Oxygonum Burch. ex Campd.

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

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.

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

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

Stem

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

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

Filaments

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

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

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.

Polygonaceae, R. A. Graham. Flora of Tropical East Africa. 1958

Habit

Polygamous, heterostylous, annual or perennial herbs or more rarely shrubs

Ocrea

Ocreae with or without a terminal fringe of setae

Flowers

Flowers borne in axillary, leafless, often triquetrous, rather slender and elongated spiciform racemes Hermaphrodite flowers tubular, the tepals marcescent, the tube very accrescent around the ovary Male flowers with a very short tube and 4–5 petaloid tepals

Bracteoles

Bracteoles 2, conjoined

Male

Male flowers with a very short tube and 4–5 petaloid tepals

Hermaphrodite

Hermaphrodite flowers tubular, the tepals marcescent, the tube very accrescent around the ovary

Stamens

Stamens 8, in 2 series; 5 outer adnate to the tepals near their bases, 3 inner with flattened bases forming a contiguous ring around the base of the style

Pistil

Styles 3, free or conjoined below; stigmas capitate

Fruits

Fruiting perianth fusiform, conical, ampulliform or lanceolate-ampulliform, trigonous or not, unarmed, or with 3 (–9) spreading prickles of varying size and development at the centre or below, or at the base, rarely with 3 additional prickles or teeth on the angles of the lower half, sometimes winged.