2 to 3 inches (5 to 7.5 cm) in diameter, white with dark purple center. Seed pod egg-shaped, enclosed by several leaflike sepals, containing 2 to 4 seeds. Seeds dark brown, fringed with soft hairs. Found in cultivated fields, along fences and roadsides, especially on sandy soils. Most troublesome in corn, soybeans, and small grain crops. Also commonly known as wild sweet potato.
143
WATERLEAF FAMILY, Hydrophyllaceae
WATERPOD, Ellisia nycfe/ea L 1, entire plant; 2, flower; 3, seed pod with enlarged calyx at base; 4, seed. Annual, reproducing by seed. Stems branch- ing widely at base, 6 to 18 inches (15 to 45 cm) tall. Leaves deeply cut into numerous divisions which are 1- to 3-toothed, alternate or opposite. Flow- ers small, 5-lobed, whitish to pale blue, borne singly on long hairy stalks. Seed pod green, hairy, drooping, 2-celled, containing 4 seeds, surrounded at base by 5 green, enlarged sepals. Seeds oval, brown, with pitted surface. Found chiefly in moist areas on wasteland and along ditches.
144
BORAGE FAMILY, Borag/ncrcecre
HOUNDSTONGUE, Cynog/ossum offic/na/e L. 1, upper part of plant; 2, leaf from lower part of stem; 3, seed pod. Biennial, with mousy odor, reproduc- ing by seeds and from thick, black roots. Stems erect, ridged, leafy; covered with short, soft hairs. Leaves in a rosette the first year, narrow and tapered (especially the upper ones) in the second year; petioles absent, leaves rounded at base, sometimes clasping, softly hairy. Flowers in racemes, nearly without bracts, with 5 dull red petals. Fruits grouped into 4 nutlets about *4 mcn (6 mm) long, that separate when ripe. The flat outer surfaces of the nutlets are bristly, and they cling to clothing and the fleece of sheep. The top of each nutlet is flat with a scar on one side near base. Found in pastures and wasteland, frequently on gravelly, somewhat alkaline soils.
145
BORAGE FAMILY, Borcrg/naceae
EUROPEAN STICKTIGHT, Lappu/a echinata Gilib. 1, upper part of plant; 2, young plant with roots; 3, seeds. Annual or winter annual, reproducing by seeds. Stem slender, widely branched above, 1 to 2 feet (30 to 60 cm) tall, entire plant covered with rough hairs. Leaves hairy, narrowly oblong, 1 to 2 inches (2.5 to 5 cm) long, at first forming a rosette at base of plant. Flowers small, with 5 blue petals, borne in the axils of small leafy bracts along upper branches. Seed pods rough with hooked spines, at maturity splitting into 4 segments, each containing 1 seed. Found in dry soils along roadsides and in wooded areas and waste places.
146
VERVAIN FAMILY, Verbenaceae
PROSTRATE VERVAIN, Verbena bracfeafa Lag. and Rodr. 1, entire plant; 2, flowering stem; 3, single flower; 4, seed pod or fruit; 5, single seed. Annual, reproducing by seed. Stems mostly prostrate, a few inches to more than a foot long, hairy, freely branching at base. Leaves numerous, small, rough, opposite, lobed and toothed, hairy. Flowers blue or purplish, small, in dense spikes, almost hidden by the conspicuous bracts. Seeds result from pod splitting into 4 segments, each with 2 flattened sides and 1 rounded side, oblong, about 1/8 inch (3 mm) long, dark brown. Found in barnyards, lawns, pastures, meadows, and waste places. Rarely found in cultivated fields.
147
VERVAIN FAMILY, Verbenaceae
BLUE VERVAIN, Verbena hasfafa L. 1, leaf from middle of stem; 2, upper part of stem; 3, seed; 4, distribution. Perennial, reproducing by seed and short rhizomes. Stems erect, branched above, 2 to 4 feet (0.6 to 1.2 m) tall, somewhat rough. Leaves opposite, simple, toothed, lanceolate, with short petioles. Flowers small, blue, in short compact spikes. Seeds borne 4 in a pod; brown, oblong. Found mostly in pastures, roadsides, fence rows, and waste places, especially on low ground.
HOARY VERVAIN, Verbena sfricta Vent. 4, distribution; 5, upper part of stem in flower; 6, single flower; 7, pod enclosed by calyx; 8, seed. Similar to the above species but hairy all over. Leaves shorter, less pointed, without petioles. Flowers purplish, borne in long spikes. Usually found in upland pastures.
WHITE VERVAIN, Verbena urticifolia L. 9, distribution. Similar to blue ver- bain. Leaves ovate with scattered hairs. Flowers white on long slender spikes. Frequently found in or near wooded areas, pastures, and waste areas.
148
MINT FAMILY, Labiatae
DRAGONHEAD, Dracocepho/um parv/florum Nutt. 1, upper part of plant; 2, lower part of plant; 3, flowers. Annual or biennial, reproducing by seeds. Stems square, erect, 8 to 40 inches (20 to 100 cm) tall, either single or in clumps, and either simple or branched. Leaves opposite, narrow to somewhat oval-shaped, pinnately veined, with petioles, and with small sharp teeth on margins. Flowers clustered in globelike spikes subtended by sharp- toothed overlapping bracts. Petals light blue to violet, tubular, strongly 2- lipped with notch in upper lip and 3 lobes in lower lip. Fruits are 4 nutlets that separate when ripe; each nutlet is about 1/16 inch (1.5 mm) long, brownish-black and granular in appearance, with a crescent-shaped scar on angular side at base. Found in meadows, fields, garden clearings, new woods, and wasteland, often on rocky or gravelly limy soils.
149
MINT FAMILY, Labiatae
GROUND IVY, G/echoma hederacea L. 1, vegetative growth of stems and leaves; 2, flower section; 3, seeds. Perennial, with shallow roots, spreading by seeds and by creeping stems. Stems 15 to 30 inches (38 to 75 cm) long, prostrate, 4-sided, rooting at the nodes. Leaves almost round or kidney- shaped, with round-toothed edges, bright green, 1/2 to ll/2 inches (13 to 39 mm) in diameter, hairy, opposite, borne on long petioles, with a minty odor. Flowers small, bluish-purple, funnel-shaped but 2-lipped, borne in small clusters in the axils of the leaves. Seeds rough, dark brown, in groups of 4, flat on 2 sides and round on the third side, with a white scar at tip. Found in lawns, orchards, and waste places, especially shady areas with damp, rich soil. Also commonly known as creeping charlie.
150
MINT FAMILY, Labiatae
HENBIT, Lomium amp/ex/cou/e L. 1, entire plant; 2, flower; 3, seeds with part of calyx; 4, single seed. Annual, reproducing by seeds. Roots fibrous. Stems 4 to 16 inches (10 to 40 cm) tall, slender, smooth, 4-angled, with many branches that are more or less prostrate with ascending tips; frequently rooting where the nodes are in contact with ground. Leaves opposite, hairy, with rounded teeth. Lower leaves with petioles; the upper without petioles and clasping stem. Flowers in whorls in the axils of upper leaves, tubular but 2-lipped, about y% inch (9 mm) long, pinkish to purple, surrounded at base by calyx with 5 sharp teeth. Seeds borne 4 in a pod, sharply 3-angled, grayish-brown, about 1/16 inch (1.5 mm) long. Found in gardens, cultivated fields, and waste places, especially those with rich soil.
151
MINT FAMILY, Labiatae
MOTHERWORT, Leonurus cardiaca L. 1, upper portion of plant; 2, base of plant; 3, seed. Perennial, reproducing by seed and rhizomes. Roots exten- sive but shallow. Stems 2 to 5 feet (0.6 to 1.5 m) tall, 4-sided, erect, coarse, stiff, nearly smooth, branched near top. Leaves opposite; lower leaves toothed and 3-lobed; upper leaves narrow, notched. Flowers in tight clus- ters in axils of leaves, spiny and burlike when dry, petals formed into 2- lipped purple or white tube. Seeds borne 4 in a pod, oval, 3-sided, dark red to brown. Found mostly in waste places and noncultivated fields. Usually not troublesome except in low, rich soils.
152
MINT FAMILY, Labiatae
FIELD MINT, Mentha arvensis 1. 1, upper part of plant; 2, lower part of plant; 3, seed. Perennial, reproducing by seeds and rhizomes, aromatic. Stems square, usually branching, up to 2^ feet (75 cm) tall; barbed hairs on angles and sometimes on sides of stem. Leaves opposite, with petioles, strongly scented, pinnately veined, narrow to oval, with small teeth on margins and with minute glandular hairs on leaf surface. Flowers clustered in axils of upper leaves. Petals pink, lavender, or occasionally white; y% to y+ inch (3 to 6 mm) long, with 5 teeth and prominent nerves in the tube. Fruits are nutlets less than 1/16 inch (1.5 mm) long, smooth, light brown, each with an irregular dark line on the convex side. Found in meadows, in pastures, along ditches and shores, mostly on damp, open gravel.
153
MINT FAMILY, Labiatae
CATNIP, Nepeta cataria L 1, lower portion of plant; 2, upper part of plant in bloom; 3, seeds; 4, single flower. Perennial, reproducing by seed and from short rhizomes. Stems covered with fine short hair, erect, 2 to 3 feet (60 to 90 cm) tall, 4-sided, light green. Leaves opposite, pointed, heart- shaped with saw-toothed margins, green above, light green or whitish un- derneath, covered with fine hairs, with a characteristic minty odor. Flowers in dense clusters at ends of stems and branches, petals formed into a 2- lipped tube, pale purple, dark-dotted. Seeds borne 4 in a pod, oval, with 2 flattened sides and 1 rounded side, dark reddish-brown with 2 white spots at one end. Found in waste places, in yards, and along roadsides. Sometimes cultivated.
154
MINT FAMILY, Labiatae
HEAL-ALL, Prunella vulgaris 1. 1, plant in flower; 2, prostrate stem; 3, single flower; 4, seed. Perennial, reproducing by seed and by runners which root freely at the nodes. Stems 2 to 24 inches (5 to 60 cm) long, erect or pros- trate, branched, 4-sided, hairy when young, becoming smooth when older. Leaves oval, opposite, margins smooth or slightly notched, 1 to 4 inches (2.5 to 10 cm) long, hairy to smooth, with moderately long petioles. Flowers 2-Iipped tubes, violet or purple, borne in the axils of short bracts in a dense spike. Seeds borne 4 in a pod, each somewhat pear-shaped, slightly flattened on 2 sides, brown with dark lines, slightly rough. Found in lawns, fields, and waste places where there is considerable moisture.
155
MINT FAMILY, Labiatae
AMERICAN GERMANDER, Teucrium canadense 1. 1, upper part of plant; 2, portion of stem and leaves; 3, diagram of growth habit showing underground rhizome; 4, flower. Perennial, reproducing from long slender rhizomes. Stems square, pubescent, especially on the angles, 1 to 2 feet (30 to 60 cm) tall, often branching. Leaves opposite, ovate, acute or acuminate at tip, rounded at base, finely toothed, pubescent, and short-petioled. Inflorescence spike- like, with several pink-purple, irregularly lobed flowers at each node. Seeds borne 4 in a nutlet, light to dark brown, surface covered with network of veins or ridges. Found on moist soils mostly in cultivated crops.
156
NIGHTSHADE FAMILY, So/anaceae
JIMSONWEED, Dafuro stramonium L. 1, upper portion of plant; 2, flower; 3, seed pod; 4, seed. Annual, reproducing by seed. Roots thick, shallow, ex- tensively branched. Stems smooth, thick, erect, branching widely in upper part, 2 to 4 feet (0.6 to 1.2 m) tall. Leaves alternate, large, coarse, smooth, ovate, with irregularly toothed edges and a distinctive rank odor. Flowers large, funnel-shaped, white to pinkish, 2 to 5 inches (5 to 12.5 cm) long, borne singly on short stalks in the axils of the branches. Seed pod about 1 inch (2.5 cm) in diameter, egg-shaped, covered with short, sharp spines. Seed dark brown to black, kidney-shaped, flattened, surface irregular and pitted. Found in cultivated crops on rich land and especially in old feedlots. This plant contains poisonous materials.
157
NIGHTSHADE FAMILY, Solanaceae
CLAMMY GROUNDCHERRY, Physalis heterophylla Nees. 1, lower portion of plant; 2, upper portion of plant; 3, flower; 4, inflated calyx surrounding fruit; 5, seed. Perennial, reproducing by seeds and rootstocks. Stems hairy, erect at first but later branching to form a dense bush 1 to 3 feet (30 to 90 cm) tall. Leaves alternate, 2 to 3 inches (5 to 7.5 cm) long, oval with round-toothed edges, hairy. Flowers bell-shaped, 5-lobed, drooping, green- ish-yellow with brown or purplish center, about z/$ inch (19 mm) in diame- ter. Fruit round, berrylike, yellow, enclosed by inflated papery calyx. Seeds numerous, small, yellow, flattened, oval, about 1/16 inch (1.5 mm) in diame- ter. Found in cultivated fields, gardens, pastures, and meadows. Several similar species differing chiefly in growth habit, growth period, and degree of hairiness are found in the region.
158
NIGHTSHADE FAMILY, So/anaceae
SMOOTH GROUNDCHERRY, Pfiyso//s subg/afarofa Mack, and Bush. 1, entire plant with perennial horizontal rootstock and young plant; 2, portion of stem with leaves and flowers; 3, fruit. Perennial, reproducing by seeds and rootstocks. Stems erect but may be widely branching; hairy on young growth, smooth later; 1 to 3 feet (30 to 90 cm) tall. Leaves alternate, thin, ovate to lanceolate, entire to slightly toothed, long-petioled, smooth or slightly hairy. Flowers bell-like, yellow to yellowish-green with purple cen- ter, calyx sharply 5-toothed. Fruit round, berrylike, reddish to purplish, en- closed by inflated papery calyx. Seeds numerous, small, yellowish-brown, flattened, and wrinkled. Found in cultivated fields, gardens, and nonculti- vated areas.
159
NIGHTSHADE FAMILY, So/anoceae
HORSENETTLE, So/anum caro/inense L. 1, top of plant; 2, lower portion of plant; 3, stem with mature berries; 4, mature and immature berries; 5, flower; 6, top and edge view of seeds; 7, distribution. Perennial, reproduc- ing by seeds from creeping rootstocks. Stems simple or branched, hairy and prickly, 1 to 4 feet (0.3 to 1.2 m) tall. Leaves alternate, oblong, wavy-edged or lobed, with yellow prickles on petioles, midrib, and veins. Flowers white or bluish, 5-lobed, about 1 inch (2.5 cm) across, borne in clusters. Berries yellow, juicy, % to */% inch (9 to 15 mm) in diameter, containing numerous seeds, borne in clusters, smooth at first but becoming wrinkled late in the season. Seeds about 1/16 inch (1.5 mm) in diameter, round, flattened, yel- lowish. Found in fields, gardens, and waste areas, especially those with sandy soil.
SILVERLEAF NIGHTSHADE, So/anum elaeagnifolium Cav. 8, distribution. Similar to the above species. Leaves somewhat narrower, less prickly, and with a silvery appearance due to numerous fine hairs.
160
NIGHTSHADE FAMILY, Solanaceae
BITTER NIGHTSHADE, So/onum dulcamara L 1, fruiting branch; 2, cluster of flowers. Perennial, reproducing by seeds and by rooting of prostrate stems. Stems slender, vinelike, somewhat woody, 2 to 10 feet (0.6 to 3 m) long, twining on low vegetation or prostrate on ground. Leaves dark green, 2 to 5 inches (5 to 12.5 cm) long, variously lobed at base, alternate, petioled, with a disagreeable odor. Flowers purplish or white, 5-lobed, about ] 2 inch (1.3 cm) across, in loose clusters from the axils of the leaves. Berries oval, about y% inch (9 mm) long, light green turning bright red at maturity, containing many seeds. Seeds about 1/16 inch (1.5 mm) in diameter, round, flattened, light yellow. Found in thickets, fence rows, edges of clearings, usually in moist soil. A mildly poisonous plant. Should not be confused with bitter- sweet, which is woody and has orange fruits and a more viny growth.
161
NIGHTSHADE FAMILY, Solanaceae
EASTERN BLACK NIGHTSHADE, Solanum pfycanfhum Dun. 1, entire plant; 2, berry; 3, flower. Annual, reproducing by seed. Stem erect or spreading, becoming widely branched, 1 to 2 feet (30 to 60 cm) tall. Leaves ovate, 1 to 3 inches (2.5 to 7.5 cm) long, alternate, edges wavy. Flowers white, 5-lobed, about Y+ inch (6 mm) across, in small clusters. Berries green, turning black at maturity, smooth, about Y% inch (9 mm) in diameter, containing numerous seeds. Seeds flattened, about 1/16 inch (1.5 mm) in diameter, dull, pitted, yellow to dark brown. Found in cultivated fields, garden areas, and waste places. Unripe berries may be poisonous. This species was formerly known as black nightshade (Solanum nigrum L.). According to recent taxonomic studies, S. nigrum occurs in the U.S. only in the western states. S. ptyconfhum, which differs slightly from S. nigrum, is the species found east of the Rocky Mountains.
162
NIGHTSHADE FAMILY, So/anaceae
BUFFALOBUR, So/anum rosfra/um Dunal. 1, entire plant; 2, 3, seed pods; 4, seed; 5, flower. Annual, reproducing by seeds. Stem erect, branched in upper portion, 6 to 24 inches (15 to 60 cm) tall, hairy, densely covered with long stiff yellow prickles. Leaves 2 to 5 inches (5 to 12.5 cm) long, alternate, petioled, densely hairy, cut into deep rounded lobes; veins, midribs, and petioles very prickly. Flowers yellow with 5 lobes, 1 to l!/2 inches (2.5 to 3.8 cm) across, in clusters from stalks on upper branches. Fruit a berry enclosed in a rough-spiny bur. Seeds numerous, round, flattened, dull brown- ish-black. Found in fields, overgrazed pastures, yards, roadsides, and waste areas.
163
FIGWORT FAMILY, Scrophu/ar/aceae
YELLOW TOADFLAX, Linaria vulgaris Hill. 1, entire plant; 2, single flower. Perennial, reproducing by seeds and rootstocks. Stems leafy, with very few branches, smooth, 1 to 2 feet (30 to 60 cm) tall, often in clumps, pale green. Leaves mostly alternate, narrow, smooth, pale green. Flowers snapdragon- like, about 1 inch (2.5 cm) long, bright yellow with deep orange center, in racemes at top of stems. Seeds dark brown or black, round, flattened, warty, numerous, in a 2-celled pod. Found in circular patches in native pastures, roadsides, and waste places, and along railroads. Sometimes cultivated in gardens, from which it escapes. Rather persistent under cultivation.
164
FIGWORT FAMILY, Scrop/iu/ar/aceae
COMMON MULLEIN, Verbascum thapsus L. 1, lower portion of plant; 2, up- per portion of plant; 3, seed; 4, distribution. Biennial, reproducing by seed. Stems 3 to 6 feet (0.9 to 1.8 m) tall, stout, usually unbranched, covered with woolly hairs. Leaves at base of plant a rosette, each leaf 6 to 18 inches (15 to 45 cm) long, oblong, densely woolly; upper leaves woolly, smaller, and more pointed, the bases attached to stem and continuing down it to the next leaf. Flowers 5-lobed, sulfur-yellow, about 1 inch (2.5 cm) in diameter, in dense spikes. Seeds about 1/32 inch (0.8 mm) across, angular, brown, roughened, numerous, contained in an egg-shaped pod. Found in pastures, fence rows, and roadsides.
MOTH MULLEIN, Verbcrscum blattaria L. 5, lower part of plant; 6, seed; 7, upper part of plant; 8, distribution. Similar in some respects to the above species. Stem slender and smooth, 2 to 4 feet (0.6 to 1.2 m) tall. Leaves on lower part of stem a rosette, dark green, smooth or only slightly hairy, ob- long, toothed or lobed; upper leaves alternate, sharp-pointed. Flowers yel- lowish or whitish, on a long, loose spike.
165
FIGWORT FAMILY, Scrop/iu/ar/aceae
PURSLANE SPEEDWELL, Veronica peregrine 1. 1, entire plant; 2, leaf from lower stem; 3, leaf from upper stem; 4, seed; 5, distribution. Annual or winter annual, reproducing by seeds. Root system fibrous. Stems numerous, erect, branching from base, smooth, seldom over 8 inches (20 cm) tall. Leaves simple, narrow; those at base opposite and slightly toothed, those on upper stem alternate, with smooth margins. Flowers small, white, in axils of upper leaves. Seed pod flattened, heart-shaped, about Y& inch (3 mm) wide. Seeds a long oval, flattened, translucent, glossy, orange-yellow, with a scar on one side. Found in lawns, waste places, fertile fields, and gardens.
THYMELEAF SPEEDWELL, Veronica serpyllifolia L. 6, distribution. Similar to the above species. Stems almost entirely creeping. Leaves opposite, ovate. Flowers blue. Found in lawns in some areas. A number of other similar species are found locally in the region.
166
BIGNONIA FAMILY, B.gnon/aceoe
TRUMPETCREEPER, Camps;s rod/cons (L.) Seem. 1, root; 2, seed pods; 3, upper part of plant with flowers; 4, lengthwise and crosswise section of seed pod. Perennial, reproducing by seeds and vigorous running roots. Stems smooth, woody, vining, 20 to 40 feet (6 to 12 m) long if undisturbed. In cultivated fields plant can maintain itself and produce stems 2 to 10 feet (0.6 to 3 m) long. Leaves opposite, 8 to 15 inches (20 to 37.5 cm) long, petioled, pinnately compound, with 7 to 11 leaflets. Flowers showy, orange and scarlet, 2^2 inches (6.3 cm) long, funnel-shaped, in short-stemmed clus- ters. Seed pod 4 to 6 inches (10 to 15 cm) long, rather cigar-shaped, smooth, ridged at the edges of the two lengthwise halves of the pod. Seeds broadly winged, in several rows on inside of pod. Found in fields, fence rows, yards. Originally cultivated as an ornamental, but has become an aggressive, widely distributed weed.
167
MARTYNIA FAMILY, Martyniaceae
DEVILSCLAW, Proboscidea louisianica (Mill.) Thell. 1, upper part of plant showing leaves and flowers; 2, seed pod. Annual, reproducing by seeds. Often possessing a pronounced odor. Stems thick, soft, widely branching, producing a bushy plant up to 3 feet (0.9 m) high and 4 feet (1.2 m) across. Leaves opposite, or the upper ones alternate, simple, rounded or kidney- shaped, up to 12 inches (30 cm) across in well-developed plants, densely covered with glandular hairs giving the plant a "clammy" feel. Flowers dull white or yellow, with purplish spots, petals united into an irregular tube, 1 to 2 inches (2.5-5 cm) across. Seed pod woody at maturity, con- sisting of a rough-surfaced body about 2 inches (5 cm) long, with 2 up- curved spines, 3 to 5 inches (7.5-12 cm) long, projecting from one end. Seeds numerous, egg-shaped, l/\ inch (6 mm) long, dull gray or silvery gray and conspicuously wrinkled. Found in dry open prairies and pastures; more abundant in western part of the range. Sometimes cultivated as an ornamen- tal. Seldom an aggressive weed, but the seed pods show up in baled hay.
168
PLANTAIN FAMILY, Plantaginaceae
BR ACTED PLANTAIN, P/onfogo or/stofo Michx. 1, entire plant; 2, single flower with bract; 3, two views of seed. Annual or winter annual, repro- ducing by seeds. Stems erect, simple, leafless, hairy, 6 to 18 inches (15 to 45 cm) tall, terminating in flower spike. Leaves at ground level in basal rosette, long, loosely hairy, becoming smooth. Flowers numerous, petals inconspicu- ous, in axils of long bracts, in spikes at top of stem. Seed pods 2-seeded. Seeds boat-shaped with groove across oval side of seed, 2 white scars in indentation on inner surface, rough-surfaced, dull light brown in color, about 14 mch (3 mm) long. Found in meadows, pastures, and waste places, usually on rather dry soil of low fertility.
169
PLANTAIN FAMILY, Plantaginaceae
BUCKHORN PLANTAIN, Plantago lanceolata L. 1, entire plant in bloom; 2, two views of seed. Perennial, reproducing by seed. Stems erect, leafless, 4 to 12 inches (10 to 30 cm) long, terminating with flower spike. Leaves at ground level in a basal rosette, hairy, 2 to 10 inches (5 to 25 cm) long, 1/4 to 1 inch (0.6 to 2.5 cm) wide, with 3 to 5 prominent veins running length- wise. Flowers numerous, petals inconspicuous, in short cylindrical spikes at ends of stems. Seed pods 2-seeded, splitting across the middle. Seeds small, brown, shiny, smooth, boat-shaped, with an indentation in the middle of one side, sticky when damp. Found in lawns, meadows, pastures, and waste places. The seeds are difficult to separate from those of small-seeded grasses and legumes.
170
PLANTAIN FAMILY, Plantaginaceae
BLACKSEED PLANTAIN, Plantago rugelii Dene. 1, whole plant; 2, mature seed pod; 3, seeds. Perennial, reproducing by seeds. Roots mostly fibrous. Stems erect, leafless, 6 to 12 inches (15 to 30 cm) tall, terminating in the flower spike. Leaves simple, broad, egg-shaped, usually wavy-edged, veins conspicuous, base of petiole purplish. Flowers numerous, petals inconspicu- ous, in spikes on the ends of the stems. Seed pods nearly cylindrical, about 3/16 inch (4.5 mm) long, splitting across the lower half, containing numer- ous seeds. Seeds dark brown or black, angular, with a scar near center on one side. Found on damp, rich soils, especially where shaded. Common in lawns.
BROADLEAF PLANTAIN, Plantago major I. 4, mature seed pod; 5, seeds. Similar to the above species. Stems shorter. Leaves smaller and without purplish coloration at base of petiole. Seed pod nearly spherical, splitting across upper half. Seeds light to dark brown, covered with fine ridges.
171
PLANTAIN FAMILY, Plantaginaceae
WOOLLY PLANTAIN, Plantago purshii Roem. and Schult. 1, entire plant with taproot; 2, lower half of seed pod; 3, upper half of seed pod; 4, seed. An- nual, reproducing by seeds. Stems erect, without leaves, 3 to 10 inches (7.5 to 25 cm) tall, woolly-haired. Leaves narrow, ascending, linear, narrowing to a petiole at the base, 3-nerved, 1 to 5 inches (2.5 to 12.5 cm) long, covered with silky, white hairs. Flowers numerous, petals inconspicuous, surrounded by bracts, in dense cylindrical spikes. Seed pod containing 2 seeds, splitting across middle. Seeds reddish-brown, with convex side and hollow inner face giving a boat-shaped appearance. Found in dry overgrazed pastures and wasteland.
172
MADDER FAMILY, Rubiaceae
POOR JOE, Diodia feres Walt. 1, plant; 2, section of stem showing flower, leaves, and young pods; 3, seed. Annual. Roots shallow, slender, taprooted. Stems hairy, branching, moderately erect, 8 to 24 inches (20 to 60 cm) long. Leaves narrow, tapering to long point, edges smooth, opposite, without petioles; fastened in pairs directly to joints of stem, together with long bristles. Flowers small, whitish-pink to lavender, at base of leaves. Seed pods hairy, with 4 short, green calyx teeth at the top; splitting, when ripe, into 2 parts. Seeds hairy, oval, light brown, Vs inch (3 mm) long, inner surface indented with a forked groove. Found in abandoned fields and along roadsides. Also known as rough buttonweed.
173
MADDER FAMILY, Rubiaceae
CATCH WEED BEOSTRAW, Galium aparine L 1, lower section of plant; 2, upper portion of stems; 3, flower; 4, seed pod; 5, seed. Annual. Roots branching, short, shallow. Stems 1 to 3 feet (0.3 to 0.9 m) long, weak, sprawl- ing, 4-sided with each edge bearing a row of downward-pointing stiff bris- tles. Leaves narrow, rough, bristle-pointed, 6 to 8 borne in a circle at each joint of stem. Flowers very small, white, with 4 petals, borne on slender branches attached at the joints of the stems. Seed pod in 2 nearly spherical halves, covered with stiff bristles. Seed ball-shaped with deep pit in one side and short, sharp spines, V6 inch (3 mm) long, on outer surface. Found on moist land in meadows, pastures, woodlands, and fence rows.
