PASSIFLORIN^. 



479 



so large that they not only meet in the centre, but also fill up the 

 ovary as far as the wall of the pericarp. The whole interior of the 

 fruit thus becomes a juicy mass in which three lines may be seen, 

 meeting in the centre (the boundaries of the individual placenta?), 

 and near the circumference 6 groups of seeds (Fig. 518 D). When 

 the carpels are equal in number to the petals they alternate with 

 them. The style is short and thick, and generally divided into 3 

 (4-5) branches, with a horse-shoe shaped stigma on each branch 



FIG. 518. Citrullus colocyntltis : A (J-flower, cut open and spread out; B stamen; 

 C ? -flower in long section ; h receptacle ; ca calyx; D transverse section or 1 ovary. 



(Fig. 518 C). The fruit is most frequently a many-seeded berry; 

 in some it attains a considerable size and has a firm external layer 

 (Gucurbita, Lagenaria, etc.). The embryo is straight, has no endo- 

 sperm, but contains a large quantity of oil. The exceptions to the 

 above characters will be found under the genera. 



Exclusively herbs, generally with stiff hairs and yellow flowers. 

 Many species are annuals, others are perennial, having tuberous 

 roots or hypocotyls. The leaves are scattered, long-stalked, in 

 most cases more or less heart-shaped, palminerved, palmilobed, 



