Oxygonum buchananii (Dammer) J.B.Gillett

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

Type

Lectotype, selected by Graham (1957): Malawi, Buchanan 550 (K, lectotype).

Habit

A robust perennial herb, sometimes bushy, with a rootstock A robust perennial herb, sometimes bushy, with a rootstock.

Stem

Stems several from the rootstock, up to 1 m long, prostrate or spreading, longitudinally striate, glabrous or sparsely papillate Stems several from the rootstock, up to 1 m long, prostrate or spreading, longitudinally striate, glabrous or sparsely papillate.

Leaves

Leaves petiolate, dark green above, paler beneath; lamina 7.5–10 × 4.5–6 cm, obovate to broadly ovate, obtuse or shortly acuminate at the apex, attenuate at the base and decurrent on the petiole, with the midrib prominent beneath, entire or slightly wavy on the margin, glabrous on both surfaces, gland-dotted beneath; petiole 1–2 cm long Leaves petiolate, dark green above, paler beneath; lamina 7.5–10 × 4.5–6 cm, obovate to broadly ovate, obtuse or shortly acuminate at the apex, attenuate at the base and decurrent on the petiole, with the midrib prominent beneath, entire or slightly wavy on the margin, glabrous on both surfaces, gland-dotted beneath; petiole 1–2 cm long.

Ocrea

Ocrea brown, 0.5–2 cm long, glabrous outside, truncate with a terminal fringe of 7–9 setae 1–3 cm long Ocrea brown, 0.5–2 cm long, glabrous outside, truncate with a terminal fringe of 7–9 setae 1–3 cm long.

Flowers

Male flowers not seen Flowers pedicellate, 2–4 in the axils of bracts, arranged in elongated spiciform terminal racemes up to 36 cm long; bracts 4–5 mm long, truncate but produced dorsally into an acute setose apex, with or without a terminal fringe of short setae up to 1 mm long; pedicels red-brown, 6–7 mm long, glabrous Hermaphrodite flowers heterostylous, long-styled flowers not seen; perianth yellowish-green, glabrous, 5-lobed; tube 2–3 mm long; lobes 3–4 mm long, oblong Flowers pedicellate, 2–4 in the axils of bracts, arranged in elongated spiciform terminal racemes up to 36 cm long; bracts 4–5 mm long, truncate but produced dorsally into an acute setose apex, with or without a terminal fringe of short setae up to 1 mm long; pedicels red-brown, 6–7 mm long, glabrous. Male flowers not seen. Hermaphrodite flowers heterostylous, long-styled flowers not seen; perianth yellowish-green, glabrous, 5-lobed; tube 2–3 mm long; lobes 3–4 mm long, oblong.

Filaments

Filaments 0.3–3.5 mm long, filiform and flattened toward the base; anthers orange, 0.5–0.55 × 0.4–0.45 mm, oblong

Ovary

Ovary 3.4 × 2.3 mm, oblong; styles c. 1 mm long

Ecology

Clay sandy soils in dry river margins; 250–700 m.

Distribution

Malawi ZAM E, MAL S, MOZ N Zambia Mozambique Also in southern Tanzania and Angola.

Pistil

Ovary 3.4 × 2.3 mm, oblong; styles c. 1 mm long.

Hermaphrodite

Ovary 3.4 × 2.3 mm, oblong; styles c. 1 mm long. Filaments 0.3–3.5 mm long, filiform and flattened toward the base; anthers orange, 0.5–0.55 × 0.4–0.45 mm, oblong. Hermaphrodite flowers heterostylous, long-styled flowers not seen; perianth yellowish-green, glabrous, 5-lobed; tube 2–3 mm long; lobes 3–4 mm long, oblong.

Fruits

Nut 8–10 mm across, trigonous, with a spine on each angle; spines 2–3 mm long, pointing somewhat downwards. Nut 8–10 mm across, trigonous, with a spine on each angle; spines 2–3 mm long, pointing somewhat downwards.

Male

Male flowers not seen.

Stamens

Filaments 0.3–3.5 mm long, filiform and flattened toward the base; anthers orange, 0.5–0.55 × 0.4–0.45 mm, oblong.