104 GROUND FEEDS. 
impunity. This is also true of seeds like Wormseed Mus- 
tard, small quantities of which have proved fatal to pigs. 
Certain other animals are similarly immune. One farmer 
tells of a flock of geese which he fed on mill screenings 
containing a large percentage of Frenchweed seeds. The 
geese became very fat, and presented such a fine appear- 
ance that he planned to present a number of them to 
friends at Christmas. On preparing one of them for the 
table, however, it was found that the flavour of French- 
weed was so strong as to render the flesh unfit for food. 
@O 
oo q 
Fig. 24.—Seeds of Field Pennycress—Thlaspi arvense. Five times 
natural size. 
Needless to say the original plan for the disposition of the 
flock was altered. 
The plant, which is another introduction from Europe, 
has spread to the prairies, where it is a troublesome weed. 
It is an erect, smooth, light green plant. The 
radicle leaves are petioled and lance-shaped, 
while those on the stem are spear-shaped. 
with coarse teeth and a sagittate base. The clear whit: 
flowers are one-eighth of an inch in diameter and open, as 
in other mustards, in a flat cluster at the end of an elong- 
ating raceme. The flat seed pods are very characteristic. 
The Plant 
and Seeds 
