Thunbergia kirkii Hook.f.

Acanthaceae (part 1), Kaj Vollesen, Flora of Tropical East Africa, 2008

Morphology General Habit

Erect shrubby herb to 1.5 m tall (rarely scandent to 3 m); branches quadrangular, narrowly winged, the wings forming rounded “ears” at nodes, glabrous or with thin line of hairs at nodes.

Morphology Leaves

Leaves dark green glossy; petiole 1–6 mm long, glabrous or puberulous; lamina lanceolate to broadly elliptic, largest 3–11(–15) × 0.5–7.5 cm, apex acute to acuminate, base cuneate to rounded (rarely attenuate), margin on some or all usually with one large triangular tooth near middle, otherwise entire to crenate-dentate or undulate, glabrous.

Morphology Reproductive morphology Flowers

Flowers in 1–6-flowered axillary racemes (rarely 2 racemes per axil or some flowers solitary); peduncles and pedicels angular, glabrous; peduncle and axis 0.2–3(–7.5) cm long; bracts minute, caducous; pedicels 0.7–1.8(–2.3) cm long; bracteoles green, ovate to oblong-elliptic, 8–14(–21) × 3–6(–8) mm, acute to obtuse (rarely subacuminate), apiculate, glabrous to finely puberulous and finely ciliate.

Morphology Reproductive morphology Flowers Calyx

Calyx to 1(–5 in fruit) mm high of which the broadly triangular lobes about half, glabrous to finely puberulous.

Morphology Reproductive morphology Flowers Corolla

Corolla limb mauve, purple or blue (rarely white), tube whitish, throat yellow; tube 1.6–2.2(–3.5) cm long; lobes 0.5–1(–1.5) cm long; filaments 3–6 and 6–9 mm long, glabrous; anthers 3–5 mm long.

Morphology Reproductive morphology Fruits

Capsule 1.5–2(–2.3) × 0.8–1 cm, minutely puberulous.

Morphology Reproductive morphology Seeds

Seed dark reddish brown, 5–6 mm in diameter.

Distribution

Range: Tanzania. Range: Kenya. Range: Mozambique Range: Mozambique Flora districts: K7 T3 T6 T7 Z

Ecology

Evergreen or semi-evergreen lowland and lower montane forest; near sea level to 1250 m

Note

The corolla of the type of T. amanensis is also said to be white, but all other material from the East Usambaras have mauve to purple corolla. It is also described as having a white corolla. Drummond & Hemsley 1883 from Morogoro District: Nguru Mts, Turiani, Mkobwe, is a scandent shrub with much larger flowers than any other specimens seen (maximum dimensions in description). This is e.g. represented by Luke et al. 7648 and 8796. There is also a very large-leaved purple-flowered form from Morogoro District: Kimboza Forest. For the time being I am keeping this material as an aberrant form of T. kirkii, but further collections from the Nguru Mts and further south are needed to clarify the status of this form. The sparse material from Mozambique has equally large white flowers. Vegetatively and in corolla size it is similar to the above mentioned. For the time being I prefer to keep it under T. kirkii.

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