646 



BOTANY 



PART II i 



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

 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. 

 Erythraea, Centaury (Fig. 681), anthers sj^irally twisted. Menyanthcs, Bog-Bean, 

 with alternate, trifoliolate leaves and long- stalked racemes of white flowers with 

 hairy petals. Limnanthemum, 

 aquatic plants with floating . 

 leaves. 



Official. — Gentiana lutca and 

 other species yield gentianae 

 EADix. Chirata is obtained 

 from Sicertia chirata (N. India). 



Family 4. Apoeynaeeae. 

 — Evergreen herbs, shrubs 

 or trees, without stipules. 

 Especially numerous in the 

 tropics. Laticiferous cells 

 in all parts of the plant. 

 Petals contorted in the bud. 

 Stigma ring-shaped. Carpels 

 only united in the rea;ion of 

 the style, free below (Fig. 

 682) 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, 

 occurring in woods (Fig. 685). 

 Keriuw oleander (Fig. 684), a 

 native of S. Europe, is commonly 

 cultivated. It has greyish-green 

 lanceolate leaves which are decus- 

 sate or in whorls of three ; flowers 

 rose-coloured, sweet-scented, and 

 conspicuous. The whole plant 

 is extremely poisonous. The floating fruit of Ccrhera (tropical) is shown in 

 Fig. 493. 



OFh-iviAL.—Stro2>hanthus ko-iahe and ,S'. ]tis2)idus{^^) (Fig. 724), lianes of tropical 

 Africa, yield stroi'HANTHi semina. 



Caoutchouc (^■') is obtained from Kickxia elastica and other sjiecies, trees of 

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

 {L. Kirkii, Heudelotii, comorcnsis, etc.), lianes which are, or formerly were, common 

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

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

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

 of the Amazon region, yields the " mangabeira " rubber. Wilhmghheia firma, 



Fig. 078.— 0?t'n evropea in fruit. (J iiat. size.) 



