Tetraphyllum

Etymology: From the Greek τετρα, tetra = four, and φυλλον, phyllon = leaf, alluding to the conspious tetramerous leaf whorl at the top of the plant.

Synonyms: -

Infrafamilial position: Didymocarpoid Gesneriaceae - "Basal Asiatic genera” (Weber 2004).

Description: Terrestrial, perrenial herbs with (lignescent?) monocarpic stem(s). Stem erect, caulescent, with tawny villose indumentum, bearing a tetramerous (pseudo-) whorl or a leaf pair at the top, and pairs of scale leaves (in some species with axillary inflorescences) along the stem. Leaves petiolate or (sub)sessile, ovate or lanceolate, partly unequal-sided. Cymes axillary, condensed, flowers nearly sessile; bracteoles small. Sepals 5, almost free to base. Corolla widely funnel-shaped, limb bilabiate to subregular, lobes obtuse. Stamens 4, didynamous, or 2, filaments emerging near corolla base, anthers coherent at the tips, opening by longitudinal slits. Nectary much reduced. Ovary ovoid, style slender, stigma obscurely bilobed. Capsule splitting loculicidally and septicidally into 4 valves, leaving the two main ribs united to the style and 4 papery enrolled placentae.

Chromosome number: Unknown.

Species number: 3, some more to be described.

Type species: Tetraphyllum bengalense C.B.Clarke

Species names (incl. publication and synonyms): See Skog, L.E. & J.K. Boggan. 2005: World checklist of Gesneriaceae: http://persoon.si.edu/Gesneriaceae/Checklist.

Distribution: NE India, Bangladesh, Burma, Thailand.

Ecology: Damp rocks in forest.

Notes: Both the habit and the peculiar fruit with persistent style base holding the main ribs of the two carpels together after the four valves have fallen, are unmistakable. The genus represents another case of transition from tetrandry to diandry.

Selected references: Burtt, Thai Forest Bull. (Botany) 29: 81-109 (2001), annot. checklist (Thailand); Burtt, rev. in prep.

Bibliography: See Skog, L.E. & J.K. Boggan. 2005. Bibliography of the Gesneriaceae. 2^nd edition: http://persoon.si.edu/Gesneriaceae/Bibliography.

Illustrations:

Tetraphyllum bengalense C.B.Clarke, type species C.B.Clarke, Commelyn. Cyrtandr. Bengal. t. 87 (1874)

Tetraphyllum roseum Stapf Thailand, Chiang Mai prov., phot. H. Kurzweil (1985)

last modified: 2007-07-13