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Tarenna Gaertn.

Fruct.Sem.Pl. 1:139 (1788)
Name Status

Scientific Description

Family Rubiaceae.

Habit and leaf form. Trees, or shrubs, or lianas. Plants unarmed. Young stems tetragonal. Self supporting, or climbing. Helophytic, or mesophytic, or xerophytic. Leaves opposite; leathery (to chartaceous); petiolate to subsessile; connate (via the stipules), or not connate; gland-dotted, or not gland-dotted; simple; epulvinate. Leaf blades entire; pinnately veined; cross-venulate. Leaves with stipules. Stipules interpetiolar (free, triangular with a central rib produced into an acumin); with colleters (secreting mucilage), or without colleters; usually persistent. Leaf blade margins entire, or serrate. Leaves without a persistent basal meristem. Domatia recorded. Stem anatomy. Nodes unilacunar, or tri-lacunar. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants homostylous, or heterostylous. Entomophilous. Pollination mechanism conspicuously specialized (with passive pollen presentation involving stylar modification), or unspecialized.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. Inflorescence many-flowered. Flowers in cymes. The terminal inflorescence unit cymose. Inflorescences terminal, or axillary. Flowers bracteolate; small; fragrant; regular; 5 merous; cyclic; tetracyclic. Free hypanthium present, or absent (depending on interpretation); obconic or conic, smooth. Perianth with distinct calyx and corolla; 10; 2 -whorled; the two whorls isomerous. Calyx 5; 1 -whorled; gamosepalous; entire, or lobed; open in bud; tubular; regular; persistent. Corolla 5; 1 -whorled; gamopetalous; contorted; tubular, or funnel-shaped; regular; hairy adaxially (hairy inside throat), or glabrous adaxially; white to yellow. Androecium 5. Androecial members adnate (to the corolla tube); free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5. Staminal insertion in the throat of the corolla tube. Stamens isomerous with the perianth; oppositisepalous; filantherous (filaments short). Anthers linear; dorsifixed (near the base); reflexed; dehiscing via longitudinal slits; introrse; tetrasporangiate; appendaged, or unappendaged; often shortly apiculate. Pollen shed in aggregates, or shed as single grains; if aggregated, in tetrads. Gynoecium 2 carpelled. The pistil 2 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious to eu-syncarpous; inferior. Ovary plurilocular; 2 locular. Gynoecium transverse. Epigynous disk present (annular). Gynoecium stylate. Styles 1; attenuate from the ovary, or from a depression at the top of the ovary; apical; shorter than the ovary at anthesis to much longer than the ovary at anthesis; becoming exserted. Stigmas 1; 2 - lobed; wet type, or dry type; papillate, or non-papillate; Group II type and Group IV type. Placentation axile. Ovules 1–15 per locule; pendulous, or horizontal, or ascending; anatropous, or hemianatropous.

Fruit and seed features. Fruit fleshy; green, or white, or black; indehiscent; a berry (globular, smooth, not splitting into pyrenes); 1 locular, or 2 locular; 1 seeded (when 1-locular), or 1–15 seeded (i.e. ‘1 to several’ when 2-locular). Seeds angular or lenticular; endospermic. Endosperm ruminate, or not ruminate; oily. Cotyledons 2. Embryo straight, or curved. Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Aluminium accumulation demonstrated, or not found.

Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia and Northern Territory. Northern Botanical Province.

Additional characters Corolla lobes spreading (reflexed).

H.R. Coleman, 8 September 2016

Taxonomic Literature

  • Reynolds, S.T.; Forster, Paul I. 2005. A taxonomic revision of Tarenna Gaertn. and Triflorensia S.T.Reynolds (Rubiaceae: Ixoroideae: Pavetteae) in Australia.
  • Wheeler, J. R.; Rye, B. L.; Koch, B. L.; Wilson, A. J. G.; Western Australian Herbarium 1992. Flora of the Kimberley region. Western Australian Herbarium.. Como, W.A..