THE DICOTYLEDONS 529 
a corymb or shortened raceme, later elongating into a loose 
raceme. Bracts at base rarely reduced, usually absent. Flowers 
regular, rarely irregular (Candytuft), tetramerous. Sepals four, 
green, equal, or two laterals at times pouched as nectar recep- 
tacles. Petals four, yellow, white, pink or purple, cruciform, 
often divisible into claw and blade. Stamens six, four being 
long and anteroposterior in position, two being short and lateral, 
Fic. 399.—The Black Mustard, Brassica nigra—Branch. (‘Sayre.) 
hence termed tetradynamous, insertion hypogynous. Pistil 
syncarpous, bicarpellate, superior, carpels lateral. Ovary one- 
celled but falsely two-celled by a placental replum (a spurious 
membranous partition dividing the ovary into 2 locules); style 
simple; stigma rounded or bifid or bilobed. Ovules several, 
rarely few, attached to marginal placenta. F ruit a siliqua, as in 
the mustards or silicule, as in the shepherd’s purse (Capsella) 
rarely indehiscent, bursting lengthwise by two valves. Seeds 
exalbuminous with folded cotyledons. (See Fig. 400.) 
