Timonius DC.
Prodr. 4:461 (1830)

Name Status: Current
Browse to the list of specimens for Timonius DC.

Scientific Description
H.R. Coleman, Thursday 8 September 2016

Family Rubiaceae.

Habit and leaf form. Trees, or shrubs. Plants unarmed. Young stems cylindrical. Helophytic, or mesophytic, or xerophytic. Leaves opposite; decussate; petiolate to sessile; connate (via the stipules), or not connate; simple; epulvinate. Leaf blades entire; pinnately veined; cross-venulate. Leaves with stipules. Stipules interpetiolar (free); with colleters (secreting mucilage), or without colleters; caducous, or persistent (terminal pair only). Leaf blade margins entire. Leaves without a persistent basal meristem. Domatia not recorded (apparently absent). Stem anatomy. Nodes unilacunar, or tri-lacunar. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers functionally male, or functionally female. Unisexual flowers present. Plants monoecious. Female flowers with staminodes (4–12, included). Male flowers with pistillodes (ovary and style rudimentary). 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’, or solitary. Inflorescence few-flowered, or many-flowered. Flowers in cymes. Inflorescences simple, or compound. The terminal inflorescence unit cymose. Inflorescences axillary; pedunculate. Flowers small to medium-sized; regular; 4–12 merous; cyclic. Free hypanthium present, or absent (depending on interpretation). Perianth with distinct calyx and corolla; 8–18; 2 -whorled; the two whorls isomerous, or anisomerous. Calyx 4–6; 1 -whorled; gamosepalous; entire, or lobed; open in bud; regular; persistent. Corolla 4–12; 1 -whorled; gamopetalous; imbricate; tubular to funnel-shaped; regular; glabrous adaxially; white. Corolla lobes thick and succulent, with a prominent rib inside. Fertile stamens present, or absent (when flower female). Androecium 4–12. Androecial members adnate (to the corolla tube); free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 4–12; remaining included, or becoming exserted (slightly); isomerous with the perianth; oppositisepalous. Anthers dorsifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate. Pollen shed in aggregates, or shed as single grains; if aggregated, in tetrads. Fertile gynoecium present, or absent (when flower male). Gynoecium 2–12 carpelled. The pistil 2–12 celled. Carpels isomerous with the perianth. Gynoecium syncarpous; synstylovarious to eu-syncarpous; inferior. Ovary plurilocular; 2–12 locular. Locules secondarily divided by ‘false septa’ (cells divided by septa into numerous sections). Gynoecium transverse. Epigynous disk present. 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; 2–12 - lobed; wet type, or dry type; papillate, or non-papillate; Group II type and Group IV type. Placentation axile. Ovules 10–50 per locule (i.e. ‘many’); pendulous, or horizontal, or ascending; anatropous, or hemianatropous.

Fruit and seed features. Fruit fleshy; green; indehiscent; a berry, or a drupe. The drupes with separable pyrenes (pyrenes numerous). Fruit 4–100 seeded. Seeds endospermic. Endosperm 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, Northern Territory, and Queensland. Northern Botanical Province.

Etymology. After Timon; name of the plant in Amboina (Ambon), on account of its black bark.

Taxonomic Literature

  • 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.