Acanthus montanus (Nees) T.Anderson

IUCN Red List of Threatened Species https://www.iucnredlist.org/species/185329/8390038

Conservation

LC - least concern

Acanthaceae, H. Heine. Flora of West Tropical Africa 2. 1963

Morphology General Habit

Plant up to 6 ft. high, stems woody, sparsely branched

Morphology Leaves

Leaves dark glossy green above, paler beneath, papery, scabrid bracts and calyx-lobes whitish with green veins

Ecology

In high forest.

J. R. Timberlake, E. S. Martins (2013). Flora Zambesiaca, Vol 8 (5) Acanthaceae Part 1. Royal Botanic Gardens, Kew

Type

Bioko (Fernando Po), xi.1841, Vogel 239 (K holotype).

Morphology General Habit

Shrubby herb or shrub to 1.5(?4) m tall; young stems sparsely and finely puberulous at nodes

Morphology Leaves

Leaves subglabrous to finely and sparsely puberulous on midrib and larger veins; petiole 0.2–1.3 cm long; lamina elliptic to obovate in outline, largest 20–28 × 7–12 cm, deeply lobed with oblong- triangular spine-tipped lobes, each lobe with 1–3 teeth on one or both sides; apex acute to cuspidate, spine-tipped; base cuneate to truncate, a pair of large spines right at base, sometimes detached

Morphology Reproductive morphology Inflorescences

Spikes solitary (rarely also 2 from upper axils), 9–31 cm long; rachis glabrous or with few scattered hairs, with stalked capitate glands upwards, with or without one pair of sterile bracts at base; bracts green, elliptic to obovate, glabrous to finely puberulous, 2.7–3.3 cm long in middle of spike, long triangular straight or recurved spine-tipped apical part 5–9 mm, with 4–7 large and small teeth per side (small sometimes absent), longest 6–8 mm long, small teeth inserted between large; bracteoles 1.9–2.6 cm long, linear-lanceolate, with 2–3 teeth per side

Morphology Reproductive morphology Flowers Calyx

Calyx green, glabrous to puberulous; dorsal sepal elliptic-oblong, 3–3.5 cm long, gradually narrowing to acute spine-tipped apex, with (1)3–7 lateral teeth on each side; ventral sepal ovate- oblong, 3–3.5 cm long, gradually narrowing to bifid apex with 2 triangular spine-tipped teeth 5–9 mm long, often themselves toothed, 1–2 central teeth in the gap, laterally also with 3–5 teeth per side; lateral sepal ovate or narrowly so, 1.2–2.3 cm long, acute to cuspidate, without lateral teeth

Morphology Reproductive morphology Flowers Corolla

Corolla white with pink to pale pink veins; tube c.3 mm long below thickened rim, rim c.4 mm long with broad dorsal shallow split; limb spreading, 5-lobed, 3–4.5 × 3–4 cm, glabrous to sparsely puberulous below, large glandular ‘blisters’ towards base, glabrous above, 3 central lobes much longer than 2 lateral; callus not grooved

Morphology Reproductive morphology Flowers Androecium Stamens Filaments

Filaments 1.5–2.2 cm long, two dorsal glabrous or sparsely hairy near base; anthers 9–11 mm long, without or with sparse long curly hairs on sides, sessile glands dorsally

Morphology Reproductive morphology Fruits

Capsule (from Angolan material) c.2.5 cm long

Morphology Reproductive morphology Seeds

Seeds rhomboid, c.9 mm long, sparsely puberulous.

Distribution

Zambia. Also in Nigeria, Cameroon, Equatorial Guinea (incl. Bioko), Sao Tomé, Gabon, Central African Republic, Congo and Angola.

Ecology

Riverine forest with Syzygium (mushitu); c.1000 m.

Conservation

Local in Flora area but widespread elsewhere; not threatened.