Order 4. Pontederiaceæ. Flowers generally zygomorphic, hypogynous, ☿, with handsome, white or violet, petaloid perianth which forms a tube at its base. The stamens are inserted at different heights in the perianth-tube, and are reduced to three (in Heteranthera seldom to one). In some the ovary is trilocular with ∞ ovules (Eichhornia), in others reduced to one loculus with one ovule (Pontederia). Fruit a capsule or nut. Embryo as long as the abundant, mealy endosperm.—Tropical water-plants (22 species) with peculiar sympodial branching, nearly the same as in Zostera. Spikes without floral-leaves. Many intercellular spaces in the stem and leaf.—In greenhouses: Eichhornia azurea, E. crassipes (both from tropical and sub-tropical S. America); the latter has swollen petioles which serve as floats and enable it to float freely on the water, sending down its roots into the mud. Heteranthera reniformis, H. zosterifolia. Pontederia cordata.
Order 5. Amaryllidaceæ (Narcissi). The flower is epigynous, otherwise exactly the same as in the Liliaceæ (6 stamens). The majority, like these, are also perennial herbs with bulbs and scapes. The fruit and the other characters as in the Liliaceæ. The external appearance is, however, very different.
A. Amarylleæ have bulbs and the leaves generally arranged in two rows; the flowers are borne singly or in umbel-like inflorescences on lateral scapes, while the main axis of the bulb is unlimited. Beneath the inflorescence is an involucre (Fig. [309]).—Galanthus, Snowdrop, has a polyphyllous perianth without corona; the three inner perianth-leaves are emarginate and shorter than the outer; the anthers dehisce apically. Leucojum differs in having the perianth-leaves equal in length.—Amaryllis has a funnel-shaped perianth, entirely or nearly polyphyllous, but somewhat zygomorphic. Crinum; Hæmanthus; Clivia.—Narcissus has a tubular corona, a ligular structure arising from the perianth-tube exterior to the outer stamens. In Pancratium (Fig. [309]) the corona is united with the filaments which appear to spring from its edge. Eucharis amazonica.
Fig. 309.—Pancratium caribæum.
B. Hypoxideæ. The leaves, which are grass-like, dry, folded, and in some hairy, spring from a rhizome, generally with a divergence of 1/3. Flowers small, perianth polyphyllous, persistent, on which account perhaps the Hypoxideæ may be considered as the least altered type. The chief characteristic is that the embryo is separated from the hilum. Hypoxis; Curculigo (C. recurvata, a favourite ornamental plant; S.E. Asia).
C. Alstrœmerieæ. (Alstrœmeria, Bomarea); stems long, leafy, often climbing.
D. Vellosieæ (Vellosia, Barbacenia); stem woody, usually dichotomously branched, with terminal, single flowers; it bears numerous aerial roots which pierce the leaves and surround the stem. Stamens often (by splitting) 6–18. High table-lands of S. America and S. Africa.
E. Agaveæ. Very similar to the Bromeliaceæ both in their distribution (nearly all American) and in external appearance. They appear as gigantic bulbous plants with perennial, aerial, generally short stem, and perennial, large, lanceolate or linear, stiff, thick, and often thorny leaves, which form a large rosette; after the course of several (8–20) years the terminal inflorescence is developed, which is 10–12 m. high, paniculate, and freely branched. Before the inflorescence expands, a large quantity of sugar-containing sap is collected from A. americana by removing the terminal bud; this on distillation yields “pulque,” the national drink of Mexico. After flowering the entire shoot dies, but the subterranean lateral shoots survive and reproduce the plant.—Agave americana, etc.; Fourcroya; Polianthes tuberosa (Tuberose; Central America).
Distribution. The 650 species are chiefly natives of S. Africa and S. America. Clivia, Hæmanthus, Amaryllis are from the Cape; Narcissus from S. Europe, whence many species have been introduced; Galanthus and Leucojum are especially from S. and Central Europe, and from the Caucasus.