Begonia johnstonii Oliv. ex Hook.f.

Begoniaceae, Vanessa Plana, Martin J.S. Sands & Henk J. Beentje. Flora of Tropical East Africa. 2006

Type

Type: see note.

Habit

Herb, possibly perennial, erect, procumbent or straggling, 20–60 cm high or to 90 cm long; stem swollen at base, succulent higher up, green with red streaks, glabrous.

Stipules

Stipules persistent, reddish, ovate to broadly ovate, 3–8 mm long, with entire margins.

Leaves

Leaves green above (and sometimes glaucous), green or often reddish beneath, ovate in outline, asymmetric, 5–18 × 2–8.5 cm, one side larger, up to 1.3 times the width of the other and with a rounded basal lobe with 2–3 main veins and 1/4 to 1/3 the total length of the lamina, base cordate, margin crenate, apex acuminate, sparsely pilose or glabrous; venation palmate-pinnate, the main vein at an angle to the petiole; petiole often reddish, or with red spots, (3–)6–16 cm long, with ring of white hairs at the junction with the lamina. Inflorescence an axillary dichasial cyme, with up to 6(–12) flowers; peduncle reddish, (3–)6–23 cm long, glabrous; each ramification subtended by a pair of opposite bracts 2–5 mm long, membranous; pedicels 5–23 long with 2 minute bracteoles on those of the ♀ flowers.

Flowers

Male flowers: tepals 4, free, pink to white, the outer obovate, 6–15 × 4–10 mm, the inner obovate, 7–19 × 5–13 mm; stamens numerous, filaments free, 1–4 mm long, anthers ellipsoid to subglobose, 0.5–1 mm. Female flowers: tepals 5, pink to white, obovate, 5–13 × 3–8 mm; ovary globose to ellipsoid, 7–8 mm long, 3-locular, 3-winged; placentation axile; styles 3, shortly forked halfway or at apex, glabrous, persistent; stigmatic band yellow, horseshoe-shaped, twisted.

Fruits

Fruit a brown capsule with red wings, globose, ovoid or ellipsoid, 7–11 × 6–9 mm excluding the wings; wings very unequal, one laterally triangular and 12–27 mm wide, the other two triangular, rounded, 6–8 mm wide; dehiscence along the junction with the wings. Fig. 2, p. 5.

Ecology

On steep rocks in forest or in moist sites, less often in forest without any specification; local, rarely locally common; 750–2400 m.

Conservation

Least concern (LC).

Note

Typification unclear: the protologue starts with an ‘ined.’ Latin description of B. johnstonii by Oliver, based on Johnston s.n. from Kilimanjaro, ‘5000–6000 feet’; the plate and main description (in English) by Hooker are based on plants grown at Kew, flowered in April 1886, from material sent by Bishop Hannington from Masailand – and there is a specimen dated 1883 at Kew. Irmscher states the Johnston plant is the holotype. We incline towards the Kew ones.

Distribution

Flora districts: K1 K4 K6 K7 T2 T3 T6 T7 Range: Not known elsewhere