Overview of gentian tribal classification

Classification list arranged by genus name

Species:  About 144-184 species in six genera. Sebaea is the largest genus.

Distribution: Old World tropics, mainly in tropical Africa, Madagascar and India.

Habitat:  Annual herbs to subshrubs up to a few meters tall, or tiny saprophytic plants (Cotylanthera).

Characteristics:   Stems often winged or with four lines. Flowers solitary, or inflorescences few or many-flowered mono- or dichasial terminal or axillary cymes. Flowers 4-merous or most commonly 5-merous, rarely zygomorphic by having fused anthers above a bent style. Calyx sometimes distinctly winged. Corollas white to blue/violet, or white to yellow. Corolla tube rather short and funnelshaped to urceolate or long-cylindric, rarely long and narrowly funnelshaped). Anthers dehiscent by longitudinal slits or by one or two apical pores (Exacum), often with apical appendages. Pollen in monads. Ovary usually without a nectary disc below it, is bilocular with axile placentas or unilocular but becoming pseudo-bilocular from the centrally-protruding parietal placentas. Fruit is a thin capsule. Seeds are usually angular with slightly to much undulated and often star-shaped testa cell walls.

Evolution and related plants: 

Economic uses:  Exacum affine (persian violet) is commercially cultivated as a pot plant.

Included genera:

Cotylanthera Blume (images)
Exacum L. (images)
Gentianothamnus Humbert
Ornichia Klack.
Sebaea Sol. ex R. Br. (images)
Tachiadenus Griseb.

Bibliography:

Klackenberg, J. 1985. The genus Exacum (Gentianaceae). Opera Bot. 84: 1-144.

Klackenberg, J. 1986. The new genus Ornichia (Gentianaceae) from Madagascar. Bull. Mus. Nat. Hist. Nat., Paris, 4 sér., 8, sect. B, Adansonia, 2: 195-206.

Klackenberg, J. 1987a. Revision of the genus Tachiadenus (Gentianaceae). Bull. Mus. Nat.. Hist. Nat. Paris , 4 sér., 9, sect. B, Adansonia 1: 43-80.

Struwe, L., J. W. Kadereit, J. Klackenberg, S. Nilsson, M. Thiv, K. B. von Hagen, & V. A. Albert. 2002. Systematics, character evolution, and biogeography of Gentianaceae, including a new tribal and subtribal classification. Pp. 21-309. In: L. Struwe & V. A. Albert (eds.), Gentianaceae: Systematics and Natural History, Cambridge University Press, Cambridge.

© Lena Struwe, 2003