Fig. 455.—A seed entire; B in longitudinal section.
Ricinus (Castor-oil) (Figs. [453–455]); monœcious; the ♂-flowers, situated in the lower portion of the inflorescence, have 5 perianth-leaves and a large number of branched stamens; the ♀-flower has 3–5 perianth-leaves; 3 bifid styles. Leaves peltate, palmately lobed. The seeds (Fig. [455]) contain an abundance of fatty oil and large aleurone grains.—Mercurialis (Mercury): the perianth is most frequently 3-merous; in the ♂-flowers 9–12 stamens; in the ♀-flowers most frequently a 2-locular gynœceum.—Phyllanthus: Pr3 + 3, A3, united in some and forming a column in the centre of the flower (Figs. [457], [458]); Xylophylla is a section of this genus.— Hura crepitans (Sand-box tree) has a many-carpellate gynœceum, which separates with great violence when ripe.—A drupe is found in Hippomane mancinella (the Mancinil-tree, W. Ind.)—Alchornea (Coelebogyne) ilicifolia is well known on account of its “parthenogenesis”; only the ♀-plant has been introduced into Europe, but it nevertheless produces seeds capable of germination; these have generally several embryos.
Figs. 456–458.—Phyllanthus (Xylophylla) angustifolius.
Fig. 456.—Leaf-like branch with flowers (nat. size).
Fig. 457.—♂-flower; and
Fig. 458, ♀-flower (mag.).
Euphorbia (Spurge) has the most reduced flowers, which are borne in a very complicated inflorescence. Each ♂-flower (Fig. [460] B) is naked, and consists of one stamen only (terminal on the axis). In the closely allied genus Anthostema, a small perianth is situated at the place where, in Euphorbia, there is a joint in the “filament,” (Fig. [461] A). The ♀-flowers (Fig. [460]) are naked, with a 3-locular ovary and 3 bifid styles. (Anthostema has a distinct perianth (Fig. [461] B); in a few Euphorbias traces of a perianth are present). In Euphorbia the ♂-and ♀-flowers are grouped into flower-like inflorescences termed “cyathia.” Each cyathium consists of a centrally placed ♀-flower which is first developed, surrounded by 5 groups of ♂-flowers (stamens) placed in a zig-zag, with a centrifugal order of development (Figs. [459], [460] B), that is, in unipared scorpioid cymes; these flowers are surrounded by an involucre of 5 leaves united into a bell-shaped structure (Fig. [459], 1–5) (resembling a calyx); on its edge are placed 4, generally crescent-like, yellow glands, one in each of the intervals, except one, between the lobes of the involucre (shaded in Fig. [459]; see also Fig. [460] A). Scale-like thin structures (floral-leaves?) are situated between the ♂-flowers. The ♀-flower has a long stalk, and finally bends down on one side, namely to the place on the edge of the involucre where the gland is not developed. These cyathia are again arranged in an inflorescence which commences as a 3–5-rayed umbellate cyme (pleiochasium), the branches of which ramify dichasially and finally as scorpioid cymes.—Latex, with peculiar-shaped starch-grains, is found in laticiferous cells (especially in the Cactus-like, leafless species.)
