EUPHORBIACE.E. 



493 



men (fig. 483); cotyledons flat (fig. 509) ; radicle superior (fig. 713). 

 Trees, shrubs, and herbs, often abounding in acrid milk, with oppo- 

 site or alternate, often stipulate leaves, sometimes none. Some look 

 on this order as apetalous, with a tendency to develop a corolla, while 

 others consider it polypetalous, with a tendency to have the corolla 



7"7 



suppressed. In European plants of the order there are usually no 

 petals present, but in those of tropical countries the corolla is fre- 

 quently well marked. In the Euphorbias of Britain, there is an evi- 

 dent involucre, surrounding a number of achlamydeous male and 

 female flowers, which by Linnaeus were looked upon as merely stamens 

 and pistils, and hence the plants were put by him in Dodecandria iu 

 place of Monoacia (see ^f 401). The flowers in Euphorbiacese vary 

 much in the number of their parts, as may be seen in figs. 545550. 

 Sometimes the general peduncle or rachis becomes flattened and leaf- 

 like (fig. 229). The inflorence is occasionally amentaceous, as in 

 the division Scepacece, which is separated, as a distinct but not fully 

 defined order, by Lindley. The plants of the order abound in warm 

 regions, especially in Equinoctial America, where they occur as trees 

 or bushes, or lactescent herbs, and often present the appearance of 

 Cactuses, from which their milky juice at once distinguishes them. They 

 are also found in North America and in Europe. In Britain there are 



Figs. 707-713. Organs of fructification of Euphorbia palustris, to illustrate the natural order 

 Euphorbiacese. 



Fig. 707. Inflorescence, with the involucre, i i, opened and spread out, to show the position 

 of the male and female flowers which it encloses, g g, Glands (glandular lobes) alternating with 

 the divisions of the involucre. 6 6, Membranous laminas, or bracts, at the base of the flowers. 

 fm,fm, Achlamydeous male flowers, consisting of a single stamen, supported on a pedicel, to 

 which it is attached by an articulation. //, Achlamydeons female flower in the centre; the 

 ovary and styles supported on a long pedicel. 



Fig. 708. Achlamydeous male flower separated, b, Rract p, TediceL /, Filament articu- 

 lated with the pedicel, a. Anther. 



Fig. 709. Female flower, p, Summit of the pedicel which supports it. e, A flattened portion 

 of the pedicel, which some call a perianth, o, Tricoccous ovary. , Styles and stigmas. 



Fig. 710. One of the cocci (carpels), c, separated, and seen on its inner surface, g. The seed 

 seen across the opening by which the nourishing vessels enter. 



Fig. 711. A coccus separated, after dehiscence and expulsion of the seed. 



Fig. 712. Seed separated. 



Fig. 713. -Seed cut vertically, t, Integument (spermoderm). p, Perisperm (fleshy albumen)- 

 .', Embryo with flat cotyledons, and a superior radicle. 



