APPENDIX A 515 



The floral formula is S. 5, P. 5, And. 5 + 5, G. 5. 



Pollination. The flower is showy, and attracts also by honey secretion 

 outside the bases of the stamens. It is markedly protandrous. The five 

 outer stamens open first, followed by the five inner, but the stigmas remain 

 closely appressed together (in.), and expand only after the pollen is shed, when 

 the anthers curve away from them (rv.). This separation of the sexes both in 

 time and space makes self-pollination highly improbable, and the plant de- 

 pends upon cross-pollination resulting from insect visits. In other species 

 of Geranium, especially the smaller-flowered, self-pollination occurs, the separa- 

 tion of the sexes being less marked. On the other hand in the Scarlet 

 Geranium of gardens (Pelargonium), the flowers are slightly zygomorphic, 

 and there is a deep honey-gland sunk in the pedicel opposite to the posterior 

 sepal, a specialisation still more perfected in the Nasturtium (Tropaeolum) . 



ORDER : TRICOCCAE. 



Family : EUPHORBIACEAE. Example : THE CAPER-SPURGE, OR OTHER 



SPECIES. 



The Euphorbiaceae, or Spurges, are a very large Family, of which the genus 

 Euphorbia is an extreme type. They have reduced, unisexual flowers, which 

 are sometimes isolated, with their floral envelopes developed, as in Phyllanthus ; 

 but in Euphorbia and others the flowers are closely grouped together, so that 

 a whole inflorescence may appear, and even functionate as a single flower. 

 The less reduced types indicate that their relation is with the Gruinales, from 

 which they may be regarded as an interesting reduction-series. 



(23) Euphorbia is represented in the British Flora by many species. They 

 are herbs or small shrubs with smooth surface, and milky juice. Their leaves 

 are exstipulate, but that is not general for the Order. The inflorescence is 

 very complicated, the apparent unit being the flower-like cyathium, which is 

 itself a very compact, compound spike (Fig. 421, i. n.)- These units are 

 borne like flowers on an inflorescence, which is usually a cymose umbel. The 

 cyathium itself consists of an external cup, which looks like a calyx, but is 

 really formed of five coalescent bracts, forming an involucre. On its margin four, 

 or occasionally five, yellowish glands are borne, a blank space being left on 

 one side ; there two teeth of the bracts are found, where the missing gland 

 might be. Within the cyathium a single stalked female flower occupies the 

 centre: it projects from the cup, and hangs over the side between the two 

 bracts which are not separated by a gland. It consists of a gynoecium of three 

 syncarpous carpels, having three styles with bifid stigmas. It is trilocular, and 

 one pendulous, anatropous ovule lies in each : the upward-directed micropyle 

 is covered by a fleshy outgrowth known as the caruncle, which is character- 

 istic. At the base of the ovary is a distended ring, held to represent the 

 abortive perianth. The gynoecium is thus superior. 



Around the female flower are a number of structures which look like stamens : 

 they are associated with minute hairy bracts. Each of these is a male flower 

 (vi.), consisting of a single stamen with a bilobed anther. The stalk which looks 

 like a filament bears about half way down a constricted joint, which is believed 

 to mark the place of an abortive perianth. The part below it would then be 

 pedicel, above it the filament. In Anthostema the perianth is better developed 



