Oxygonum Burch. ex Campd.

Flora Zambesiaca. Vol. 9, Part 3. Polygonaceae-Myriaceae. Pope GV, Polhill RM, Martins ES. 2006.

Morphology General Habit

Annual or perennial polygamous herbs, more rarely shrubs, glabrous or hairy, sometimes with papillae or scales A shrub or scrambling plant from a woody rootstock, ± pubescent Annual or perennial polygamous herbs, more rarely shrubs, glabrous or hairy, sometimes with papillae or scales.

Morphology Leaves

Leaves alternate, sessile or petiolate, entire or pinnatifid Leaves alternate, sessile or petiolate, entire or pinnatifid. Leaves sessile, dull green, 2–6.8 × 0.3–1.3(1.7) cm, elliptic.lanceolate, acute at the apex often mucronate, attenuate to the base, entire or slightly sinuous on the margin, with the midrib prominent beneath, ± pubescent and punctate with black dots on both surfaces

Morphology Leaves Ocrea

Ocrea membranous or chartaceous, with or without a fringe of setae at the apex Ocrea membranous or chartaceous, with or without a fringe of setae at the apex. Ocrea 10–15 mm long, chartaceous, thinly covered with short hairs, truncate and fringed with red-brown setae c. 8 mm long at the apex

Morphology Stem

Stems sometimes much branched; branches ascending; bark red-brown

Morphology Reproductive morphology Flowers

Hermaphrodite flowers heterostylous; perianth wine-red outside and white inside, tubular with 5 spreading lobes; tube 6–8 mm long and slightly constricted at the apex; lobes 5–8 mm long, oblong-lanceolate or oblong-oblanceolate, acute or apiculate at the apex Flowers pedicellate, clustered in axils of bracts, borne in slender or laxly spiciform, terminal or axillary, leafless racemes; bracteoles 2, united; pedicels becoming thicker and sometimes longer as the fruit matures Hermaphrodite flowers heterostylous, 4–5-merous; perianth tubular, with relatively short lobes; as the fruit matures the receptacle enlarges and invests the fruit with the withered perianth persisting above it and constricted at the base; stamens 8 in 2 series, the 5 outer stamens adnate to the perianth segments near their bases, the 3 inner with flattened bases forming a contiguous ring around the base of the style; anthers oblong; styles 3; stigmas capitate Hermaphrodite flowers heterostylous, 4–5-merous; perianth tubular, with relatively short lobes; as the fruit matures the receptacle enlarges and invests the fruit with the withered perianth persisting above it and constricted at the base; stamens 8 in 2 series, the 5 outer stamens adnate to the perianth segments near their bases, the 3 inner with flattened bases forming a contiguous ring around the base of the style; anthers oblong; styles 3; stigmas capitate. Male flowers with a short tube and 4–5 petaloid perianth segments Flowers pedicellate, clustered in axils of bracts, borne in slender or laxly spiciform, terminal or axillary, leafless racemes; bracteoles 2, united; pedicels becoming thicker and sometimes longer as the fruit matures. Male flowers with a short tube and 4–5 petaloid perianth segments. Male flowers not seen Flowers pedicellate, 1–3 in the axils of bracts, arranged in terminal spiciform rigid racemes c. 25 cm long; bracts 7–10 mm long, chartaceous, obliquely truncate and produced dorsally into an acute or acuminate setose apex, glabrous or ± puberulous; bracteoles 2, c. 5 mm long, hyaline with 1–2 short setae at the apex; pedicels c. 6 mm long, articulated near the apex

Morphology Reproductive morphology Flowers Androecium Stamens Filaments

Filaments (1.5)4–11 mm long, filiform; anthers 1–1.3 × 0 4–0.5 mm

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary 7–8 mm long, ellipsoid, glabrous; styles of long-styled flowers 6–7 mm long; styles of short-styled flowers 4–5 mm shorter than the stamens

Morphology Reproductive morphology Fruits

Nut red-brown at maturity, 9–12 × 4–5 mm, oblong-ellipsoid, glabrous, longitudinally sulcate and transversally wrinkled. Fruiting receptacle hardened and enclosing the fruit Fruiting receptacle hardened and enclosing the fruit. Nut fusiform, conical, ampulliform or lanceolate-ampulliform, trigonous or not, unarmed or with 3(9) spreading prickles or teeth of varying size and development at the centre or below, or at the base, sometimes winged. Nut fusiform, conical, ampulliform or lanceolate-ampulliform, trigonous or not, unarmed or with 3(9) spreading prickles or teeth of varying size and development at the centre or below, or at the base, sometimes winged.

Ecology

Miombo and Cryptosepalum woodland, often on Kalahari Sands; 1000–1750 m.

Distribution

A genus of c. 35 species, mostly confined to Africa where it is widespread, one species being endemic in Madagascar. ZAM B, ZAM N, ZAM W Zambia Also in Angola and Dem. Rep. Congo.