APOCYNACE.E 217 



ovules in each carpel are usually geminate or few and arranged 

 in a double series, or indefinite and arranged in many series, 

 very rarely solitary. They are frequently inserted by the 

 ventral surface, peltate and amphitropous, or almost ana- 

 tropous and pendulous, very seldom erect as in some species 

 of Acokanthera and Vallesia. The fruit may consist of one 

 undivided piece, and be indehiscent, fleshy or rarely dry and 

 hard or samaroid ; in many other cases the two carpels are 

 merely united at the base or are entirely free, and the 

 fruit is baccate, drupaceous and indehiscent, or follicular and 

 dehiscing by the ventral suture, liberating the linear placentas. 

 Rarely the fruit is united into one piece or the carpels dehisce 

 by two valves. The seed is very variable in outline, and is 

 sometimes peltate and sessile, but oftener more or less com- 

 pressed with the ventral face flat or concave, and affixed to 

 the placenta by the middle or higher up by a filiform funicle. 

 The testa is membranous or subcoriaceous and occasionally 

 produced into a wing, or develops at one or both ends into a 

 tuft of long cottony hairs. The endosperm is fleshy or almost 

 cartilaginous, but is often restricted to a thin layer and some- 

 times entirely absent. The embryo is large, straight, and 

 almost equals the endosperm in length as well as width, with 

 foliaceous and flat, concave, rarely convolute or twisted coty- 

 ledons. The radicle is terete and shorter, rarely longer than 

 the cotyledons and superior, very rarely pointing to the base 

 of the fruit. There are several exceptions to the general rule 

 in the Order. Undivided and dehiscent fruits occur in Chilo- 

 carpus and Allamanda, with distinct carpels dehiscing by two 

 valves in Aspidosperma. Endosperm is wanting in Aspido- 

 sperma, Willughbeia, Cerbera and allied genera, Leuconotis 

 and Carpodinus ; it is ruminated in Alyxia and in several 

 other genera of the tribe PlumeriaB. The margins of the coty- 

 ledons are infolded in Adenium, folded together in Holarrhena, 

 convolute in Wrightia, and much twisted in Kickxia. The 

 radicle is inferior in Vallesia and some species of Eauwolfia. 

 Acokanthera Thunbergii is notable for its baccate two-celled 

 fruit, containing a large peltate seed in each cavity. The coty- 

 ledons of the embryo are foliaceous, roundly ovate and petiolate, 

 about equalling the radicle and petioles in length. 