174
TEASEL FAMILY, D/psococeae
TEASEL, Dipsacus sylvestris Huds. 1, portion of stem with flowers; 2, seed. Biennial, reproducing by seed. Stem the second year, coarse, upright, prickly, 2 to 5 feet (0.6 to 1.5 m) tall. Leaves lance-oblong, toothed, prickly on mar- gin; a rosette the first year, opposite the second year. Flowers lilac or white, with 4 petals, in dense ovoid heads with numerous slender bracts that be- come stiff-hooked prickles at maturity. Seeds about 3/16 inch (4.5 mm) long, 4-angled, ridged, hairy, grayish-brown. Found in roadsides, pastures, and old fields.
175
GOURD FAMILY, Cucurb/faceae
BUFFALO GOURD, Cucurb/fa foetidissima H.B.K. 1, upper part of plant show- ing fruit; 2, root system. Perennial, reproducing by seed and roots. Tap- root yellow inside, carrotlike, very thick and fleshy, often more than 6 inches (15 cm) across, sometimes over 5 feet (1.5 m) long. Stems trailing and rooting at joints, 15 to 30 feet (4.5 to 9 m) long, stout, angled, ridged, rough-hairy, many-branched. Leaves thick, simple, sharply toothed, 4 inches to 1 foot (10 to 30 cm) long, ovate, long-pointed, rough above, gray-hairy beneath, with strong, rough-hairy petioles. Flowers bright yellow, deeply 5-lobed, 3 to 4 inches (7.5 to 10 cm) long and nearly as broad, in leaf axils. Male and female flowers separate but on the same plant. Fruit globular, 3 inches (7.5 cm) long, with yellow and green markings and a hard, smooth rind. Seeds numerous, oval, flattened, similar to pumpkin seed but about half as large, light straw-colored. Found on dry, sandy soil in fields and waste places, and along fence rows. The entire plant has an offensive odor, especially when bruised.
176
GOURD FAMILY, Cucurb/faceoe
WILD CUCUMBER, Echinocystis /obafcr (Michx.) T. and G. 1, plant, showing leaves and flower clusters; 2, flower; 3, fruit and seed. Annual, reproducing by seed. Stems vinelike, branched, nearly smooth, except that they are grooved and are sometimes hairy at nodes or joints. Vine may extend 15 to 25 feet (4.5 to 7.5 m). Leaves alternate, usually with 5 to 7 sharply pointed lobes, similar in appearance to a cultivated-cucumber leaf. Flowers light yellowish-white, in clusters. Male and female flowers separate but often borne together. Seed pod a pulpy fruit covered with sharp spines, contain- ing 4 seeds. Seeds brown or black, spindle-shaped, flattened, about ^ inch (1.9 cm) long. Found mainly in some river-bottom areas, covering corn and soybeans and making harvest difficult. Occasionally found in fence rows and thickets, especially in low areas.
177
GOURD FAMILY, Cucurb/faceae
BUR CUCUMBER, S/cyos angulatus L. 1, portion of plant showing stem, leaves, tendrils, and flowers; 2, cluster of pods containing seeds. Annual, reproducing by seeds. Stem forms a creeping vine several yards or meters long, with numerous branched, climbing tendrils. Leaves alternate, more or less circular in outline but with 3 to 5 shallow lobes, margins finely toothed. Well-developed leaves 4 to 8 inches (10 to 20 cm) wide. Flowers unisexual; some are male, producing only pollen; others are female and produce seeds; both are whitish, with 5 united petals about 1/2 inch (1.3 cm) across. Seeds borne singly in a flat, egg-shaped pod, l/2 to 34 inch (1.3 to 1.9 cm) long and !/4 inch (0.6 cm) thick, covered with barbed, prickly bristles. Found in wooded areas along stream banks and roadsides and in other shady, damp places. Fast-growing in early summer and very con- spicuous, but not usually an aggressive weed in cultivated fields.
178
BLUEBELL FAMILY, Camponu/aceae
CREEPING BELLFLOWER, Campanula rapunculoides 1. 1, upper part of plant; 2, lower part of plant; 3, seedling showing basal leaves. Perennial, spreading by short stolons, root fragments, and seed. Roots tuberlike, both fibrous and fleshy. Stems erect, 1 to 3 feet (30 to 90 cm) tall, smooth, leafy, with milky juice. Basal leaves long-petioled, heart-shaped; upper leaves short - petioled or sessile. Flowers numerous, nodding, bell-shaped, about % inch (1.9 cm) long with 5 teeth, purple, scattered along upper portion of the stem. Seeds shiny, oval, straw-colored, rounded on one side, ridged on the other, 1 millimeter long. Found in dense patches on roadsides, in fence rows, lawns, gardens, and waste places. Often spreads from areas where grown as an ornamental.
179
COMPOSITE FAMILY, Compos/foe
COMMON YARROW, Ach///ea millefolium L 1, plant in flower; 2, disk flower; 3, ray flower; 4, flower head; 5, root system. Perennial, reproducing by seed and underground rhizomes. Stems 1 to 2 feet (30 to 60 cm) tall, branching at top, covered with grayish-green hairs. Each crown may pro- duce several stems. Leaves soft, covered with hairs, finely divided, fernlike. Basal leaves longer than those attached to stems. Flower heads small with 5 to 10 white ray flowers and yellow disk flowers, in flat-topped clusters at top of branches. Pink-flowered forms occur rarely. Seed tiny, flat, oblong, white or gray. Found in meadows, pastures, and waste places; not common in cultivated fields. Persists mostly on thin soil where conditions are un- favorable for the growth of more desirable plants. The plant has an offen- sive odor and bitter taste.
180
COMPOSITE FAMILY, Compos/foe
COMMON RAGWEED, Ambrosia artemisiifolia L. 1, plant; 2, seed; 3, distri- bution. Annual, shallow-rooted. Stems rough, hairy, erect, branched, 1 to 4 feet (0.3 to 1.2 m) tall. Leaves nearly smooth, deeply cut into a number of lobes, mostly alternate. Flowers of two kinds; male pollen-producing flowers in small inverted clusters at tips of branches; seed-producing flowers fewer, borne at the bases of leaves and in forks of upper branches. Seed about V6 inch (3 mm) long, enclosed in woody hull, light brown, top-shaped, pointed, bearing several longitudinal ridges ending in short, spiny projections. Found in old pastures, wasteland, roadsides, stubblefields, and cultivated land. Pro- duces pollen abundantly and is a hazard to hay fever sufferers.
LANCELEAF RAGWEED, Ambrosia b/denfafa Michx. 4, portion of stem show- ing toothed leaves and flowers; 5, seed; 6, distribution. Similar to the above. Leaves abundant, lanceolate, partly clasping the stem, hairy, bearing 1, 2, or more large sharp teeth on each side of a broad base. Seeds 4-angled with 4 sharp spines.
181
COMPOSITE FAMILY, Compos/foe
WESTERN RAGWEED, Ambrosia psilostachya DC. 1, male flowers on spike; 2, female flowers; 3, seed; 4, entire plant. Perennial, reproducing by root- stocks and seeds. Stem erect, normally less than 20 inches (50 cm) tall, hairy, bushy, branched above, often growing in dense patches. Leaves with short petioles, alternate or opposite, ovate-lanceolate, with very deep lobes, sometimes compound, rough. Flowers of two kinds. Male flowers in clusters on ends of stems and branches; female flowers few, without petals, in axils of upper leaves. Seed about Vg inch (3 mm) long, with a woody hull that has a pointed tip surrounded by short spines. Found in prairies, plains, and uncultivated areas. The pollen is a hazard to hay fever sufferers. Also known as perennial ragweed.
182
COMPOSITE FAMILY, Compos/foe
GIANT RAGWEED, Ambrosia trifida 1. 1, portion of stem showing leaves and flowers; 2, seed. Annual, reproducing by seed. Stems coarse, rough, reach- ing a height of 12 to 18 feet (3.6 to 5.4 m) on fertile, moist soils; 4 to 8 feet (1.2 to 2.4 m) in less fertile, drier areas. Leaves distributed in pairs at nodes; large, slightly hairy, entire, with 3 or, occasionally, 5 lobes. Flowers separated, with male flowers abundant in clusters on tips of branches and stems. Female flowers sparse, without petals, in axils of upper leaves. Seeds l/4 to l/2 inch (0.6 to 1.3 cm) long, with a woody hull bearing blunt ridges that end in several short, thick spines at the tip. Found mostly on fertile, moist soils, especially bottomlands. May be serious in corn, soybeans, and other cultivated crops. The abundant pollen is a hazard to hay fever suf- ferers. Also known as horseweed.
183
COMPOSITE FAMILY, Compos/foe
SKELETONLEAF BURSAGE, Ambrosia tomentosa Nutt. 1, top of plant; 2, root system and young plant; 3, male flowers; 4, seed. Perennial, reproducing by seeds and deep creeping rhizomes. Stems bushy, branched, usually 1 to 2 feet (30 to 60 cm) tall. Leaves alternate, divided into narrow lobes, hairy on underside, 2 to 5 inches (5 to 12.5 cm) long. Flowers small, male and female borne separately but on the same plant. Male flowers in small droop- ing heads along tips of branches; female in axils of upper leaves. Burs sur- rounding female flowers bear 1 to 3 seeds, have sharp spines when mature. Found in moist cultivated fields, waste places, pastures, and irrigated areas, especially if poorly drained.
WOOLLYLEAF BURSAGE, Ambrosia gray/ (A..Nels.) Shinners. A species closely related to the above. Leaves covered with short woolly hairs on both surfaces, terminal lobe quite large. Bur has curved rather than straight spines.
184
COMPOSITE FAMILY, Compos/toe
PLANTAINLEAF PUSSYTOES, Antennaria planiaginifolia (L) Hook. 1, part of plant, showing rooting of creeping stem, and a vertical flowering shoot; 2, detail of staminate head; 3, female flower; 4, male flower. Perennial, reproducing by seeds and creeping stems; forms patches. Stems decumbent or creeping until flowering, when erect flowering stems 4 to 20 inches (10 to 50 cm) high are formed. Leaves at base alternate, petioled, simple, entire, strongly rounded at summit, tapering at base, with hoary upper surface and white-woolly under surface; stem leaves fastened directly to stem with no petiole, small, narrow, white-woolly. Flowers borne in small clustered heads, 3 to 30 heads on a stem. Male and female flowers on separate plants; plants bearing male flowers smaller. Seeds about 1/32 inch (0.8 mm) long, with circle of long hairs attached at top. Found in run-down pastures, meadows, and waste places; one of the typical "poverty weeds."
185
COMPOSITE FAMILY, Compos/fae
MAYWEED, Anthemis cofu/o L. 1, portion of plant in flower; 2, seedling; 3, seed. Annual or winter annual with short, thick taproot, reproducing only by seed. Stems erect, slender, much branched, nearly smooth, 12 to 18 inches (30 to 45 cm) tall. Leaves finely divided, with a strong disagreeable odor. Flower heads resembling those of a daisy, 1/2 to 1 inch (1.3 to 2.5 cm) across, borne singly at ends of branches. Ray flowers white, surrounding a mass of numerous small yellow disk flowers. Seeds brown, oblong, 10- ribbed, with a rough seed coat. Found most commonly in abandoned fields, barnyards, and waste places. Also known as dog fennel.
186
COMPOSITE FAMILY, Compos/foe
COMMON BURDOCK, Arcf/um minus (Hill) Bernh. 1, root; 2, crown and first- year leaf; 3, upper part of second-year growth; 4, seed. Biennial, reproduc- ing by seed only. Taproot large, fleshy, living over one winter. Stem a crown close to the soil surface the first year; the second year much branched, 3 to 5 feet (0.9 to 1.5 m) tall, hairy, and somewhat grooved or angular. Leaves large, with heart-shaped base, covered with hairs; the first year forming a dense rosette, the second year distributed alternately on stem with the larger leaves near the base. Flower heads made up of numer- ous small red-violet disk flowers surrounded by numerous hooked bracts which later form a bur about 1/2 inch (1-3 cm) in diameter. Seeds rather rough, mottled dark gray, about V4 inch (6 mm) long. Found in waste places where soil is productive and not disturbed. Not commonly found in culti- vated areas.
GREAT BURDOCK, Arcfium lappa I. Similar in appearance to above but larger in all respects. Much less common in our region.
187
COMPOSITE FAMILY, Compositae
ABSINTH WORMWOOD, Artemisia absinthium 1. 1, lower part of leafy stem; 2, upper part of stem with flowers; 3, flower head; 4, seed. Perennial, fra- grant herb or shrub, reproducing by seed and by branching rootstocks. Stems up to about 3 feet (90 cm) tall, clumped, often woody at base and hoary with soft, short gray hairs. Leaves alternate, lower leaves with long petioles, upper with short or no petioles. The blade, 2 to 5 inches (5 to 12.5 cm) long, is divided 2 or 3 times into leaflets which are covered with silky hairs. Flower heads yellowish, about }/& inch (3 mm) in diameter, hanging from leafy panicles. Fruits 1-seeded (achenes), smooth, about 1/16 inch (1.5 mm) long, flattened, narrow at base and rounded at tip, light gray- brown. Found in pastures, in waste places, and on roadsides, often on dry soils. If grazed by cattle, it is likely to flavor the milk.
188
COMPOSITE FAMILY, Compos/foe
ANNUAL WORMWOOD, Artemisia annua 1. 1, upper leaves and flowers; 2, lower leaves; 3, flowers. Annual, with taproot, reproducing by seed only. Stem smooth, erect, without hairs, slender, branched in upper portion, 1 to 4 feet (0.3 to 1.2 m) tall. Leaves on lower part of stem alternate, sweet- scented, divided into 3 sharply toothed lobes. Upper leaves much smaller. Flower heads drooping, greenish, about 3/16 inch (4.5 mm) in diameter, composed of disk flowers without conspicuous petals, in loose panicles. Seeds about 1/16 inch (1.5 mm) long, angled, oval, light yellow. Found in sandy soils, especially roadsides, wasteland, and fallow fields. Not a trouble- some weed. A number of similar species are found in the area.
189
COMPOSITE FAMILY, Compositae
HEATH ASTER, Aster er/co/c/es L. 1, root; 2, upper part of stem with flower; 3, seed. Perennial, growing from a slender rhizome. Stems erect, much branched, 1 to 3 feet (30 to 90 cm) tall, densely covered with hairs. Leaves small, 14 to l/2 inch (0.6 to 1.3 cm) long, rigid, linear, entire, numerous. Flowers l/\ to l/2 inch (0.6 to 1.3 cm) across when open, very numerous; 8 to 20 white ray flowers, yellow disk flowers. Seeds silky-hairy, 1/16 inch (1.5 mm) long, light brown. Found in pastures, meadows, and waste places, and on roadsides.
190
COMPOSITE FAMILY, Compos/foe
WHITE HEATH ASTER, Aster pilosus Willd. 1, basal part of plant; 2, flower- ing part of plant; 3, flower head; 4, seed with down attached. Perennial, with fibrous roots developing from the hard enlarged crown. Stems erect, 1 to 4 feet (0.3 to 1.2 m) tall, hard and tough, smooth or usually hairy or stiff-hairy, upper two-thirds much branched. Leaves at base narrowly lance- shaped, those on upper stem becoming very small and narrow, sharp-pointed, numerous. Flower heads Vz to */* inch (1.3 to 1.9 cm) in diameter, very numerous, mostly on upper sides of branches; white ray flowers surrounding the yellow disk flowers. Seeds small, oblong, light brown, with a tuft of silky hairs attached to the top. Found in pastures, meadows, roadsides, and waste places. Difficult to control in areas that cannot be cultivated. A number of species resembling the one described are found in the region.
191
COMPOSITE FAMILY, Compos/foe
SPANISHNEEDLES, Bidens bipinnata 1. 1, lower portion of plant; 2, upper portion of stem and flower heads; 3, mature flower; 4, seed. Annual, tap- rooted with numerous side branches. Stems erect, smooth, branching in upper portions. Leaves with petioles, divided several times into fine seg- ments; borne opposite at nodes of both stems and branches. Flower heads found singly at the ends of long, slender, nearly leafless branches, pale yellow ray flowers surrounding yellow disk flowers. Seeds about Yz inch (1.3 cm) long, narrow, sharp-pointed, brown to black, bearing 3 to 4 stiff spines covered with short, down-pointed bristles. Found in waste places and grain stubble fields.
192
COMPOSITE FAMILY, Compos/foe
DEVIL'S BEGGARTICKS, Bic/ens frondosa L. 1, entire plant; 2, seed; 3, flower head. Annual, reproducing by seed. Taproot much branched and shallow. Stems 3 to 5 feet (0.9 to 1.5 m) tall, slightly hairy and somewhat 4-sided. Most branching occurs near the top. Leaves opposite, 4-ranked, deeply pin- nately divided, and covered with minute hairs. Flower heads about 1 inch (2.5 cm) in diameter, surrounded by leafy bracts. Ray flowers around the outer edge yellow, disk flowers in the center brownish-yellow. Seed flat, brown, about Vi inch (1.3 cm) long with 2 barbed spines attached at upper end. Found frequently on rich, moist soil in low areas and waste places. Not found in cultivated fields. Several other species similar to this one are found in the region.
193
COMPOSITE FAMILY, Compos/fae
SPOTTED KNAPWEED, Cenfaurea macu/osa Lam. 1, portion of stem with leaves; 2, upper portion of stem with flower heads; 3, single flower head. Biennial, reproducing by seed. Stems erect or ascending, slender, 1 to 3 feet (30 to 90 cm) tall, hairy, branching. Leaves alternate, deeply divided into narrow segments, covered with short hairs, much reduced in size near top of the plant. Flower heads about 34 mcn d-9 cm) across, numerous, consisting only of pink to purple disk flowers; heads both terminal and in axils of upper leaves; each head surrounded by leaflike bracts with dark tips bearing a fringe of bristly hairs. Seed brownish, Vs inch (3 mm) long, notched on one side of base, with a short tuft of bristles on tip end. Found in pastures, fields, and roadsides, especially those with dry, gravelly, or sandy soils.
194
COMPOSITE FAMILY, Compos/fae
RUSSIAN KNAPWEED, Cenfaureo repens L. 1, stem and leaves; 2, new shoots; 3, seeds; 4, root. Perennial, reproducing by seeds and rhizomes. Roots deep and extensive with new shoots coming from various depths. Stems 2 to 3 feet (60 to 90 cm) tall, very hairy, ridged, tough, and woody, branches numerous, tipped with flower heads. Leaves hairy; lower ones deeply indented, resembling those of dandelions; upper leaves short, nar- row, and smooth-edged. Flower heads about 1 inch (2.5 cm) in diameter, composed of disk flowers only, which vary from white to light rose or light blue; each head surrounded by small, leafy bracts with smooth tips. Seed grayish or yellowish, smooth, about 1/8 inch (3 mm) long. Found in waste places or dry-land areas. Persists in cultivated fields when established.
195
COMPOSITE FAMILY, Compos/foe
OXEYE DAISY, Chrysanthemum leucanthemum L 1, entire plant showing flower heads; 2, ray flower or petal; 3, disk flower; 4, seed; 5, base of plant with numerous stems. Perennial, reproducing by rhizomes and seeds. Root system fibrous. Stems smooth, seldom branched, 1 to 3 feet (30 to 90 cm) high. Leaves alternate, simple, usually conspicuously lobed, especially near base of plant. Flower heads occurring singly at the ends of the stems, 1 to 2 inches (2.5 to 5 cm) in diameter. Ray flowers with white petals, disk flowers yellow. Seeds oval, usually curved, with one side straight and other convex, 1/16 inch (1.5 mm) long, with a prominent knoblike scar on top. Seeds black with 8 to 10 white or gray ridges or ribs. Found in old pastures, especially those low in fertility. Not a problem in cultivated fields.
196
COMPOSITE FAMILY, Compos/foe
CHICORY, C/c/ior/um intybus L. 1, root and crown; 2, upper portion of stems with flowers; 3, individual flower; 4, seed. Perennial, reproducing by seed. Taproot large, deep, and fleshy. Stem erect, branched, smooth, and with a milky sap. Leaves basal and along the stems. Basal leaves forming a rosette, 6 to 8 inches (15 to 20 cm) long, lobed, and resembling those of a dandelion. Leaves on stems smaller and either less lobed or entire. Flower heads of ray flowers only, bright blue, about 1 inch (2.5 cm) across, formed at ends of branches and in the axils of leaves of upper part of plant. Flowers are most conspicuous in the morning and close later in the day. Seeds dark brown, wedge-shaped, about ]/& inch (3 mm) long. Found along roadsides, in meadows and pastures. Seldom thrives in cultivated fields.
197
COMPOSITE FAMILY, Compos/foe
PLUMELESS THISTLE, Ccrrduus crccrnfho/des L. 1, upper portion of plant showing stem, leaves, and flower head; 2, seed. Biennial as a rule, but sometimes winter annual or annual. Stem erect, with spiny wings, 3 to 6 feet (0.9 to 1.8 m) tall, branched. Leaves deeply divided with alternate lobes. Rosette and lower stem leaves large, decreasing in size up the stem; hairs scattered on upper leaf surface, denser on lower surface, especially along midrib. Lobes on leaves and stem ending with white to yellowish spine. Flower heads globe-shaped, erect, single or loosely clustered, with spiny wings to base. Blooms reddish-purple, 1/2 to 1 inch (1.3 to 2.5 cm) in diame- ter, occurring from late May through early July. Seed maturing 5 to 12 days after full bloom; oblong; usually straight but sometimes slightly curved; straw-colored with brown striations to collar where pappus is at- tached. Pappus light-colored, not plumed. Found in pastures, meadows, and waste areas.
198
COMPOSITE FAMILY, Compos/foe
MUSK THISTLE, Carduus nutans L. 1, upper part of stem; 2, portion of stem showing leaf attachment; 3, seed. Biennial, large, coarse plant. Stem erect, spiny, with spiny wings, 3 to 6 feet (0.9 to 1.8 m) tall, lower portion branched. Stems and branches densely covered with short hairs. Leaves alternate, coarsely toothed, extending down the stem, very spiny. Flower heads as much as 2 inches (5 cm) across, on the ends of long, nearly naked stems, frequently drooping or nodding; flowers purple or lavender; spiny- tipped bracts surrounding the head. Seeds about 3/16 inch (4.5 mm) long, glossy yellowish-brown; pappus hairlike. Found in pastures, meadows, and waste areas. Considerable variation may be found because this species is a polymorphic complex, with numerous semidistinct phases.
199
COMPOSITE FAMILY, Composite
CANADA THISTLE, Cirsium arvense (L) Scop. 1, upper part of plant; 2, seed; 3, down with seed; 4, new shoot; 5, base of stem; 6, root system. Perennial, reproducing by seeds and horizontal roots. Roots extend several feet deep and some distance horizontally. Stems 2 to 5 feet (0.6 to 1.5 m) tall, grooved, branching only at top, slightly hairy when young, increasingly hairy as they mature. Leaves usually with crinkled edges and spiny margins, somewhat lobed, and smooth. Flower heads numerous, compact, about 34 inch (1.9 cm) or less in diameter, of lavender disk flowers only. Surrounded by bracts without spiny tips. Male and female flowers usually in separate heads and borne on different plants. Seed brown, smooth-coated, slightly tapered, about 3/16 inch (4.5 mm) long and with a ridge around the blossom end. Seed attached to tannish down that is easily broken off. Found in all crops; a persistent and troublesome weed. While this description fits most Canada thistles, there are a number of varieties differing slightly in appearance.
200
COMPOSITE FAMILY, Compos/fae
FLODMAN THISTLE, Cirsium floe/mam (Rydb.) Arthur. 1, lower part of leafy stem; 2, upper portion of stem; 3, seed. Perennial, deep-rooted, reproducing from creeping rhizomes and seed. Stem 2 to 3 feet (60 to 90 cm) tall, covered with white felt, sparingly branched. Leaves in a rosette, light green to grayish on upper side, white with matted hair on lower side. First rosette leaves may be entire; later rosette and stem leaves become increasingly divided into needlelike lobes, cut sometimes to the midrib. Flowers reddish- purple, borne in heads surrounded by prickly bracts and often subtended by small, prickly leaves at base of head. Dorsal ridge of bracts may be resinous and sticky. Fruits 1-seeded (achenes), about \fa inch (3 mm) long. Found in pastures, fields, and meadows; often a problem in rural cemeteries.
201
COMPOSITE FAMILY, Compos/foe
BULL THISTLE, C/rs/um vu/gare (Savi) Tenore. 1, portion of stem showing leaf attachments; 2, upper portion of stem; 3, flower head; 4, seed. Biennial, reproducing by seed. In first year forms rosette with large fleshy taproot. Stem second year, 2 to 4 feet (0.6 to 1.2 m) tall, heavy, often branched, more or less hairy. Leaves deeply cut, spiny, green on both upper and lower surfaces despite presence of hair. Leaf bases running down stem to give stem winged appearance. Spines on lobes of leaves and stems. Flower heads compact, 1 to 2 inches (2.5 to 5 cm) in diameter, rose to reddish-purple; each head surrounded by spiny-tipped bracts. Seeds straw- colored, striped with brown, ridged around one end, tipped with an easily detached plumose pappus. Found in pastures, meadows, and other unculti- vated land. Does not survive cultivation.
TALL THISTLE, Cirsium altissimum (I.) Spreng. Similar to above. Biennial, re- producing by seed. Stems 3 to 10 feet (0.9 to 3 m) tall. Leaves may vary from entire to lobed, and are dark green on upper surface and white woolly on lower surface. Flower heads about 1 inch (2.5 cm) in diameter, rose- purple.
202
COMPOSITE FAMILY, Compos/foe
SCOTCH THISTLE, Onopordum acanthium 1. 1, upper portion of plant show- ing stem, leaves, and flower heads; 2, seed. Biennial, rarely winter annual, reproducing by seed. Leaves at base of plant in rosette first year, coarse, nearly fleshy, grayish with dense hairs, appearing almost cottony at center of rosette. Stem erect, 2 to 6 feet (0.6 to 1.8 m) tall, strongly branched with upper branches taller than terminal flower. Stem strongly winged, with wings continuous and lobes spined. Stem leaves lobed, not deeply cut, lobes with sharp spines. Flower heads 1 to 2 inches (2.5 to 5 cm) wide, flattened, reddish-purple, short spines on bracts becoming harsh and sharp at maturity. Blooms from mid-June through July with seed maturing through July and August. Seeds about 3/16 inch (4 to 5 mm) long, plump, dark brown to black, and rugose or wrinkled. When mature, seeds are forced out of head by crowding. Pappus short, straw-colored, with stiff hairs but not plumed. Found in pastures, meadows, and noncropland.
203
COMPOSITE FAMILY, Compos/foe
HORSEWEED, Conyza canadensis (L) Cronq. 1, lower part of leafy stem; 2, upper part of stem with flowers; 3, mature flower head; 4, seed; 5, dis- tribution. Annual, reproducing by seed. Stem stout, erect, unbranched at base, 1 to 6 feet (0.3 to 1.8 m) tall, with bristly hairs. Leaves numerous, without petioles, linear, dark green, with scattered coarse white bristles, margins toothed or entire. Flower heads numerous, small, in axillary pan- icles, a narrow-pointed bract at the base of each head. Ray flowers greenish- white, scarcely noticeable, surrounding yellow disk flowers. Seeds about 1/16 inch (1.5 mm) long with numerous slender white bristles on one end. Found in pastures, roadsides, and wasteland. Also known as marestail.
DWARF FLEABANE, Conyza ramosissima Cronq. 6, plant; 7, distribution. Similar to the above but smaller and bushy. Stem 6 to 18 inches (15 to 45 cm) tall, much branched. Leaves narrow. Flower heads few, scattered. Found in dry fields and old pastures.
204
COMPOSITE FAMILY, Compos/foe
PLAINS COREOPSIS, Coreopsis tinctoria Mutt. 1, plant showing growth habit; 2, seed. Annual, reproducing by seeds. Root system fibrous. Stems smooth with many slightly angled branches, up to 4 feet (1.2 m) tall. Leaves smooth, opposite or alternate, petioled; lower leaves divided into narrow, linear, or lance-shaped segments, upper leaves narrow and undivided. Flower heads numerous, slender-stalked, about 1 inch (2.5 cm) in diameter; ray flowers yellow or orange, with or without purplish-brown base, disk flowers dark purple or brown. Seed small, linear-oblong, incurved, wingless, black with a white scar. Found in fields and waste places, most abundant on low, moist, poorly drained soils.
205
COMPOSITE FAMILY, Compos/fae
SMOOTH HAWKSBEARD, Crepis capillaris (L) Wallr. 1, entire plant; 2, flower head; 3, seed. Annual or biennial, reproducing by seeds only. Stems slender, erect, leafy, with milky juice, often branching at base, 1 to 2 feet (30 to 60 cm) tall. Leaves alternate, nearly free of hairs, spatulate with spreading lobes at base, margins cut or toothed. Flower heads about l/2 inch (13 mm) in diameter, composed of yellow ray flowers, on long stalks at tips of branches. Seeds tapered on both ends, about 1/16 inch (1.5 mm) long, brownish, with numerous soft white bristles at upper end. Found in hayfields, pastures, and wasteland.
