Tetradenia Benth.

First published in Edwards's Bot. Reg. 15: t. 1300 (1830)
This genus is accepted
The native range of this genus is Eritrea to S. Africa, Madagascar.

Descriptions

Lamiaceae (Labiatae), A.J. Paton, G. Bramley, O. Ryding, R.M. Polhill, Y.B. Harvey, M. Iwarsson, F. Willis, P.B. Phillipson, K. Balkwill, C.W. Lukhoba, D.F. Otieno, & R.M. Harley. Flora of Tropical East Africa. 2009

Morphology General Habit
Aromatic dioecious shrubs
Morphology Stem
Stems thick and usually fleshy when young, bearing 4 distinctive callosities at each node
Morphology Leaves
Leaves petiolate, dentate, deciduous; midrib and major veins fleshy, prominent on lower surface
Morphology Reproductive morphology Inflorescences
Inflorescence a large panicle-like thyrse, often produced on leafless plants during the dry season, the branches bearing numerous spikes composed of many sessile usually 3-flowered cymes of tiny flowers; lowermost bracts leaf-like; verticil bracts small, persistent or caducous, green
Morphology Reproductive morphology Flowers Calyx
Calyx tubular, 2-lipped, 5-lobed; posterior lobe usually rounded, not decurrent, lateral and anterior lobes smaller, subequal, acute, separated by a deep basal sinus giving the appearance of two emarginate lateral lobes; fruiting calyx slightly enlarged; lateral and anterior lobes closed around nutlets; posterior lobe usually held open
Morphology Reproductive morphology Flowers Corolla
Corolla white or pale pink to violet, trumpet to funnel-shaped, weakly 2-lipped; posterior lip 2-lobed, ascending; lateral lobes spreading; anterior lip formed by a single longer horizontal or deflexed lobe; corolla tube ± straight, villous within
Morphology Reproductive morphology Flowers Androecium Stamens
Stamens 4, subequal, exserted, attached in the throat; filaments straight, glabrous; anthers synthecous, rounded; staminodes present in female flowers, often minute
Morphology Reproductive morphology Flowers Disc
Disk 4-lobed, fleshy
Morphology Reproductive morphology Flowers Gynoecium Ovary
Ovary glabrous, deeply 4-lobed; style gynobasic, filiform, glabrous, exserted, bifid at apex; a rudimentary gynoecium with a reduced bifid style present in male flowers
Morphology Reproductive morphology Fruits
Nutlets ovoid to oblong, brown, not mucilaginous when wetted.
Note
The identity of the East African species has been greatly confused in the past - Brenan in T.T.C.L.: 256 (1949) recognised three species (which he placed in the genus Iboza), more recently, these and other species from other regions have been placed as synonyms of T. riparia (Hochst.) Codd (Codd, 1983 and K.T.S.L.: 635, 1994). We take a narrower view of species circumscription in the genus, limiting T. riparia to populations from southern Africa (South Africa to Malawi), resuscitating some of the synonyms and describing two new species from the Flora area (Phillipson & Steyn, 2008). T. riparia is also cultivated as a garden ornamental, including within the Flora area: Kenya, Kiambu District, Muguga, Cult. Hort. 26 Aug. 1961, Greenway 10203!; Tanzania, Lushoto, Jaegerstal, 21 Apr. 1971, Mshana 161! & Lushoto Boma Garden, 11 July 1978, Ruffo 1362! It is most similar to T. galpinii in the Flora area, the differences are given under that species.
[FTEA]

Harley, R.M. et al. (2004). Labiatae, in The Families and Genera of Vascular Plants (K. Kubitzki, ed. in chief) VI: 167-275. Springer-Verlag, Berlin, Heidelberg, New York.

Morphology General Habit
Fleshy, dioecious, rarely hermaphrodite, aromatic shrubs
Morphology Leaves
Leaves simple
Morphology Reproductive morphology Inflorescences
Inflorescence thyrsoid, paniculately branched with cymes sessile, 2-5-flowered
Morphology Reproductive morphology Inflorescences Bracts
Bracts persistent, inconspicuous, not coloured
Morphology Reproductive morphology Flowers Calyx
Calyx shortly tubular, straight, strongly 2-lipped, 5-lobed (1/4), lobes unequal, posterior ovate, not decurrent; anterior lanceolate with a sinus between the median pair giving the appearance of two emarginate lateral lobes, throat open, glabrous
Morphology Reproductive morphology Flowers Corolla
Corolla 2-lipped, 5-lobed (4/1), white or pink, posterior lip with the median lobes ascending, shallow, lateral lobes spreading, held between the median lobes and anterior lip, anterior lip horizontal or deflexed, concave, corolla-tube straight or sometim
Morphology Reproductive morphology Flowers Androecium Stamens
Stamens (male flowers) 4, porrect, exserted, posterior attached near throat or at midpoint of corolla-tube, anterior attached at throat
Morphology Reproductive morphology Flowers Gynoecium Stigma
Stigma-lobes short, equal, connivent, often non-functional
Morphology Reproductive morphology Flowers
Female flowers lacking stamens
Morphology Reproductive morphology Flowers Gynoecium Style
Style with 2 stigma-lobes
Morphology Reproductive morphology Flowers Disc
Disc equally 4-lobed or with anterior lobe larger
Morphology Reproductive morphology Fruits
Nutlets oblong, glabrous, not mucilaginous.
Note
2n = 42.  Fifteen to 20 species
Distribution
In Madagascar and Southern and Tropical Africa.
[LKGF]

Sources

  • Flora of Tropical East Africa

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

  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2022. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2022 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 2022. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2022 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0
  • Lamiaceae Key Genus Fact Sheets

    • Nina Davies, Gemma Bramley and Don Kirkup, Royal Botanic Gardens, Kew
    • http://creativecommons.org/licenses/by/3.0