114 



FAMILIES OF FLOWEEING PLANTS 



more of the petals spurred at the base. Our common "Dutchman's 

 breeches," species of BikukuUa, are good examples of this division of 

 the family. 



A narcotic property is present in the milky juice of most Papaver- 

 aceae, but is particularly prominent in Papaver, and it is from the juice 

 of P. somniferum that the drug opium is obtained. 



Family Cruciferae. Mustard or Cress 

 Family. The Cruciferae are distin- 

 guished easily from related gi'oups by 

 the peculiarity of their stamens, two of 

 which are shorter than the other four; 

 this condition is called teiradynamous 

 by botanists. The plants are herbs, with 

 a watery pungent juice, the flowers hav- 

 ing 4 petals and 4 sepals after the pat- 

 tern of a cross, whence the name Crucif- 

 erae is derived. The ovary consists of 

 two united carpels, separated by a thin 

 l)artition; in fiiiit it becomes a 2-celled 

 pod-like fruit known as a silique; in a 

 few exceptional cases it is indehiscent 

 (not splitting open at maturity), and is 

 then called a loment. TVHiile the flow- 

 ers are very much alike in most of the 

 genera, being white, yellow or pink in 

 color, the differences in the fmit and 

 seeds are very considerable. It is this 

 fact that renders the Cruciferae a very 

 difficult one for the beginner. 



The family contains about 190 genera 

 and 1500 species, of very wide distribu- 

 tion, but most abundant in temperate 

 regions. Many of them are common 

 weeds of early spring; others are exclus- 

 ively alpine; a few are garden vegeta- 

 bles, and some are even cultivated for 

 ornament. Figure 96 shows one of the yellow marsh cresses of the 

 genus Rorippa, which also includes the common water-cress. Another 

 type of fruit may be seen in the next illustration (Fig. 97), which rep- 

 resents a delicate little Californian annual known as lace-pod {Thysaiio- 

 carpus curvipes). 



The cabbage and turnip belong to the genus Brassica, the former 

 vegetable consisting of the mass of young leaves compacted into a 



Fig. 98. Flowering branch and sepa- 

 rate pod of Brassica cainpestris, the latter 

 with one valve turned back showing seeds; 

 all natural size. Original. 



