MUSTARD FAMILY. 103 
The seeds are either olive brown or greenish yellow, 
slightly roughened, oblong, angular, and about one- 
twenty-fifth of an inch long. The radicle shows up prom- 
inently through the thin seed coat, the grooves on each 
side being darkened. The palisade cells of this seed, like 
those of Wild Mustard, form a cherry red compound 
with chloral hydrate and hydrochloric acid. 
Fig. 23.—Seeds of Tumbling Mustard—Sisymbrium altissimum. 
Five times natural size. 
FIELD PENNYCRESS—Thlaspi arvense L. 
Other Common Names: Frenchweed, Stinkweed. 
The seeds of this plant are pungently bitter, and sick- 
ening to taste, owing to a peculiar oil. For this reason 
they are seldom eaten by pigs, on which such 
Effect of seeds have the strongest effects. Samples with 
iy ™ accompanying complaints indicate that consid- 
erable quantities of shorts and bran have been 
made unfit for use as feed for pigs owing to the unpal- 
atableness of the Field Pennycress seeds. If eaten, the 
plant and seeds have the same poisonous effect as 
the other plants of the mustard family. On some ani- 
mals this effect is less apparent than on others. It would 
seem, for example, that rabbits can eat the seeds with 
