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._~ [Illustration: 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.