206
COMPOSITE FAMILY, Compos/foe
ROUGH FLEABANE, Erigeron strigosus Muhl. 1, plant; 2, leaf from middle of stem; 3, seed. Annual, winter annual, or biennial, reproducing by seeds. Stems clustered, 1 to 3 feet (30 to 90 cm) tall, hairy, with numerous branches from the upper part. Leaves variable, lower ones ovate, upper lanceolate, blade often tapering toward base to form more or less winged petiole. Flower heads l/2 to 1 inch (1.3 to 2.5 cm) in diameter, white to lavender ray flowers surrounding the yellow disk flowers. Seeds 1/16 inch (1.5 mm) long, wedge-shaped, with a tuft of short white bristles at top. Found most commonly in old hayfields and thin pastures. Several similar species differing slightly from the above occur in the region. Also known as daisy fleabane.
207
COMPOSITE FAMILY, Compos/foe
WHITE SNAKEROOT, Eupcrforium rugosum Houtt. 1, upper part of plant; 2, root; 3, flower head; 4, single flower; 5, seed. Perennial, spreading by seeds and short rhizomes. Roots much branched and fibrous. Stem 1 to 3 feet (30 to 90 cm) tall, smooth, and branched near top. Leaves opposite, elliptical, thin, smooth, with toothed edges and slender petioles. Flower heads small, of white disk flowers only. Seed black, angular, about Ys inch (3 mm) long, with a tuft of white hairs. Found in hardwood timber areas, woodland, pastures, and waste places. It grows only in shaded areas. Contains a cumu- lative poison that causes the disease known as "trembles" in cattle and horses. Dairy products from animals that have eaten the plant are poisonous to man, causing "milk sickness," one of the serious scourges of pioneers in the region.
208
COMPOSITE FAMILY, Compositae
LATE EUPATORIUM, Eupcrfor/um serotinum Michx. 1, lower portion of plant with roots; 2, upper portion of plant in blossom; 3, flower head; 4, seed. Perennial, reproducing by seed. Roots shallow, fibrous. Stems hairy, erect, 3 to 6 feet (0.9 to 1.8 m) tall, upper portion much branched. Leaves narrow, tapering to a point, petioled, edges toothed; upper leaves alternate, lower ones opposite. Flower heads small, cylindrical, of whitish disk flowers only, borne in a compact, flat-topped cluster at top of plant. Seed narrow, oblong to oval with several longitudinal ribs and with a tuft of whitish bristles at top. Found on moist soils in feedlots, old pastures, and wasteland. A num- ber of other somewhat similar species of Eupofor/um (e.g., E. perfo//afum, E. purpureum, E. altissimum, E. macu/afum) are found in the region, under the common names of thoroughwort, boneset, or joe-pye weed. They are all more or less similar to this illustration. In several states, one or more of these are much more common than E. serof/nurn.
209
COMPOSITE FAMILY, Compos/foe
SMALLFLOWER GALINSOGA, Galinsoga parviflora Cay. 1, entire plant; 2, flower head; 3, ray flower. Annual, reproducing by seeds. Stem 1 to 2 feet (30 to 60 cm) tall, erect or spreading, much branched, slender, hairy. Leaves opposite, oval to lance-shaped, pointed at tip, thin, with toothed margin. Flower heads small, numerous, scattered at ends of branches. Ray flowers very small, white, 4 to 5 in number, surrounding the small yellow disk flowers. Seed about 1/16 inch (1.5 mm) long, wedge-shaped, 4-sided, dark brown to black, with a fringe of tiny scales at one end. Found in gardens, dooryards, waste places, and lowland fields, especially in damp areas with rich soil. Hairy galinsoga, Go//nsoga ci/icrfa (Raf.) Blake, is similar to the above and is found in similar places, often more commonly. It has a more pubescent stem than smallflower galinsoga, and has well developed pappus scales on the ray flowers. Ray flowers of smallflower galinsoga have either very small or no pappus scales.
210
COMPOSITE FAMILY, Compos/foe
FRAGRANT CUDWEED, Gnaphalium obtusifolium L. 1, plant in flower; 2, seed. Biennial, reproducing by seed. Stem slender, 1 to 3 feet (30 to 90 cm) tall, branching mostly in the upper portion; covered with white, felt like hair. Leaves covered with same type of hair; lower leaves a rosette, usually spatulate; stem leaves narrow, without petioles. Flower head small, of white disk flowers only, clustered at ends of upper branches. Seed about 1/32 inch (0.8 mm) long, wedge-shaped, with a tuft of hairs on one end. Found in old fields, pastures, and dry unproductive areas. Does not persist in cultivated fields.
211
COMPOSITE FAMILY, Compos/foe
GUM WEED, Grindelia squarrosa (Pursh) Dunal. 1, top of plant; 2, root and lower stem. Biennial, reproducing by seeds. Stems erect, 1 to 3 feet (30 to 90 cm) tall, branching near top, rough, somewhat sticky. Leaves coarse, oblong, slightly cupped with heavy midrib and toothed edges, alternate, partially clasping stem. Flower heads about 1 inch (2.5 cm) in diameter, yellow ray flowers surrounding the yellow disk flowers. Bracts surrounding the head are covered with a sticky resinous substance. Seeds light gray, flattened, curved, somewhat 4-angled, with longitudinal lines. Found in dry meadows, pastures, and waste places.
212
COMPOSITE FAMILY, Compos/foe
COMMON BROOMWEED, Guf/errez/a dracuncu/o/des (DC.) Blake. 1, plant in flower; 2, flower head; 3, ray flower; 4, disk flower; 5, seed; 6, root system. Annual, reproducing by seed. Taproot with many fibrous branches. Stem erect, tough or almost woody, bushy-topped, 15 to 30 inches (37.5 to 75 cm) tall. Leaves linear, about 1 inch (2.5 cm) long and l/» inch (3 mm) wide. Flower heads small, at tips of the many fine branches. Ray flowers 5 to 10 in number, bright yellow, surrounding the pale yellow disk flowers. Found mostly in pastures. Sometimes the dominant weed in many pastures, although its abundance varies greatly from year to year.
213
COMPOSITE FAMILY, Compos/foe
BITTER SNEEZEWEED, He/enium amarum (Rafin.) H. Rock. 1, plant; 2, flower head; 3, seed. Annual, with short branching taproot. Stems smooth, erect, 6 to 30 inches (15 to 75 cm) tall, branching in upper portion. Leaves numer- ous, smooth, threadlike, without petioles, alternate, and crowded along main stem and branches. Flower heads about y<\ inch (1.9 cm) in diameter, ray flowers yellow with toothed tip, surrounding dome-shaped mass of yellow disk flowers. Seed reddish-brown, hairy along edges, wedge-shaped, bearing bristle-tipped scales at top. Found in old feedlots, pastures, idle land, and wasteland. Does not persist under cultivation.
214
COMPOSITE FAMILY, Compos/foe
COMMON SNEEZEWEED, Helenium autumnale L 1, upper part of plant; 2, lower stem and roots. Perennial, reproducing by seeds and a spreading crown. Roots much branched, somewhat fleshy. Stems slender, erect, 2 to 5 feet (0.6 to 1.5 m) tall, smooth to rough, narrowly branched, with winged appendages along the stem, especially on upper part. Leaves alternate, slen- der, oblong to lanceolate, 2 to 4 inches (5 to 10 cm) long, gray and hairy when young, becoming greenish and smooth later. Flower heads sunflower- like, about 1 inch (2.5 cm) across. Ray flowers yellow, drooping, surround- ing the greenish-yellow disk flowers. Seed about 1/16 inch (1.5 mm) long, hairy. Found around water holes and ditches where water is readily avail- able. Whether dry or fresh, poisonous to livestock, especially sheep. Most serious in the western areas.
215
COMPOSITE FAMILY, Compos/foe
COMMON SUNFLOWER, He/ionthus onnuus L. 1, upper stem with flowers; 2, lower stem and root system; 3, seed; 4, distribution. Annual, reproduc- ing only by seed. Root system fibrous. Stem erect, stout, rough, 2 to 10 feet (0.6 to 3 m) tall, freely branching. Leaves alternate, simple, rough, hairy, mostly with saw-toothed margins; lower ones long-petioled. Flower heads 1 to 5 inches (2.5 to 12.5 cm) in diameter. Ray flowers yellow, surrounding brown or reddish-brown disk flowers. Seed l/& to nearly 1/2 inch (0.3 to 1.3 cm) long, ovate to wedge-shaped, slightly 4-angled and flattened, white, or gray or dark brown with lighter stripes or spots, without hairs except at the tip. Found in cultivated land, pastures, and waste places.
PRAIRIE SUNFLOWER, Helianthus petiolaris Nutt. 5, distribution. Similar to the above but smaller and more slender. Annual. Stems 6 inches to 6 feet (15 cm to 1.8 m) tall, rough. Leaves usually pale green, simple, slender, petioled, rough on both sides, all but lowest alternate. Flower heads 1 to 2 inches (2.5 to 5 cm) in diameter. Found in dry prairies and uncultivated land.
216
COMPOSITE FAMILY, Compos/foe
MAXIMILIAN SUNFLOWER, Helianthus maximiliani Schrad. 1, plant in flower; 2, disk flower; 3, ray flower. Perennial, reproducing by seed and fleshy roots and thickened rhizomes. Stem stout and rough, 1 to 5 feet (0.3 to 1.5 m) tall. Leaves numerous, alternate or lower ones opposite, lanceo- late, 3 to 7 inches (7.5 to 17.5 cm) long, with short petioles or none at all, rough on both sides, folding in drying. Flower heads 3 to 4 inches (7.5 to 10 cm) in diameter, few to many, ray and disk flowers both yellow. Seed gray, mottled with black, wedge-shaped, flattened, about l/4 inch (6 mm) long. Found on dry prairies and in pastures.
217
COMPOSITE FAMILY, Compos/foe
JERUSALEM ARTICHOKE, Helianthus tuberosus L. 1, lower part of stem with roots, rhizomes, and immature tubers; 2, section from middle of stem; 3, upper portion of stem with flower heads. Perennial, reproducing by rhi- zomes, tubers, and seeds. Roots fibrous, from short rhizomes which bear edible white tubers at tips. Stems erect, usually branching above, rough- hairy, up to 9 feet (2.7 m) high. Leaves simple, large, opposite on lower part and alternate on upper part of stem, upper surface very rough, lower surface hairy, varying from egg-shaped to lance-shaped, edges saw- toothed. Flower heads about 2 inches (5 cm) in diameter, with large yellow ray flowers surrounding yellow disk flowers. Seed flattened, wedge-shaped, smooth, often mottled with black. Found in moist fields, fence rows, road- sides, and woods. Troublesome when established in cultivated fields.
218
COMPOSITE FAMILY, Compos/foe
ORANGE HAWKWEED, Hieracium aurantiacum 1. 1, entire plant, showing roots, stolons, leaves, and flower stalk; 2, single flower; 3, seed. Perennial, reproducing by seeds and stolons. Roots fibrous. Stolons run along ground, rooting at the nodes. Stems erect, 6 to 18 inches (15 to 45 cm) tall, covered with stiff hairs, containing a milky juice. Leaves basal, without petioles, simple, covered with stiff hairs. Flower heads about y$ inch (1.9 cm) in diameter, clustered at the top of the leafless stems, composed of conspicuous orange-red ray flowers only. Seeds about 1/16 inch (1.5 mm) long, dark brown or black, cylindrical, elongated, and covered with longitudinal ridges. Found in poor pastures and other poor noncultivated soils. Does not per- sist in cultivated crops.
219
COMPOSITE FAMILY, Compos/foe
YELLOW HAWKWEED, Hieradum pratense Tausch. 1, entire plant; 2, seed. Perennial, reproducing by seeds, by slender rhizomes, and by occasional stolons that develop late in summer. Stems 6 inches to 3 feet (15 to 90 cm) tall, coarse, hairy, containing milky juice; upper parts with blackish, gland- tipped hairs. Leaves simple, without petioles, about 10 inches (25 cm) long, spatula-shaped, with bristles on both surfaces. Usually they grow from the base of the stem, although 1 to 3 well-developed leaves are borne higher on the stem. Flower heads each have 12 or more yellow flowers. Fruits 1-seeded (achenes), about 1/16 inch (1.5 mm) long, dark brown or black, and cylin- drical with vertical ridges. Found in clearings, meadows, pastures, grass- lands, and old fields on dry, gravelly, and somewhat acid soil.
220
COMPOSITE FAMILY, Compos/foe
POVERTYWEED, Iva axillaris Pursh. 1, entire plant; 2, flower head; 3, seed. Perennial, reproducing by seeds and creeping rootstocks. Stems 6 inches to 2 feet (15 to 60 cm) tall, erect, branched, very leafy. Leaves without petioles, opposite or the upper ones alternate, narrowly oblong, somewhat thick or fleshy, stiff, and rough to the touch. Flower heads small, drooping, sur- rounded by bracts in the form of a 5-lobed cup, borne in axils of the upper leaves. Several greenish-yellow disk flowers included in each head. Seeds egg-shaped, flattened, sometimes curved, grayish-brown in color. Found in grain fields, meadows, cultivated crops, and waste places. Common in dry areas on alkaline or saline soils.
221
COMPOSITE FAMILY, Compos/fae
MARSHELDER, Iva xanthifolia Nutt. 1, plant in bloom; 2, root; 3, seeds; 4, flowers. Annual with taproot, reproducing by seeds. Stem 3 to 8 feet (0.9 to 2.4 m) tall, moderately branched, grayish-green, smooth. Leaves broad, mostly opposite, light grayish-green, covered with small short hairs, with toothed margins. Flower heads small, drooping, borne in panicles at top of stem and in axils of upper leaves. Flowers either male or female but borne in the same head, without petals, greenish-yellow in color. Seeds gray to black, triangular, somewhat flattened with a ridged surface, about i/z inch (3 mm) long, produced in abundance. Found along roadsides, in farmyards, ditches, and pastures. Infrequent in cultivated fields.
222
COMPOSITE FAMILY, Compos/foe
BLUE LETTUCE, Locfuco pulchella (Pursh) DC. 1, lower portion of stem show- ing long leaves with notched margins; 2, upper stem showing smooth leaf margins and flowering habit; 3, seed with bristles; 4, new shoots as they emerge from soil; 5, root system. Perennial, reproducing by seeds and creeping roots. Stems 1 to 4 feet (0.3 to 1.2 m) tall, branching at top, smooth and leafy. Leaves bluish-green, with smooth surface. Those on lower stem 2 to 8 inches (5 to 20 cm) long with notched margins; those on upper stem shorter with smooth margins. Flower heads about 1 inch (2.5 cm) in diame- ter, composed of pale blue or violet ray flowers. Seed oblong, flat, gray or reddish-brown, with 3 ridges on face, and tapering to a beak with soft white bristles. Entire plant contains a bitter, milky white juice. Found in pastures, grain fields, and waste areas. Difficult to eradicate from cultivated areas.
223
COMPOSITE FAMILY, Compos/foe
PRICKLY LETTUCE, Lacfuca serr/o/a L. 1, lower portion of plant; 2, upper part of plant with flowers; 3, seed; 4, distribution. Annual or winter an- nual, reproducing by seed. Taproot large. Stem erect, 2 to 6 feet (0.6 to 1.8 m) tall, stiff, leafy, hollow, prickly on the lower part and containing milky juice. Leaves large, coarse; lower leaves more or less lobed, upper ones small, linear; all with prickles along margin and along center of lower sur- face of midrib. Flower heads about 3/16 inch (4.5 mm) across, in open terminal clusters, composed of yellow ray flowers only. Seed black, rough, slender-tipped with a tuft of white bristles at upper end. Found in roadsides, fence rows, and wasteland.
TALL LETTUCE, Lactuccr canadens/s L. 5, distribution. Similar to the above. Biennial, reproducing by seed. Leaves basal the first year, covered with powdery bloom, usually lanceolate, entire or with wavy margins, edges smooth, midrib without prickles but may have a few hairs.
224
COMPOSITE FAMILY, Compositae
SKELETONWEED, Lygodesmia /"uncea (Pursh) D. Don. 1, upper part of stem with flowers; 2, flower head; 3, seed. Perennial, reproducing from long taproot and by seeds. Stem 10 to 20 inches (25 to 50 cm) tall, rigid, much branched, usually tufted, finely grooved, containing milky juice, rushlike. Leaves alternate, narrow, lower ones about 1 to 2 inches (2.5 to 5 cm) long, upper ones reduced to scales or sharp-pointed bracts making the stem ap- pear leafless. Flowers pink or white, mostly 5 per head at end of stems. Fruits are 1-seeded (achenes), 3/16 to l/+ inch (4.5 to 6 mm) long, narrow with 8 to 10 ribs on each side of achene. Found in meadows, plains, and waste places, mostly on light dry soils. The bitter milky juice of stems and leaves is suspected of being poisonous to livestock.
225
COMPOSITE FAMILY, Compos/fae
FALSE CHAMOMILE, Matricaria maritime I. var. agrestis (Knaf) Wilmott. 1, stems, leaves, flowers; 2, seeds. Winter annual or annual, reproducing by seed. Taproot system with extensive secondary roots. Stems 1 to 3 feet (30 to 90 cm) tall, frequently branched, especially from the crown area. Leaves dark green, 1 to 3 inches (2.5 to 7.5 cm) long, finely divided. Flowers occurring singly at end of branches, 1/2 inch (1.3 cm) in diameter, with center of yellow disk flowers and with ray flowers having white petals. Seeds gray to black, 1/16 inch (1.5 mm) long, 3-angled. Found along road- sides, fences, tree belts, and ponds. It may be a problem in cultivated fields when fall rosettes are not destroyed with spring tillage before planting.
226
COMPOSITE FAMILY, Compos/foe
PINEAPPLEWEED, Matricaria matricarioides (Less.) Porter. 1, entire plant; 2, flower head; 3, seed. Annual. Stems smooth, without hairs, much- branched, 6 to 18 inches (15 to 45 cm) tall. Leaves alternate, finely divided, smelling like pineapple when bruised. Flower heads numerous, on the ends of branches, without ray flowers, consisting of a mass of greenish-yellow disk flowers grouped into a cone-shaped head about 1/4 inch (6 mm) in diameter. Seeds about 1/16 inch (1.5 mm) long, 3- to 5-ribbed. Found on roadsides and in barnyards, waste places, gardens, and sometimes cultivated fields.
227
COMPOSITE FAMILY, Compos/foe
BLACKEYED SUSAN, Rudbeckia hirta L 1, lower part of plant; 2, upper part of plant with flowers; 3, seed. Perennial, reproducing by seeds. Stems bristly-hairy, erect, 1 to 3 feet (30 to 90 cm) tall, with a few branches. Leaves at base of stem ovate; upper leaves somewhat linear, coarsely toothed or entire, without petioles. Flower heads 2 to 3 inches (5 to 7.5 cm) in diameter, on long terminal stalks. Ray flowers orange-yellow, sur- rounding a conelike mass of purplish-brown disk flowers. Seed 4-angled, about l/s inch (3 mm) long. Found in old hay fields and upland pastures with dry soil.
228
COMPOSITE FAMILY, Compos/fae
CUTLEAF CONEFLOWER, Rudbeckia laciniata L 1, plant in flower; 2, ray flower; 3, seed. Perennial, reproducing by rhizomes and seed. Root system fibrous. Stems 3 to 7 feet (0.9 to 2 m) tall, often whitish. Leaves alternate, deeply pinnately lobed or compound, long-petioled. Flower heads 2 to 4 inches (5 to 10 cm) in diameter on long bare stalks. Ray flowers long, yel- low, soon drooping, surrounding a conelike mass of yellowish disk flowers. Seed gray, about % inch (9 mm) long, straight or curved, 4-angled, with 4 short teeth on one end. Found in rich low ground, pastures, and woodland, especially along streams. Also called goldenglow.
229
COMPOSITE FAMILY, Compos/foe
GOLDEN RAGWORT, Senec/o oureus L. 1, plant in flower; 2, ray flower; 3, disk flower; 4, section of flower head; 5, seed. Perennial, reproducing by seed and short rhizomes. Stems erect, usually 1 to 2 feet (30 to 60 cm) tall, smooth, branched near top. Leaves on lower part of stem with long petioles and ovate blades rounded at the tip and with round-toothed mar- gins. Leaves on upper part of stem with deeply cleft margins, the segments often toothed, alternate, without petioles. Flower heads on slender branches, 1/2 to 1 inch (1.3 to 2.5 cm) in diameter. Ray flowers numerous, deep yellow, surrounding a mass of yellow disk flowers. Seeds elongated, smooth, with a tuft of barbed white hairs at the tip. Found in swamps and wet meadows.
230
COMPOSITE FAMILY, Compositae
CUPPLANT, Silphium perfoliatum L 1, upper portion of plant; 2, ray flower. Perennial, reproducing by seed. Stem stout, square, erect, 4 to 8 feet (1.2 to 2.4 m) tall, branching slightly at the top. Leaves opposite, bases extend- ing around stem to form a cup, rough on both sides, with saw-toothed edges. Larger leaves 6 to 12 inches (15 to 30 cm) long, 4 to 8 inches (10 to 20 cm) wide. Flower heads 2 to 3 inches (5 to 7.5 cm) across, composed of bright yellow ray flowers surrounding yellow disk flowers. Seeds gray to black, oblong, flat, notched at end. Found in fence rows, roadsides, waste places. Does not persist in cultivated land. Also known as cup rosinweed.
231
COMPOSITE FAMILY, Compos/foe
GRAY GOLDENROD, Solidago nemorcr/is Ait. 1, basal part of stem and rootstock; 2, upper stem and flower clusters; 3, flower head; 4, seed. Peren- nial, reproducing by seeds and by persistence of the stout, branched base of the stem. Stems 6 to 30 inches (15 to 75 cm) tall, hairy, grayish. Leaves on lower part of plant petioled and tongue-shaped; upper leaves smaller, oblong, grayish-hairy. Flower heads small, cylindrical in a slender, curving, 1 -sided cluster, 2 to 8 inches (5 to 20 cm) long. Ray flowers few, small, yellow; disk flowers few, small, yellowish. Seeds oblong, about 1/16 inch (1.5 mm) long, bearing a tuft of white bristles on the top. Found in recently abandoned fields, fence rows, and open woods especially on dry sites. A number of species resembling the one described are found in the region.
232
COMPOSITE FAMILY, Compos/foe
RIGID GOLDENROD, Solidago rigida 1. 1, lower part of plant; 2, upper part of plant; 3, flower head; 4, seed. Perennial, reproducing by seeds and by persistence of a stout, branched base of the stem. Stem coarse, slightly hairy, up to 5 feet (1.5 m) tall. Leaves alternate, stiff and thick, grayish- hairy, margins smooth or with shall owly rounded teeth ; lower leaves longer petioled than upper, upper may be without petioles. Flowers terminal in dense heads, large with 30 to 40 yellow flowers per head. Fruits 1 -seeded (achenes), smooth or hairy at tips, with 10 to 15 ridges on the surface. Found in dry, gravelly open places of woods or on prairies.
233
COMPOSITE FAMILY, Compos/foe
PERENNIAL SOWTHISTLE, Sonchus arvensis L. 1, lower part of plant; 2, up- per part of stem with flowers; 3, seed. Perennial, reproducing by seed and creeping roots. Roots may penetrate soil to a depth of several feet and spread horizontally, producing shoots from buds on the roots. Stems smooth, 3 to 7 feet (0.9 to 2 m) tall, erect, with a milky juice and a whitish bloom on the surface. Leaves 4 to 8 inches (10 to 20 cm) long, alternate, irregularly toothed, lobed, edges spiny. Flower heads about IVi inches (3.8 cm) across, composed of deep yellow ray flowers. Seed dark reddish-brown, about Vs inch (3 mm) long, slightly flattened, 5- to 7-ribbed with smaller cross wrinkles and with a tuft of hair on one end that is easily broken off. Found in cultivated fields, pastures, and wasteland. It is not easily destroyed and becomes a serious problem in grain and row crops.
234
COMPOSITE FAMILY, Compos/foe
ANNUAL SOWTHISTLE, Sonchus oleraceus L 1, top of plant in bloom; 2, seed. Annual, reproducing by seed. Stem smooth, erect, 1 to 6 feet (0.3 to 1.8 m) tall, with a milky juice. Leaves at base of stem more or less petioled; upper leaves clasping the stem with pointed projections; deeply cut, usually with a large end segment, margins with soft prickles. Flower heads about 94 inch (1.9 cm) across, of light yellow ray flowers; borne on numerous branches at top of plant. Found in gardens, pastures, wasteland, and road- sides.
SPINY SOWTHISTLE, Sonchus osper (L.) Hill. Similar to the above. Annual. Leaves nearly entire, prickly-edged, stem leaves clasping the stem with large, rounded, earlike lobes.
235
COMPOSITE FAMILY, Compos/foe
TANSY, Tanacetum vulgare L 1, plant in flower; 2, root system showing rhizome; 3, section of a flower head; 4, seed. Perennial, reproducing by seed and short rhizomes. Root system strong, fibrous. Stems stout, erect, smooth or slightly hairy, 1 to 4 feet (0.3 to 1.2 m) tall, unbranched, except for the flowering portion. Leaves alternate, compound with oblong segments having toothed edges, smooth or nearly so, lower leaves sometimes 12 inches (30 cm) long. Flower heads numerous, button-shaped, about l/2 inch (1.3 cm) in diameter, composed of many small yellow ray flowers, in a flat- topped cluster at the top of the stem. Seed flat, about 1/16 inch (1.5 mm) long, 5-angled, yellowish-brown, tipped with small scales. Found along roadsides, in gardens and waste places. The plant has an unpleasant odor.
236
COMPOSITE FAMILY, Compositae
COMMON DANDELION, Taraxacum off/c/na/e Weber. 1, plant in flower; 2, single ray flower; 3, seed. Perennial, reproducing by seed. Root thick, fleshy, often with branches. New sprouts can come from roots or root seg- ments. Stem never elongates but produces a rosette of leaves. Leaves sim- ple, variously lobed, 3 to 10 inches (7.5 to 25 cm) long, containing a milky juice, arising from a crown at or slightly below the surface of the ground. Flower heads 1 to 2 inches (2.5 to 5 cm) in diameter, of yellow ray flowers, borne on a long, bare, hollow stalk. Seed tannish, about 3/16 inch (4.5 mm) long, elongated, with a slender tip bearing a tuft of hairs that are easily broken off. One variety has reddish-brown seeds. Found in lawns, meadows, gardens, and waste places.
237
COMPOSITE FAMILY, Compos/fae
WESTERN SALSIFY, Tragopogon c/ub/us Scop. 1, plant with head of mature seed; 2, seed; 3, single flower; 4, plant in flower. Biennial, reproducing by seeds. Taproot fleshy. Stem erect, branched, smooth, 1 to 3 feet (30 to 90 cm) tall, containing milky juice. Leaves grasslike, with a clasping base that encloses the stem, alternate, iong, narrow, light green, smooth with smooth margins. Flower heads 1 to 2 inches (2.5 to 5 cm) in diameter, solitary at top of stem, composed of bright yellow ray flowers. Seeds about 1/2 inch (1.3 cm) long, narrow, rough, ridged with slender tip on one end, to which is attached a parachutelike appendage. Found in meadows, pas- tures, waste places, roadsides, and fence rows. The white, sticky juice of this plant is bitter, making the plant unpalatable to livestock. A similar species having purple flowers is found in some areas. Also commonly known as yellow goatsbeard.
238
COMPOSITE FAMILY, Composiiae
TALL IRONWEED, Vernon/o altissima Nutt. 1, upper portion of stem; 2, flower head; 3, single flower; 4, seed; 5, distribution. Perennial, reproduc- ing by rhizomes and seed. Roots strong, fibrous. Stems erect, 3 to 6 feet (0.9 to 1.8 m) tall, widely branched in the upper portion. Leaves long, lan- ceolate to narrowly ovate, sharply toothed, with short hairs on the lower surface. Flower heads about */& inch (9 mm) across, numerous, surrounded by smooth-tipped leafy bracts, borne in a flat-topped cluster at the ends of the branches. Disk flowers reddish-purple. Seed mostly oblong, prominently ribbed, with short bristles at the tip. Found in meadows, pastures, and wastelands.
