526 



PART IV. CLASSIFICATION. 



perianth sometimes consists of calyx and corolla, sometimes it is 

 simple, and occasionally it is absent : the ovary is usually trilo- 

 cular, with one or two anatropous and generally suspended ovules 

 in each loculus ; the seed contains endosperm : the structure of the 

 flowers is very various. 



Order 1. EUPHORBIACE^E. The fruit is usually dry and dehis- 

 cent, a schizocarp splitting into cocci. The micropyle of the 

 solitary suspended ovule is directed outwards. They are plants 

 of very, various habit and floral structure, and they mostly contain 

 milky juice. 



The genus Euphorbia has cymose umbels or dichasia, the 

 branches of which terminate in what were formerly regarded as 

 hermaphrodite flowers, but are really inflorescences, each one being 

 termed a c.yatliium. The cyathium consists of a tubular involucre 

 (Fig. 341 p\ between the five lobes of 

 which glandular appendages, often of 

 a semilunar form, are situated (Fig. 

 341 dr}. Within this involucre are 

 numerous staminate flowers in five 

 groups, each of which consists of a single 

 stamen (Fig. 341 a) and is terminal on 

 a long pedicel, and one carpellary flower 

 (Fig. 341 </), consisting of a trilocular 

 ovary (Fig. 341 /), at the base of which 

 an indication of a perianth mav in some 

 cases be detected. That the cyathium 

 is an inflorescence and not a single 

 flower is most clearly visible in some 

 foreign genera (e.g. Monotaxis), in which 

 a perianth is distinctly developed round 

 each stamen. There is a single ovule 

 in each loculus of the trilocular ovary : 

 the seed has a peculiar appendage (arilode, p. 416). 



In Mercurialis the inflorescence is racemose : the staminate flowers 

 have a three-leaved perianth and numerous stamens ; the carpellary 

 flowers have a similar perianth and a bilocular ovary. The juice 

 is not milky. 



Ricinus bears its monoecious flowers in a compound inflorescence, 

 in which the staminate flowers are placed below and the carpellary 

 flowers above. The perianth is simple and five-lobed, the stamens 

 numerous and much branched (Fig. 278). 



FIG. 341. Part of an inflores- 

 cence of a Euphorbia: b 6 bracts 

 in the axils of which are the 

 flower bnds (fcn) ; p is the invo- 

 lucre of the cyathium ; dr the 

 g'nnds; a the male flowers; g 

 tMe pedicel of the female flower 

 (/) ; n the st'gmas (enlarged). 



