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MAY im 


FEB 1 2 19?5 

EB 1 1 1975 
IdEC 4 198 

L161 — O-1096 






Associate Curator of the Herbariuu 

Leaflet 17 



The Botanical Leaflets of Field Museum are designed to give 
brief, non-technical accounts of various features of plant life, especially 
with reference to the botanical exhibits in Field Museum, and of the 
local flora of the Chicago region. 


No. 1. Figs $ .10 

No. 2. The Coco Palm 10 

No. 3. Wheat 10 

No. 4. Cacao 10 

No. 5. A Fossil Flower 10 

No. 6. The Cannon-ball Tree 10 

No. 7. Spring Wild Flowers .25 

No. 8. Spring and Early Summer Wild Flowers . . .25 

No. 9. Summer Wild Flowers 25 

No. 10. Autumn Flowers and Fruits 25 

No. 11. Common Trees 25 

No. 12. Poison Ivy 15 

No. 13. Sugar and Sugar-making 25 

No. 14. Indian Corn 25 

No. 15. Spices and Condiments 25 

No. 16. Fifty Common Plant Galls of the Chicago Area .25 

No. 17. Common Weeds 25 


. OCT 161934 


Field Museum of Natural History 

Chicago. 1934 numbek 17 
Copyright 1934 by Fikld Museum op Natukai. Hmtoky 



(Rumez crispus) 

Like most of our commonest weeds, yellow dock is an 
immigrant from Eiirope, brought long ago to America, 
and now thoroughly established in almost all regions as a 
pernicious weed of cultivated and waste ground. It grows 
from a thick yellow parsnip-like root, and has succulent 
wavy leaves. The small green flowers are followed by 
dense brown clusters of winged fruits, each containing 
a single 3-angled achene or "seed." 

In spite of its weedy nature, the plant is of some 
utility to man, for its leaves often are gathered in spring 
to be cooked and eaten as "greens." Several other kinds 
of dock grow plentifully about Chicago, some of them 
European in origin, others native American plants. 
(Buckwheat family.) 

Field Museum of Natural History 


{Setaria viridis) 
A tall grass, with bright green flower spikes, in appear- 
ance much like cultivated millet. Even more abundant 
is the common foxtail, which has tawny yellow spikes. 
Both these grasses are abundant in summer in fallow 
fields where oats and wheat have been cut, and one or the 
other inhabits almost every vacant city lot. (Grass family.) 

Common Weeds 


{Cenchrus pauciflorus) 
Barefooted children know this grass to their sorrow. 
The sharp-pointed spines of its burs penetrate the skin 
easily, and are extracted with difficulty. They will even 
pierce the leather of shoes. In the Chicago region the 
sandbur grows mostly in sandy fields and on the dunes, 
but it often invades cultivated fields and pastures. When 
the plants are too plentiful in hayfields, the crop is worth- 
less, for cattle will not eat hay filled with burs. This is 
so pernicious a weed that no labor should be spared to 
prevent its entry into ground not already infested with 
it. (Grass family.) 

Field Museum of Natural History 


{Polygonum lapathifolium) 
Several different kinds of smartweed grow about 
Chicago. Some are tall plants, and others low, but all 
agree in having spikes of small, white, red, or pink flowers, 
which often are rather showy. The smartweeds, as a 
rule, prefer moist or wet ground. (Buckwheat family.) 

Common Weeds 


(Polygonum Convolvulus) 

Although black bindweed belongs to the same genus 
or group as smartweed, the plants are very unlike in habit 
and general appearance. Bindweed is a slender vine that 
forms dense tangles over other weeds and shrubbery. It 
is a great nuisance if it becomes established among garden 
shrubs, for the stems are so numerous, and so tightly 
twisted about the branches of the shrubs, that it is difficult 
to remove them. 

Black bindweed is a close relative of cultivated buck- 
wheat, and it is sometimes called wild buckwheat. Its 
black "seeds" or achenes resemble buckwheat, except for 
being much smaller. The minute flowers are white or 
tinged with pink. (Buckwheat family.) 

Field Museum of Natural History 


{Amaranthus hyhridus) 
Several kinds of pigweed are all too common every- 
where in cultivated and waste ground. Some are low 
plants that spread closely over the ground; one is a bushy 
tumbleweed that may be seen blowing across the fields 
in winter; this is a tall and ugly plant that grows thickly 
in gardens in late summer after cultivation is discon- 
tinued. (Pigweed family.) 

Common Weeds 

{Chenopodium album) 
No weed is more plentiful in gardens and cultivated 
fields than this, and it thrives equally well in waste ground, 
reaching sometimes the size of a large shrub, and develop- 
ing almost woody stems. All parts of the plant are covered 
with extremely minute, pale globules, that give a whitish 
or grayish cast to the foliage. It often is called pigweed. 
(Goosefoot family.) 






1 •. 

