Oxygonum stuhlmannii Dammer

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

Type

Type from Tanzania.

Habit

Perennial herb, with several stems from a woody rootstock Perennial herb, with several stems from a woody rootstock.

Stem

Stems red-brown, trailing or ascending, 40–50 cm long, longitudinally striate, puberulous Stems red-brown, trailing or ascending, 40–50 cm long, longitudinally striate, puberulous.

Leaves

Leaves 1.5–5 × 0.6–1.2 cm, lanceolate or elliptic.lanceolate to ± deltate, apex acute, base narrowed into a petiole up to 1 cm long, margin usually ± shallowly lobed, sometimes entire, midrib prominent beneath, lamina sparsely puberulous on both surfaces Leaves 1.5–5 × 0.6–1.2 cm, lanceolate or elliptic-lanceolate to ± deltate, apex acute, base narrowed into a petiole up to 1 cm long, margin usually ± shallowly lobed, sometimes entire, midrib prominent beneath, lamina sparsely puberulous on both surfaces.

Ocrea

Ocrea 5–8 mm long, membranous, truncate with a terminal fringe of reddish wavy setae c. 5 mm long Ocrea 5–8 mm long, membranous, truncate with a terminal fringe of reddish wavy setae c. 5 mm long.

Flowers

Hermaphrodite flowers strongly heterostylous; perianth 5-lobed; tube 1.5 mm long, pubescent outside; lobes 2–2.5(5) mm long, oblong Male flowers not seen Flowers pedicellate, 1–4 in the axil of bracts, arranged in an elongated spiciform raceme up to c. 35 cm long; raceme erect or slightly arcuate; bracts 2.5–4 mm long, puberulous to glabrous, truncate, fringed at the apex with 3–5 setae c. 2 mm long; pedicels 4–6 mm long; bracteoles 2.5–4 mm long Flowers pedicellate, 1–4 in the axil of bracts, arranged in an elongated spiciform raceme up to c. 35 cm long; raceme erect or slightly arcuate; bracts 2.5–4 mm long, puberulous to glabrous, truncate, fringed at the apex with 3–5 setae c. 2 mm long; pedicels 4–6 mm long; bracteoles 2.5–4 mm long. Hermaphrodite flowers strongly heterostylous; perianth 5-lobed; tube 1.5 mm long, pubescent outside; lobes 2–2.5(5) mm long, oblong. Male flowers not seen.

Filaments

Filaments 2–3 mm long; anthers 0.3–0.4 × 0.2–0.3 mm, ellipsoid

Ovary

Ovary 3–3.5 mm long, fusiform; styles of long-styled flowers 3–3.5 mm long, free almost to the base, strongly exserted; styles of short-styled flowers c. 1 mm long

Ecology

On disturbed soils, sandy soils on roadsides, in miombo woodland; 775–2100 m.

Note

This species shows considerable variation in leaf shape and in the hairiness of the leaves. Oxygonum baumii, the type of which is the only record for Angola, was included here with doubt by Graham, loc. cit. (1957).

Distribution

MAL N Malawi Also in Dem. Rep. Congo (Kivu), Kenya, Tanzania and Angola.

Male

Male flowers not seen.

Stamens

Filaments 2–3 mm long; anthers 0.3–0.4 × 0.2–0.3 mm, ellipsoid.

Hermaphrodite

Filaments 2–3 mm long; anthers 0.3–0.4 × 0.2–0.3 mm, ellipsoid. Ovary 3–3.5 mm long, fusiform; styles of long-styled flowers 3–3.5 mm long, free almost to the base, strongly exserted; styles of short-styled flowers c. 1 mm long. Hermaphrodite flowers strongly heterostylous; perianth 5-lobed; tube 1.5 mm long, pubescent outside; lobes 2–2.5(5) mm long, oblong.

Pistil

Ovary 3–3.5 mm long, fusiform; styles of long-styled flowers 3–3.5 mm long, free almost to the base, strongly exserted; styles of short-styled flowers c. 1 mm long.

Fruits

Nut c. 5 mm long, fusiform, trigonous, papillose, with 3 spreading prickles on the angles a little below the middle, 3–5 mm long. Nut c. 5 mm long, fusiform, trigonous, papillose, with 3 spreading prickles on the angles a little below the middle, 3–5 mm long.