Stathmostelma gigantiflorum K.Schum.

Apocynaceae (part 2), David Goyder, Timothy Harris, Siro Masinde, Ulrich Meve, Johan Venter. Flora of Tropical East Africa, 2012

Morphology General Habit

Perennial herb with a single branched annual stem arising from a stout napiform or globose tuber.

Morphology Stem

Stem erect or ascending, 0.3–1 m long, branched from near the ground, minutely pubescent with short white hairs

Morphology Leaves

Leaves mostly subsessile, occasionally with petiole to 10 mm long; lamina linear or occasionally lanceolate, 10–25 × 0.2–1(–2) cm, acute, base cuneate, indumentum mostly restricted to margins and midvein.

Morphology Reproductive morphology Inflorescences

Inflorescences terminal and extra-axillary with 3–6 flowers in an erect umbel.

Morphology Reproductive morphology Inflorescences Peduncles

Peduncles erect, 2–17 cm long, the lower inflorescences generally with longer peduncles than the upper ones, minutely pubescent.

Morphology Reproductive morphology Inflorescences Bracts

Bracts filiform, pubescent.

Morphology Reproductive morphology Flowers Calyx

Sepals triangular to broadly ovate, 6–12(–14) × 2–3(–9) mm, acute, subglabrous to densely pubescent

Morphology Reproductive morphology Flowers Corolla

Corolla rotate to slightly reflexed, subglabrous or pubescent on outer surface, minutely papillose within, white or green outside, white, green or pink and occasionally speckled purple within; lobes ovate to elliptic, (15–)20–30 × 7–15 mm, acute, somewhat replicate

Morphology Reproductive morphology Flowers Gynostegium

Gynostegium with stipe ± 3 mm long

Morphology Reproductive morphology Flowers Corona

Corona lobes erect, white or green, frequently speckled with purple towards upper margin, 8–15 × 4–7 mm, mostly overtopping column by at least half their length, concave-cucullate for most of their length, weakly pouched either side of the midline towards the base, apex rounded to attenuate distally, the inner apical margins produced into a pair of upward- or inward-pointing acute teeth, inner margins of lobe papillose, cavity without a median tooth

Morphology Reproductive morphology Flowers Androecium Stamens Anthers

Anther wings 4–6 mm long, curved, the basal tails free from the column; anther appendages ± 1.5 mm long, semicircular and inflexed over apex of stylar head; corpusculum black, obovoid to subcylindrical, ± 0.7 × 0.3 mm; translator arms with a membranous, obovate, convex and somewhat contorted proximal part ± 3.5 × 1.5 mm, and a filiform distal part ± 1 mm long broadening abruptly into a clasping overlap with the pollinium.

Morphology Reproductive morphology Flowers Pollinia

Pollinia oblong, ± 1.5 × 0.5 mm, flattened

Morphology Reproductive morphology Flowers Gynoecium Style

Stylar head flat

Morphology Reproductive morphology Flowers Pedicel

Fruiting pedicel not contorted. Pedicels 2–5 cm long, minutely pubescent

Morphology Reproductive morphology Fruits

Follicle erect, narrowly fusiform, 10–16 × 0.5–0.8 cm, with a basal stipe, not inflated, smooth, minutely but densely pubescent

Morphology Reproductive morphology Seeds

Seeds ± 3 × 2 mm, verrucose.

Ecology

Seasonally waterlogged grassland on black clay soils; 500–1800 m

Note

The broadly ovate sepals of S. gigantiflorum sensu Bullock (1953a) contrast with the lanceolate sepals of other collections but as the other differences listed by Bullock can be observed elsewhere in the complex I have chosen to interpret the two collections as extreme variants within a variable species. Collections from Kenya and southern Tanzania have distinctive facies recognised by Bullock (1953a, 1953b) when he described S. praetermissum and S. nomadacridum. However, the characters which combine to give these appearances (principally the form of the apex and teeth of the corona lobes) break down in the intervening territory. I have reluctantly come to the conclusion that, as it is only possible to divide the variation on completely arbitrary grounds, the species must be redefined in the broad sense of N.E. Brown (1902) with no infraspecific taxa recognised. S. bicolor ( A. muhindensis) appears, from the limited material available (a single flower from the type), to be a poorly developed specimen of S. gigantiflorum and I have therefore included it in the synonymy of this species. Bidgood et al. 2295 from Chunya district in southern Tanzania probably also belongs here but has exceptionally broad leaves and smaller corona lobes than in other material.

Distribution

Flora districts: K4 T1 T2 T4 T5 T7 Range: E Zambia and central Malawi

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation

Predicted extinction risk: not threatened. Confidence: confident