WESTERN IRONWEED, Vernonia baldwini Torr. 6, flower head; 7, distribu- tion. Similar to the above species. Leaves densely hairy on lower surface. Flower heads surrounded by bracts with hooked tips. Found in prairie pastures.
239
COMPOSITE FAMILY, Compos/foe
COMMON COCKLEBUR, Xanthium strumarium L. 1, upper part of plant; 2, seed; 3, bur; 4, seedling plant. Annual, reproducing by seed. Taproot rather woody, stout. Stem erect, normally bushy, 2 to 4 feet (0.6 to 1.2 m) tall, ridged, rough-hairy, often spotted. Leaves alternate, simple, tri- angular in outline, toothed or lobed, rough, with long petioles. Flowers small, male and female flowers separate but borne together in clusters in axils of the upper leaves. Two female flowers are enclosed in each oval bur. At maturity the bur is hard, woody, and covered with hooked prickles, and ends in 2 curved spines. Male flowers numerous, in clusters on short stalks, dropping soon after pollen is shed. Seeds about 1/2 inch (1.3 cm) long, dark brown, rather slender with pointed tips. Found in cultivated fields, abandoned land, poor pastures, and roadsides.
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Keys
Glossary
Indexes
KEYS FOR IDENTIFYING WEEDS1
How a Key Is Used
A key is a device for identifying plants. It is an outline consist- ing of alternative statements about structure or appearance. From each pair of statements, you choose the one that applies to the plant you are identifying. After you have made your first choice, you then choose from the next pair subordinate to the first, and so on, until you come to the name of the plant.
As an example, a short key to certain well-known legumes is given below. First look at the two headings labeled "1." If the plant to be identified has a rounded head of flowers, it will be found under the second "1," and you will ignore everything under the first "1," since all the plants under that heading will have flowers in slender spikes. Next, you look at the flowers, which are white, so you choose the second "3." Under the second "3" is a pair of "4's." The plant has a prostrate stem that seemingly roots at the nodes. It is white clover.
1. Flowers in slender spikes.
2. Flowers yellow. YELLOW SWEETCLOVER
2. Flowers white. WHITE SWEETCLOVER 1. Flowers in rounded heads.
3. Flowers pink to red. RED CLOVER 3. Flowers white or pinkish.
4. Plants trailing, rooting at nodes; flowers white.
WHITE CLOVER 4. Plants ascending, not rooting at nodes; flowers white, becoming pink.
ALSIKE CLOVER
Note that you always choose between two alternatives, and that the two alternatives bear the same number. Note also that a given number is used for only one pair of headings and is not repeated.
When you use the longer keys beginning on page 247, you will find that often one of a pair of statements will be widely separated from the other. For example, under the first "1" in Key 1, there are pairs of "2's," "3's," "4's," "5's," and "6's" before you come to the second "1." Sometimes the separation is so wide that you have to turn a couple of pages before you come to the second of a pair of statements. In all cases, choose between two statements bearing the same number and keep on choosing until the plant is identified.
1 Prepared by DUANE ISELY, Iowa State University. Journal paper No. J-9255 of the Iowa Agriculture and Home Economics Experiment Sta- tion, Ames, Iowa. Project 1983.
243
Use of Technical Plant Characters in a Key
Individuals who easily recognize plants sometimes wonder why it is necessary to use technical details in a key, details that need not be observed in recognizing a plant. However, recognizing a known plant and identifying an unknown one are two different processes.
An analogy: Most people interested in cars can usually differ- entiate, even at a distance, between popular makes, regardless of model, year, or body type. This recognition is based on a knowledge both of general form and of the detailed variations from model to model and from year to year, and involves a rapid, subconscious sorting of these details. But if one is to write down features that will allow a person who doesn't know cars to distinguish between makes, one must turn to characteristics that are consistent regard- less of year or model. For example, the insignias on the front of the hood may be constant enough to furnish a means of identifica- tion. And possibly characters of the grille, the curvature of the fenders, or the nature of the hubcaps would also be valuable.
A plant is usually recognized by a combination of superficial and often variable characters that, if put into words, would require an involved description. Plants must be identified by consistent characters, sometimes small or technical, that serve as "signposts."
Technical Terms
Arising from the need for technical characters is the necessity for technical terms. Most botanical keys contain many. Such words make it hard for the person who has little familiarity with plants to use the key. But — returning to automobiles — one could scarcely discuss the ailments of his car intelligently with a mechanic if he did not know a few words such as carburetor, water pump, and rings. In the same way, if plants are to be described with any pre- cision, it is necessary to have words for their parts.
I've tried to use as few technical terms as possible in the follow- ing keys. Usually descriptive phrases are substituted. Sometimes the more exact technical term is placed in parentheses after the descriptive phrase or vice versa. The following paragraphs define words that are used most frequently without definition in the keys. A glossary beginning on page 291 defines othgr words sometimes used in the keys and also in the weed descriptions.
Duration of weed. Annual — lives one year. Biennial — lives two years, usually forming a rosette the first year and sending up an inflorescence the second. Perennial — lives several years. Annuals
244
and biennials usually have only a taproot with small branches or, if grasses, a fibrous root system. Perennials possess overwintering parts — for example, thickened crowns from which new shoots arise, bulbs or tubers, or creeping underground rootstocks, which may be either stems (rhizomes) or roots.
Arrangement of leaves. Alternate — one leaf at each level on the stem. Opposite — two leaves opposite one another and paired. Whorled — three or more leaves at each level on the stem.
Nature of leaf. Simple — the leaf blade consists of a single piece and is not divided into separate leaflets. However, simple leaves are frequently toothed or lobed. Maple and elm leaves are simple leaves. Compound — the leaf blade is divided into several leaflike parts called leaflets. A hickory, locust, or marijuana leaf is compound.
Leaf shape. Ovate — egg-shaped, nearly elliptic but broadest at base. Lanceolate — lance-shaped, longer than ovate and usually pointed at tip. Linear — long and narrow with nearly parallel sides. Grass leaves are linear.
Arrangement of flowers. If the flowers are in a definite cluster, usually at the top of the plant, they are said to be in an inflores- cence. On some plants the flowers may be borne along the stem, in the angles (leaf axils) between the stems and the leaves. Such flowers are said to be axillary, and if in groups, comprise axillary clusters.
Flower parts. The details of flower and fruit structure provide the best characters for identifying plants. But because of the tech- nical nature of these parts, they are little used in these keys. The expanded and usually colored parts of the flower are the petals. The sepals form the greenish hull around the flower when it is in bud; when the flower is open, they lie outside and below the petals. Many flowers have no petals and are usually greenish or incon- spicuous.
The "flowers" of members of the composite family (e.g., dande- lion, sunflowers, thistle) are in reality whole inflorescences (heads) of tiny flowers.
Nature and Arrangement of the Keys
In the following keys, precision of statement has been sacrificed to minimize the use of technical terms. As a result, some leads are ambiguous. As far as possible, such difficulties have been antici- pated and the plants concerned have been entered under both al- ternatives, that is, they may be keyed out in either "direction."
The keys on pages 247 to 288 include all the weeds described in this manual except dodder, bracken, and field horsetail. Key 1
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(page 247) includes plants with yellow, orange, or cream flowers ; Key 2 (page 257), plants with white flowers; Key 3 (page 267), plants with red, pink, blue, lavender, or purple flowers ; Key 4 (page 274), grassy plants with green flowers; Key 5 (page 280), broad- leaf plants with green flowers ; Key 6 (page 286), woody plants.
Usually flower color will indicate the key to be used. In doubt- ful cases, the following analysis in the form of a key will help.
1. Plant a yellowish, twining vine without leaves, growing parasitically on legumes or flax. DODDER (Cuscuta spp.)2 p. 141
1. Plants not as above.
2. Plants producing neither flowers nor seeds; leaves (as described below) fernlike, or absent.
3. Plant a fern; leaves (fronds) large, divided into numerous seg- ments. BRACKEN (Pteridium aquilinum) p. 12
3. Plant(s) with hollow, jointed stems and no leaves; stems of two kinds ; one coming up early in the spring is whitish, unbranched, with a conelike structure at tip; the second is green, with clusters of branches arising at each level.
FIELD HORSETAIL (Equisetum arvense) p. 11 2. Plants producing flowers and seeds ; leaves present, various in nature.
4. Plants not woody.
5. Flowers with yellow, orange, cream, or white petals or petallike structures, occasionally greenish white or faintly streaked with pink (the center of the flower, or flower head, is sometimes colored differently). 6. Flowers yellow to orange, or cream. KEY 1, page 247
6. Flowers white or greenish white. KEY 2, page 257 5. Flowers other than yellow, orange, cream, or white.
7. Flowers red, pink, lavender, blue, or purple; petals usually present. KEY 3, page 267
7. Flowers greenish to greenish brown ; petals usually absent.
8. Plants grasslike; leaf blades sessile (without a stalk or
petiole) and attached to a sheath that encircles the stem;
blades narrowly strap-shaped or linear, entire (without
teeth or lobes), with numerous parallel veins.
KEY 4, page 274
8. Plants neither grasses nor grasslike; leaves without a basal sheath, not parallel-veined; with 1 main vein and branches (pinnately veined) or with 3 to 5 main veins from base of blade (palmately veined), the interspaces net-veined; leaf blades various in shape, usually not linear, often toothed or lobed or compound. KEY 5, page 280
4. Plants woody vines or shrubs. KEY 6, page 286
1 Several kinds of dodder may attack leguminous crops. Dodders also infest a variety of wild plants.
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KEY 1. PLANTS WITH YELLOW, ORANGE, OR CREAM FLOWERS
1. Plants (leaves or stems) spiny or prickly; plants commonly possessing a milky juice. 2. Plants consisting of spiny pads or disks, without leaves; flowers more
than 2 inches (5 cm) in diameter. PRICKLYPEAR (Opuntia spp.) p. 128 2. Plants not as above, with leaves; flowers or flower heads less than 2 inches
(5 cm) in diameter.
3. Leaves and stems densely covered with rigid spines; flowers separate;
juice not milky. BUFFALOBUR (Solanum rostratum) p. 163
3. Leaves prickly along margins and sometimes lower midrib but stems
not spiny; flowers tiny, in heads that look like single flowers (e.g.,
dandelion) ; juice milky.
4. Flowers (flower heads) less than \/2 inch (1.3 cm) across, straw-yellow, numerous, in a branched flower cluster (panicle) ; leaves prickly on lower midrib as well as margins.
PRICKLY LETTUCE (Lactuca serriola) p. 224
4. Flower heads 1/2 to \y2 inches (1.3 to 3.8 cm) across, bright yellow, usually 5 to 20 in number; leaves not prickly on lower midrib. 5. Flower heads more than 1 inch (2.5 cm) in diameter (slightly smaller than those of a dandelion) ; plants perennial from creeping roots. PERENNIAL SOWTHISTLE (Sonchus arvensis) p. 234 5. Flower heads 1/2 to 1 inch (1.3-2.5 cm) in diameter (about half the size of those of a dandelion) ; plants from an annual taproot. 6. Leaf margin sharply prickly; base of the blade usually curled and clasping the stem (auriculate) ; seeds (achenes) not cross- wrinkled. SPINY SOWTHISTLE (Sonchus asper) p. 235 6. Leaf margin soft-prickly; leaf base tapering, not clasping the stem, or some of upper leaves slightly clasping ; achenes irregu- larly ridged and cross-wrinkled.
ANNUAL SOWTHISTLE (Sonchus oleraceus) p. 235
1. Plants (leaves or stems) not spiny; in a few cases, the fruit is spiny or prickly.
7. Plants with neither a leafy stem nor prostrate stolons; leaves all in a clus- ter (rosette) at ground level; flower heads solitary on hollow, leafless stalks.
8. "Seeds" (achenes) olive-drab to dull brown; leaves extremely variable, deeply dissected or only irregularly toothed; inner bracts around head not appendaged ; the usual dandelion.
COMMON DANDELION (Taraxacum officinale) p. 237
8. Achenes red-brown to reddish purple; leaves usually dissected nearly to the midrib with narrow, frequently downwardly curved (runcinate) lobes; inner bracts around head with hornlike appendages; uncommon. REDSEED DANDELION (Taraxacum erythrospermum) not illustrated
7. Plants with an erect or prostrate leaf-bearing stem; flowers or flower heads various, not arising directly from a basal rosette (stem leaves are few or reduced in hawkweeds, Hieracium, which, however, usually have stolons).
9. Plants prostrate, trailing, or spreading. 10. Leaves compound.
11. Leaflets 8 to 16; fruit a spiny bur.
PUNCTURE VINE (Tribulus terrestris) p. 113
247
11. Leaflets 3; fruit a 1-seeded pod.
BLACK MEDIC (Medicago lupulina) p. 109 10. Leaves simple.
12. Plant fleshy with small, entire leaves, flowers less than 1/2 inch (1.3 cm) across; fruit a small capsule, less than 1 inch (2.5 cm) long. PURSLANE (Portulaca oleracea) p. 71
12. Plant not fleshy, with large, irregularly toothed or lobed leaves; flowers large, 1-2 inches (2.5-5 cm) long; fruit large, more than 1 inch (2.5 cm) long.
13. Plant with tendrils; flowers 3-4 inches (7.5-10 cm) long, soli- tary in leaf axils, fruits gourdlike, not beaked.
BUFFALO GOURD (Cucurbita foetidissima) p. 176 13. Plants lacking tendrils; flowers to 2 inches (5 cm) long, in inflorescenses ; fruit a capsule with an incurved or hooked beak several inches long.
DEVILSCLAW (Proboscidea louisianica) p. 168
9. Plants erect or ascending (some may root at lower nodes or have trail- ing stolons as well as erect stems).
14. Leaves compound, divided into distinct leaflets ; or some or all of leaves dissected into numerous fine segments and usually appearing fernlike.
15. Leaves compound, divided into distinct leaflets that are ordinarily more than !/£ inch (6 mm) wide.
16. Leaves opposite; flowers in heads that look like single flow- ers; fruits 1-seeded (achenes), with 2 barbed, sharp projec- tions (awns) at top.
DEVIL'S BEGGARTICKS (Bidens frondosa) p. 193 16. Leaves alternate ; flowers not in heads ; fruits various.
17. Leaflets 3, entire except for a notch at apex (obcordate) ; each flower producing a single, many-seeded fruit (cap- sule). COMMON YELLOW WOODSORREL
(Oxalis stricta) p. Ill
17. Leaflets various in number, toothed or lobed; fruits not capsular, several frequently produced by each flower. 18. Leaves pinnately compound (leaflets arising from an elongated midrib or axis) ; flowers umbellate (numer- ous flower stalks arising from same point) ; each flower producing 1 fruit, which, at maturity, splits into 2 flat, 1-seeded segments (mericarps).
WILD PARSNIP (Pastinaca sativa) p. 133 18. Leaves palmately compound (leaflets arising fingerlike from apex of leaf stalk); flowers not umbellate; each flower producing several 1-seeded fruits (achenes). 19. Leaflets lobed or dissected, frequently running to- gether at base, their exact number difficult to de- termine; stipules (appendages where leaf stalk joins stem) not evident.
TALL BUTTERCUP (Ranunculus acris) p. 83 19. Leaflets toothed, clearly distinguishable and easy to count ; stipules present.
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19a. Under surface of leaves silvery-hairy. SILVERY CINQUEFOIL
(Potentilla argentea) p. 105 19a. Under surface of leaves greenish.
20. Leaflets 5 to 9; petals large, longer than other flower parts. SULPHUR CINQUEFOIL
(Potentilla recta) p. 106
20. Leaflets 3 ; petals small and inconspicuous, scarcely longer than sepals. ROUGH CINQUEFOIL
(Potentilla norvegica) p. 106
15. Leaves not divided into distinct leaflets; but some or all of leaves dissected into numerous fine segments usually less than 1/4 inch (6 mm) wide, the whole leaf presenting a fernlike appearance. 21. Leaves all alternate.
22. Flowers with 4 distinct petals set at right angles to one another; fruit resembling a slender pod (silique) and con- taining several yellowish seeds; plants not strongly scented.
23. Mature pods more than 2 inches (5 cm) long; main segments of basal (rosette) leaves usually not dissected into secondary segments (1-pinnatifid). TUMBLE MUSTARD (Sisymbrium altissimum) p. 102 23. Mature pods less than 1 inch (2.5 cm) long, main seg- ments of basal leaves usually dissected into secondary segments (2-pinnatifid).
TANSY MUSTARD (Descurainia pinnata) p. 94
22. Flowers (flower heads) without petals or marginal petal- like structures, the heads button- or bell-shaped; fruits 1-seeded, not podlike, clustered together in the heads ; plants usually strongly scented.
22a. Flower heads yellow or orange, erect, Vi inch (6 mm) or more wide.
22b. Plants perennial: stems usually a foot (0.3 m) or more high; main leaf segments crowded, pin- natifid; flower heads orange, in a dense, flat- topped cluster.
TANSY (Tanacetum vulgare) p. 236 22b. Plants annual; stems less than a foot (0.3 m) high; leaf segments slender, entire, distant; flower heads yellowish, not densely clustered. PINEAPPLEWEED
(Matricaria matricarioides) p. 227
22a. Flower heads yellowish-white, gray, yellow, or green- ish, frequently bent over (nodding), distinctly less than 14 inch (6 mm) wide.
24. Plants greenish, relatively smooth, strong-scented annuals arising from a taproot. ANNUAL WORMWOOD
(Artemisia annua) p. 189
249
24. Plants white-silky or woolly, scarcely scented ; perennials from spreading rhizomes. ABSINTH WORMWOOD
(Artemisia absinthium) p. 188 21. Leaves all opposite, or only the lower opposite.
25. Flower heads with a dark center and large, petallike mar- ginal (ray) flowers; lower leaves with threadlike (fili- form) segments, the upper mostly undivided.
PLAINS COREOPSIS (Coreopsis tinctoria) p. 205 25. Flower heads without a dark center; ray flowers, if pres- ent, small and inconspicuous ; leaves f ernlike. 26. Leaves all opposite ; flower heads single or in small groups at tips of branches, with small ray flowers; seeds columnar with points at the tip that readily ad- here to clothing.
SPANISHNEEDLES (Bidens bipinnata) p. 192
26. Leaves alternate above, opposite below; upper flower
heads in slender spikes, producing pollen only and not
setting seed; seeds broad, produced in axils of upper
leaves, not adhering to clothing.
27. Plants annual, very common ; leaves smooth above, usually much divided, i.e., the main segments dis- sected into secondary divisions (2-pinnatifid) ; fruits with a distinct crown of points at tip. COMMON RAGWEED
(Ambrosia artemisiifolia) p. 181
27. Plants perennial from creeping roots (first-year plants appear annual), similar in appearance to common ragweed but much less common ; leaves rough on upper surface, less divided than those of common ragweed, the main segments frequently lobed but not again divided (1-pinnatifid) ; fruits with a very short crown of points or nearly smooth at tip. WESTERN RAGWEED
(Ambrosia psilostachya) p. 182
14. Leaves neither compound nor dissected into fine segments; if lobed or divided (pinnatifid), the blades not f ernlike, or the segments relatively broad or coarse.
28. Petals 4, placed at right angles to one another (flowers cross- like) ; fruit podlike (a silique), elongate or "ball-shaped," several- seeded (one exception), frequently with a beak at the tip. 29. Pods upwardly appressed against stem.
30. Flowers less than i/£ inch (6 mm) across; beak of pod indistinct, less than 1/16 inch (1.5 mm) long; upper leaves with 3 narrow lobes.
HEDGE MUSTARD (Sisymbrium officinal e) p. 103
30. Flowers more than 1/4 inch (6 mm) across; beak of pod evident, about V& inch (3 mm) long; upper leaves irregu- larly toothed. BLACK MUSTARD (Brassica nigra) p. 88
29. Pods spreading, ascending, or nearly erect, but not appressed against stem.
31. Pods spherical (globose) to egg-shaped (ovoid) ; leaves clasping the stem by basal lobes.
250
32. Plants perennial from creeping roots ; pods splitting open at maturity (dehiscent), with numerous tiny seeds. AUSTRIAN FIELDCRESS (Rorippa austriaca) p. 101
32. Plants annual; pods not splitting open at maturity (indehiscent), with 1 large seed, or sometimes 2.
BALL MUSTARD (Neslia paniculata) p. 99 31. Pods oblong to linear ; leaves clasping or not.
33. Plants smooth or with a few scattered hairs or very tiny appressed hairs.
34. Leaves with a pair of basal lobes clasping about the stem, otherwise entire (neither toothed nor lobed) ; seed pods frequently 3 inches (7.5 cm) long, and often nearly vertical in position. HARE'S EAR MUSTARD
(Conringia orientalis) p. 93
34. Leaves entire, toothed or lobed, not clasping the stem; seed pods various, if vertical, shorter than above.
35. Leaves not lobed, usually nearly entire, narrow (linear-lanceolate) ; pod stalk (pedicel) slender, often y2 to z/4 inch (13 to 19 mm) long. WORMSEED MUSTARD
(Erysimum cheiranthoides) p. 95 35. Leaves lobed, usually broad; pod stalk coarser and shorter than above.
36. Basal leaves with a broadly rounded termi- nal lobe; foliage shiny green; seed pods usually not longer than 1 inch (2.5 cm) ; seeds somewhat flattened. YELLOW ROCKET
(Barbarea vulgaris) p. 86
36. Basal leaves with pointed lobes; foliage often somewhat whitish-green; seed pods usually longer than 1 inch (2.5 cm) ; seeds spheroidal. INDIAN MUSTARD
(Brassica juncea) p. 88
33. Plants conspicuously bristly-hairy.
37. Fruit jointed at maturity, breaking crosswise into segments containing 1 or 2 seeds; basal leaves usually divided to the midrib into separate seg- ments.
WILD RADISH (Raphanus raphanistrum) p. 100
37. Fruit splitting longitudinally to release seeds at maturity; basal leaves irregularly toothed or pin- natiful, but not divided to midrib.
WILD MUSTARD (Brassica kaber) p. 89
28. Petals not 4 in number; fruit various, not a silique.
38. Leaves alternate, occasionally the uppermost or the lower
opposite, or (rarely) nearly all in basal clusters (rosettes).
39. Fruit a 3-lobed, 3-seeded capsule that hangs downward at
maturity; leaves narrowly strap-shaped, crowded on the
mostly unbranched stem; juice milky.
251
40. Leaves about y& inch (3 mm) wide.
CYPRESS SPURGE (Euphorbia cyparissias) p. 117
40. Leaves 1/4 to 34 inch (6 to 19 mm) wide.
LEAFY SPURGE (Euphorbia esula) p. 118 39. Fruit not a 3-lobed, 3-seeded capsule; plants otherwise not with the above combination of characters.
41. Flowers without petals or petallike structures; inflo- rescences appearing as erect or drooping yellow disks, or as a cluster of short, flat spikes.
42. Leaves grasslike ; stems 3-angled ; triangular in cross section; inflorescence a cluster of short, flat spikes.
YELLOW NUTSEDGE (Cyperus esculentus) p. 44 42. Leaves not grasslike ; stems rounded ; inflorescence of disklike flower heads.
43. Flowers (flower heads) on stalks in a branched flower cluster ; stem leaves strap-shaped, not toothed; seeds with a cluster of hairs (pappus) at tip.
44. Stem unbranched below inflorescence, often 3 to 6 feet (0.9 to 1.8 m) tall; leaves crowded, strap-shaped.
HORSE WEED (Conyza canadensis) p. 204 44. Stem branched, low, usually not much ex- ceeding 1 foot (0.3 m) ; leaves narrowly linear. DWARF FLEABANE
(Conyza ramosissima) p. 204
43. Flower heads not stalked (sessile), arising di- rectly from an unbranched axis; leaves usually with a pair of teeth at base ; seeds not possess- ing a pappus. LANCELEAF RAGWEED
(Ambrosia bidentata) p. 181 41. Flowers with petals or petallike structures.
45. Flowers closely associated in heads, each head simulating a single flower; flowers in the head either all similar — strap-shaped, with each appear- ing like a single petal (ray flowers) ; or of two kinds — small tubular flowers crowded together in a central disk (disk flowers), and marginal (ray) flowers that look like petals ; each head setting several to many seeds (achenes), which often bear a cluster of hairs or bristles (pappus) at the apex. 46. Heads with no central disk; flowers all strap- shaped and petallike (ray-flowers) ; fresh plants frequently with a milky juice. 47. Leaves entire, grasslike; heads large, 11/2 to 21/2 inches (3.8 to 6.3 cm) across. WESTERN SALSIFY
(Tragopogon dubius) p. 238
47. Leaves not grasslike, some or all usually toothed or lobed; heads usually less than 1 inch (2.5 cm) across.
252
48. Leaves mostly in basal rosettes; erect stems bearing only 1 to 3 reduced blades; prostrate leaf-bearing stolons often evi- dent. 48a. Flower heads orange.
ORANGE HAWKWEED
(Hieracium aurantiacum) p. 219 48a. Flower heads yellow.
YELLOW HAWKWEED
(Hieracium pratense) p. 220 48. Leaves of mature plants not mostly in rosettes, those on stems numerous; sto- lons not present.
49. Leaves soft-prickly, the teeth or lobes drawn out into bristles, or leaves soft-prickly on lower midvein. 50. Midvein on undersurface of leaves prickly with a row of bristles; most of stem leaves twisted side- wise so that blade is in a vertical position (one edge above the other) ; heads less than y£ inch (1.3 cm) in diameter. PRICKLY LETTUCE
(Lactuca serriola) p. 224
50. Midvein not prickly; leaves hori- zontal ; heads more than 1/2 inch (1.3 cm) in diameter. ANNUAL SOWTHISTLE
(Sonchus oleraceus) p. 235 49. Leaves not prickly-margined.
51. Branches bearing flower clusters arched or recurving, bearing the crowded flowering heads primar- ily on one side in a curved wand; leaves mostly stalked, not clasp- ing the stem.
GRAY GOLDENROD
(Solidago nemoralisY p. 232 51. Branches of inflorescence erect or ascending, bearing upright heads at tip ; stem leaves mostly without stalks (sessile), with lower portion of the blade clasp- ing.
52. Plants 3 to 8 feet (0.9 to 2.4 m) tall with densely leafy stems; heads numerous, less than 1/2 inch (1.3 cm) wide; seeds (achenes) black, beaked. TALL LETTUCE
(Lactuca canadensis) p. 224
1 And other species of goldenrod, including rigid goldenrod (Solidago ri- gida) p. 233.
253
52. Plants low, usually about 1 foot (30 cm) tall, often with several branches from base; heads y& to 3/4 inch (10 to 19 mm) in diameter ; seeds (achenes) brown, not beaked. SMOOTH HAWKSBEARD
(Crepis capillaris) p. 206
46. Heads with a central disk that is margined by petallike ray flowers; plants without a milky juice.
53. Central disk of head (tubular flowers) black or dark brown.
54. Seeds (achenes) black, brick-shaped, \/& inch (3 mm) or less long ; leaves oblong to strap-shaped, less than 1 inch (2.5 cm) wide. BLACKEYED SUSAN
(Rudbeckia hirta) p. 228
54. Seeds white, gray, or brown, larger than above; leaves usually broadly ovate to lanceolate and 1 inch (2.5 cm) or more wide.
55. Leaves rough (scabrous) ; seeds (achenes) dull white to gray, hairy at tip, 1/4 to y& inch (6 to 10 mm) long ; common. COMMON SUNFLOWER
(Helianthus annuus) p. 216 55. Leaves hairy but not markedly rough ; seeds pale brown, hairy all over, less than 14 inch (6 mm) long; not com- mon in agricultural areas. PRAIRIE SUNFLOWER
(Helianthus petiolaris) p. 216 53. Entire head yellow.
56. Seeds bearing at apex a cluster (pappus)
of numerous fine bristles. (In immature
flowering heads, the pappus is hidden by
the flowers and the head must be split
to find it; after the head begins to ripen,
the pappus is easily visible externally.)
57. Stem leaves pinnatifid (lobed along
an elongated midrib) ; flower heads
more than 1/2 inch (1.3 cm) across.
GOLDEN RAGWORT
(Senecio aureus) p. 230 57. Stem leaves toothed or entire ; flower heads not exceeding 1/2 inch (1.3 cm). GRAY GOLDENROD
(Solidago nemoralis)4 p. 232
4 And other species of goldenrod including rigid goldenrod (Solidago rigida) p. 233.
254
56. Seeds not bearing a pappus of fine bris- tles; pappus absent, or of scales, or of a few (5 to 10) somewhat flattened, stiff bristles.
