Acanthaceae

Thunbergia Retz.

First published in Physiogr. Sälsk. Handl. 1: 163 (1780)
This genus is accepted
The native range of this genus is Tropical & Subtropical Old World.

Descriptions

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

Morphology General Habit
Erect, trailing or twining annual or perennial herbs, or erect or scandent shrubs or woody twiners; cystoliths absent.
Morphology Leaves
Leaves opposite, entire to crenate or dentate; venation pinnate or palmate.
Morphology Reproductive morphology Flowers
Flowers axillary, solitary or paired or in racemes; bracteoles 2, large, hyaline to leathery, connate for 2/3–3/4 dorsally and about 1/4 ventrally (rarely free to base).
Morphology Reproductive morphology Flowers Calyx
Calyx a subentire to undulate rim or with 10–20 triangular to linear teeth.
Morphology Reproductive morphology Flowers Corolla
Corolla contorted in bud; tube straight or curved, cylindric or campanulate, widening at point of insertion of stamens, with subsessile capitate glands on the inside; limb spreading, subequally 5-lobed.
Morphology Reproductive morphology Flowers Androecium Stamens
Stamens 4, didynamous or subequal, inserted at transition from throat to tube, included (rarely exserted); anthers 2-thecous, one or both thecae with a setosely bristled boss or a spur at base (rarely muticous); thecae linear to ovoid, opening by apical slits.
Morphology Reproductive morphology Flowers Disc
Disc conspicuous, annular, fleshy.
Morphology Reproductive morphology Flowers Gynoecium Ovary
Ovary 2-locular with 2 collateral ovules per locule; stigma funnel-shaped or with two large unequal lobes (one erect the other horizontal) or subequally 2-lobed with two erect flattened lobes.
Morphology Reproductive morphology Fruits
Fruit a 2–4-seeded thick-walled woody capsule, triangular with weakly defined beak or subglobose with sharply defined beak.
Morphology Reproductive morphology Seeds
Seed hemispherical, hollow on the proximal face, smooth to reticulate, tuberculate, lamellate or otherwise sculptured; retinaculae absent.
Distribution
Range: A number of species are widely grown as ornamentals. Range: 100–150 species, mostly in Eastern and Southern Tropical Africa, also from India to SE Asia and Australia, introduced in America.
Note
A number of the indigenous species have at one time or other also been cultivated. Several Indian and SE Asian species have been cultivated as ornamentals but, apart from T. laurifolia, never seem to have become naturalized. They include T. alata, battiscombei, erecta, gibsonii, gregorii, holstii, kirkii, petersiana and vogeliana.
[FTEA]

Adhikari, B., Pendry, C.A., Watson, M.F. et al. 2013. Kew Bulletin 68: 651. https://doi.org/10.1007/s12225-013-9481-x

Morphology General Habit
Herbaceous or woody isophyllous climbers, rarely erect or trailing herbs, cystoliths absent
Morphology Leaves
Leaves opposite, petiolate, ovate or lanceolate to hastate or sagittate
Morphology Reproductive morphology Flowers
Flowers pedicellate, solitary and axillary, or up to 4 in axillary fascicles or many in racemes
Morphology Reproductive morphology Inflorescences Bracts
Bracts leaf-like; bracteoles paired, large, enclosing calyx and most of corolla tube, sometimes fused on one side, persistent
Morphology Reproductive morphology Flowers Calyx
Calyx annular, subentire, undulate or 5 – 20-toothed
Morphology Reproductive morphology Flowers Corolla
Corolla with a straight or curved tube, tube cylindrical, ventricose or gradually widened towards apex; lobes 5, subequal, spreading
Morphology Reproductive morphology Flowers Androecium Stamens
Stamens 4, anthers 2-celled, spurred or muticous
Morphology Reproductive morphology Flowers Gynoecium Ovary
Ovary 2-locular, ovoid; stigma funnel shaped, bilobed or 2-cleft
Morphology Reproductive morphology Fruits
Capsule woody, with subglobose basal part and elongated beak; seeds 2 – 4, hemispherical, smooth or sculptured.
[KBu]

