ROSE FAMILY 



483 



pistil forms a pod known as the silique. The four petals, when 

 opened out, suggest the Greek cross, whence the name Cru- 

 ciferae (Fig. 1^.29). 



To this family belong such useful plants as the Cabbage, 

 Turnip, Kohlrabi, Brussels Sprouts, and Rape. 



A number of plants of this family, such as Peppergrass, 

 Shepherd's Purse, White and Black Mustard, Tumbling Mus- 

 tard, Indian Mustard, and Charlock are weeds. Their seeds 



FIG. 429. The character of the 

 plant, flowers, and fruit of the Black 

 Mustard (Brassica nigra). At the 

 right, a plant in flower (X^), and a 

 mature pod about natural size; at the 

 left, above, a flower, and below, an 

 open pod. After Vasey and Nature. 



FIG. 430. 

 One of the Pop- 

 pies, showing 

 the character of 

 the flowers and 

 pod. After Le- 

 comte. 



are troublesome impurities in commercial seeds, and the seeds 

 of some are poisonous. 



Associated with the Mustard family is the Poppy family 

 (Papaveraceae), characterized by a milky juice and represented 

 by Bloodroot, common in the woods, and by the California 

 Poppy from the juice of which opium is obtained (Fig. 4$0). 



Rose Family (Rosaceae). To this family belong about 2000 

 species of herbs, shrubs, and trees. In most plants of this 

 family, there is an indefinite number of stamens and one to 

 many separate carpels. The flowers of Strawberries and Black- 

 berries, for example, have many stamens and many separate 