58. Stem leaves narrowly linear or threadlike ; southern. 59. Heads 1/2 to K inch (1.3 to 1.9 cm) wide ; marginal ray flowers lobed at tip. BITTER SNEEZEWEED
(Helenium amarum) p. 214
59. Heads less than 1/2 inch (1.3 cm) wide ; ray flowers not lobed. COMMON BROOMWEED
(Gutierrezia dracunculoides) p. 213 58. Leaves broader than above, not lin- ear ; central and northern.
60. Stems winged by attached basal portions of leaf blades (leaves decurrent) ; ray flowers 3-toothed or lobed at tip.
COMMON SNEEZEWEED
(Helenium autumnale) p. 215 60. Stems not winged; ray flowers not toothed.
61. Plants finely hairy, often somewhat rough; perennial from rhizomes and tubers; heads not sticky or gummy. 62. Central disk of heads (not including petallike rays) usually y$ to Y* inch (1 to 1.9 cm) broad; lowermost leaves opposite; rhizomes bearing enlarged tubers. JERUSALEM ARTICHOKE (Helianthus tuberosus) p. 218 62. Central disk of heads 3/4 to 11/2 inches (1.9 to 3.8 cm) broad; leaves all alternate; rhizomes not tuber-bear- ing.
MAXIMILIAN SUNFLOWER (Helianthus maximiliani) p. 217 61. Plants smooth (glabrous), without rhizomes or tubers; heads gummy. GUMWEED
(Grindclia squarrosa) p. 212
45. Flowers separate, not associated in heads; fruits and seeds various, without a pappus. 63. Leaves velvety-hairy or densely woolly.
255
64. Fruit a berry enclosed in an angular, papery husk ; plant perennial from creeping root- stocks. CLAMMY GROUNDCHERRY
(Physalis heterophylla) p. 158 64. Fruit a dry capsule which splits open at maturity, not enclosed within a husk; plants annual or biennial, without creeping root- stocks.
65. Plants gray-woolly; flowers in a dense spike ; leaves not heart-shaped at base. COMMON MULLEIN
(Verbascum thapsus) p. 165 65. Plants velvety; flowers not in a spike; leaves heart-shaped at base. VELVETLEAF
(Abutilon theophrasti) p. 122
63. Leaves smooth (glabrous) or hairy, but neither velvety nor densely woolly.
66. Basal leaves palmately divided into 3 to 7 main segments which are further subdivided. 67. Flowers pale yellow, purplish in center; each flower produces a single, large, sev- eral-seeded fruit (capsule) partially sur- rounded by a bladdery hull; plants an- nual. VENICE MALLOW
(Hibiscus trionum) p. 123
67. Flowers bright yellow throughout; each flower produces numerous small seed- like fruits; plants perennial.
TALL BUTTERCUP
(Ranunculus acris) p. 83 66. Basal leaves not palmately dissected.
68. Basal (rosette) leaves as broad as long, heart-shaped.
SMALLFLOWER BUTTERCUP
(Ranunculus abortivus) p. 82 68. Basal leaves longer than broad, not heart-shaped.
69. Leaves entire, strap-shaped, not hairy; flowers not symmetrical, the petals of different sizes (irregular). YELLOW TOADFLAX
(Linaria vulgaris) p. 164 69. Leaves not strap-shaped, usually toothed or shallowly lobed, hairy; flowers with petals of same size (reg- ular) or fused together.
70. Petals fused into a single piece like a petunia (gamopetalous) ; fruit a berry enclosd in a husk. SMOOTH GROUNDCHERRY (Physalis subglabrata) p. 159
256
70. Petals separate; fruit not a berry. 71. Leaves stalked (petioled) ; flowers scattered; fruit split- ting into 5 seeds. PRICKLY SIDA
(Sida spinosa) p. 126 71. Leaves not stalked (sessile); flowers in a terminal spike; fruit with many seeds. COMMON EVENINGPRIMROSE (Oenothera biennis) p. 129 38. Leaves all opposite.
72. All leaves, or only the lower, lobed or cleft into segments. 73. Flowers (flower heads) in narrow spikes, without petals or petallike structures; leaves mostly with 3 to 5 big lobes (palmately lobed).
GIANT RAGWEED (Ambrosia trifida) p. 183
73. Flower heads separate at stem tips, with large petal- like ray flowers; lower leaves with 3 to 7 lobes (pin- nately lobed), upper blades often unlobed. CUTLEAF CONEFLOWER
(Rudbeckia laciniata) p. 229 72. Leaves toothed or entire.
74. Bases of upper, paired leaves joined together and forming a cup about stem at nodes.
CUPPLANT (Silphium perfoliatum) p. 231 74. Bases of leaves not joined together.
ST. JOHNSWORT (Hypericum perforation) p. 127
KEY 2. PLANTS WITH WHITE FLOWERS
1. Leaves opposite or whorled.
2. Leaves whorled (several at each level on stem).
3. Plants forming prostrate mats; flowers in small axillary clusters; seeds very small, reddish. CARPETWEED (Mollugo verticillata) p. 70
3. Plants spreading or erect, not forming prostrate mats; flowers in branched or rounded inflorescences; seeds not as above. 4. Stems spreading or nearly prostrate (decumbent), covered with fine hooked bristles and readily adhering to clothing; fruit separating into two globular, 1-seeded sections.
CATCHWEED BEDSTRAW (Galium aparine) p. 174
4. Stems erect or ascending, without hooked bristles; fruits many-seeded.
5. Stems nearly simple (unbranched) ; flowers in umbels (numerous
flower stalks arising from the same place) ; pods milkweedlike,
more than 1 inch (2.5 cm) long; seeds large, tufted with long hairs.
EASTERN WHORLED MILKWEED (Asclepias verticillata) p. 138
5. Stems much branched; flowers in branched inflorescences; fruits a
fraction of an inch long; seeds small, without hairs.
CORN SPURRY (Spergula arvensis) p. 79 2. Leaves opposite (uppermost rarely alternate).
257
6. Plant a twining or climbing vine; leaves heart-shaped at base; fruits milkweedlike. HONEYVINE MILKWEED (Ampelamus albidus) p. 135 6. Plants not vines ; leaves and fruits various, not as above.
7. Leaves pinnately lobed (lobes approximately at right angles to midrib
of blade); mature fruits (capsules) hanging downward; plants evident
in spring. WATERPOD (Ellisia nyctelea) p. 144
7. Leaves various, not as above; mature fruits not hanging down; plants
flowering at various times of the season.
8. Leaves entire (edge without teeth), or (rarely) the lowermost toothed; flowers not borne in heads; fruits often capsules contain- ing several seeds.
9. Long bristles (stipules) present at leaf bases; fruits splitting
into 2 or 3 large seedlike fragments, each with 3 or 4 scalelike
appendages at tip. POORJOE (Diodia feres) p. 173
9. Stipules not present; seeds not as above, released from within
fruits at maturity.
10. Flowers borne in the axils of conspicuous alternate bracts (reduced leaves) ; plants appearing fleshy ; fruits somewhat 2-lobed.
PURSLANE SPEEDWELL (Veronica peregrina) p. 166 10. Flowers not borne in the axils of alternate bracts ; bracts and leaves all opposite ; plants not fleshy ; fruits not 2-lobed. 11. Plants with a milky juice; fruit long and slender, shaped somewhat like a pencil; seeds with a tuft of long, fine hairs. HEMP DOGBANE (Apocynum cannabinum) p. 134 11. Plants without a milky juice; fruit short; seeds without hairs.
12. Plants low or creeping, rarely more than a few inches high; flowers V6 inch (3 mm) or less in diameter. 13. Lower leaves stalked (petioled) ; plants hairy only on angles of stems and leaf stalks. COMMON CHICKWEED (Stellaria media) p. 80
13. Leaves without stalks (sessile) ; plants densely hairy all over.
MOUSE-EAR CHICKWEED
(Cerastium vulgatum) p. 73
12. Plants erect, frequently exceeding 1 foot (0.3 m) in height; flowers usually V£ inch (1.3 cm) or more across.
14. Plants glabrous (not hairy).
15. Stem sticky; fruit (capsule) surrounded by a tight-fitting hull (calyx) ; plant annual. SLEEPY CATCHFLY (S//ene antirrhina) p. 76
15. Stem not sticky; capsule surrounded by swol- len, bladdery calyx hull; plant perennial. BLADDER CAMPION (Silene cucubalus) p. 77
14. Plants hairy (pubescent).
16. Stems sticky, or viscid-hairy; 3 styles (branches of the stalk from the pistil) ; plant annual, with single stout stem. NIGHT-FLOWERING CATCHFLY
(Silene noctiBora) p. 78
258
16. Stems soft-hairy, not sticky or viscid; 5 styles; plant biennial or perennial, with several stems from its base.
WHITE COCKLE (Lychnis alba) p. 74
8. Leaves toothed or lobed; flowers in dense clusters (often in heads that superficially appear like single flowers), or spikes; fruits not capsules.
17. Leaves lobed, the lower somewhat maplelike; flower clusters
becoming spiny in fruit.
MOTHERWORT (Leonurus cardiacs) p. 152 17. Leaves toothed; flower spikes or clusters not becoming spiny
in fruit.
18. Flowers in spikes or in dense clusters in leaf axils; fruits splitting into four 1-seeded segments; stems conspicuously square. 19. Flowers in spikes terminating stems.
20. Flowers closely overlapping in dense spikes ; plants
aromatic (leaves with a strong odor when crushed) ;
seeds (nutlets) with a pair of white spots at base.
CATNIP (Nepeta cataria) p. 154
20. Flowers not closely crowded, but in loose, narrow spikes, the fruits well separated and not at all over- lapping; plants not aromatic; seeds without a pair of white spots at base.
WHITE VERVAIN (Verbena urtici folia) p. 148 19. Flowers in dense clusters in leaf axils along the stem, not terminating it.
FIELD MINT (Mentha arvensis) p. 153
18. Flowers in small heads that appear somewhat like individual flowers; fruits (achenes) 1-seeded, topped by a fine cluster of hairs or scales; stems not conspicuously square. 21. Flower heads with white petallike marginal (ray) flow- ers and a yellow center; leaves with 1 main midvein; plants annual. SMALLFLOWER GALINSOGA
(Galinsoga parviffora) p. 210
21. Flower heads entirely white; leaves with 3 main veins; plants perennial.
22. Leaves broadly lanceolate, finely hairy; clusters of small leaves usually present in the axils of the main blades; heads usually with fewer than 15 flowers. LATE EUPATORIUM
(Eupatorium serotinum) p. 209
22. Leaves ovate, concavely tapering to a point (acumi- nate), not hairy; clusters of small leaves not present in axils of main blades; heads usually with more than 15 flowers.
WHITE SNAKEROOT (Eupatorium rugosum) p. 208
1. Leaves alternate or sometimes most of them in a basal cluster (rosette). 23. Leaves, stems, or both prickly or spiny.
24. Flowers more than 2 inches (5 cm) in diameter; leaves with prickly teeth along edge.
BLUESTEM PRICKLEPOPPY (Argemone intermedia) p. 84
259
24. Flowers less than 1 inch (2.5 cm) in diameter ; stem and leaf surfaces with yellowish thorns. HORSENETTLE (Solatium carolinense) p. 160
23. Leaves and stems not spiny, but fruits sometimes prickly or spiny.
25. Petals 4, placed at right angles to one another and presenting a cross- like appearance ; fruits several-seeded.
26. Fruits flat.
27. Fruit triangular (or sometimes viewed as an upside down heart), plant covered with tiny (hand lens needed), branched (stellate) hairs.
SHEPHERD'S PURSE (Capsella bursa-pastoris) p. 91 27. Fruit circular; plants smooth or with unbranched hairs.
28. Fruit about 1/2 inch (1.3 cm) in diameter; seeds dark brown; leaves toothed.
FIELD PENNYCRESS ( Thlaspi arvense) p. 104 28. Fruit Y& inch (3 mm) or less in diameter; seeds reddish- yellow; lower leaves pinnatifid (irregularly lobed, with lobes more or less at right angles to long midrib).
VIRGINIA PEPPERWEED (Lepidium virginicum) p. 98 26. Fruits inflated on one or both sides, or globular. 29. Plants densely hairy.
30. Pods short-cylindric, twice as long as wide; leaves entire (not toothed).
HOARY ALYSSUM (Berteroa incana) p. 87 30. Pods circular or broadly elliptic, nearly as broad as long; leaves wavy-toothed, or the lower somewhat lobed. 31. Plants perennial from creeping roots ; pods inflated on both sides, with a distinct beak at tip.
HOARY CRESS (Cardaria draba) p. 92
31. Plants annual; pods flat on one side, inflated on the other, with little or no beak.
FIELD PEPPERWEED (Lepidium campestre) p. 96 29. Plants without hairs (glabrous) or with inconspicuous hairs. 32. Pods well over 1/4 inch (6 mm) long, with a short beak (about 1/4 the length of pod) ; seeds about 1/10 inch (2.5 mm) long.
LARGESEED FALSEFLAX (Camelina sativa) p. 90 32. Pods Vi inch (6 mm) or less long, with a somewhat longer beak (about half the length of pod) ; seeds less than 1/16 inch (1.5 mm) long.
SMALLSEED FALSEFLAX (Camelina microcarpa) p. 90 25. Petals not 4 or, if so (rarely), not placed at right angles to one an- other; fruits various.
33. Plants vinelike, trailing, twining, or climbing ; leaves heart- or arrowhead-shaped (cordate, hastate, or sagittate), or palmately lobed.
34. Plants with tendrils ; leaves palmately lobed, the lobes acute tipped. 35. Plants pubescent (hairy) ; fruits in burlike clusters.
BUR CUCUMBER (Sicyos angulatus) p. 178
35. Plants nearly glabrous (smooth) ; fruits like a spiny gourd,
solitary. WILD CUCUMBER (Echinocystis lobata) p. 177
260
34. Plants without tendrils; leaves not palmately lobed, or, if so, the lobes rounded.
36. Plants thick-stemmed (14 to Vi inch [6 to 13 mm] in diame- ter), with a musky odor; flowers not morningglorylike; fruits with incurved beaks several inches long.
DEVILSCLAW (Proboscidea louisianica) p. 168 36. Plants slender-stemmed (less than 14 inch [6 mm] in di- ameter), not odoriferous; flowers, except for wild buck- wheat, morningglorylike ; fruits without a long beak. 37. Flowers small, clustered in upper leaf axils, greenish- white, not morningglorylike ; fruit resembling a buck- wheat seed, 3-angled (triangular in cross section), 1- seeded, not splitting open at maturity (indehiscent) ; young stems with membranous sheaths (ochreae) at attachment of leaf blades.
WILD BUCKWHEAT (Polygonum convolvulus) p. 51 37. Flowers large, morningglorylike, fruit a capsule, ripen- ing several large seeds ; young stems without membra- nous sheaths at attachment of leaf blades. 38. Leaves deeply 3-lobed.
IVYLEAF MORNINGGLORY
(Ipomoea hederacea) p. 142
38. Leaves not deeply lobed, usually heart- or arrow- head-shaped (cordate, hastate, or sagittate). 39. Leaves arrowhead-shaped (sagittate or hastate) with pointed basal projections; plants perennial from slender creeping rootstocks. 40. Flowers roughly the size of a quarter ; leaves lanceolate to oblong with narrow basal lobes, the blade continuing in essentially the same direction as the leaf stalk (petiole) ; plants more often trailing than climbing. FIELD BINDWEED
(Convolvulus arvensis) p. 139
40. Flowers about the size of a silver dollar; leaves tending to be triangular with broad, basal lobes, the blade bent back at right angles to the petiole ; plants twining and climbing. HEDGE BINDWEED
(Convolvulus sepium) p. 140
39. Leaves heart-shaped (cordate) with rounded basal lobes ; plants annual or perennial.
41. Flowers about 2 inches (5 cm) broad, not dark purple inside; plants annual, twining. TALL MORNINGGLORY
(Ipomoea purpurea) p. 142
41. Flowers frequently 3 inches (7.5 cm) broad, dark purple inside of tube; plants perennial from very large roots, usually trailing on ground. BIGROOT MORNINGGLORY
(Ipomoea pandurata) p. 143
261
33. Plant erect, ascending, or sometimes prostrate, but not vinelike; leaves various, usually not as above.
42. Leaves (especially the lower ones) deeply palmately cleft (lobes dissected, fingerlike, to base of blade) or palmately compound, the segments in turn toothed or cleft. 43. Leaf segments closely crowded together, the blade as a whole nearly circular in outline; flowers without a purple center ; fruit slender and pointed. CAROLINA GERANIUM (Geranium carolinianum) p. 112
43. Leaf segments not crowded together, the blade not circular in outline; flowers with a purple center; fruit nearly as thick as long.
VENICE MALLOW (Hibiscus trionum) p. 123 42. Leaves various, not palmately cleft or palmately compound (sometimes shallowly palmately lobed).
44. Leaves pinnately compound (leaflets arising from an elon- gated midrib), or dissected into fine segments.
45. Flowers in compound umbels, with numerous flower stalks arising from about the same point; fruits longi- tudinally ribbed, splitting into two 1-seeded segments at maturity.
46. Leaves fernlike, dissected into ultimate segments often no more than 1/16 inch (1.5 mm) wide. 47. Plants hairy (pubescent), annual; fruits bristly. WILD CARROT (Daucus carota) p. 132 47. Plants smooth (glabrous), perennial; fruits not bristly.
POISON HEMLOCK (Conium maculatum) p. 131 46. Leaves not fernlike, the segments 1/4 to 1/2 inch (6 to 13 mm) wide. SPOTTED WATERHEMLOCK
(Cicuta maculata) p. 130
45. Flowers in heads that look somewhat like individual flowers (but surrounded by numerous involucral bracts that flowers don't have), or in a spike; fruits various, not as above.
48. Leaves compound with about 13 to 15 entire (not toothed) leaflets; flowers in a spikelike cluster (ra- ceme) ; fruit a burlike prickly pod.
WILD LICORICE (Glycyrrhiza lepidota) p. 108 48. Leaves dissected into fine, fernlike segments; flow- ers in flowerlike heads; fruit not a burlike pod; plants usually strong-scented.
49. Flower heads yellow in center, 1-2 inches (2.5-5 cm) wide ; leaves bright green. 50. Heads 1 inch (2.5 cm) wide or less; widely distributed, central and east.
MAYWEED (Anthemis cotula) p. 186 50. Heads distinctly more than 1 inch (2.5 cm) wide; north and west, primarily North Da- kota. FALSE CHAMOMILE
(Matricaria maritima) p. 226
262
49. Flower heads gray-white, smaller than above; leaves densely hairy or smooth. 51. Flower heads erect in a flat-topped cluster rising above the leaves; plants usually hairy, perennial from a tangle of short rhizomes. COMMON YARROW
(Achillea mill e folium) p. 180
51. Flower heads usually drooping from leafy, spreading, or ascending branches ; plants hairy or smooth, perennial or annual. 52. Plant smooth, annual.
ANNUAL WORMWOOD
(Artemisia annua) p. 189 52. Plant silky or woolly-hairy, perennial. ABSINTH WORMWOOD
(Artemisia absinthium) p. 188 44. Leaves simple, not compound or dissected.
53. Plants with a strong, onionlike odor, arising from a fleshy bulb; leaves fleshy, narrowly linear, mostly arising at or near base of stem; flowers umbellate (numerous flower stalks arising in close proximity) ; southern. 54. Leaves mostly in a cluster at ground level.
WILD ONION (Allium canadense) p. 46
54. Leaves borne on stem as well as at ground level.
WILD GARLIC (Allium vineale) p. 46 53. Plants and flowers various, not as above.
55. Stems and leaves gray- or white-woolly, at least on lower surface; flowers in white or gray-white cottony heads that look like individual flowers.
56. Leaves spoon-shaped, mostly borne in basal clus- ters (rosettes) or on horizontal stolons (prostrate stems) ; heads dirty white, in small, erect clusters. PLANTAINLEAF PUSSYTOES
(Antennaria pi antagini folia) p. 185
56. Leaves lanceolate, borne on an erect stem; heads clean white, frequently in rather dense clusters. FRAGRANT CUDWEED
(Gnaphalium obtusifolium) p. 211
55. Stems and leaves not woolly ; flowers or flower heads various, not as above.
57. Flowers in heads having a yellow center (tubular flowers) and white petallike marginal (ray) flow- ers.
58. Heads more than 1 inch (2.5 cm) across; basal leaves oblong or irregularly spoon-shaped, lobed (pinnatifld) or toothed with more or less rounded segments. OXEYE DAISY
(Chrysanthemum leucanthemum) p. 196
58. Flower heads less than 1 inch (2.5 cm) across ; leaves various, not as above.
263
59. Plants perennial from horizontal rhizomes, flowering in early fall ; stems ordinarily bearing clusters of reduced leaves in axils of main blades, often considerably branched below inflorescence; flower heads often borne from one side of spreading or nearly horizontal inflorescence branches ; fall- flowering.
60. Flower heads mostly 1/2 inch (1.3 cm) or more across; involucral bracts, un- der the heads, tending to be rolled up lengthwise at tip; stems glabrous or stiffly hairy, branched mostly in in- florescence. WHITE HEATH ASTER
(Aster pilosusY p. 191
60. Flower heads mostly less than i/2 inch (1.3 cm) across; involucral bracts not rolled up, often bent backward; stems usually finely fuzzy (pubescent), dif- fusely branched throughout. HEATH ASTER
(Aster ericoidesY p. 190
59. Plants annual or biennial from taproots, flowering in summer or fall ; axillary clus- ters of reduced leaves not present; flower heads on erect ascending branches in dense or flat-topped clusters.
61. Flower heads about 1/4 inch (6 mm) or less across, numerous in a dense, horse- taillike cluster (panicle) ; stem usually unbranched below inflorescence, very closely leafy with crowded, strap- shaped blades.
HORSEWEED
(Conyza canadensis) p. 204 61. Flower heads 1/2 inch (1.3 cm) or more across in a flat-topped cluster (cor- ymb) ; stem branched or unbranched, loosely leafy with well-spaced, oblong to ovate, frequently toothed blades. 62. Stem hairs conspicuous, spreading; stem leaves mostly toothed, the lowermost strongly toothed or shal- lowly lobed. ANNUAL FLEABANE
(Erigeron annuus) not illustrated 62. Stem hairs inconspicuous, upwardly appressed against stem (strigose) ; leaves, except for the lower, mostly untoothed. ROUGH FLEABANE
(Erigeron strigosus) p. 207
5 These are but two of the several species of Aster that are conspicuous in early fall.
264
57. Flowers not in heads, or if in headlike clusters, not colored as above. 63. Leaves entire, neither toothed nor lobed.
64. Fruit a capsule with an incurved or hooked beak several inches long; leaves cordate (heart-shaped), lobed or not; plant sprawl- ing, robust, thick-stemmed; flowers large, about 1 inch (2.5 cm) long, speckled. DEVILSCLAW
(Proboscidea louisianica) p. 168 64. Fruit not having a long beak; leaves and plants various.
65. Fruit a fleshy berry, purplish when mature, bearing black, shiny seeds ; leaves borne on distinct stalks (peti- oled) ; plants often 3 feet (0.9 m) or more high. COMMON POKEWEED
(Phytolacca americana) p. 69 65. Fruit dry ; seeds not as above ; leaves narrowed to base, but without a dis- tinct petiole ; plants usually less than 3 feet (0.9 m) high.
66. Plants prostrate or ascending, usu- ally less than 1 foot (0.3 m) tall, not possessing a milky juice; flow- ers inconspicuous, in leaf axils ; fruits 1-seeded, triangular. 67. Plants prostrate, forming flat mats or ascending at tips; or completely ascending, but usu- ally only a few inches high; leaves blue-green, oblong to narrowly elliptic ; a very com- mon urban and waste area weed. PROSTRATE KNOTWEED (Polygonum aviculare) p. 49
67. Plants ascending, frequently about 1 foot (0.3 m) high; leaves yellow-green, elliptic to broadly elliptic, less common than above.
ERECT KNOTWEED
(Polygonum erectum) p. 49
66. Plants erect, usually more than 1
foot (0.3 m) high, with a milky
juice; flowers in terminal clusters;
fruits 3-lobed, 3-seeded capsules.
68. Plants annual ; leaves, especially upper, with a white margin and greenish center; flower clusters small, somewhat hidden by the leaves; fruits hairy. SNOW-ON-THE-MOUNTAIN
(Euphorbia marginata) p. 120
265
68. Plants perennial ; leaves all green; flower clusters conspicu- ous, white ; fruits smooth. FLOWERING SPURGE
(Euphorbia corollata) p. 116 63. Leaves toothed or lobed.
69. Leaves as broad as or broader than long, roughly circular with a basal notch; fruits circular, dry, when mature breaking into several 1-seeded, wedge-shaped segments. COMMON MALLOW
(Malva neglecta) p. 124
69. Leaves and fruits various, not as above. 71. Fruit a small berry, black when ma- ture, green when immature; flowers look like tiny potato flowers; leaves wavy-toothed or shallowly lobed, al- most always with insect holes. EASTERN BLACK NIGHTSHADE
(Solatium ptycanthum) p. 162 71. Fruit a capsule, dry when mature; flowers not like potato flowers; leaves variable, some of them usually lobed or pinnatifid ; insect injury usually not obvious.
72. Plants low or sprawling, flowering in early spring; leaves all deeply pinnatifid; capsule hairy, with four large seeds. WATERPOD
(Ellisia nyctelea) p. 144 72. Plants erect, flowering in summer and fall ; leaves variously lobed or toothed; capsules not as above. 73. Flowers large, 3 to 5 inches (7.5 to 12.5 cm) long; fruits large, spiny; plants rank, much branched, frequently becoming 5 feet (1.5 m) high. JIMSONWEED
(Datura stramonium) p. 157 73. Flowers much smaller than above; fruits small, smooth; plants little branched, usually not more than 4 feet (1.2 m) high. MOTH MULLEIN
(Verbascum blattaria) p. 165
266
KEY 3. PLANTS WITH RED, PINK, BLUE, LAVENDER, OR PURPLE FLOWERS
1. Plants (leaves, stems) spiny or thorny.
2. Leaves opposite. TEASEL (Dipsacus sylvestris) p. 175
2. Leaves alternate.
3. Leaves attached directly to stem (sessile), edges prickly; flowers in dense, globular, flowerlike, prickly heads; fruit seedlike, dry; plants erect, 1 to 6 feet (0.3 to 1.8 m) tall, little branched with the main axis (stem) predominant, thistlelike. 4. Stems, especially near base, white-woolly, not prickly.
FLODMAN THISTLE (Cirsium Bodmani) p. 201 4. Stems green and smooth or hairy ; or whitish and prickly.
5. Plants perennial from creeping roots and without a basal cluster of leaves (rosette) ; stems usually 2 to 3 feet (0.6 to 0.9 m) high, crowded together; flower heads to 1 inch (2.5 cm) across (often less) when in flower.
CANADA THISTLE (Cirsium arvense) p. 200
5. Plants biennial, from a basal rosette (may be gone when plants reach flowering), with taller stems (2y$ to 6 feet [0.75"-1.8 m] high), often well separated; flower heads more than 1 inch (2.5 cm) across (except for plumeless thistle).
6. Head very large, 11/2 inches (3.8 cm) or more across, solitary, usually on a long stalk which is bent or somewhat recurved.
MUSK THISTLE (Carduus nutans) p. 199
6. Heads less than n/2 inches (3.8 cm) across, usually several, scarcely stalked above uppermost leaves.
7. Stems not prickly; leaves white beneath, this color contrasting to the usually greenish stems ; fruits (achenes, "seeds") with a wide yellow band at top.
TALL THISTLE (Cirsium altissimum) p. 202 7. Stems prickly (because the prickly leaves are decurrent) ; leaves not white or, if somewhat so, the stems of about the same color ; fruits lacking a wide apical yellow band. 8. Prickly foliar wings on stems often y2 inch (1.3 cm) wide or more; foliage often green-grey; achenes ("seeds") strongly cross-wrinkled (rugose).
SCOTCH THISTLE (Onopordum acanthium) p. 203 8. Prickly wings on stems less than 1/2 inch (1.3 cm) wide (prickles may be longer); foliage usually greenish; achenes not rugose.
9. Heads less than 1 inch (2.5 cm) across; pappus bristles not branched.
PLUMELESS THISTLE (Carduus acanthoides) p. 198 9. Heads 1 inch (2.5 cm) or more across; pappus bristles feathery-branched (plumose) — use hand lens or hold up to light. BULL THISTLE (Cirsium vulgare) p. 202
3. Leaves attached to stem with slender stalks (petioles), edges not prickly; flowers separate, resembling potato flowers; fruit a berry; plants rarely more than iy2 feet (0.45 m) tall, branched and spreading. 10. Plants white-hairy; leaves lanceolate to oblong, wavy-margined but not lobed; flowers blue-purple.
