GEKANiACE^E 297 



4. Endosperm is wanting and the embryo straight and 

 fleshy in Tropaeolum, Limnanthes, Flcerkea, Impatiens, and 

 Hydrocera, belonging to three different tribes, which some 

 authors consider distinct Orders. The ovary of Tropseolum is 

 trilobed, three-celled, and contains a single pendulous ovule 

 in each cell, with a superior micropyle. The fruit is at first 

 fleshy, but when mature becomes a schizocarp, breaking up 

 into three indehiscent cocci, which fall away from the short 

 persistent axis, and have hardened, rugose walls, ultimately 

 becoming dry and cortical. The seed is exalbuminous, and 

 the straight embryo consists of two thick and fleshy closely 

 applied or almost conferruminate cotyledons, which, together 

 with the extremely short radicle, completely fill the cavity of 

 the seed, which again fills the carpel. 



When the embryo is still very young, the cotyledons are 

 oval or transversely oblong, entire, deep green, and diverging 

 widely. Later on they become broadly cordate, and deeply 

 concave on the inner faces. At a further stage they become 

 fleshy, and form more or less completely a sphere, while the 

 notch at the base becomes deeper until distinct auricles are 

 produced. Finally they become closely applied to one another 

 but separable, while the basal auricles become quite close, 

 embedding the radicle, and leaving only its extreme tip exposed. 

 At the same time they lose their green colour, and, being 

 globose, completely fill the seed. The fruit, seed, and embryo 

 of Flcerkea conform very closely in structure to those of Tro- 

 pseolum, while Limnanthes differs in having five carpels. The 

 fruit of neither is fleshy, and the receptacle or tbalarnus is 

 nearly flat, while the carpels are beakless. The cotyledons are 

 thick, fleshy, and cordate at the base, enclosing the very short 

 radicle. The fruit of Impatiens is a five-celled capsule, the 

 valves of which on maturity spring elastically from the pla- 

 centas, from the base upwards, and roll backwards or down- 

 wards from the top inwards. The seeds of I. parviflora (fig. 233) 

 are pendulous, anatropous, obovoid, and marked longitudinally 

 with lines of minute protuberances. The chalaza is apical, 

 forming a small thickened knob externally to the testa, which 

 is here slightly indented. The embryo is straight, and the 

 cotyledons obovate-oblong, fleshy, plano-convex, subcordate at 



