genus descriptions: SSTAs

Herbs attached to rocks in fast-flowing freshwater; basal part thalloid, bearing long simple or branched branches floating in current. Leaves alternate, arranged all along branches at regular intervals, usually +/- dichotomously divided. Flowers arranged in pedicelled or sessile inflorescences, either on main branches or on short branches in leaf axils; spathellas each enclosing an inverted flower, ovoid or ellipsoid, opening irregularly from the apex; pedicel far exserted after anthesis. Tepals 2. Stamens 2, surrounded by tepals, usually shorter than ovary; filaments fused in basal part; anthers introrse; pollen in diads. Ovary unilocular, very narrowly ellipsoid, borne on a well-developed gynophore; placenta central; ellipsoid, bearing many anatropous ovules; stigmas 2, conical; slightly fused at base. Capsule 8-ribbed, dehiscing by 2 equal valves remaining attached at apex. Seeds many, small, with reticulate testa.

Trees or lianes; indumentum of branching-stellate, +/- erect hairs. Leaves mostly cordate at base, main lateral nerves pronounced, in 15-60 pairs. Inflorescence paniculate, divaricately branched, with flowers clustered in many dense, obovoid-globose heads at ends of inflorescence branches. Male flowers with 2-6 anthers. Seed with fleshy aril, laciniate almost to base.

Low, soft-wooded, rhizomatous shrubs; branchlets glabrous, longitudinally striate. Leaves alternate, petiolate, spathulate to narrowly oblanceolate, chartaceous, glabrous, with numerous small raised dots on lower surface. Inflorescences axillary, 4-7-flowered pseudofascicles. Flowers bisexual or female; female flowers consisting only of calyx and gynoecium. Calyx 5, imbricate, broadly ovate to suborbicular, minutely fimbriate to erose, glandular. Petals 5, very shortly connate, imbricate, lanceolate, sparsely dotted, abaxially minutely puberulous. Stamens 5; filaments very short, flattened and fused into a short staminal tube fused to corolla tube; anthers large, narrowly lanceolate, acuminate to apiculate at apex, often with dark dots on dorsal face, longitudinally dehiscent. Ovary ovoid to conical, sparsely lepidote towards apex; free-central placenta with 6-8 ovules; style filiform; stigma punctiform. Fruit a globose, 1-seeded, indehiscent, glabrous drupe with brittle endocarp. Seed globose, covered with membranous rudiments of placenta.

Small to tall trees, non-resinous; bark greenish with many whitish lenticels arranged in horizontal lines. Leaves glabrous; veins prominent on upper surface. Inflorescences: fascicles or short panicles. Flowers bisexual, greenish or yellow. Calyx with 5 glabrous, +/- elliptic sepals fused at base. Petals 5, free to base, lanceolate. Stamens 5, epipetalous, free, adpressed to inner face of petals; filaments broad, fleshy and flattened; anthers opening by longitudinal slits. Disc adnate to ovary, rugose. Ovary (4)5-locular; ovule 1 per locule, pendent from a central placenta; style conical, with channels, terminating in a (4)5-lobed stigma. Fruit a +/- spherical drupe with a prominent equatorial ridge. Seed 1, +/- spherical; endosperm copious.