1836 



A TEXTBOOK OF THEORETICAL BOTANY 



The flowers (Fig. 1738) are dioecious or monoecious and generally 

 much reduced. For example in Euphorbia the male flowers consist of a 

 single stamen. Occasionally, as in the genus Croton, both calyx and 

 corolla are present but more often one or both are wanting. 



Fig. 1738. — Floral diagram of Euphorbia 

 peplus (cyathium). {After Eicliler.) 



The androecium varies in number of parts from one to many. Fre- 

 quently they may be equal in number to the perianth segments. 



The gynoecium is usually tricarpellary and syncarpous. The ovary 

 is trilocular and superior. There are one or two pendulous, anatropous 

 ovules in each loculus. 



The fruit is a schizocarp, often breaking violently and dehiscing into 

 one-seeded cocci. 



The seed is endospermic and frequently has a caruncle developed from 

 the micropyle. The cotyledons either lie flat in the endosperm or are bent 

 or folded. The relative breadth of the cotyledons is used as a character in 

 classification within the family. 



The family is a large one with about 220 genera and some 4,000 species. 

 It is world-wide in distribution. The chief centre is in Indo-Malaya 

 but, with the exception of the Arctic, members of the family occur almost 

 everywhere. Their ubiquity, coupled with their very great variety of form, 

 makes them a very interesting family systematically, moreover many are of 

 great economic importance. There are no anatomical features which are 

 characteristic of the whole order but a laticiferous system is found in the 

 majority and is of great economic importance. The following is an outline 

 of the classification of the family according to Pax. 



A. PLATYLOBEAE 



Cotyledons much broader than the radicle. 

 I. Phyllanthoideae 



There are two ovules in each loculus. Laticiferous tissue and internal 

 phloem are absent. 



