CRUCIFERAE— THLASPI 



495 



Thlaspi arvense. Field pennycress, Frenchweed or Stinkweed 



A smooth annual with small white flowers; pod, broadly winged, about 

 Yi inch in diameter, deeply notched at top. Commonly naturalized in some 

 places; becoming more abundant in the Northwest. A common weed in grain 

 fields. It is common in the Canadian Northwest and not infrequent in Iowa 

 and Minnesota, abundant in the Dakotas. 



Poisonous properties. Probably causes counter-irritation. In the Canadian 

 Rockies the weed is carefully avoided by stock because of its pungent properties. 



Fig. 258. Field Pennycress 

 (Thlaspi arvense). (After 



Fitch). 



Capparidaceae. Caper Family 



Herbs, shrubs or, occasionally, trees; alternate leaves and cruciform flowers ; 

 sepals 4-8; petals 4 or none; stamens 6-numerous, not tetradynamous ; fruit 

 a 1-celled pod or berry with 2 parietal placentae; seeds similar to those of the 

 Cruciferae, but with the embryo coiled. An order of about 35 genera and 

 400 species. Generally found in warm regions, few in the United States. 

 The plants are often acrid or pungent; the flower-buds of one, the Caper 

 (Capparis spinosa), are pickled. Several of the species like the Rocky Moun- 

 tain bee plant are cultivated for ornamental purposes. A few of the plants are 

 weedy. 



Capparis contains the coloring matter rutin. 



Genera of Capparidaceae 



Plants clammy pubescent. 



Stamens 8 or more 2 Polanisia 



Plants not clammy pubescent. 



Stamens 6, pod few seeded 3 Cleomella 



Stamens 6, pod many seeded 1 Cleome 



1. Cleome L. 



Glabrous annuals ; leaves trifoliolate or simple ; flowers in leafy bracted 

 racemes; petals entire, with claws; stamens 6; pistil with a 1-celled ovary; 



