1. Acanthaceae Juss.

    1. This family is accepted.

[FTEA]

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

Habit
Herbs, shrubs, twiners or (rarely) trees; branches often angled or ridged, with a usually distinct transverse ridge at nodes.
Stem
Stems and leaves often with cystoliths (linear intercellular calcium carbonate concretions) looking like small white streaks or rods.
Leaves
Leaves opposite, rarely whorled or in rosettes, without stipules.
Inflorescences
Inflorescences of single flowers or dichasia or cymules which are often aggregated into axillary and/or terminal paniculate to racemoid cymes; bracts from foliaceous to distinctly differentiated or minute; bracteoles usually present.
Flowers
Flowers nearly actinomorphic to zygomorphic, bisexual.
Calyx
Calyx 4–5-lobed (or in Thunbergioideae a subentire to undulate rim or of 10–20 irregular lobes), fused at least at base, with equal to unequal lobes or distinctly 2-lipped.
Corolla
Corolla sympetalous, with a narrow basal tube widening into a more or less distinct throat, limb from almost regularly 5-lobed to distinctly 2-lipped, more rarely 1-lipped, lobes imbricate or contorted in bud.
Stamens
Stamens 4, usually didynamous, or 2 and then with or without 2–3 staminodes, attached at base of throat or in narrow corolla tube, basal part of filaments often connate in two pairs; anthers 2- or 1-thecous, thecae usually parallel attached at same height or one above the other, at base rounded, mucronate to apiculate or with distinct appendages or spurs, dehiscing longitudinally (rarely with apical or basal pores).
Ovary
Ovary superior, 2-locular, at base surrounded by an annular disc, with 2 collateral ( Thunbergioideae) or with 2–28 superposed ovules per locule; style simple, filiform, with 2 linear (one often reduced) to oblong or ovoid or capitate stigmatic lobes.
Fruits
Fruit a 2-locular loculicidal capsule (rarely a drupe), usually explosively dehiscent, the placentae sometimes separating from the capsule wall on opening.
Seeds
Seeds 1 to over 20 per locule, held on thickened curved laterally compressed hook-shaped outgrowths (retinaculae) from the funicle (retinaculae papilliform in Nelsonioideae and absent in Thunbergioideae), discoid to spheroid, reniform or cordiform to subglobose, surface often covered in hygroscopic hairs or glabrous and then smooth or variously sculptured.
Distribution
Range: In the Flora area 50 genera and 550–600 species. Range: About 250 genera and 2500–3000 species widely distributed in all tropical and subtropical regions, extending sparingly into warm temperate zones in Europe and Asia and as far north as Canada in temperate North America. Range: The largest diversity at both genus and species level is in the dry woodland, bushland and grassland regions of tropical and southern Africa, Madagascar, India and Central and South America.
Note
The system used for arranging the genera here is an amalgam of those outlined by Bremekamp in Bull. India 7: 21–30 (1965), Scotland & Vollesen in Kew Bull. 55: 513–589 (2000) and Manktelow et al in Syst. Bot. 26: 104–119 (2001).
[FWTA]

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

Habit
Herbaceous or climbing, rarely somewhat shrubby
Leaves
Leaves opposite, often with distinct cystoliths; stipules absent
Flowers
Flowers hermaphrodite, zygomorphic, often with conspicuous bracts
Calyx
Calyx-segments or lobes 4 or 5, imbricate or valvate; rarely the calyx reduced to a ring
Corolla
Corolla gamopetalous, 2-lipped or sometimes 1-lipped, lobes imbricate or contorted
Androecium
Stamens 4, didynamous or 2, inserted on the corolla-tube and alternate with its lobes; filaments free amongst themselves or partially connate in pairs; anthers 2-celled or 1-celled by reduction, cells confluent or separated, sometimes one much smaller than the other, opening lengthwise
Nectaries
Disk present
Gynoecium
Ovary superior, sessile on the disk, 2-celled
Fruits
Capsule mostly elastically dehiscent from the apex downwards, the valves recurved and leaving the central axis
Seeds
Seeds mostly with indurated funicle; endosperm rarely present; embryo large
Diagnostic
Recognised by the usually herbaceous habit, opposite leaves and the peculiar capsule
[FWTA]

