SECT. II 



PHANEROOAMIA 



651 



This genus affords one of the best examples <>! si-a>on;il dimorphism, i.e. the split- 

 ting of a species into two closely related forms which develop at different season.-. 

 Since the height of the vegetative period of the Alpine meadows coincides with 

 their annual mowing, this expresses itself in the distinction of an early form, fruiting 

 before the meadows are cut, and a late form developing after this has taken place. 

 Eri/thraea, Centaury (Fig. 722), anthers spirally twisted. Menyanthes, Bog-Bean, 

 with alternate, trifoliolate leavt-> 

 and long-stalked racemes of white 

 flowers with hairy petals. Lim- 

 nanthcmum, aquatic plants with 

 floating leaves. 



OFFICIAL. Gentiana lutca arid 

 other species yield GENTIANAE 

 KADIX. CHIKATA is obtained 

 from Su'ertia chirata (N. India). 



Family 4. Apocynaeeae. 

 Evergreen herbs, shrubs 

 or trees, without stipules. 

 Especially numerous in the 

 tropics. Laticiferous cells 

 in all parts of the plant. K5, 

 0(5), A5, G(2). Petals con- 

 torted in the bud. Stigma ring- 

 shaped. Carpels only united 

 in the region of the style, 

 free below (Fig. 723) and 

 separating after fertilisation. 

 Usually two follicles. Seeds 

 provided with a tuft of hairs. 



IMPORTANT GENERA. The only 

 British species is Vinca minor, 

 the evergreen Periwinkle, occur- 

 ring in woods (Fig. 726). Nerium 

 oleander (Fig. 725), a native of S. 

 Europe, is commonly cultivated. 

 It has greyish -green, lanceolate 

 leaves which are decussate or in 

 whorls of three ; flowers rose- 

 coloured, sweet-scented and conspicuous. The whole plant is extremely poisonous. 



OFFICIAL. Strop/tanthus /combe and S'. hispidus ( Wa ) (Fig. 724), lianes of tropical 

 Africa, yield STKOPHAMHI SEMINA. 



Caoutchouc ( 43 ) is obtained from Kickxin ehisticn and other species, trees of 

 tropical "W. Africa. It is also obtained from numerous species of Landolphia 

 \ L. Kirkii, Heudelotii, comvrensis, etc.), lianes which are, or formerly were, common 

 throughout tropical Africa. Together with species of Carpodimtu (Angola) which 

 yield the root-rubber, these plants supply the main part of the rubber obtained 

 from Africa. Hancornia speciosa, a tree of the dry Brazilian Campos to the south 

 of the Amazon region, yields the " mangabeira " rubber. Jl'-illomjlibfio firma, 



Km. 71!'. Olea evropea in fruit. (J nat. size.) 



