100 NATURE STUDY AND AGRICULTURE 
stamens, one pair being shorter than the other pair. The 
plant is a foot or two in height and is covered with short, white 
hairs ; the branches are nearly erect, the leaves, 
very narrow. Another gerardia, often found in 
the same places, is a smaller plant, has smaller 
flowers, and is smooth to the touch instead of 
rough. 
45. Zygadenus: Swamp Camas. — Bears 
handsome greenish white flowers at the end ofa 
straight and slender stem that is a foot or two 
high. The leaves are narrow and parallel- 
veined ; the entire plant is very smooth and has 
the structure and general appearance of a small 
lily. It grows from a bulb, in moist places. 
A related species with yellowish flowers is poisonous to stock. 
46. Canada Milk Vetch.—A sturdy plant of the Pea 
family, standing quite erect, 2 or 3 feet high, and bearing 
large racemes of greenish white flowers. These are not 
pretty, but usually attract attention as 
the plant is large and quite conspicu- 
ous. The pods remain on the old plants 
all winter. 
There are many other, but smaller, 
species of milk vetches growing on the 
prairies. They were given this name 
in Europe because a certain member of 
the group was supposed to increase the 
yield of milk from goats that fed upon 
it. Our Canada milk vetch, however, 
is too tough for stock to eat. 
47. Thistle. — The common wild thistle of our prairies 
is the wavy-leaved thistle with purple flowers. It is a harm- 
ZYGADENUS 
Canapa MILK VETCH 
