544 DICOTYLEDONES. 



regular; corolla-lobes oblique, aestivation twisted. The stamens 

 are individually free, and the pollen-grains are free or at most 

 united in fours (see Asclepiadaceae). The two carpels have 2-oo 

 ovules, in all cases there is only 1 style and a capitate stigma, 

 which towards the base is widened out into a disc-like table (stigma- 

 disc) abstricted in the centre ; but the carpels in most of the 

 genera (e.g. those mentioned below) are entirely separate, and the 

 fruit consists of two follicles, the seeds of which often have a tuft 

 of woolly hairs projecting from the micropyle, less frequently of 

 two drupes. In some other genera there is a 1-locular (provided 

 with 2 parietal placentae) or a 2-locular ovary becoming a 2- 

 valved capsule or a berry. Endosperm abundant. 



Vinca (Periwinkle) has a salver-shaped corolla, which is twisted 

 to the left in sestivation (i.e. the left edge of the petals is free) ; 

 nectaries 2, alternating with the carpels; the summit of the style 

 is hairy. Follicles ; seeds without hairs. Mostly creeping, perennial, 

 evergreen plants, whose large flowers are apparently axillary ; in reality they 

 are terminal, but by the development of the bud in the axil of one of the two 

 uppermost leaves, they are thus displaced over the other leaf of the pair 

 {a helicoid sympodium being formed). Plumeria, Taberncemontana, Cerbera 

 (drupe). Aspidosperma. 



Nerium (Oleander). The leaves are in whorls of 3. Corolla 

 funnel-shaped, in aestivation twisted to the right, and with a corona 

 resembling that of Lychnis. The anthers are prolonged at the 

 the base and each also bears at the apex a long, linear, hairy 

 appendage ; these finally become spirally twisted. Follicles ; 

 seeds hairy. Apocynum, Echites, etc. Epigijnum is epigynous. 



124 genera, 1,000 species ; principally in the Tropics. Only 2 species of 

 Vinca are natives of this country ; the following are cultivated as ornamental 

 plants : Vinca minor, V. major, V. (Lochnera) rosea, Amsonia salicifolia, 

 Nerium oleander (Eastern Mediterranean). The latex of some is poisonous 

 (Tanghinia venemfera, Cerbera). Caoutchouc is obtained from others (Han- 

 kornia, Landolphia, Vahea, etc.). Tough bast is frequently developed. The 

 bark of Aspidosperma quebracho and the seeds of Strophanthus hispidus are 

 used in medicine (also for African arrow-poison), the latter is officinal. 



Order 3. Asclepiadaceae. A natural and easily recognised 

 order, closely allied to the Apocynaceee, having, .like it, frequently 

 a poisonous latex, opposite, single, entire leaves and fundamentally 

 the same floral diagram and floral structure (S5, P5, A5, G2) ; 

 but in some the aestivation of the corolla is valvate. The carpels 

 here also have free ovaries, but are united for some distance above 

 into a large, shield-like, ^-angular head, having on its under-side 