Common Weeds ii 


(Salsola pestifer) 

Russian thistle is one of the worst pests among our 
weedy plants of European origin. Imported from Eastern 
Europe with seed grain about fifty years ago, it spread 
across the United States with astounding rapidity, and 
caused great alarm among farmers. A huge volume of 
printed matter was published regarding it. However, 
in the Eastern States climatic conditions did not suit the 
plant, and in the West it was found that it could be held 
in check with proper cultivation. 

Few weeds are more aggressive than this in the Chicago 
Region, where it occupies most of the city lots, and large 
areas of the dunes along the lake shore. After the thick, 
bushy, somewhat spiny plants have been killed by frost, 
their short roots are easily pulled from the soil, and as 
tumbleweeds they are blown about by the wind, until 
they finally come to rest against some fence or thicket. 
Thus they distribute their seeds with almost mechanical 
efficiency. (Goosefoot family.) 


Field Museum of Natural History 

-<V'^.- .,"-^.^y^^J^-.-;'' "'■ 


{Cycloloma atriplicifolium) 
Red tumble weed, or winged pigweed as it is sometimes 
called in books, is similar in its habits to the Russian 
thistle, but a much less aggressive plant. It thrives only 
in sandy soil, especially on the dunes, where it springs up 
in early summer, grows rapidly, and reaches maturity at 
the end-of the summer. It is then a plant of neat bushy 
habit, beautifully tinted with red and purple. This hand- 
some coloration disappears with the first frost, when the 
plants turn black. After they are torn from the ground, 
they are so brittle that they soon are broken apart. 
(Goosefoot family.) 

Common Weeds 



{Portulaca oleracea) 

If one of the succulent matlike plants of pusley is 
pulled from the ground and placed on a board in the 
sun, it will continue to open its small bright yellow flowers 
every morning, and the leaves will not wither for weeks. 
It is this quality of persistence that makes the plant such 
a pest in vegetable gardens, where it is difficult to destroy 
it unless the plants are pulled and removed to a dump heap. 

Pusley is a palatable vegetable if gathered when young 
and cooked like spinach, to which it is little inferior, and 
in some regions it is much used in this way. Although 
so common in America, this is another plant introduced 
from Europe. Its seed pod opens by a lid or cap, and 
exposes the small, black seeds. (Purslane family.) 

14 Field Museum of Natural History 

(Melilotus alba) 
The white flowers of sweet clover are pretty, and the 
fragrance of the fohage is agreeable, but the plant is an 
aggressive weed, esteemed only by bees, which make 
honey from it. Yellow sweet clover, with yellow blossoms, 
also is a common weed. (Pea family.) 

Common Weeds 


{Abutilon Theophrasti) 
The original home of this plant is believed to be India, 
but it is now abundant in cornfields throughout eastern 
United States. The yellow flowers are rather showy. 
The large gray leaves resemble flannel. The seed pods 
have a starlike form, being composed of twelve to fifteen 
pointed compartments, each with several dark seeds. 
(Mallow family.) 


Field Museum of Natural History 


(Verbena stricta) 
Several kinds of vervain, much alike in general appear- 
ance, grow in the Chicago region. Although not bad 
weeds in cultivated ground, they are plentiful in waste 
places. This one is a rather showy plant, two to three 
feet high or more, with dense spikes of small but brilliant 
purple flowers. The foliage is whitish or grayish, because 
of the dense covering of pale hairs. (Verbena family.) 

Common Weeds 




{Plantago major) 

In lawns even dandelions are no worse a pest than 
plantain. The short thick bases of the plants are fixed 
firmly in the soil by many long tough roots, and few weeds 
are more difficult to dig from the ground. Plantain has 
no apparent use, except that its seeds are eaten by birds, 
but the fondness of these creatures for seeds is not suffi- 
cient to decrease the abundance of the plant. 

Plantain was introduced long ago from Europe, and 
is said to have spread across the continent almost as 
rapidly as man. The explanation of this phenomenon 
is that the mucilaginous seeds become sticky when wet 
and adhere to shoes and to the feet of animals, which 
ensures their wide distribution. (Plantain family.) 


Field Museum of Natural History 


{Erigeron cana(hnsis) 
Of all the weeds of cultivated ground and waste land, 
none is less graceful or more ordinary in appearance than 
this. It is a tall plant, with spindling stems, in late 
summer almost devoid of foliage. The extremely small 
flower heads are greenish or whitish. (Sunflower family.) 

Common Weeds 



{Xanthium spp.) 
Cockleburs thrive best in low alluvial ground, but they 
grow luxuriantly in most of Chicago's vacant lots. The 
hard burs, covered with short spines, are familiar objects. 
Some of the spines are hooked, and thus the burs become 
attached to clothing, so that they are scattered widely. 
The burs sometimes remain in the soil for several years 
before germinating. (Sunflower family.) 


