114 FAMILIES OF FLOWERING PLANTS 
more of the petals spurred at the base. Our common “Dutchman’s 
breeches,” species of Bikukulla, 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 groups by 
the peculiarity of their stamens, two of 
which are shorter than the other four; 
this condition is called tetradynamous 
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 
partition; in fruit 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. While the flow- 
ers are very much alike in most of the 
genera, being white, yellow or pink in 
color, the differences in the fruit 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 
wee pied elena tre, Weeds of early spring; others are exclus- 
with one valve turned back showing seeds; ively alpine; a few are garden vegeta- 
SReieee: Cae 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 (Thysano- 
carpus curvipes). : 
The cabbage and turnip belong to the genus Brassica, the former 
vegetable consisting of the mass of young leaves compacted into a 