SILVERLEAF NIGHTSHADE (Solanum el aeagni folium) p. 160
267
10. Plants greenish; leaves ovate to lanceolate, frequently lobed; flow- ers usually light lavender.
HORSENETTLE (Solanum carolinense) p. 160
1. Plants (leaves, stems) not spiny or thorny (fruits or fruit clusters sometimes spiny). 11. Leaves opposite (the uppermost rarely alternate).
12. Leaves entire, without teeth or lobes along the margin."
13. Flowers in dense, often globelike clusters (umbels) ; fruit a soft
pod several inches long; seeds flat, wind-borne by clusters of hairs.
14. Leaves usually 2 to 4 inches (5 to 10 cm) wide ; flower clusters
pinkish; pods ^£ to 1 inch (1.3 to 2.5 cm) in diameter at base,
soft-prickly ; common in variety of habitats.
COMMON MILKWEED (Asclepias syriaca) p. 137
14. Leaves not more than 1 inch (2.5 cm) wide; flower clusters bright red; pods about 1/2 inch (1.3 cm) in diameter, smooth; poorly drained soil.
SWAMP MILKWEED (Asclepias incarnata) p. 136
13. Flowers not in clusters; fruit smaller than above.
15. Plants creeping with short, erect, flowering branches at most a few inches high.
16. Flowers not hidden by broad, overlaoping bracts. THYMELEAF SPEEDWELL (Veronica serpylli folia) p. 166
16. Flowers partly hidden by broad, overlapping bracts.
HEAL-ALL (Prunella vulgaris) p. 155 15. Plants erect, 6 inches (15 cm) to several feet tall.
17. Leaves stalked (petioled) ; fruits 1-seeded or breaking into four 1-seeded segments (nutlets).
18. Leaves somewhat heart-shaped (cordate) ; plants usually about 2 feet (0.6 m) high; flowers 2 or 3 together, borne above a membranous "umbrella" (involucre).
WILD FOUR-O'CLOCK (Mirabilis nyctaginea) p. 68
18. Leaves not cordate; plants frequently less than 1 foot (0.3 m) high; flowers borne in a dense spike, and partly hidden by broad, overlapping bracts.
HEAL-ALL (Prunella vulgaris) p. 155 17. Leaves not stalked (sessile) ; fruits many-seeded capsules.
19. Plant hairy; flowers purple-red, not crowded together.
CORN COCKLE (Agrostemma githago) p. 72 19. Plants smooth; flowers pinkish, usually crowded to- gether.
20. Calyx (the green hull around the base of the flower) tubular, round in cross section ; plants perennial.
BOUNCINGBET (Saponaria officinalis) p. 75 20. Calyx becoming swollen, angular in cross section; plants annual.
COW COCKLE (Vaccaria segetalis) p. 81 12. Leaves toothed or lobed along margin, not entire.
0 Two weeds in this group may have both entire and toothed leaves on the same plant. They are keyed out in both directions.
268
21. Leaves cut nearly to midrib (pinnatifid) into toothed segments or lobes; plants low, spreading, or nearly prostrate.
PROSTRATE VERVAIN (Verbena bracteata) p. 147 21. Leaves toothed or lobed (usually in palmate or fingerlike fashion) but the incisions not extending to midrib; plants usually either erect or strictly prostrate and rooting at nodes.
22. Plants prostrate, usually ascending at the tip, or with short erect branches.
23. Flowers borne usually 2 or 3 together in axils of ordinary foliage leaves ; uppermost leaf pairs sessile and grown together (connate) at base.
24. Stems extensively trailing; leaves smooth, frequently broader than long; seeds with white spot at base.
GROUND IVY (Glechoma hederacea) p. 150
24. Stems short, prostrate to low-ascending ; leaves finely hairy, frequently longer than broad; seeds without white spot at base. HEN BIT (Lamium amplexicaule) p. 151
23. Flowers borne in short, erect spikes in the axils of bracts or reduced leaves ; uppermost leaves not connate.
25. Stems extensively trailing; flowers borne in the axils of narrow, alternate bracts.
THYMELEAF SPEEDWELL
(Veronica serpyllifolia) p. 166
25. Stems short, trailing or entirely erect; flowers borne in the axil of very broad bracts, and almost hidden from external view. HEAL-ALL (Prunella vulgaris) p. 155 22. Plants erect or ascending.
26. Flowers in dense clusters in the axils of foliage leaves. 27. Lower leaves maplelike, broad, palmately lobed; flower clusters becoming spiny in fruit.
MOTHERWORT (Leonurus cardiaca) p. 152
27. Lower leaves not as above, ovate to lanceolate and toothed ; flower clusters not becoming spiny.
FIELD MINT (Mentha arvensis) p. 153 26. Flowers in spikes, terminating stems above leaves.
28. Bracts accompanying flowers broad, conspicuous, prickly or marginally hairy (white), often partially hiding flow- ers.
29. Leaves barely toothed; bracts entire, marginally hairy but not prickly.
HEAL-ALL (Prunella vulgaris) p. 155
29. Leaves sharply toothed; bracts toothed, prickly. DRAGONHEAD (Dracocephalum parvifforum) p. 149
28. Bracts accompanying flowers narrow or inevident.
30. Flowers distinctly 2-lipped (zygomorphic), the petals different in size and shape.
31. Leaves sharply toothed; flowers pinkish, crowded, usually overlapping. AMERICAN GERMANDER
(Teucrium canadense) p. 156
269
31. Leaves vaguely toothed; flowers blue, widely spaced.
LANCE-LEAF SAGE
(Salvia refiexa) not illustrated
30. Flowers slightly 2-lipped (nearly actinomorphic), the petals of nearly the same size and shape.
32. Plants 2 to 3 feet (0.6 to 0.9 m) high, scarcely branched except for cluster of spikes at top; leaves very hairy; flowers i/i inch (6 mm) across.
HOARY VERVAIN (Verbena stricta) p. 148 32. Plants frequently 3 to 4 feet (0.9 to 1.2 m) high, often branched; leaves inconspicuously hairy; flowers less than 1/4 inch (6 mm) across.
BLUE VERVAIN (Verbena hastata) p. 148 11. Leaves alternate or mostly in a basal cluster. 33. Leaves compound with entire leaflets.
34. Leaves pinnately compound, terminated by tendrils; flowers pea- like (but considerably smaller).
NARROWLEAF VETCH (Vicia angusti folia) p. 110
34. Leaves palmately compound, not possessing tendrils ; flowers not pealike.
ROCKY MOUNTAIN BEEPLANT (Cleome serrulata) p. 85 33. Leaves various, rarely compound (if so with lobed or toothed leaflets).
35. Plants vining, trailing, twining, or climbing; leaves with a pair of downwardly or outwardly pointed basal lobes (cordate, sagittate or hastate), or main body of blade divided into 3 segments.
36. Fruit a red berry with numerous small, flat seeds; flowers purple, shaped like potato flowers; plants irregularly sprawling or climbing, often woody at base; leaves frequently of several shapes. BITTER NIGHTSHADE (Solanum dulcamara) p. 161 36. Fruit a dry capsule with few, large seeds ; flowers morning- glorylike ; plants prostrate or climbing, not woody at base ; leaves on a single plant consistent in shape.
37. Flowers pinkish to lavender; leaves -with pointed basal cor- ners (lobes) that stick outward or downward (sagittate or hastate) ; plants perennial from slender rootstocks. 38. Flowers roughly the size of a silver dollar; leaves tend- ing to be triangular with broad basal lobes, the blade bent back at right angles to the petiole; plants twining and climbing.
HEDGE BINDWEED (Convolvulus sepium) p. 140
38. Flowers roughly the size of a quarter; leaves tending to be oblong with narrow basal lobes, the blade continuing in essentially the same direction as the leaf stalk (petiole) ; plants more often trailing than climbing.
FIELD BINDWEED (Convolvulus arvensis) p. 139 37. Flowers usually deep purple or blue; leaves cordate with rounded basal lobes or deeply 3-lobed; plants annual.
39. Leaves heart-shaped (cordate) ; calyx lobes (the lobes of the greenish hull at the base of the flower) abruptly pointed, relatively short.
TALL MORNINGGLORY (Ipomoea purpurea) p. 142
270
39. Leaves deeply 3-lobed; calyx lobes slender, drawn out, and gradually tapering to point (attenuate). IVYLEAF MORNINGGLORY
(Ipomoea hederacea) p. 142
35. Plants various, sometimes trailing, but not vinelike ; leaves various, not as above.
40. Leaves about as broad as long, roughly circular in outline (although sometimes lobed into numerous segments) ; flowers pink to lavender, relatively small and inconspicuous; plants spreading or low ascending.
41. Leaf blades fingerlike, palmately dissected into lobed segments; fruit extended into a pointed beak. CAROLINA GERANIUM (Geranium carolinianum) p. 112 41. Leaf blades irregularly scalloped or shallowly lobed; fruit flat.
42. Petals evident, much longer than sepals (the greenish hull of the flower) ; fruit with a crenate (wavy) outline, usually hidden by the sepals, not reticulate (with a net- work of lines) on the outside.
COMMON MALLOW (Malva neglecta) p. 124 42. Petals small, scarcely longer than sepals ; fruit evenly circular, often hidden by sepals, reticulate at full ma- turity. DWARF MALLOW (Malva rotundifolia) p. 125 40. Leaves longer than broad, not circular; flowers and plants various.
43. Stems encircled by short membranous sheaths (ochreae) just above the attachment of each leaf; flowers bright pink or reddish to salmon-pink in short spikes; leaf blades en- tire ; mature seeds black, smooth.
44. Plants perennial from creeping rhizomes; stems and leaves covered with fine, close-appressed hairs; plants usually growing in wet or poorly drained soil, especially along roadside ditches.
SWAMP SMARTWEED (Polygonum coccineum) p. 50 44. Plants annual ; stems and leaves smooth ; plants common in all kinds of soil.
45. Flowers bright rose or pink; stem sheaths (ochreae) smooth or torn at the top; hulled achenes ("seeds") about ' 8 inch (3 mm) long. PENNSYLVANIA SMARTWEED
(Polygonum pensylvanicum) p. 52
45. Flowers dull pink to salmon-pink; ochreae topped by a line of hairs (ciliate) ; hulled "seeds" less than i/£ inch (3 mm) long.
LADYSTHUMB (Polygonum persicaria) p. 52 43. Stems not possessing ochreae; flowers blue to purple or lavender or, if pinkish, in globular, flowerlike heads; leaves and seeds various, usually not as above.
46. Fruit a red berry; flowers similar in shape to potato flowers; plant reclining or sprawling, somewhat woody at base ; leaves heart-shaped or 2-lobed at base. BITTER NIGHTSHADE (Solanum dulcamara) p. 161
271
46. Fruit dry, not a berry; flowers not resembling potato flowers; plants erect or ascending; leaves not as above. 47. Fruits (or burlike hulls enclosing a cluster of fruits) spiny or prickly.
48. Mature fruits much less than 1 inch (2.5 cm) long, breaking into 2 to 4 prickly 1-seeded seg- ments that readily stick to clothing. 49. Flowers blue, small (about Vs inch or 3 mm across) ; leaves narrow. EUROPEAN STICKTIGHT
(Lappula echinata) p. 146
49. Flowers reddish to reddish-purple, V£ to V£ inch (6 to 13 mm) across; lower leaves large and broad.
HOUNDSTONGUE
(Cynoglossum officinale) p. 145
48. Fruits about 1 inch (2.5 cm) long, enclosing numerous seeds; or burs containing several 1- seeded fruits.
50. Flowers large, 2 to 5 inches (5 to 12.5 cm) long; fruit a capsule, prickly with short, straight spines, bearing numerous rounded or kidney-shaped seeds; leaves irregularly wavy- toothed or lobed.
JIMSONWEED (Datura stramonium) p. 157 50. Flowers smaller than above, aggregated into burlike heads about 1 inch (2.5 cm) long; burs soft-prickly with hooked bristles, bearing several oblong, 1-seeded fruits (achenes) ; leaves mostly entire.
COMMON BURDOCK (Arctium minus) p. 187 47. Fruits not prickly.
51. Inflorescence an unbranched spike; flowers large with 5 petals; fruit a many-seeded capsule. CREEPING BELLFLOWER
(Campanula rapunculoides) p. 179 51. Inflorescence various, branched; flowers small, in flowerlike heads; fruits 1-seeded achenes, several to a head.
52. Plants with a milky juice; individual flowers in the head strap-shaped and petallike. 53. Flowers pink; leaves small, entire; stem conspicuously ridged, the upper portion practically leafless. SKELETONWEED
(Lygodesmia juncea) p. 225 53. Flowers blue; leaves (at least the basal ones) large, pinnatifid, or coarsely toothed; stem not conspicuously ridged. 54. Plant with numerous well-developed stem leaves, the upper narrowly strap- shaped and entire (usually with no
272
teeth) ; stems straight, ordinarily branched only at top ; "seeds" (achenes) flattened, with a short beak. BLUE LETTUCE
(Lactuca pulchella) p. 223 54. Plant with well-developed leaves mostly at base, the upper ones re- duced; stem much branched; achenes neither flattened nor beaked. CHICORY (Cichorium intybus) p. 197 52. Plants not possessing a milky juice; individ- ual flowers tubular, not petallike. 55. Flower heads y2 inch (1.3 cm) or more across; lower leaves pinnatifid or irregu- larly toothed, the upper essentially entire or with slender divisions; plants usually less than 3 feet (0.9 m) high. 56. Plants perennial from creeping roots; heads not dark-spotted on outside ; "seeds" (achenes) ivory-colored, with- out a crown of bristles at top. RUSSIAN KNAPWEED
(Centaurea repens) p. 195
56. Plants biennial from a taproot; heads dark-spotted on outside; achenes dark, with an oblique notch at base and a crown of bristles at top. SPOTTED KNAPWEED
(Centaurea maculosa) p. 194
55. Flower heads about Vfc inch (6mm) across;
lower and upper leaves essentially similar
with numerous even teeth; plants often
more than 3 feet (0.9 m) high.
57. Lower surface of leaves covered with dense film of fine hairs; greenish bracts on outside of flower heads (involucral bracts) recurved at tips. WESTERN IRONWEED
(Vernonia baldwini) p. 239 57. Lower surface of leaves smooth or sparsely hairy; involucral bracts not recurved. TALL IRONWEED
(Vernonia altissima) p. 239
273
KEY 4. PLANTS WITH GREENISH FLOWERS, GRASSES OR GRASSLIKE
1. Plants with a strong onionlike odor, arising from a fleshy bulb, bearing clus- ters of small scaly bulblets below flowers. 2. Leaves mostly in a cluster at ground level.
WILD ONION (Allium canadense) p. 46
2. Leaves borne on stem as well as at ground level.
WILD GARLIC (Allium vineale) p. 46 1. Plants not possessing an onionlike odor, not bearing aerial bulblets.
3. Stems triangular in cross section; leaves harsh and somewhat stiff, arising in 3 rows.
4. Plants arising from heavy, creeping rhizomes (underground stems) ; fruits usually borne in broad spikes; "seeds" (1-seeded fruits) produced within an inflated, saclike structure (perigynium).
HOP SEDGE (Carex lupulina)1 p. 43
4. Plants with slender, stringlike rhizomes and small tubers; fruits borne in narrow, clustered, yellowish-green spikes; "seeds" (1-seeded fruits) hidden by closely overlapping bracts, but not in saclike structures.
YELLOW NUTSEDGE (Cyperus esculentus) p. 44
3. Stems not triangular in cross section, but round or flattened ; leaves various, usually arising in 2 rows from opposite sides of the stem.
5. Fruit a spiny bur.
LONGSPINE SANDBUR (Cenchrus longispinus) p. 20 5. Fruit not a spiny bur.
6. Plants low and wiry, rarely found in tilled soil; flowers numerous in nearly flat-topped clusters with tiny, green petals and sepals; fruits bearing many very small, dustlike seeds.
SLENDER RUSH (Juncus tenw's) p. 45
6. Plants various; flowers not in flat-topped clusters, without petals and
sepals, usually hidden from external view by enclosing hulls; fruit
(the grain) 1-seeded, much larger than above. (GRASSES)*
7. Stem or its main branches terminated by a single flowering spike
(like wheat) ; spikes neither borne in clusters at stem tip nor arising
from leaf axils along the stem.
8. "Seeds" (spikelets), when "shucked" from the spikes, rounded or elliptic, not sharply pointed or terminated by a bristle; spikes usually dense and cylindric, bristly from clusters of stiff hairs that surround the seeds (but are not borne by the seed hulls). 9. Spikes stickery and readily adhering to clothing or hands if
touched ; plants of only local abundance. BRISTLY FOXTAIL (Setaria verticillata) p. 37
1 Numerous sedges (Carex spp.) are minor agricultural weeds. They are usually conspicuous in the spring, growing in wet, low meadows and along ditches. They are rare in tilled soil. All species of Carex have the seed borne within the saclike perigynium. The size, appearance, and arrangement of the perigynia are variable.
Although many grasses are easily recognized, it is difficult to identify them in a key without the use of technical characteristics. This key, avoiding the use of exact (and more technical) terms, is necessarily less precise than if such terms were employed. Reference to the illustrations may facilitate keying grasses.
274
9. Spikes neither stickery nor adherent; plants widespread, com- mon weeds.
10. Spikes erect; "seeds" (spikelets) broadly oval, Vi inch (3 mm) or more long; hard inner hull (lemma) coarsely cross-wrinkled; bristles tawny yellow; a few long, slender hairs present on upper side of blade at base ; sheaths not finely hairy (ciliate) along overlapping margins.
YELLOW FOXTAIL (Setaria lutescens) p. 36 10. Spikes somewhat or much drooping at tip; "seeds" (spike- lets) narrowly oval, less than V£ inch (3 mm) long ; inner hull (lemma) granular or faintly cross-wrinkled; bristles green or pale yellow when dry; leaves without hairs on upper surface, or entirely covered with fine, short hairs; sheath marginally hairy, or ciliate (hand lens will help). 11. Leaves without hairs (glabrous) on upper surface; spikes slightly drooping at tip; plants usually less than 3 feet (0.9 m) high.
GREEN FOXTAIL (Setaria viridis)' p. 38
11. Leaves finely hairy on upper surface; spikes drooping
at tip; plants sometimes 6 feet (1.8 m) high or more.
GIANT FOXTAIL (Setaria faberi) p. 35
"Seeds" (spikelets or florets), when "shucked" from spike, ob- long to lanceolate, pointed at tip (or entire spike fragmenting into seed-containing bony joints — JOINTED GOATGRASS, lead 12) ; hulls frequently terminated by bristles ; spikes various, bristly or not bristly.
12. Spike axis with hard, bony joints, the seeds contained within these joints; bristles few, 3 or 4 long ones protruding from tip of spikes, the ones below becoming progressively shorter to base; plant occurring mostly in southern part of our range. JOINTED GOATGRASS (Aegilops cylindrica) p. 13 12. Spike axis not as above; seed-bearing units produced in vari- ous manners but not inside of joints of spike axis. 13. Spikes dense, bristly or plumelike with numerous bristles arising between the "seeds" (florets) as well as from the tips of them; bristles mostly considerably longer than the seeds.
14. Spikes plumelike with numerous long, green or silvery bristles protruding in all directions.
FOXTAIL BARLEY (Hordeum jubatum) p. 27
14. Spikes stiff (like a small head of barley) with rigid, ascending bristles about as long as or slightly longer than the seeds.
LITTLE BARLEY (Hordeum pusillum) p. 27
13. Spikes looser, the seed-bearing units (spikelets) usually
clearly separate from one another; bristles absent, or, if
present, relatively short, and arising only from the tips
of the seeds.
'This weed seems to cross with foxtail millet (Setaria italics). The hybrids are common in some areas and may be as tall as giant foxtail. Some have lobed, strongly drooping spikes.
275
15. Seed-bearing units (spikelets) placed with narrow edge against spike axis; plants annual, primarily small grain weeds. DARNEL (Lolium temulentum) p. 28
15. Seed-bearing units (spikelets) placed with the broader, flat edge against spike axis; plants perennial from scaly, creeping rhizomes, abundant throughout most of north central states.
QUACKGRASS (Agropyron repens) p. 14
7. Stems not terminated by a single spike; inflorescences various — if spikelike, the spikes borne in leaf axils along stem or clustered together in fingerlike fashion at tip.
16. Inflorescence of 2 to 5 spikes, which arise in fingerlike fashion from tip of stems ; bristles (awns) not present. 17. Plants perennial with short, ascending branches arising from extensively creeping stolons (prostrate stems) ; leaves at base of erect branches much reduced; seed-bearing units (spikelets) not hairy, 1-seeded.
BERMUDAGRASS (Cynodon dactylon) p. 21 17. Plants annual, ascending or sprawling and rooting from lower nodes; none of leaves reduced; spikelets finely hairy or several-seeded.
18. Spikes mostly less than y& inch (3 mm) wide ; seed-bear- ing units (spikelets) finely hairy, 1-seeded; a fine row of hairs (ligule) present at base of upper side of blade where it joins the sheath.
19. Stems and leaf sheaths hairy; seeds (spikelets) nar- rowly oval, the inner hull brownish.
LARGE CRABGRASS (Digitaria sanguinalis) p. 22 19. Stems and leaf sheaths almost without hairs; spike- lets broadly oval, the inner hull (when mature) black. SMOOTH CRABGRASS (Digitaria ischaemum) p. 22 18. Spikes broader than y& inch (3 mm) ; spikelets smooth, bearing several seeds ; ligule a fine membrane rather than a row of hairs. GOOSEGRASS (Eleusine indica) p. 24 16. Inflorescences not of 2 to 5 spikes or, if spikelike, bristly or long-hairy.
20. Seed-bearing units (spikelets) without bristles (awns), sometimes with sharp points to Vs inch (3 mm) long. 21. Spikelets oblong, several-seeded, with several or numer- ous hulls (lemmas) overlapping in shinglelike fashion. 22. Spikelets with about 6 overlapping hulls, leaves with- out glands; turf weed.
ANNUAL BLUEGRASS (Poa annua) p. 34 22. Spikelets with more than 10 overlapping hulls, con- spicuously flattened, leaves with small, bumpy glands, especially along edges (hand lens) ; waste area weed. STINKGRASS (Eragrostis c/7/anens/s)10 p. 25 21. Spikelets oval, 1-seeded, without a series of shinglelike hulls.
'"Two additional species of Eragrostis are common late-summer, waste area or roadside weeds ; usually in dry soil.
276
23. Inflorescences diffusely branched (a panicle), the spikelets usually separated from one another at the tips of the ultimate branchlets; plants annuals. 24. Spikelets (seeds) about the size of sorghum seeds or a bit smaller, 1/4 inch (6 mm) or more long. 25. Spikelets paired, one larger and hard, the other short-stalked and soft ; spikelets and axis with fine hairs (hand lens needed).
SHATTERCANE (Sorghum bicolor) p. 39
25. Spikelets not paired, all of the same kind; spikelets without hairs (glabrous).
WILD PROSO MILLET
(Panicum miliaceum) p. 33
24. Seeds about the size of bluegrass seeds, much smaller than sorghum seeds and less than Vi inch (6 mm) long.
26. Plant erect or ascending, densely hairy.
WITCHGRASS (Panicum capillare) p. 31 26. Plant prostrate-spreading or ascending, smooth. FALL PANICUM
(Panicum dichotomiflorum) p. 32
23. Inflorescences various but not a diffuse panicle; sometimes a series of spikes or appearing almost spikelike (the branches ascending and pressed to- gether), or the spikelets irregularly congested. 27. Inflorescences sticking up beyond leaves, irregu- larly congested and lopsided, or consisting of an aggregation of short spikelets, each shelling down to a hard, broad, shiny hull ; plant annual, husky, with stems usually more than yfc inch (6 mm) in diameter; ligule absent.
BARNYARDGRASS (Echinochloa crusgalli) p. 23 27. Inflorescences usually overtopped by some of the leaves, not lopsided, but narrow and spikelike in appearance or a series of spikes; plants often wiry or slender-stemmed; ligule present. 28. Plants perennial from scaly rhizomes ; seed head usually evident; weeds of cultivated soil. 29. Inflorescence axis hairy ; spikelets ("seeds") nearly i/i inch (6 mm) wide. WOOLLY CUPGRASS
(Eriochloa villosa) p. 26
29. Inflorescence axis without hairs; spikelets tiny, less than V& inch (3 mm) wide. WIRESTEM MULHY
(Muhlenbergia frondosa) p. 29
28. Plants annual, without rhizomes; seed head
spikelike, often nearly hidden in upper leaf
sheaths; a weed usually of dry, sterile areas.
ANNUAL DROPSEED
(Sporobolus neglectus) p. 41
277
20. Spikelets with short or long bristles or awns.
30. Inflorescences with dense, long, silky hairs, resembling a series of separate or congested plumes. 31. Plants 2 to 4 feet (0.6 to 1.2 m) tall, in small, erect clumps or bunches, without conspicuous rhizomes, lower portion of stem flattened with keeled edges. BROOMSEDGE (Andropogon virginicus) p. 15
31. Plants 4 to 12 feet (1.2 to 3.6 m) tall from creeping rhizomes.
SILVER PLUMEGRASS
(Miscanthus saccharifiorus) not illustrated 30. Inflorescences not silky-hairy; pubescence (hairs), if] present, relatively short ; plants various.
32. Bristles (awns) 3-branched (shorter unbranched bris- tles may also be present).
PRAIRIE THREEAWN (Aristida oligantha) p. 16 32. Awns unbranched.
33. Some or all awns spirally twisted at base.
34. Awn 3 to 4 inches (7.6 to 10 cm) long, several times length of seed, frequently twisted for much of its length.
PORCUPINEGRASS (Stipa spartea) p. 42 34. Awn scarcely more than 1 inch (2.5 cm) long, up to about twice the length of seeds, usually twisted near the base.
35. Spikelets about ^ inch (1.9 cm) long (ex- cluding awns), gaping open at the tip when mature, 2- to 3-seeded; plants annual, oat- like in appearance ; primarily western part of range.
WILD OAT (Avena fatua) p. 17 35. Spikelets (excluding awns) about 1/4 inch (6 mm) long, not opening at tip, 1-seeded; "seeds" (spikelets) plump, elliptic, straw- colored to shiny black; plants perennial or annual, resembling sorghum or sudangrass; primarily southern part of range. 36. Plants perennial from creeping rhi- zomes usually 3 to 6 feet (0.9-1.8 m) high; ripe spikelets ("seeds") with in- ner black hulls. JOHNSONGRASS
(Sorghum halepense) p. 40 36. Plants annual, 4 to 8 feet (1.2 to 2.4 m) high, sometimes to 12 feet (3.6 m) ; ripe spikelets various in color, com- monly tan. SHATTERCANE
(Sorghum bicolor) p. 39 33. Awns not spirally twisted.
37. Inflorescence open, branched (a panicle), sometimes appearing somewhat plumelike, the
278
spikelets usually well separated from one an- other; spikelets large, oblong, y2 to 34 inch (1.3-1.9 cm) long (excluding awns), with a series of hulls overlapping in shinglelike fash- ion and breaking into several seeds at matur- ity.
38. Stems essentially smooth and without hairs; awns usually rather short.
CHEAT (Bromus secalinus) p. 18 38. Stems finely hairy; awns long and con- spicuous.
39. Spikelets and seeds finely hairy; pan- icle rather dense, often turning reddish- purple at maturity and appearing plumelike ; spring-flowering. DOWNY BROME
(Bromus tectorum) p. 19 39. Spikelets and seeds not hairy; panicle more open, neither becoming reddish nor appearing plumelike ; late spring to summer flowering. JAPANESE BROME
(Bromus japonicus) p. 18
37. Inflorescence not open-branched, usually ir- regularly congested or very slender, the spike- lets crowded together; spikelets broadly or narrowly elliptic, 1-seeded, less than ^ inch (1.3 cm) long (excluding awns). 40. Plants annual, ascending or sprawling, husky, growing in the open ; stems usually more than Vi inch (6 mm) in diameter; inflorescence an irregular, often lopsided cluster of broadly rounded spikelets that are often covered with short bristles; lig- ule absent; annual of agricultural soil. BARNYARDGRASS
(Echinochloa crusgalli) p. 23 40. Plants commonly prostrate, rooting at nodes with ascending branches, often grow- ing in partial shade; stems less than 1/4 inch (6 mm) in diameter; inflorescence long and narrow; spikelets small, narrowly elliptic; ligule present; perennial, usually of shady turf. NIMBLEWILL
(Muhlenbergia schreberi) p. 30
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KEY 5. PLANTS WITH GREENISH FLOWERS, NOT GRASSES
1. Stem not leaf-bearing; leaves all in a basal cluster (rosette) at ground level. 2. Leaves broadly ovate or elliptic ; flower-producing portion of spike longer than stalk (peduncle) ; seeds irregular in shape, several in each seed pod (capsule).
