Acanthaceae
Thunbergia

Thunbergia oblongifolia Oliv.

First published in Trans. Linn. Soc. London 29: 125 (1875)
This species is accepted
The native range of this species is Tanzania to S. Tropical Africa. It is a perennial and grows primarily in the seasonally dry tropical biome.

Descriptions

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

Type
Tanzania, Mpwapwa Dist., Usagara Mts, Rubeho, xii.1860, Speke & Grant s.n. (K holotype).
Morphology General Habit
Perennial herb with 1 to several stout erect stems from a large woody rootstock, sometimes forming large clumps; stems to 0.7(1) m long, 3–7 mm wide at base, subquadrangular, glabrous to densely pubescent with curly glossy hairs, if glabrous then with a thick band of setose glossy hairs at nodes
Morphology Leaves
Leaves penninerved or with 2 weak lateral veins running less than half way up, glabrous to puberulous, often distinctly ciliate with long curly glossy hairs when young; petiole 0–1 mm long; lamina lanceolate to elliptic or obovate, largest 3–11 × 0.4–3 cm; apex acuminate to acute, apiculate, base attenuate to subauriculate; margin entire
Morphology Reproductive morphology Flowers
Flowers solitary; pedicel 1–2.5(6 in fruit) cm long, glabrous to pubescent; bracteoles pale to dark green or tinged purple, with obscure reticulation, 1.5–3.2 × 0.5–1.5 cm, ovate to elliptic or oblong, acute to obtuse, glabrous to puberulous
Morphology Reproductive morphology Flowers Calyx
Calyx glabrous to finely puberulous, 1–3(6 in fruit) mm long, the broadly triangular lobes about half
Morphology Reproductive morphology Flowers Corolla
Corolla limb and upper part of tube blue to dark blue or mauve, rarely white, lower part of tube white to pale yellow, throat yellow; tube 2.5–4.5 cm long, 0.8–1.7 cm wide at mouth; lobes 1–2.2 × 1.2–2.5 cm
Morphology Reproductive morphology Flowers Androecium Stamens Filaments
Filaments 9–11 mm long, glabrous; anthers 2–2.5 mm long; style glabrous or with scattered capitate glands
Morphology Reproductive morphology Fruits
Capsule 10–13(15) mm wide, beak 17–24(28) mm long
Morphology Reproductive morphology Seeds
Seeds brown, 6–9 mm in diameter, slightly reticulate on back, with broad entire or laciniate lateral wing.
Distribution
Zambia, Zimbabwe. Also in Tanzania, Burundi and Congo.
Ecology
Woodland, bushland and grassland, appearing shortly after burning, persisting in disturbed vegetation and cultivated areas, on sandy to loamy soil or on rocky slopes; 900–1600 m.
Conservation
Widespread; not threatened.
Recognition
In its typical form this species is easily distinguished from Thunbergia lancifolia by the lighter coloured corolla and hairy stems. But subglabrous forms, common in Zimbabwe, are almost inseparable from T. lancifolia and future field studies may eventually show that the two taxa are better treated at subspecific level. In Tanzania the two are much more clearly separated.
[FZ]

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

Morphology General Habit
Perennial herb with 1-several stout erect stems from large woody rootstock, sometimes forming large clumps; stems to 0.7(–1) m long, 2–8 mm in diameter at base, subquadrangular, glabrous to puberulous or pubescent with curly glossy hairs, if glabrous with band of setose glossy hairs at nodes.
Morphology Leaves
Leaves penninerved or with two weak lateral veins running less than half way up; petiole 0–1 mm long, glabrous to puberulous or pubescent; lamina narrowly elliptic to elliptic or narrowly obovate to obovate, largest 3–10 × 0.7–4 cm, apex acuminate to obtuse, apiculate, base attenuate to subauriculate, margin entire, glabrous to puberulous, distinctly ciliate with long curly glossy hairs at least when young.
Morphology Reproductive morphology Flowers
Flowers solitary; pedicels 0.7–2.5(–4.5 in fruit) cm long, glabrous to puberulous or pubescent, rarely with intermixed capitate glands or of glands only; bracteoles pale green to dark green or tinged purple, with obscure (rarely conspicuous) reticulation, ovate to elliptic or oblong, 1.5–3.5(–4) × 0.5–1.7 cm, acute to obtuse, with sparse to dense (to 1 mm long) capitate glands, usually with intermixed non-glandular hairs or with non-glandular hairs only or glabrous but for distinctly ciliate margin.
Morphology Reproductive morphology Flowers Calyx
Calyx glabrous to finely puberulous, 1–3(–5 in fruit) mm high of which the broadly triangular lobes about half.
Morphology Reproductive morphology Flowers Corolla
Corolla limb and upper part of tube white, pale blue to blue or mauve, lower part of tube white to pale yellow, throat yellow; tube 2–4.5(–5.5) cm long and 0.7–2 cm in diameter at mouth; lobes 1–2.2(–2.8) × 1.2–2.8 cm.
Morphology Reproductive morphology Flowers Androecium Stamens Filaments
Filaments 8–13 mm long, glabrous; anthers 2–2.5 mm long.
Morphology Reproductive morphology Flowers Gynoecium Style
Style with scattered capitate glands.
Morphology Reproductive morphology Fruits
Capsule 10–13(–15) mm in diameter, beak 17–24(–28) mm, long.
Morphology Reproductive morphology Seeds
Seed brown, 6–9 mm, in diameter, slightly reticulate on back and with a broad entire or laciniate lateral wing.
Ecology
Brachystegia-Julbernardia woodland, montane grassland, appearing shortly after burning, on sandy to stony or loamy soil or on rocky slopes; 750–2250 m
Note
Glabrous specimens are also quite similar to T. graminifolia but always have a distinct line of glossy setose hairs at the nodes and lack the very conspicuous rib-like veins of that species. Included here is an array of specimens varying from almost glabrous to densely hairy. What keeps them together and separate from T. lancifolia is a pale corolla combined with distinctly ciliate leaves.
Distribution
Flora districts: T1 T2 T4 T5 T6 T7 T8 Range: Congo-Kinshasa, Burundi, Zambia, Zimbabwe Range: Congo-Kinshasa, Burundi, Zambia, Zimbabwe
[FTEA]

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
[AERP]

Sources

  • Angiosperm Extinction Risk Predictions v1

    • Angiosperm Threat Predictions
    • http://creativecommons.org/licenses/by/4.0

  • Flora Zambesiaca

    • Flora Zambesiaca
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Flora of Tropical East Africa

    • Flora of Tropical East Africa
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Herbarium Catalogue Specimens

    • 'The Herbarium Catalogue, Royal Botanic Gardens, Kew. Published on the Internet http://www.kew.org/herbcat [accessed on Day Month Year]'. Please enter the date on which you consulted the system.
    • Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2025. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0

  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2025. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0