Family Joinvilleaceae

Joinvilleaceae Tomlinson & A.C. Sm.

Habit and leaf form. Coarse, reedlike, unbranched, erect herbs (to 5 m tall). Perennial; with neither basal nor terminal aggregations of leaves; to 3–5 m high; rhizomatous (the rhizomes congested, sympodial). Leaves large (the lamina up to 1 m long); alternate; distichous; flat; sessile; sheathing. Leaf sheaths tubular; with free margins. Leaves simple. Lamina entire; linear, or lanceolate (grasslike, not cirrhose); palmately veined to parallel-veined (most of the veins entering the blade from the sheath, but a few originating from the base of the midrib). Leaves ligulate (and more or less auriculate). Lamina margins serrate. Vernation plicate.

General anatomy. Plants with silica bodies (abundant throughout the plant, deposited in the epidermal walls and as silica bodies around the vascular bundles). Chlorenchyma without ‘peg cells’.

Leaf anatomy. Epidermis conspicuously differentiated into ‘long’ and ‘short’ cells (cf. Gramineae); containing silica bodies. Stomata present; paracytic. Guard-cells ‘grass type’.

The mesophyll not containing mucilage cells; without calcium oxalate crystals (? — no raphides). Vessels present; end-walls scalariform, or reticulately perforated and scalariform.

Stem anatomy. Stems with hollow internodes. Secondary thickening absent. Xylem with vessels. Vessel end-walls scalariform and simple (mostly simple).

Root anatomy. Root xylem with vessels; vessel end-walls scalariform and simple.

Reproductive type, pollination. Plants hermaphrodite. Floral nectaries absent (?). Pollination anemophilous.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in panicles; not in ‘spikelets’. Inflorescences terminal; much branched, terminal panicles. Flowers bracteate; fairly small; regular; 3 merous; cyclic; pentacyclic. Perigone tube present to absent (the perianth members free to basally connate). Hypogynous disk absent.

Perianth of ‘tepals’; 6; free to joined; 2 whorled; isomerous; sepaloid (bractlike); similar in the two whorls to different in the two whorls (chaffy, the outer members much larger); green, or cream; persistent.

Androecium 6. Androecial members free of the perianth; free of one another; 2 whorled. Androecium exclusively of fertile stamens. Stamens 6; isomerous with the perianth. Anthers basifixed (sagittate); non-versatile; dehiscing via longitudinal slits; latrorse; tetrasporangiate. The endothecial thickenings girdling. Microsporogenesis successive. Pollen shed as single grains. Pollen grains aperturate; 1 aperturate; ulcerate. The ulcus without an operculum (or with a vestigial operculum represented by coarse granules or exine fragments); with an annulus. Interapertural exine scrobiculate. Interapertural interstitium columellate. Pollen grains 3-celled.

Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary 3 locular. Gynoecium non-stylate (with three more or less sessile stigmatic areas), or stylate. Styles when developed, 3; free to partially joined; apical; shorter than the ovary (persistent). Stigmas 3. Placentation axile to apical. Ovules 1 per locule; pendulous; orthotropous. Outer integument contributing to the micropyle. Antipodal cells formed; 3; not proliferating. Synergids non-haustorial. Endosperm formation nuclear. Embryogeny probably asterad.

Fruit fleshy; indehiscent; a drupe (red, yellow or black). The drupes with one stone (with 1–3 seeds). Fruit 1–3 seeded. Seeds copiously endospermic. Endosperm mealy, starchy. Seeds with starch. Embryo rudimentary at the time of seed release, or weakly differentiated (undifferentiated, minute, discoid). Testa without phytomelan; thin.

Geography, cytology. Paleotropical. Tropical. Western Malaysia, Pacific. X = 18.

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Commeliniflorae; Poales. APG 3 core angiosperms; Superorder Lilianae; commelinid Monocot; Order Poales.

Species 2. Genera 1; only genus, Joinvillea.

Tomlinson and Smith 1970, Campbell and Kellogg 1987.

Illustrations.
• Joinvillea ascendens: photo (Scott Zona).