Field Museum of Natural History 


{Ambrosia artemisiaefolia) 
Ragweed is in some respects the most important of 
all our weeds, because it is the principal cause of hay 
fever, which, from August until frost, causes discomfort 
for many thousands of persons. This malady is induced 
by pollen from various plants, but the most important 
agent is ragweed pollen. (Sunflower family.) 

Common Weeds 



(Ambrosia trifida) 
Giant ragweed, also, causes hay fever. If not so 
abundant as common ragweed, the greater size of the 
plants and their quantities of pollen compensate for their 
lesser number. Giant ragweed grows in city lots, but 
reaches its greatest vigor in alluvial soil. (Sunflower 


Field Museum of Natural History 


{Iva xanthiifolia) 
Closely related to the ragweeds, marsh elder is much 
like them in appearance. (Sunflower family.) 

Common Weeds 



(Galinsoga parviflora) 
This is an insignificant weed of slight general interest 
or importance, but almost every one in Chicago must 
have seen it. It is the one plant that seems to prosper 
in the courts of apartment buildings, where there is too 
much shade for most plants, and the soil is heavy and 
sour. It is surprising to learn that this is a native of 
tropical mountains. It is one of very few northern weeds 
that have come from Mexico. (Sunflower family.) 


Field Museum of Natural History 

Common Weeds 25 


{Helianthus annuus) 

The sunflower is a native American plant. It grows 
in the greatest profusion almost anywhere about Chicago, 
and in late summer forms handsome displays of brilliant 
color in vacant lots and poorly cultivated ground. It 
grows almost equally well in sand, loam, or clay soils. 

The sunflower is a coarse tall plant of almost tropical 
appearance. In cultivation there have been developed 
numerous ornamental forms, some with double flowers 
or with quilled rays or "petals;" others with rays of brown 
or deep red. The flower heads of cultivated plants often 
attain a great size, with a diameter of twelve inches or 
more; and proportionally large seeds. 

In some parts of Europe the sunflower is grown exten- 
sively for its seeds, which are rich in oil. They have a 
sweet and pleasant flavor, and in Russia are eaten in 
large quantities, like peanuts. They are a favorite food 
of many birds, and also suitable for poultry and caged 

. The sunflower is properly a plant of the western 
prairies, and probably did not grow originally in the 
Chicago region, in spite of its great abundance at the 
present time. (Sunflower family.) 


Field Museum of Natural History 

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{Anthemis Cotula) 
Barnyards are the favored habitat of dogfennel, but 
it grows almost as well in vacant lots, and especially on 
the borders of country roads. It is a low bushy weed, 
one to two feet high, with white daisylike heads scarcely 
an inch broad. (Sunflower family.) 

Common Weeds 



(Arctium minus) 
In spring the huge, Hmp, heart-shaped leaves of this 
plant develop, to be followed soon by the stiff flower stalks 
with their globular heads of purple or lilac flowers. The 
heads are covered with green bracts, each tipped with a 
hooked spine. (Sunflower family.) 


Field Museum of Natural History 

{Cirsimn arvense) 
The plant pest most dreaded by farmers of Illinois and 
Indiana is the Canada thistle, a weed so pernicious that 
its destruction is ordered by state laws. The long under- 
ground rootstocks cause it to spread rapidly and make 
its eradication difficult. The rose-purple heads are all 
too handsome for so vile a weed. (Sunflower family.) 

Common Weeds 


{Lactuca Scariola) 
Prickly lettuce grows profusely in gardens in sum- 
mer after cultivation has ceased, and it thrives in all 
waste ground, even the most sterile. Its pale yellow 
flower heads ripen into heads of seeds, each of which 
bears a tuft of hairs, enabling it to be carried long distances 
by the wind. Prickly lettuce, a relative of garden lettuce, 
is a native of Europe. (Sunflower family.) 


Field Museum op Natural History 


(Sonchiis asper) 

Sow thistle is found commonly in the sour soil of 

city alleys or barnyards, and grows almost anywhere 

that the down-tufted seeds fall. It is a succulent plant, 

with milky sap and yellow flower head. (Sunflower family.) 

Common Weeds 



{Taraxacum officinale) 
One of the earliest flowers of spring, blooming some- 
times even in winter, there is no dispute that the dandelion 
is a beautiful plant, but when it invades lawns and 
crowds out the grass, their owner has little admiration 
for the plant. It is one of the plant immigrants from 
Europe that could best be spared. (Sunflower family.) 

This is the fifth of a series of Field Museum Leaflets 
dealing with some of the common and conspicuous plants 
of the Chicago region. The earlier ones treat of the 
flowers of spring, spring and early summer, summer, and 

The photographs of the following plants were obtained 
from L. W. Brownell: green foxtail, goosefoot, pusley, 
sweet clover, plantain, galinsoga, mayweed, and dandelion.