622 PART III. THE CLASSIFICATION OF PLANTS. 



The inflorescence requires special consideration : it is, generally- 

 speaking, of the mixed type, the earlier branchings being racemose 

 whilst the final branchings are cymose : in the monoecious plants, 

 as a rule, both kinds of flowers are borne in the same inflorescence, 

 the 9 flowers above, the <$ flowers below. 



In the family Euphorbieae the general inflorescences are cymose 

 umbels or dichasia, the branches of which terminate in what 

 were formerly regarded as ambisporangiate flowers, but are really 

 inflorescences, each one being termed a cyathium. The cyathium 

 consists of a tubular involucre (Fig. 425 j>), consisting of bracts, 

 often brightly-coloured {e.g. Poinsettia), between the five lobes 

 of which glandular appendages, often of a semilunar form, are 

 situated (Fig. 425 dr). Within this involucre are numerous 

 flowers in five groups, each of which consists of a single stamen 

 (Fig. 425 a) and is terminal on a long pedicel, and one ? flower 

 (Fig. 425 g), consisting of a trilocular ovary (Fig. 425 /), at the 

 base of which an indication of a perianth may in some cases be 

 detected. That the cyathium is an inflorescence and not a single 

 flower is most clearly visible in the genus Anthostema, in which a 

 perianth is distinctly developed round each stamen. 



Of Euphorbia, the Spurge, most indigenous species are annual herbs, as E. 

 Peplus, exigua, platypliyllos and helioscopia (the common Sun Spurge), whilst 

 others are perennial (E. amygdal aides, and Paralias) : some South European 

 forms are small shrubs, as E. dendroides and fruticosa : in Africa and the 

 Canary Islands the genus is represented by species which much resemble 

 Cactacese in appearance ; their stems are thick and cylindrical or angular 

 or sometimes spherical, producing small leaves which usually soon fall off. 

 In Mercurialis the flowers are apetalous ; the $ flowers have a three-leaved 

 perianth and numerous stamens ; the $ flowers have a similar perianth 

 and a bilocular ovary : Mercurialis annua and perennis (Dog's Mercury) are 

 weeds, the first common in cultivated ground, the second in woods; their 

 flowers are dioecious. Kicinus bears its monoecious apetalous flowers in a 

 compound inflorescence, in which the $ flowers are placed below and the ? 

 flowers above: the perianth is simple and five-lobed: Ricinus communis (the 

 Castor-oil plant) is a native of Africa, now frequently cultivated ; Castor-oil is 

 obtained from its seeds. Croton-oil is obtained from the seeds of Croton 

 Tiglium. Some species - of Pbyllanthus (Xylophylla) have phylloid branches 

 which bear their small flowers in the axils of minute bristle-like leaves situated 

 in indentations at the edge of the phylloclade. The root of Manihot utilis- 

 sima, a South American plant, when ground, constitutes cassava, and it yields 

 the starchy meal known in commerce as tapioca. From Siphonia elastica, a 

 species growing iu Central America, most of the caoutchouc is obtained. 



Order 2. BUXACEJ;. Disc wanting : flowers monoecious, in 