3. Leaves glossy-green, almost without hairs; petioles usually purple at base; seeds black when mature (immature ones brownish).
BLACKSEED PLANTAIN (Plantago rugelii) p. 171
3. Leaves dull green or gray-green, covered with fine hairs ; petioles not purple ; seeds brown when mature.
BROADLEAF PLANTAIN (Plantago major) p. 171
2. Leaves lanceolate to linear; flower-producing portion of spike about as long as, or much shorter than peduncle ; seeds 2 in each capsule, and boat- shaped.
4. Plants perennial, usually appearing smooth; leaves narrowly elliptic to lance-shaped ; flowering spike less than 1/5 as long as stalk (peduncle) ; mature seeds glossy, without a white line on the concave side.
BUCKHORN PLANTAIN (Plantago lanceolata) p. 170 4. Plants annual; usually appearing hairy or woolly; leaves narrowly ob- long to linear ; flowering spike 1/3 as long or nearly as long as peduncle ; mature seeds not glossy, with an elliptic, white line on concave surface. 5. Bracts much longer than flowers and giving the spike a bristly ap- pearance; plants loosely hairy (villous) or occasionally smooth; most common in the southern part of our range.
BRACTED PLANTAIN (Plantago aristata) p. 169
5. Bracts mostly shorter than flowers and hidden by them; entire plant,
including spike, woolly; most common in western portion of our
range. WOOLLY PLANTAIN (Plantago purshii) p. 172
1. Stem leaf-bearing with opposite or alternate blades at time of flowering (a
basal rosette of leaves may or may not also be present).
6. Leaves palmately compound with 5 to 7 narrow leaflets arising fingerlike from the same point at end of leaf stalk. HEMP (Cannabis sativa) p. 47 6. Leaves various, not palmately compound.
7. Leaves fernlike, divided into numerous, narrow segments (1- or 2-pin- natifid) ; plants ragweedlike, topped by a spike (raceme) of yellowish- green, sterile, pollen-producing flowers (flower heads). 8. Leaves woolly beneath or on both sides; fruit a spiny bur, usually with 2 or 3 seeds; plants primarily of western portion of our range. 9. Leaves woolly beneath; stamen-producing flowers (flower heads) short-stalked ; fruits with straight spines.
SKELETONLEAF BURSAGE (Ambrosia tomentosa) p. 184
9. Leaves woolly on both sides; stamen-producing flowers (flower heads) slender-stalked ; fruits with curved spines.
WOOLLYLEAF BURSAGE (Ambrosia gray/) p. 184 8. Leaves not woolly; fruit 1-seeded, not a spiny bur; plants abundant throughout our range.
10. Plants annual, very common; leaves smooth above, usually much divided, the main segments being cut into secondary divisions (2- pinnatifid) ; fruits with a distinct crown of points at tip.
COMMON RAGWEED (Ambrosia artemisii/olia) p. 181 10. Plants perennial from creeping roots (first-year plants appear an- nual), similar in appearance to above, but much less common;
280
leaves rough on upper surface, less divided than in above species, the main segments frequently lobed but not again divided (1-pin- natifid) ; fruits with a very short crown of points or nearly smooth at tip. WESTERN RAGWEED (Ambrosia psilostachya) p. 182 7. Leaves not fernlike ; entire, toothed, or lobed but not pinnatifid (rarely lowermost leaves pinnatifid but the middle stem ones not) ; plants vari- ous. 11. Plant a twining or prostrate vine with tendrils.
12. Plant a twining vine ; leaves arrowhead- or spear-shaped ; fruit not burlike.
WILD BUCKWHEAT (Polygonum convolvulus) p. 51
12. Plant a prostrate vine with tendrils; leaves not arrowhead-shaped; fruit a prickly bur. BUR CUCUMBER (Sicyos angulatus) p. 178
11. Plant not a twining or tendril-bearing vine.
13. Stem encircled by a white or brownish membranous sheath (och- rea) for a short distance just above attachment of each leaf (this sheath is easily seen on younger parts of stem — it is frequently broken and partly destroyed on older portions) ; "seeds" (achenes) 3-angled.
14. Plants with a basal rosette of leaves as well as stem leaves (rosette blades may mostly be gone on old plants) ; flowers in a terminal branched spike ; seeds (achenes) shiny. 15. Leaves arrowhead-shaped (hastate) with pointed basal lobes; plants with creeping rootstocks; fruit hulls (calyx lobes) tightly appressed to fruit.
RED SORREL (Rumex acetosella) p. 53
15. Leaves not hastate; plants not possessing creeping root- stocks ; fruit hulls loose around fruit.
16. Leaves smooth and even, neither closely wavy along margin nor lobed at base ; fruiting hulls, when mature, about 1/4 inch (6 mm) long.
PALE DOCK (Rumex altissimus) p. 54 16. Leaves either closely wavy-crisped along margin or slightly basally lobed (cordate) ; fruiting hulls less than 1/4 inch (6 mm) long.
17. Leaves ovate to oblong, mostly somewhat cordate at base, frequently with reddish veins; fruit hulls toothed along margin.
BROADLEAF DOCK (Rumex obtusifolius) p. 55 17. Leaves oblong, with crisped or wavy-curved edges, rarely red-veined; fruit hulls not toothed.
CURLY DOCK (Rumex crispus) p. 55
14. Plants not possessing a basal rosette; flowers axillary ; "seeds" (achenes) usually dull.
18. Plants prostrate, forming flat mats or ascending at tips, or completely ascending, but only a few inches high; leaves blue-green, oblong to narrowly elliptic; a very common urban weed.
PROSTRATE KNOTWEED (Polygonum aviculare) p. 49 18. Plants ascending, frequently about 1 foot (0.3 m) high; leaves yellow-green, elliptic to broadly elliptic; less com- mon. ERECT KNOTWEED (Polygonum erectum) p. 49
281
13. Stem not encircled by a sheath as above described ; fruits various, not as above.
19. Leaves entire, neither toothed nor lobed. 20. Plants spiny.
21. Upper leaves narrow, hardened, and spine-tipped; seeds snaillike in appearance.
RUSSIAN THISTLE (Salsola kali) p. 61
21. Leaves all normal, the spines arising in pairs at base of leaf stalks ; seeds lens-shaped, black.
SPINY AMARANTH (Amaranthus spinosus) p. 66 20. Plants not spiny (fruit sometimes a spiny bur).
22. Plants with a milky juice ; leaves without stalks (ses- sile) or very short-stalked, strap-shaped or oblong; flower clusters yellowish-green or greenish-white.
23. Flowers with small greenish-white petals; leaves with very short stalks; fruit long and slender. HEMP DOGBANE (Apocynum cannabinum) p. 134 23. Flowers borne above yellowish-green bracts; leaves without stalks, strap-shaped ; fruit as wide as long. 24. Leaves about V& inch (3 mm) wide. CYPRESS SPURGE
{Euphorbia cyparissias) p. 117
24. Leaves usually Vi to V£ inch (6-13 mm) wide. LEAFY SPURGE (Euphorbia esula) p. 118 22. Plants not possessing milky juice; leaves stalked or sessile ; flower clusters not yellow-green. 25. Plant prostrate, forming a mat on ground. PROSTRATE PIGWEED
(Amaranthus blitoides) p. 63 25. Plants erect or ascending. 26. Plants woolly.
WOOLLY CROTON (Croton capitatus) p. 115 26. Plants smooth or hairy, but not woolly.
27. Plants perennial from creeping rootstocks ; leaves elliptic to oblong, not stalked (ses- sile), 2-veined; flower clusters borne in leaf axils; mostly western portion of our range. POVERTYWEED (Iva axillaris) p. 221 27. Plants annual; leaves various, not as above described; flower clusters (except for bushy- branched Amaranthus albus, below) in ter- minal branched spikes ; plants widely dis- tributed.
28. Leaves not stalked (sessile), narrowly strap-shaped (linear) to lanceolate ; seed brownish, longer than wide.
KOCHIA (Kochia scoparia) p. 60 28. Leaves stalked (petioled), ovate to lan- ceolate; seeds black when mature, circu- lar.
282
29. Plants bushy-branched, the main axis not dominating; flowers borne in clusters in leaf axils. TUMBLE PIGWEED
(Amaranthus a/6 us) p. 62 29. Plants branched or not, but the main axis predominant ; flowers in dense terminal spikes.
30. Spikes dense, bristly in appear- ance and somewhat prickly to touch ; leaves finely hairy, usually broadly lanceolate and upwards of 11/2 inches (3.8 cm) in width. 31. Spikes thick, the main portion more than 1/3 inch (1.3 cm) thick (this plant is not always clearly distinguishable from the following). REDROOT PIGWEED {Amaranthus retroffexus) p. 65 31. Spikes narrow, the main por- tion less than l/2 inch (1.3 cm) across. SMOOTH PIGWEED
(Amaranthus hybrid us) p. 64 30. Spikes often interrupted, and not especially dense, not bristly or prickly to touch; leaves smooth, usually narrowly lanceolate and less than 1 inch (2.5 cm) wide. TALL WATERHEMP (Amaranthus tuberculatus)n p. 67
19. Leaves, at least the lower, toothed (the teeth sometimes small or scattered) or lobed.
32. Fruit a bur covered with numerous hooked spines; leaves long-stalked, irregularly shallowly lobed and toothed, rough
COMMON COCKLEBUR (Xanthium strumarium) p. 240 32. Fruit not a spiny bur; leaves various.
33. Plants with milky juice, rarely more than 1 foot (0.3 m) high; leaves frequently with dark blotches or spots, all opposite. 34. Plants prostrate.
PROSTRATE SPURGE
(Euphorbia maculata) p. 119
34. Plants ascending, usually with slanting stems which frequently recurve at tip.
SPOTTED SPURGE (Euphorbia preslii) p. 119 33. Plants not possessing milky juice; leaves various, not spotted — if all opposite, the plants usually much taller than above described.
11 Some of the waterhemp found in the region is probably a hybrid complex among various species of waterhemp.
283
cluster
35. Leaves all alternate or the lowest in a basal
(a rosette as in pepperweed) ; the lower leaves not opposite.
36. Fruits circular, flat, each 2-seeded; flowers usu- ally with tiny white petals (close examination required). GREENFLOWER PEPPERWEED
(Lepidium densiflorum) p. 97
36. Fruits variously shaped, not flat, usually 1- seeded; flowers lacking petals. 37. Fruits produced in irregularly branched spikes that protrude beyond leaves, 1-seeded; seeds lens-shaped, usually black after being rubbed to remove scurf; plants not re- stricted to southern part of range. 38. Fruits (actually fruits plus enveloping calyx) with a marginal wing; upper por- tion of stem often nearly naked at ma- turity; leaves sharply sinuate-toothed; mostly limited to western portion of our range. WINGED PIGWEED
(Cycloloma atriplicifolium) p. 59 38. Fruits without a marginal wing; leaves retained at maturity, i.e., stem not be- coming naked; leaves variously toothed; plants not restricted to western portion of north central states. 39. Plants strongly aromatic; leaves ob- long, wavy-toothed or shallowly lobed, not white-mealy beneath. MEXICANTEA
(Chenopodium ambrosioides) p. 57 39. Plants not aromatic; leaves ovate to oblong, irregularly lobed, toothed or nearly entire, often white-mealy be- neath.
40. Seeds (easily rubbed out of hulls) about 1/16 inch (1.5 mm) in di- ameter; leaves dull green to green, often scurfy-whitish be- neath, the large blades usually not longer than 2 to 3 inches (5-7.5 cm) ; common weed. COMMON LAMBSQUARTERS (Chenopodium album) p. 57 40. Seeds 1/16 to ys inch (1.5 to 3 mm) in diameter; leaves bright green, the larger blades often 4 inches (10 cm) or more long; only locally common. MAPLELEAF GOOSEFOOT (Chenopodium hybridum) p. 58
284
37. Fruits solitary or in small clusters at base of upper leaves, often mostly hidden by the leaves, forming 2 to 4 seeds ; seeds usually turtle-shaped ; plants restricted to southern portion of our range. TROPIC CROTON
(Croton glandulosus) p. 115
35. Lower leaves opposite, the upper becoming alter- nate, or all leaves opposite. (If lowest leaves have fallen off, their position can be verified by noting leaf scars at stem nodes.)
41. Flower clusters produced in leaf axils and not protruding above leafy stem. 42. Leaves all opposite; stems frequently more than 2 feet (0.6 m) high, with stinging hairs; flower clusters slender, catkinlike, drooping from leaf axils. STINGING NETTLE (Urtica dioica) p. 48
42. Leaves mostly alternate, usually with insect holes; stems usually less than 2 feet (0.6 m) high, without stinging hairs ; flower clusters mostly hidden by toothed bracts in leaf axils. VIRGINIA COPPERLEAF
(Acalypha virginica) p. 114
41. Flower clusters in simple or branched spikes (racemes or panicles), entirely or in part borne apically on stem above leaves.
43. Seeds circular in outline, blackish, borne within a pair of pointed husks, which fit together in clamshell-like fashion; leaves often arrowhead-shaped (hastate). SPREADING ORACH
(A triplex patula) p. 56
43. "Seeds" (fruits) not circular, not borne as above described ; leaves not hastate. 44. Leaves narrow, usually with 1 or 2 up- ward-pointing teeth on each side; plants low, usually not much more than 1 foot (0.3 m) high, restricted to southern por- tion of our range. LANCELEAF RAGWEED
(Ambrosia bidentata) p. 181 44. Leaves broad and large, with numerous teeth, or 3- to 5-lobed; plants tall, often more than 3 feet (0.9 m) high. 45. Leaves, except sometimes for the uppermost, 3- to 5-lobed; fruits with a crown of points at tip. GIANT RAGWEED
(Ambrosia trifida) p. 183 45. Leaves unlobed ; fruits seedlike with- out a crown of points. MARSHELDER
(Iva xanthifolia) p. 222
285
KEY 6. PLANTS WOODY
Only four woody plants are illustrated in this circular. However, a num- ber of shrubs and trees often occur as brush in pastures and, under these conditions, are considered weeds. The following key includes some common brushy weeds.
Warning — Poison ivy and poison oak have compound leaves with three leaflets. Don't pick or handle leaves of this type. 1. Plants thorny or spiny. 2. Leaves simple.
3. Leaves entire ; fruit the size of a large orange, green.
OSAGEORANGE (Madura pomifera)
3. Leaves toothed or lobed; fruits like small crabapples, usually reddish.
HAWTHORN (Crataegus spp.) 2. Leaves compound.
4. Leaflets toothed ; shrubby plants.
5. Stipules (appendages at the base of the leaves) fused to petioles; flowers 1 inch (2.5 cm) or more across, roselike.
6. Robust bush, or tangle-forming shrub 6-10 feet (1.8-3 m) ; flowers usually white, the styles (see glossary if necessary) united into a single column, protruding and evident ; commonly weedy in brushy pastures. MULTIFLORA ROSE (Rosa multiHora)
6. Bushes or low shrubs much smaller than above ; flowers usually pink, the styles separate and not evident ; rarely weedy.
Other Rosa spp. including ARKANSAS ROSE (Rosa arkansana) p. 107
5. Stipules essentially free from petioles; flowers less than 1 inch (2.5 cm) across. BRAMBLES, WILD BLACKBERRIES (Rubus spp.) 4. Leaflets entire; trees.
7. Some of leaves twice-compound (i.e., the main divisions of the leaves, in turn compound) ; thorns various, becoming more than 1 inch (2.5 cm) long and branched. HONEYLOCUST (Gleditisa triacanthos) 7. Leaves all once-compound; thorns (spines) less than 1 inch (2.5 cm) long, unbranched. BLACK LOCUST (Robinia pseudoacacia)
1. Plants not thorny or spiny. 8. Leaves compound. 9. Leaves opposite.
10. Plant a vine with trumpet-shaped, orange-red flowers 2 to 3 inches (5-7.6 cm) long. TRUMPETCREEPER (Campsis radicans) p. 167 10. Plants shrubs or trees ; flowers small.
11. Flowers white, in conspicuous flat- or convex-topped clusters (corymbs) appearing in summer; fruit a small fleshy berry; twigs with conspicuous, light-colored bumps (lenticels).
ELDER (Sambucus spp.)
11. Flowers greenish-yellow, inconspicuous, appearing with or be- fore leaves; fruit dry, winged (a samara); twigs not as above. 12. Leaflets 3-5, conspicuously toothed or lobed ; young twigs usually with a whitish-waxy covering.
BOXELDER (Acer negundo)
286
12. Leaflets 5 to 7, entire or finely toothed; twigs not whitish waxy. ASH (Fraxinus spp.)
9. Leaves alternate.
13. Leaflets 3; fruits berrylike, white; plants trailing, climbing or form- ing small shrubs (poisonous to touch!).
POISON IVY (Rhus radicans) p. 121
13. Leaflets 5 or more, fruits not white; plants large shrubs or trees. 14. Fruits small, reddish "berries" in dense clusters at branch tips; leaves mostly with more than 9 leaflets. SUMAC (Rhus spp.) 14. Fruits hickory nuts; leaves of common kinds with 5 to 7 leaflets.
HICKORY (Carya spp.) Leaves simple, not divided into leaflets. 15. Plants evergreen, with needlelike or scalelike leaves. 16. Leaves needlelike, in clusters of 2 to 5 ; fruit a cone.
PINE (Pinus spp.)
16. Leaves overlapping scales, or, on young plants, sometimes like short needles (but not in clusters) ; fruit berrylike.
EASTERN REDCEDAR (Juniperus virginiana)
15. Plants with deciduous leaves (falling off in winter) that are neither scalelike nor needlelike.
17. Leaves opposite.
18. Leaves broad, palmately lobed; fruit dry. MAPLE (Acer spp.) 18. Leaves elliptic, entire; fruit a berry.
19. Stems viny or forming mats on the ground.
JAPANESE HONEYSUCKLE (Lonicera japonica) 19. Stems erect ; plants forming low shrubs.
BUCKBRUSH (Symphoricarpos spp.) 17. Leaves alternate.
20. Plants vinelike, trailing or climbing ; fruit a berry.
21. Plants with tendrils; leaves palmately lobed.
WILD GRAPE (Vitis spp.)
21. Plants without tendrils; leaves ovate and entire or with 1 or 2 irregular lobes at base; flowers resembling those of potatoes.
BITTER NIGHTSHADE (Solatium dulcamara) p. 161
20. Plants shrubs or trees; fruit various, usually not a berry.
22. Leaves lobed.
23. Leaves densely white-hairy beneath.
WHITE POPLAR (Populus alba) 23. Leaves not white-hairy underneath.
24. Leaves both lobed and serrate; fruit fleshy; plants
with milky juice. MULBERRY (Morus spp.)
24. Leaves not serrate; fruit an acorn; juice not milky.
OAK (Quercus spp.)
22. Leaves not lobed.
25. Leaves 3 to 5 times as long as wide (in common species) ; buds covered by a single hoodlike scale.
WILLOW (Salix spp.)
287
25. Leaves less than 3 times as long as wide ; buds various, usually with several overlapping scales. 26. Leaves palmately veined with 3 (sometimes 5) main veins from base of blade.
27. Leaves lopsided or asymmetric at base ; fruit fleshy, 1-seeded; bark usually with distinctive nar- row ridges or bumps. HACKBERRY (Celtis spp.) 27. Leaves essentially symmetric ; fruit if fleshy with several seeds.
28. Juice milky; fruits fleshy, several-seeded; leaf petioles scarcely flattened.
MULBERRY (Morus spp.)
28. Juice not milky; fruits dry with tiny air-borne seeds; petioles often flattened.
COTTONWOOD, POPLAR (Populus spp.) 26. Leaves pinnately veined, with one main vein from base of blade. 29. Leaves asymmetric (lopsided) at base.
ELM (Ulmus spp.) 29. Leaves symmetric.
30. Leaves nearly as broad as long, abruptly pointed; petioles flattened; buds sticky.
COTTONWOOD (Populus spp.) 30. Leaves various, but distinctly longer than wide; petioles not flattened; buds not sticky. 31. Leaf petioles with 1, 2, or several small glands at upper end; flowers white, con- spicuous; fruits fleshy.
WILD CHERRY (Prunus spp.) 31. Leaf petioles not bearing glands; flowers greenish, some of them in catkins; fruit dry.
32. Some of leaves crowded together on
short spurs; fruits in conelike clusters.
BIRCH (Betula spp.)
32. Leaves alternate, not crowded together ; fruit a nut enclosed in a husk.
HAZEL (Cory/us spp.)
288
COMMON WEED SEEDLINGS OF CORN AND SOYBEANS
These short keys list only the most common weed seedlings of the middle North Central states. The explanatory footnotes are grouped together follow- ing the keys.
Seven Annual Grasses1
1. Leaf sheaths (of all leaves, or just the lower) conspicuously pubescent. 2. All leaves pubescent.
3. Seedlings slender, the first leaves usually less than % inch (3 mm) wide; ligule a fringe of hairs (hard to see on first leaves) ; surface of leaf blades often without hairs.1 WITCHGRASS (Pan/cum capillare)
3. Seedlings quickly robust, second to third leaves usually V4 to ^ inch (6 to 9 mm) wide; ligule a membrane; surface of leaf blades usually hairy.' LARGE CRABGRASS (Digitaria sanguinalis)
2. Only lower two leaf sheaths pubescent, the remainder essentially without hairs. FALL PANICUM (Panicum dichotomittorum)
1. Leaf sheaths not pubescent or the hairs inconspicuous.
4. Seedlings with inconspicuous hairs on leaf sheath or blade as described below (foxtails). 5. Leaf blade with fine hairs over entire upper surface.4
GIANT FOXTAIL (Setaria faberi)
5. Leaf blade without hairs or with a few restricted to basal portion. 6. Leaf sheaths ciliate (with a line of hairs along edges).9
GREEN FOXTAIL (Setaria viridis)
6. Leaf sheaths not ciliate; instead a few filmy hairs present at base of blade (second to third leaf stage).
YELLOW FOXTAIL (Setaria lutescens)
4. Seedlings without hairs.
7. Ligule present.6 ' FALL PANICUM (Panicum dichotomifiorum)
7. Ligule absent.8 BARNYARDGRASS (Ecbinochloa crusgalli)
Seven Broadleaf Weeds
1. Cotyledons s/6 to li/$ inches (1.5 to 3 cm) long, more than 1/4 inch (6 mm) wide; leaves (above cotyledons) paired or nearly so.
2. Cotyledons more than 1 inch (2.5 cm) long.*
COMMON COCKLEBUR (Xanthium strumarium)
2. Cotyledons less than 1 inch (2.5 cm) long.10
COMMON SUNFLOWER (Helianthus annuus)
1. Cotyledons usually smaller than above; leaves plainly alternate when ex- panded (may appear paired when just starting to develop).
3. Cotyledons nearly as broad as long.11
VELVETLEAF (Abutilon theophrasti)
3. Cotyledons much longer than wide.
4. Cotyledons about y& inch (1.5 cm) long, Vfc inch (3 mm) wide; midvein scarcely discernible; surface even, not blotched."
PENNSYLVANIA SMARTWEED (Polygonum pensylvanicum)
4. Cotyledons about y& inch (1 cm) long, 1/16 inch (2 mm) wide, not possessing above combination of surface characters.
289
5. Cotyledons with good midvein, surface finely blotched; first leaves not as below. 6. Stem soon becoming hairy.
REDROOT PIGWEED (Amaranthus retroffexus) 6. Stem remaining glabrous.
TALL WATERHEMP (Amaranthus tuberculatus)
5. Cotyledons not possessing an evident midvein, surface not blotched; first leaves, especially undersurface, granular-mealy.
COMMON LAMBSQUARTERS (Chenopodium album)
Footnotes
1. Grass seedlings look alike. The identification characters are small, requiring good eyes or a hand lens and some knowledge of the structure of the grass leaf.
2. The grass leaf consists of three parts: (1) the blades; (2) the sheath, which is rolled into a tube around the stem, the edges usually overlapping; and (3) the ligule, which is a fringe of hairs or a narrow membrane, positioned at the juncture of the blade and sheath (on side next to stem). To see the ligules on grass seedlings, you must usually pull the leaf away from the stem and use a hand lens.
3. Seedlings of witchgrass and crabgrass are easily confused.
4. The first leaf of giant foxtail seedlings lacks the hairs but subse- quent ones have them. The hairs form a dense but inconspicuous covering. The young eyes of undergraduate students see them easily. Others can hold the leaf up to the light or use a hand lens. The furry covering on leaves of older plants can be felt by rubbing your finger over the upper surface — but this is a "no go" on seedlings.
5. The hairs are readily evident on well-developed plants, less so on seedlings. Hand lens may be necessary. If you can't see them, pull leaf off stem. Sometimes, the first sheath may have tiny hairs on surface as well as margin.
6. The ligule in fall panicum is a tiny fringe of hairs. It's necessary to pull the leaf away from the plant and use magnification to see it.
7. We have two crabgrasses. Large crabgrass is entered in the outline above. Smooth crabgrass (Digitaria ischaemum) lacks hairs entirely or, at the third to fourth leaf stage, has filmy hairs on margin of base of leaf blade. It will key out here, but differs from fall panicum in having a mem- branous ligule ; that of fall panicum is a fringe of hairs.
8. Barnyard grass is unusual in not possessing a ligule. The juncture of the leaf and blade is well marked by a whitish, almost bony area — but there is no ligule.
9. Common cocklebur seedlings are big, often with purple stems, and the cotyledons are inconspicuously glandular. The stem is somewhat hairy.
10. The stem below the cotyledons is smooth; that above is strongly hairy.
11. Velvetleaf seedlings are finely downy; the cotyledons are nearly as broad as long, have several veins, and are stalked.
12. We have several kinds of smartweeds. All have a membrane (ochrea) around stem just above the node; the ochreae are easily evident after 2 or 3 leaves have developed but not at the cotyledon stage. Ladys- thumb (Polygonum persicaria) is second to Pennsylvania smartweed in abundance. It has somewhat smaller seedlings. The upper edges of the ochreae have a fringe of hairs on ladysthumb but not on Pennsylvania smartweed.
290
GLOSSARY
Alternate (leaf arrangement). One leaf at each node of the stem.
Annual. A plant that lives a year or less.
Aromatic. Having an odor; fragrant.
Anther. The pollen-producing part of the stamen.
Auricle. One of a pair of lateral projections at juncture of sheath and blade of certain grass leaves.
Awn. A bristlelike tip; most frequently used to donote projections from glumes, lemmas, or paleas of grass spikelets.
Axil. The angle between a leaf and a stem in which branches or flowers may arise.
Axillary. Of or related to the axil.
Biennial. A plant that lives two years.
Bract. A modified, reduced leaf that subtends a flower or portion of an inflorescence.
Bulb. An underground, perennial storage organ consisting of a stem axis and numerous overlapping leaf scales.
Calyx. The outer whorl of flower parts; the sepals. The calyx is usually greenish and covers the other flower parts in bud.
Capsule. A dehiscent, dry, several-seeded fruit.
Caryopsis. The grass fruit; one-seeded, indehiscent; also called a grain.
Collar. Junction of the leaf blade and leaf sheath in grasses.
Complete flower. A flower possessing all flower parts: sepals, petals, sta- mens, and pistil(s).
Compound (leaf). A leaf divided into two or more distinct leaflets.
Cordate. Heart-shaped; usually used to describe leaves with a pair of rounded basal lobes.
Corolla. The petals; the usually colored flower parts immediately inside the calyx.
Cotyledons. Seed leaves; the first leaflike structures, usually paired, ap- pearing above ground in most dicotyledonous plants; e.g., cocklebur, soybean. The cotyledons are often thick and fleshy and serve as food storage organs for the embryo plant. The so-called cotyledon (scutel- lum) of monocotyledons; e.g., foxtails, corn, does not emerge from the seed.
Culm. The stem of a grass.
Decumbent. Sprawling, prostrate, but usually with young growth ascend- ing.
Dehiscent. Referring to a dry fruit that splits open at maturity, releasing the seeds; e.g., milkweed pods.
Dentate. Toothed, with the teeth directed at right angles to the edge; usually employed with reference to leaf margins.
Digitate. Having several parts or branches arising at or near the same point; fingerlike.
Dioecious. Referring to a plant with unisexual flowers, the pistillate and staminate flowers being borne by different individuals.
