Order 2. Amarantaceæ. The flowers are essentially the same as in the Chenopodiaceæ and the extremely reduced Caryophyllaceæ (Fig. [361] F); they are regular, hypogynous, generally ☿, have 5 free (rarely slightly united) perianth-leaves; in front of these 5 stamens, which are often united at their base into a shorter or longer tube and have stipule-like teeth between them (the division Gomphreneæ has 2-locular anthers, each of which opens longitudinally); and a 2–3 carpellate gynœceum with one loculus and most frequently one, more rarely several ovules; the fruit is a nut, more rarely (in Celosia, Amarantus, Gomphrena) a capsule, dehiscing irregularly, or like a pyxidium. The characters which especially separate them from the allied orders are found in the perianth. The perianth-leaves are not green and herbaceous, but membranous, dry, and often coloured; they are frequently produced into a bristle or awn; they have also both subtending floral-leaves and 2 large bracteoles similar to the perianth; all these dry leaves persist without alteration after the withering of the flower.—The flowers are without scent. They are arranged in spike- or capitulum-like inflorescences; sometimes placed singly, sometimes aggregated in the panicle-like inflorescences; in others, on the contrary, in dichasia. The majority are herbs, some are shrubs. The leaves are scattered, or opposite, but always simple and without stipules; some are smooth, others hairy.
450 species; especially in the Tropics, principally S. Am. and E. Ind.: few are found outside these countries.—Only a few are used; some, chiefly E. Indian species, are cultivated as ornamental plants: Amaranthus (Fox-tail); Gomphrena globosa; Celosia cristata (Cock’s-comb) remarkable for its fasciated inflorescence; Alternanthera. Some are employed as culinary plants in the Tropics, and in a few of the E. Indian species the seeds are farinaceous, and used for food.
Order 3. Chenopodiaceæ. Generally herbaceous plants like the Caryophyllaceæ, but the leaves are arranged spirally (except Salicornia), and are simple, exstipulate; they are generally fleshy and like the stem “mealy,” that is, covered with small hairs, whose large spherical terminal cell readily falls away; otherwise they are seldom hairy. The inflorescences are generally flower-clusters borne in panicles. Bracteoles generally absent. Flowers generally unisexual: with the single exception of Beta the flowers are hypogynous; they are regular, small and inconspicuous, with single, green, 5-leaved, but more or less united perianth; 5 stamens opposite the perianth, and a 2–5-carpellate, unilocular ovary with 1 basal, curved ovule; but in some genera the number of the perianth-leaves and stamens is reduced to 3–2–1–0. The fruit is generally a nut,—thus this flower and fruit are the same as in the reduced Caryophyllaceæ (Fig. [361] F). The seed is similar to that generally found in the family (for exceptions see the genera).
The floral diagram most frequently present is the same as in Fig. [361] F. There is no indication of corolla or of corolla-stamens, which may be supposed to have belonged to the plant, but which are now entirely and completely suppressed. This order appears to have been an offshoot from the Caryophyllaceæ.—The perianth persists after the withering of the flower, and envelopes the nut; it is very variable, and, together with the position of the seed, the form of the embryo, the sex of the flowers, etc., gives the characters of the genera.
1. Chenopodieæ, Goosefoot Group (Fig. [365]), has ☿ (or polygamous) flowers, with regular 5-parted perianth (C); the embryo is ring-like (H). The leaves have the ordinary flat forms.—Chenopodium (Goosefoot). The flower is hypogynous, and the fruit (which is compressed) perfectly free; Mulberry-like collections of fruits are formed in some species (sub-genus Blitum) by the perianth becoming finally fleshy and coloured.—Beta (Beet, Mangold, Fig. [365]) differs from all genera in the perianth, which finally becomes cartilaginous, being epigynous (D). Small, most frequently 2–3-flowered clusters without bracteoles, situated in a long, interrupted axis (A, B); the flowers and fruits in each cluster are more or less united individually, and fall off together—they are commonly known as seeds (E, F). The seed lies horizontally.—Hablitzia (H. tamnoides).
Fig. 365.—Beta vulgaris.
Fig. 366.—Salsola soda: embryo.
2. Salsoleæ, Saltwort Group, has cylindrical or semi-cylindrical leaves. Perianth as in the preceding group; the fruit is most frequently compressed. The two first mentioned genera differ from most of the others in the order in having a spirally-coiled, and not a ring-like embryo, so that the endosperm is slight or wanting (Fig. [366]). These plants are sometimes placed as a group by themselves, Spirolobeæ—in contradistinction to which the others are termed Cyclolobeæ.—Salsola (Saltwort); leaves subulate, with spiny tips; the flowers have 2 spinous bracteoles: during the ripening of the fruit a tough leathery wing is developed transversely to the back of the perianth.—Chenopodina deviates from Chenopodium chiefly in the embryo and want of endosperm.—Kochia has a somewhat similar perianth to Salsola, but a ring-like embryo; it differs from the others in being hairy.