M. Thulin. Flora of Somalia, Vol. 1–4 [updated 2008] https://plants.jstor.org/collection/FLOS

Distribution
Some 100 species in the Old World tropics.
Morphology General Habit
Herbs with erect to twining stems, shrubs or woody climbers
Morphology Leaves
Leaves opposite, pinnately or palmately veined, without cystoliths
Morphology Reproductive morphology Flowers
Flowers solitary in leaf-axils or in racemes; bracteoles 2 large, partially connate, enclosing base of flower
Morphology Reproductive morphology Flowers Calyx
Calyx cup-shaped, a narrow rim, or with 10–20 unequal linear lobes
Morphology Reproductive morphology Flowers Corolla
Corolla-tube widening in upper part; limb subequally 5-lobed, spreading
Morphology Reproductive morphology Flowers Androecium Stamens
Stamens 4, included, subequal or 2 long and 2 short; anthers 2-celled, spurred or ornamented at the base
Morphology Reproductive morphology Flowers Gynoecium Ovary
Ovary 2-celled, with 2 ovules in each cell; style mostly included; stigma funnel-shaped or unequally 2-lobed
Morphology Reproductive morphology Fruits
Capsule broadly triangular and obscurely beaked to subglobose with a sharply differentiated beak, without jaculators
Morphology Reproductive morphology Seeds
Seeds broadly elliptic.
[FSOM]

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

Morphology General Habit
Erect, trailing or twining annual or perennial herbs, or erect or scandent shrubs or woody twiners; cystoliths absent
Morphology Leaves
Leaves opposite, entire to crenate or dentate; venation pinnate or palmate
Morphology Reproductive morphology Flowers
Flowers axillary, solitary or paired or in racemes; bracteoles 2, large, hyaline to leathery, joined for ± 2/3 their length dorsally and ± 1/4 ventrally, rarely free to base
Morphology Reproductive morphology Flowers Calyx
Calyx a subentire to undulate rim or with 10–20 triangular to linear teeth
Morphology Reproductive morphology Flowers Corolla
Corolla contorted in bud; tube straight or curved, cylindric or campanulate, widening at point of insertion of stamens; limb spreading, subequally 5-lobed
Morphology Reproductive morphology Flowers Androecium Stamens
Stamens 4, didynamous or subequal, inserted at transition from cylindric tube to throat, included (rarely exserted); anthers 2-thecous, one or both thecae with a setosely bristled boss or a spur at base (rarely muticous); thecae linear to ovoid, opening by apical slits
Morphology Reproductive morphology Flowers Gynoecium Ovary
Ovary 2-locular with 2 collateral ovules per locule; stigma funnel-shaped or with two large unequal lobes (one erect the other horizontal) or subequally 2-lobed with two erect flattened lobes
Disc
Disc conspicuous, annular, fleshy
Morphology Reproductive morphology Fruits
Fruit a 2–4-seeded thick-walled woody capsule, triangular with a weakly defined beak or (usually) subglobose with sharply defined beak; retinaculae absent
Morphology Reproductive morphology Seeds
Seed hemispherical, hollow on proximal face, smooth to reticulate, tuberculate, lamellate or otherwise sculptured.
Distribution
A genus of 100–150 species, mostly in E and S tropical Africa and South Africa, also from India to SE Asia and Australia, introduced in America.
[FZ]

Uses

Use
A number of species are widely cultived as ornamentals.
[FZ]

Sources

  • Flora Zambesiaca

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

  • Flora of Somalia

    • Flora of Somalia
    • 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.

  • Interactive Key to Seed Plants of Malesia and Indo-China

    • The Malesian Key Group (2010) Interactive Key to Seed Plants of Malesia and Indo-China (Version 2.0, 28 Jul 2010) The Nationaal Herbarium Nederland Leiden and The Royal Botanic Gardens Kew

  • 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 Bulletin

    • Kew Bulletin
    • http://creativecommons.org/licenses/by-nc-sa/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

  • Kew Science Photographs

    • Copyright applied to individual images