Disk. The central portion of flower heads of members of the composite family; it is composed of tubular flowers.
Dissected (leaf). A leaf whose blade is cut up into numerous, narrow lobes.
291
Entire. A leaf margin that is untoothed, smooth.
Filament. The stalklike portion of a stamen.
Floret. A grass flower and its surrounding lemma and palea; the word
floret is sometimes also used for a small flower in a dense cluster. Genus. A group of similar species such as the clovers (Trifolium) or the
bluegrasses (Poa). Glabrous. Without hairs.
Glaucous. Having a waxy whitish covering, a "bloom." Glume. One of the two sterile bracts at the base of a grass spikelet. Grain. The grass fruit; characterized by being one-seeded, indehiscent;
also called a caryopsis. Hastate. Spearhead-shaped; used especially to describe leaves with a
pair of basal lobes, these lobes directed outward. Head. An inflorescence in which the sessile flowers arise essentially at
more or less the same level from an enlarged stem tip; e.g., Canada
thistle. Herbaceous. Soft; lacking woody tissue. Used with respect to plants
without woody tissue or with reference to the above-ground parts
that do not live over winter.
Imperfect flower. A flower lacking either stamens or pistils; unisexual. Indehiscent. Referring to a fruit that does not split open and release
the seed or seeds at maturity; e.g., a peanut.
Inflorescence. A cluster of flowers, or the flower-bearing portion or por- tions of a plant.
Internode. Portion of a stem between nodes.
Involucre. A circle of bracts surrounding a flower cluster or single flower. Irregular. A flower with petals that differ in size; e.g., a bean flower. Lanceolate. Narrow and tapering from the base to the tip; e.g., a willow
leaf.
Leaflet. A secondary division of a compound leaf. Lemma. The larger of the two bracts surrounding a grass flower. Ligule. An appendage (a short membrane or row of hairs) on the upper
side of the grass leaf at the juncture of the leaf and blade. Linear. Long and narrow, with parallel margins, as the blade of a grass
leaf.
Lobed. Shallowly or deeply divided into usually rounded sections or di- visions; ordinarily employed with respect to leaves or leaf margins. Lyrate (leaf). Deeply cut, with a large rounded terminal lobe and lateral
lobes becoming smaller toward the base.
Membranous. Like a membrane, commonly brownish and translucent. Monoecious. A plant with unisexual flowers and both pistillate and
staminate flowers borne by the same individual. Node. That part of the stem from which leaves and branches arise. Nutlet. Seedlike fruit segment of the mints and related families. The
fruit splits longitudinally into four sections; each segment, shaped
like a quarter section of an apple, is a nutlet. Oblanceolate. Relatively narrow but broadening from the base to the
tip.
Obovate. Inversely ovate, egg-shaped in two dimensions, with the broad- est end upward.
292
Ochrea. A membranous sheath surrounding the stem immediately above attachment of the leaves in members of the smartvveed family.
One-celled. Referring to a pistil or ovary containing but a single chamber or cell inside.
Opposite (leaves). The leaves paired at each node.
Ovary. The basal portion of the pistil containing the ovules.
Ovate. Egg-shaped in two dimensions with the broad end at the attach- ment end; usually used to describe shape of leaves.
Palea. The smaller of the two bracts surrounding a grass flower.
Palmately compound. A compound leaf in which the leaflets all arise from the same point.
Panicle. A branched inflorescence.
Pappus. A cluster of fine hairs or scales born by the "seeds" (achenes) of some members of the composite family: e.g., dandelion or thistles.
Pedicel. The stalk of an individual flower.
Peduncle. The stalk of an inflorescence or part of an inflorescence, but not of an individual flower.
Perennial. A plant that may live several years.
Perfect (flower). A flower that contains both stamens and pistils.
Perigynium. A saclike structure surrounding the flower and fruit of plants belonging to the Carex genus.
Petal. A single member of the usually colored flower parts, collectively the corolla.
Petiole. The stalk of a leaf.
Pinnately compound (leaf). A compound leaf in which the leaflets are arranged feather-fashion along an elongate axis.
Pistil. The central female part of the flower that develops into the fruit.
Pubescent. Possessing hairs; hairy.
Pungent. With an acrid or biting flavor.
Raceme. An unbranched, elongating inflorescence in which the flowers are stalked.
Rachilla. A short stalk, usually appressed against the lower portion of the palea of certain grass "seeds" (florets). Rachilla-possessing florets originate from several-flowered spikelets. The rachilla represents that portion of the spikelet axis lying between the two contiguous florets.
Rachis. An axis bearing flowers or leaflets.
Ray (flower). Strap-shaped irregular flowers characteristic of the heads of certain members of the composite family. Ray flowers may con- stitute the entire head (e.g., dandelion) or make up the marginal petal- like flowers in head types possessing both ray and tubular flowers (e.g., daisy).
Regular. Referring to flowers in which petals are of the same size, the flower thus being radially symmetrical.
Rhizome. An underground creeping stem; most frequently characteristic of perennial grasses.
Rosette. A basal cluster of leaves not separated by evident intcrnodal stem elongation.
Rootstock. The underground overwintering part of a perennial herb; a rootstock may be either a rhizome (a stem) or a root.
293
Sagittate. Arrowhead-shaped; used especially to describe leaves hav- ing a pair of basal lobes, these lobes usually directed downward.
Scape. A leafless flowering stem arising from the ground; e.g., onions.
Sepal. A member of the outer whorl of flower parts, collectively the calyx. Usually the sepals are greenish and cover the other flower parts in bud.
Serrate. Toothed, the teeth slanting somewhat forward; usually employed with reference to leaf margins.
Sessile. A leaf or flower attached directly to the axis; without petiole or pedicel.
Sheath. The tubular lower portion of a grass leaf surrounding the stem.
Silique. The fruit of the mustard family; typically two-chambered, dry, usually dehiscent.
Simple (leaf). The leaf blade in one piece; not divided into separate leaflets.
Sinuate. Wavy; used especially to describe leaf margins.
Spatulate. Spoon-shaped.
Species. A distinct kind of plant, such as wheat, alfalfa, buckhorn plan- tain, or common ragweed.
Spike. An unbranched inflorescence in which the flowers or flowering units are sessile.
Spikelet. The basic flowering unit within a grass inflorescence; con- sisting of a condensed stem apex bearing a pair of sterile bracts (glumes) at base and one or more florets above.
Stamen. One of the male, pollen-producing organs of the flower.
Stigma. The terminal pollen-receptive portion of the pistil.
Stipules. Appendages, usually paired, arising from the stem at either side of petiole attachment; particularly characteristic of legume family.
Stolon. A prostrate stem or runner that roots at the nodes; e.g., straw- berry or bermudagrass.
Striation. A fine longitudinal line or streak.
Style. The stalklike part of the ovary that bears the stigma.
Subtend. To bear above; used especially with reference to a bract or a leaf that bears a flower in its axil.
Tuber. A swollen underground storage stem; e.g., a potato.
Tubular (flower). Regular flowers characteristic of many members of the composite family; such flowers may constitute the entire head, or form only the center portion of the head.
Umbel. An inflorescence in which the pediceled flowers arise essentially from the same point.
Utricle. A one-seeded fruit with a thin wall, often dehiscent with the top part (lid) falling off.
Whorled. A leaf arrangement in which three or more leaves are borne at each stem node.
Winter annual. An annual plant that usually initiates growth in the fall, lives over winter, and produces seed the following spring.
294
INDEX TO SPECIES
COMMON NAMES
Absinth wormwood, 188 Alyssum, hoary, 87 Amaranth, spiny, 66 American germander, 156 Annual bluegrass, 34
dropseed, 41
sowthistle, 235
wormwood, 189 Arkansas rose, 107 Aster, heath, 190
white heath, 191 Austrian fieldcress, 101
Ball mustard, 99 Barley, foxtail, 27
little, 27
Barnyardgrass, 23 Bedstraw, catchweed, 174 Beeplant, Rocky Mountain, 85 Beggarticks, devil's, 193 Bellflower, creeping, 179 Bermudagrass, 21 Bigroot morningglory, 143 Bindweed, field, 139
hedge, 140 Bitter nightshade, 161
sneezeweed, 214 Blackeyed Susan, 228 Black medic, 109
mustard, 88 Blackseed plantain, 171 Bladder campion, 77 Bluegrass, annual, 34 Blue lettuce, 223 Bluestem pricklepoppy, 84 Blue vervain, 148 Bouncingbet, 75 Bracken, 12 Bracted plantain, 169 Bristly foxtail, 37 Broadleaf dock, 55
plantain, 171 Brome, downy, 19
Japanese, 18 Broomsedge, 15 Broomweed, common, 213 Buckhorn plantain, 170 Buckwheat, wild, 51 Buffalobur, 163 Buffalo gourd, 176 Bull thistle, 202 Bur cucumber, 178
Burdock, common, 187
great, 187 Bursage, skeletonleaf, 184
woolly leaf, 184 Buttercup, smallflowcr, 82
tall, 83
Campion, bladder, 77 Canada thistle, 200 Carolina geranium, 112 Carpetweed, 70 Carrot, wild, 132 Catchfly, night-flowering, 78
sleepy, 76
Catchweed bedstraw, 174 Catnip, 154 Chamomile, false, 226 Cheat, 18 Chickweed, common, 80
mouse-ear, 73 Chicory, 197 Cinquefoil, rough, 106
silvery, 105
sulphur, 106
Clammy groundcherry, 158 Cockle, corn, 72
cow, 81
white, 74
Cocklcbur, common, 240 Common broomweed, 213
burdock, 187
chickweed, 80
cocklebur, 240
dandelion, 237
evcningprimrose, 129
lambsquarters, 57
mallow, 124
milkweed, 137
mullein, 165
pokeweed, 69
ragweed, 181
sneezeweed, 215
sunflower, 216
yarrow. 180
yellow woodsorrel, 111 Coneflower, cutleaf, 229 Copperleaf, Virginia, 114 Coreopsis, plains, 205 Corn cockle, 72
spurry, 79 Cow cockle, 81 Crabgrass, large, 22
295
Crabgrass, smooth, 22 Creeping bellflower, 179 Cress, hoary, 92 Croton, tropic, 115
woolly, 115 Cucumber, bur, 178
wild, 177
Cudweed, fragrant, 211 Cupgrass, woolly, 26 Cupplant, 231 Curly dock, 55 Cutleaf coneflower, 229 Cypress spurge, 117
Daisy, oxeye, 196 Dandelion, common, 237 Darnel, 28
Devil's beggarticks, 193 Devilsclaw, 168 Dock, broadleaf, 55
curly, 55
pale, 54 Dodder, 141 Dogbane, hemp, 134 Downy brome, 19 Dragonhead, 149 Dropseed, annual, 41 Dwarf fleabane, 204
mallow, 125
Eastern black nightshade, 162
whorled milkweed, 138 Erect knotweed, 49 Eupatorium, late, 209 European sticktight, 146 Eveningprimrose, common, 129
Fall panicum, 32 False chamomile, 226 Falseflax, largeseed, 90
smallseed, 90 Field bindweed, 139 Fieldcress, Austrian, 101 Field horsetail, 11
mint, 153
pennycress, 104
pepperweed, 96 Fleabane, dwarf, 204
rough, 207 Flodman thistle, 201 Flowering spurge, 116 Four-o'clock, wild, 68 Foxtail, bristly, 37
giant, 35
green, 38
yellow, 36
Foxtail barley, 27 Fragrant cudweed, 211
Galinsoga, smallflower, 210 Garlic, wild, 46 Geranium, Carolina, 112 Germander, American, 156 Giant foxtail, 35
ragweed, 183 Goatgrass, jointed, 13 Golden ragwort, 230 Goldenrod, gray, 232
rigid, 233
Goosefoot, mapleleaf, 58 Goosegrass, 24 Gourd, buffalo, 176 Gray goldenrod, 232 Great burdock, 187 Greenflower pepperweed, 97 Green foxtail, 38 Groundcherry, clammy, 158
smooth, 159 Ground ivy, 150 Gumweed, 212
Hare's ear mustard, 93 Hawksbeard, smooth, 206 Hawkweed, orange, 219
yellow, 220 Heal-all, 155 Heath aster, 190 Hedge bindweed, 140
mustard, 103 Hemlock, poison, 131 Hemp, 47
Hemp dogbane, 134 Henbit, 151 Hoary alyssum, 87
cress, 92
vervain, 148
Honeyvine milkweed, 135 Hop sedge, 43 Horsenettle, 160 Horsetail, field, 11 Horseweed, 204 Houndstongue, 145
Indian mustard, 88 Ironweed, tall, 239
western, 239 Ivy, ground, 150 Ivyleaf morningglory, 142
Japanese brome, 18 Jerusalem artichoke, 218 Jimsonweed, 157
296
Johnsongrass, 40 Jointed goatgrass, 13
Knapweed, Russian, 195
spotted, 194 Knotweed, erect, 49
prostrate, 49 Kochia, 60
Ladysthumb, 52 Lambsquarter, common, 57 Lanceleaf ragweed, 181 Large crabgrass, 22 Largeseed falseflax, 90 Late eupatorium, 209 Leafy spurge, 118 Lettuce, blue, 223
prickly, 224
tall, 224
Licorice, wild, 108 Little barley, 27 Longspine sandbur, 20
Mallow, common, 124
dwarf, 125
Venice, 123
Mapleleaf goosefoot, 58 Marshelder, 222 Maximilian sunflower, 217 Mayweed, 186 Medic, black, 109 Mexicantea, 57 Milkweed, common, 137
eastern whorled, 138
honey vine, 135
swamp, 136 Millet, wild proso, 33 Mint, field, 153 Morningglory, bigroot, 143
ivyleaf, 142
tall, 142
Moth mullein, 165 Motherwort, 152 Mouse-ear chickweed, 73 Muhly, wirestem, 29 Mullein, common, 165
moth, 165 Musk thistle, 199 Mustard, ball, 99
black, 88
hare's ear, 93
hedge, 103
Indian, 88
tansy, 94
Mustard, tumble, 102 wild, 89 wormseed, 95
Narrowleaf vetch, 110 Nettle, stinging, 48 Night-flowering catchfly, 78 Nightshade, bitter, 161
eastern black, 162
silverleaf, 160 Nimblewill, 30 Nutsedge, yellow, 44
Oat, wild, 17 Onion, wild, 46 Orach, spreading, 56 Orange hawkweed, 219 Oxeye daisy, 196
Pale dock, 54 Panicum, fall, 32 Parsnip, wild, 133 Pennsylvania smartweed, 52 Pennycress, field, 104 Pepperweed, field, %
greenflower, 97
Virginia, 98
Perennial sowthistle, 234 Pigweed, prostrate, 63
red root, 65
smooth, 64
tumble, 62
winged, 59 Pineappleweed, 227 Plains coreopsis, 205 Plantain, blackseed, 171
bracted, 169
broadleaf, 171
buckhorn, 170
woolly, 172
Plantainleaf pussytoes, 185 Plumeless thistle, 198 Poison hemlock, 131
ivy, 121
Pokeweed, common, 69 Poor joe, 173 Porcupinegrass, 42 Povertyweed, 221 Prairie sunflower, 216
threeawn, 16
Pricklepoppy, bluestem, 84 Prickly lettuce, 224 Pricklypear, 128 Prickly sida, 126
297
Prostrate knotweed, 49
pigweed, 63
spurge, 119
vervain, 147 Puncturevine, 113 Purslane, 71 Purslane speedwell, 166 Pussytoes, plantainleaf, 185
Quackgrass, 14
Radish, wild, 100 Ragweed, common, 181
giant, 183
lanceleaf, 181
western, 182 Ragwort, golden, 230 Red root pigweed, 65 Red sorrel, 53 Rigid goldenrod, 233 Rocket, yellow, 86 Rocky Mountain beeplant, 85 Rose, Arkansas, 107 Rough cinquefoil, 106
fleabane, 207 Rush, slender, 45 Russian knapweed, 195
thistle, 61
St. Johnswort, 127 Salsify, western, 238 Sandbur, longspine, 20 Scotch thistle, 203 Sedge, hop, 43 Shattercane, 39 Shepherd's purse, 91 Sida, prickly, 126 Silverleaf nightshade, 160 Silvery cinquefoil, 105 Skeletonleaf bursage, 184 Skeletonweed, 225 Sleepy catchfly, 76 Slender rush, 45 Smallflower buttercup, 82
galinsoga, 210 Smallseed falseflax, 90 Smartweed, Pennsylvania, 52
swamp, 50 Smooth crabgrass, 22
groundcherry, 159
hawksbeard, 206
pigweed, 64 Snakeroot, white, 208 Sneezeweed, bitter, 214
common, 215
Snow-on-the-mountain, 120 Sorrel, red, 53 Sowthistle, annual, 235
perennial, 234
spiny, 235
Spanishneedles, 192 Speedwell, purslane, 166
thymeleaf, 166 Spiny amaranth, 66
sowthistle, 235 Spotted knapweed, 194
spurge, 119
waterhemlock, 130 Spreading orach, 56 Spurge, cypress, 117
flowering, 116
leafy, 118
prostrate, 119
spotted, 119 Spurry, corn, 79 Sticktight, European, 146 Stinging nettle, 48 Stinkgrass, 25 Sulphur cinquefoil, 106 Sunflower, common, 216
Maximilian, 217
prairie, 216 Swamp milkweed, 136
smartweed, 50
Tall buttercup, 83
ironweed, 239
lettuce, 224
morningglory, 142
thistle, 202
waterhemp, 67 Tansy, 236 Tansy mustard, 94 Teasel, 175 Thistle, bull, 202
Canada, 200
Flodman, 201
musk, 199
plumeless, 198
Russian, 61
Scotch, 203
tall, 202
Threeawn, prairie, 16 Thymeleaf speedwell, 166 Toadflax, yellow, 164 Tropic croton, 115 Trumpetcreeper, 167 Tumble mustard, 102
pigweed, 62
298
Velvetleaf, 122 Venice mallow, 123 Vervain, blue, 148
hoary, 148
prostrate, 147
white, 148
Vetch, narrowleaf, 110 Virginia copperleaf, 114
pepper weed, 98
Waterhemlock, spotted, 130 Waterhemp, tall, 67 Waterpod, 144 Western ironweed, 239
ragweed, 182
salsify, 238 White cockle, 74
heath aster, 191
snakeroot, 208
vervain, 148 Wild buckwheat, 51
carrot, 132
cucumber, 177
four-o'clock, 68
garlic, 46
Wild licorice, 108
mustard, 89
oat, 17
onion, 46
parsnip, 133
proso millet, 33
radish, 100 Winged pigweed, 59 Wirestem muhly, 29 Witchgrass, 31
Woodsorrel, common yellow, 1 1 1 Woolly croton, 115
cupgrass, 26 Woollyleaf bur sage, 184 Woolly plantain, 172 Wormseed mustard, 95 Wormwood, absinth, 188
annual, 189
Yarrow, common, 180 Yellow foxtail, 36
hawkweed, 220
nutsedge, 44
rocket, 86
toadflax, 164
SCIENTIFIC NAMES
Abutilon theof>hrasti, 122 Acalypha virginica, 114 Achillea millefolium, 180 Aegihps cylindrica, 13 Agropyron repens, 14 Agrostemma githago, 72 Allium canadense, 46
vineale, 46 Amaranthus albus, 62
blitoides, 63
hybridus, 64
retroflexus, 65
spinosus, 66
tuberculatus, 67 Ambrosia artemisiifolia, 181
bidentata, 181
grayi, 184
psilostachya, 182
tomentosa, 184
trifida, 183
Ampelamus albidus, 135 Andropogon z-irginicus, 15 Antennaria plantaginifolia, 185 Anthemis cotula, 186
Apocynum cannabinum, 134 Arc Hum lap pa, 187
minus, 187
Arycmonc intermedia, 84 Aristida oligantha, 16 Artemisia absinthium, 188
annua, 189 Asclepias incarnata, 136
syriaca, 137
verticil lata, 138 Aster ericoides, 190
pilosus, 191 A triplex fatula, 56 A vena fatua, 17
Barbarea vulgaris, 86 Berteroa incana, 87 Widens bipinnata, 192
frondosa, 193 Brassica juncea, 88
kaber, 89
nigra, 88 Bromus jafonicus, 18
secalinus, 18
tectorum, 19
299
Came Una microcarpa, 90
saliva, 90
Campanula rapunculoides, 179 Campsis radicans, 167 Cannabis sativa, 47 Capsella bursa-pastoris, 91 Cardaria draba, 92 Carduus acanthoides, 198
nutans, 199 Career lupulina, 43 Cenchrus longispinus, 20 Centaurea maculosa, 194
re pens, 195
Cerastitim vulgatum, 73 Cheno podium album, 57
ambrosioides, 57
hybridum, 58
Chrysanthemum leucanthemum, 196 Cichorium intybus, 197 Cicuta maculata, 130 Cirsium altissimum, 202
arvense, 200
flodmani, 201
vulgare, 202 Cleome serrulata, 85 Conium maculatum, 131 Conringia orientalis, 93 Convolvulus arvensis, 139
sepium, 140 Cony^a canadensis, 204
ramosissima, 204 Coreopsis tinctoria, 205 Crepis capillaris, 206 Croton capitatus, 115
glandulosus, 115 Curcurbita foetidissima, 176 Cuscuta spp., 141 Cycloloma atriplici folium, 59 Cynodon dactylon, 21 Cynoglossum officinale, 145 Cyperus esculentus, 44
Datura stramonium, 157 Daucus car ota, 132 Descurainia pinnata, 94 Digitaria ischaemum, 22
sanguinalis, 22 Diodia teres, 173 Dipsacus sylvestris, 175 Dracocephalum parviflorum, 149
Echinochloa crusgalli, 23 Echinocystis lobata, 177
Eleusine indica, 24 Ellisia nyctelea, 144 Equisetum arvense, 11 Eragrostis cilianensis, 25 Engeron strigosus, 207 Eriochloa villosa, 26 Erysimum cheiranthoides, 95 Eupatorium serotinum, 209
rugosum, 208 Euphorbia corollata, 116
cyparissias, 117
<?jM/a, 118
maculata, 119
marginal a, 120 /u, 119
Galinsoga pann flora, 210 Galium aparine, 174 Geranium carolinianum, 112 Glechoma hederacea, 150 Glycyrrhiza lepidota, 108 Gnaphalium obtusifolium, 211 Grind elia squarrosa, 212 Gutierrezia dracunculoides, 213
Helenium amarum, 214
autumnale, 215 Helianthus annuus, 216
maximiliani, 217
petiolaris, 216
tuberosus, 218 Hibiscus trionum, 123 Hieracium aurantiacum, 219
pratense, 220 Hordeum jubatum, 27
pusillum, 27 Hypericum perforatum, 127
Ipomoea hederacea, 142
pandurata, 143
purpurea, 142 /m axillaris, 221
xanthifolia, 222
Juncus tenuis, 45 Kochia scoparia, 60
Lactuca canadensis, 224
pulchella, 223
serriola, 224
Lamium amplexicaule, 151 Lappula echinata, 146
300
Leonurus cardiaca, 152 Lepidium campestre, 96
densiflorum, 97
virginicum, 98 Linaria vulgaris, 164 Lolium temulentum, 28 Lychnis alba, 74 Lygodesmia juncea, 225
Malva neglecta, 124
rotundifolia, 125 Matricaria tnaritima, 226
matncarioides, 227 Medicago lupulina, 109 Mentha arvensis, 153 Mirabilis nyctaginea, 68 Mollugo verticillata, 70 Muhlenbergia frondosa, 29
schreberi, 30
Nepeta cataria, 154 Neslia paniculata, 99
Oenothera biennis, 129 Onopordum acanthium, 203 Opuntia spp., 128 Oxalis stricta, 111
Panicum capillare, 31
dichotomiflorum, 32
miliaceum, 33 Pastinaca saliva, 133 Phy salts heterophylla, 158
subglabrata, 159 Phytolacca americana, 69 Plantago aristata, 169
lanceolata, 170
major, 171
purshii, 172
rugelii, 171 Poo annua, 34 Polygonum aviculare, 49
corcmeum, 50
convolvulus, 51
erectum, 49
pensylvanicum, 52
persicaria, 52 Portulaca oleracea, 71 Potentilla argentea, 105
norvegica, 106
rec/a, 106 Proboscidea louisianica, 168
Prunella vulgaris, 155 Pteridium aquilinum, 12
Ranunculus abortivus, 82
arm, 83
Raphanus raphanistrum , 100 /?/IMJ radicans, 121 Rorippa austriaca, 101 T?OJO arkansana, 107 Rudbeckia hirta, 228
laciniata, 229 Rumex acetosella, 53
altissimus, 54
crispus, 55
obtusifolius, 55
Salsola kali, 61 Saponaria officinalis, 75 Senecio aureus, 230 Setaria faberi, 35
lutescens, 36
verticillata, 37
viridis, 38
Sicyos angulatus, 178 ^t'Ai spinosa, 126 Silene antirrhina, 76
cucubalus, 77
noctiflora, 78 Silphium perfoliatum, 231 Sisymbrium altissimum, 102
officinale, 103 Solanum carolinense, 160
dulcamara, 161
elaeagnifolium, 160
ptycanthum, 162
roj/ra/um, 163 Solidago nemoralis, 232
rigida, 233 5o«fAuj arvensis, 234
asper, 235
oleraceus, 235 Sorghum bicolor, 39
halepense, 40 Spergula arvensis, 79 Sporobolus neglectus, 41 Stellaria media, 80 .S"/t/>a spartea, 42
Tanacetum vulgare, 236 Tara^-arMm officinale, 237 Teucrium canadense, 156 T Mas pi arvense, 104
301
Tragopogon dubius, 238 Verbena stricta, 148
Tribulus terrestris, 1 13 urtici folia, 148
Vernonia altissima, 239 Urtica dioica, 48 baldwini, 239
Veronica peregrina, 166
Vaccaria segetalis, 81 serpyllifolia, 166
Verbascum blattaria, 165 FtVta angustifolia, 110
thaf>sus, 165
Verbena bracteata, 147 Xanthium strumarium, 240
hastata, 148
302
INDEX TO FAMILIES
Aizoaceae, 70 Amaranthaceae, 62-67 Anacardiaceae, 121 Apocynaceae, 134 Asclepiadaceae, 135-138
Bignonia, 167 Bignoniaceae, 167 Bluebell, 179 Borage, 145-146 Boraginaceae, 145-146 Buckwheat, 49-55
Cactaceae, 128 Cactus, 128 Caltrop, 113 Campanulaceae, 179 Cannabaceae, 47 Caper, 85 Capparaceae, 85 Carpetweed, 70 Caryophyllaceae, 72-81 Cashew, 121 Chenopodiaceae, 56-61 Compositae, 180-240 Composite, 180-240 Convolvulaceae, 139-143 Crowfoot, 82-83 Crucifcrae, 86-104 Cucurbitaceae, 176-178 Cyperaceat, 43-44
Dipsacaceae, 175 Dogbane, 134
Equisetaceae, 11 Euphorbiaceae, 114-120 Eveningprimrose, 129
Fern, 12
Figwort, 164-166 Four-O'Clock, 68
Geraniaceae, 112 Geranium, 112 Goose foot, 56-61 Gourd, 176-178 Gramineae, 13-42 Grass, 13-42 Guttiferae, 127
Hemp, 47 Horsetail, 11 Hydrophyllaceae, 144
Juncaceae, 45
Labiatae, 149-156 Legume, 108-110 Leguminosae, 108-110 Liliaceae, 46 Lily, 46
Madder, 173-174 Mallow, 122-126 Malvaceae, 122-126 Martynia, 168 Martyniaceae, 168 Milkweed, 135-138 Mint, 149-156 Morningglory, 139-143 Mustard, 86-104
Nettle, 48
Nightshade, 157-163 Nyctaginaceae, 68
Onagraceae, 129 Oxalidaceae, 111
Papaveraceae, 84 Parsley, 130-133 Phytolaccaceae, 69 Pigweed, 62-67 Pink, 72-81
Plantaginaceae, 169-172 Plantain, 169-172 Pokeweed, 69 Polygonaceae, 49-55 I'olypodiaceae, 12 Poppy, 84 Portulacaceae, 71 Purslane, 71
Ranunculaceae, 82-83 Rosaceae, 105-107 Rose, 105-107 Rubiaceae, 173-174 Rush, 45
St. Johnswort, 127 Scrophulariaceae, 164-166 Sedge, 43-44 Solanaceae, 157-163 Spurge, 114-120
Teasel, 175
Umbelliferae, 130-133 Urticaceae, 48
Verbenaceae, 147-148 Vervain, 147-148
Waterleaf, 144 Woodsorrel, 111
Zygophyllaceae, 113
303
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