CRUCIFERAE MUSTARD FAMILY 
FIELD PENNYCRESS. MITHRADATE MUSTARD 
Thlaspi arvense L. 
The Field Pennycress is a smooth annual which is not 
common in the southern part of the state but becomes more 
frequent farther north and in Canada is often a pernicious weed. 
It is a native of Asia and Europe and 
from the latter was introduced into 
this country. It blooms from June to 
September. 
This plant grows in fields, roadsides 
and waste places, is 6-18 inches high 
and usually somewhat branched above, 
though frequently simple in colonies. 
The basal leaves are petioled but they 
soon disappear and then all the leaves 
are like those shown, oblong or lanceo- 
late, slightly dentate and sessile by 
arrow-shaped bases. They are alternate 
as in all Mustards. 
The numerous small flowers are 
white, each of the 4 petals being about 
one-eighth of an inch long. There are 
6 very short stamens and a single pistil 
with a flattened ovary, which in fruit 
becomes enlarged to a diameter of one- 
half inch and is distinctly winged. This | 
pod is longitudinally divided, with 2-8 
seeds in each half. | 
Wild Peppergrass or Birdseed, Lepz- 
dium virginicum L., is a very common smooth annual of yards and 
waste places alike. It grows up to 1 foot high and becomes much 
branched as the season advances. The leaves are variable, the 
obovate or spatulate basals having large terminal lobes and small 
lateral ones, and the small, very numerous and linear or lanceolate 
stem leaves are more or less toothed and sessile. The small white 
flowers are born at the summit of elongating racemes. Stamens are 
2. The flat round fruits are notched at the apex, about one-eighth 
inch across, and have 2 cells each containing 1 seed. Seed-eating 
birds like the fruits. Illinois is well within the range of this plant, 
which is from Quebec to Minnesota, south to Florida, Texas and 
Mexico. The blooming season is June to September. 
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