Avicenniaceae, F.N. Hepper. Flora of West Tropical Africa 2. 1963

Habit
Shrubs or trees, branches terete
Leaves
Leaves opposite and decussate, simple, entire; stipules absent
Inflorescences
Inflorescences axillary or terminal; flowers sessile, hermaphrodite, actinomorphic
Calyx
Calyx very deeply 5-lobed, lobes imbricate, subtended by a pseudo-involucre composed of a scale-like bractlet and 2 alternate scale-like prophylla
Corolla
Corolla gamopetalous, campanulate-rotate, actinomorphic, deeply 4-lobed
Androecium
Stamens 4, inserted in throat of the corolla-tube, equal or subdidynamous
Gynoecium
Ovules 4, pendulous Style shortly divided Ovary superior, with 2 united carpels, placenta free, central
Fruits
Fruit dehiscent by 2 valves, usually only 1 seed develops
Seeds
Seed with 2 cotyledons, embryo viviparous
[FZ]

Flora Zambesiaca. Vol 8, Pt 7. Avicenniaceae, R. Fernandes. Nesogenaceae, M.A. Diniz. Verbenaceae, R. Fernandes. Lamiaceae, R. Fernandes. 2005.

General
Glabrous (or canescent) evergreen small trees of mangrove swamps, with extensive widely-spreading root systems bearing pneumatophores
Inflorescences
Inflorescences terminal or axillary, of contracted cymes at the end of short peduncles Inflorescences terminal or axillary, of contracted cymes at the end of short peduncles
Flowers
Flowers actinomorphic, hermaphrodite, sessile, subtended by an involucre formed by a bract and two bracteoles Flowers actinomorphic, hermaphrodite, sessile, subtended by an involucre formed by a bract and two bracteoles
Calyx
Calyx gamosepalous, deeply 5-lobed with lobes imbricate Calyx gamosepalous, deeply 5-lobed with lobes imbricate
Corolla
Corolla gamopetalous, campanulate or campanulate-rotate; tube short; limb 4(5)-lobed, spreading, with subequal lobes or the posterior lobe slightly broader Corolla gamopetalous, campanulate or campanulate-rotate; tube short; limb 4(5)-lobed, spreading, with subequal lobes or the posterior lobe slightly broader
Stamens
Stamens 4, inserted in the corolla throat and alternating with the lobes, equal or sub-didynamous; filaments ± short, filiform; anthers ovoid or suborbicular, subexserted
Ovary
Ovary superior, 2-carpellate, but appearing 4-locular due to ovary wall intrusions (false septa); placenta free, axile; style 1 short, bifid or bilobed, with apical stigmas; ovules 4, with 1 each apparent locule, pendent, orthotropous
Seeds
Seed without a testa; embryo with large longitudinally folded cotyledons and a villous radicle, viviparous; endosperm fleshy. Seed without a testa; embryo with large longitudinally folded cotyledons and a villous radicle, viviparous; endosperm fleshy
Note
Usually treated as a subfamily of the Verbenaceae , it is here recognized as a separate family readily distinguished by the involucre of 1 bract and 2 bracteoles which subtend each flower, the free-central placentation with a c. 4-winged placenta, the orthotropous ovules and by the viviparous embryo and fleshy endosperm.  Molecular evidence now places it near the more basal Acanthaceae , with which it shares few essential morphological characters.  [A.E. Schwarzbach & L.A. Mc Dade.  Phylogenetic relationships of the mangrove family Avicenniaceae based on chloroplast and nuclear chromosomal DNA sequences.  Systematic Botany 27 : 84–98 (2002)].
Distribution
A monogeneric family of the Old and New World tropics and subtropics.
Habit
Glabrous (or canescent) evergreen small trees of mangrove swamps, with extensive widely-spreading root systems bearing pneumatophores
Leaves
Leaves simple, decussate, petiolate, without stipules; lamina entire, pulverulent (powdery)-puberulent or felted-tomentellous on lower surface, ± coriaceous Leaves simple, decussate, petiolate, without stipules; lamina entire, pulverulent (powdery)-puberulent or felted-tomentellous on lower surface, ± coriaceous
Androecium
Stamens 4, inserted in the corolla throat and alternating with the lobes, equal or sub-didynamous; filaments ± short, filiform; anthers ovoid or suborbicular, subexserted
Gynoecium
Ovary superior, 2-carpellate, but appearing 4-locular due to ovary wall intrusions (false septa); placenta free, axile; style 1 short, bifid or bilobed, with apical stigmas; ovules 4, with 1 in each apparent locule, pendent, orthotropous
Fruits
Fruit a capsule, l-seeded (by abortion of 3 ovules), usually asymmetric, compressed, opening by 2(4) thickened valves Fruit a capsule, l-seeded (by abortion of 3 ovules), usually asymmetric, compressed, opening by 2(4) thickened valves

Images

Acanthaceae Juss. appears in other Kew resources:

First published in Gen. Pl. [Jussieu] 102. 1789 [4 Aug 1789] (1789)

Accepted by

  • APG IV (2016) http://dx.doi.org/10.1111/boj.12385

Sources

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

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

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2018. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0