Commersonia J.R.Forst. & G.Forst.
Char.Gen.Pl. 43, Tab.22 (1775)

Name Status: Current
Browse to the list of specimens for Commersonia J.R.Forst. & G.Forst.

Scientific Description
B. Richardson, Thursday 8 September 2016

Family Sterculiaceae.

(Subfamily Byttnerioideae), Tribe Byttnerieae, sometimes misspelt Commerconia.

Habit and leaf form. Shrubs; evergreen; non-laticiferous and without coloured juice. ‘Normal’ plants. Leaves well developed. Plants with roots; non-succulent. Leaves cauline. To 1 m high. Self supporting. Mesophytic. Not heterophyllous. Leaves small, or medium-sized; alternate; with blades; petiolate, or subsessile; with ‘normal’ orientation; simple; not peltate. Leaf blades neither inverted nor twisted through 90 degrees; dorsiventral; dissected; flat; ovate, or obovate; pinnately veined. Mature leaf blades adaxially pubescent (sparsely stellate hairy); abaxially pubescent (white stellate hairy). Leaves with stipules. Stipules caducous. Leaf blade margins entire, or crenate (‘undulate’); revolute. Leaf anatomy. Hairs present; complex hairs present. Complex hairs stellate.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants homostylous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; not crowded at the stem bases. Inflorescence few-flowered. Flowers in cymes. Inflorescences simple; axillary. Flowers pedicellate; bracteate. Bracts deciduous. Flowers small; regular; not resupinate; neither papilionaceous or pseudo-papilionaceous; 5 merous; cyclic; tetracyclic. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous; lobed. Calyx lobes markedly longer than the tube. Calyx hairy (stellate hairy outside, finely stellate hairy, or with simple hairs inside); exceeding the corolla, or more or less equalling the corolla; regular; neither appendaged nor spurred; white (‘whitish’ Jessop (1986)). Epicalyx absent. Corolla present; 5; 1 -whorled; appendiculate (ligulate in upper portion); polypetalous; regular. Androecium present. Fertile stamens present. Androecial members definite in number. Androecium 10. Androecial members branched (‘staminodes tripartite’); free of the perianth; free of the gynoecium; markedly unequal; free of one another; 1 -whorled. Androecium including staminodes. Stamens 5; all more or less similar in shape; isomerous with the perianth; alternisepalous; all opposite the corolla members; filantherous. Filaments filiform. Anthers separate from one another; all alike; extrorse; bilocular. Fertile gynoecium present. Gynoecium 5 carpelled. The pistil 5 celled. Carpels isomerous with the perianth. Gynoecium syncarpous; eu-syncarpous; superior. Ovary plurilocular; 5 locular; sessile. Gynoecium stylate. Styles 5; free (‘adhering to form a column’); simple; apical. Stigmas 1; 1 - lobed; capitate. Placentation axile.

Fruit and seed features. Fruit hairy (‘usually pubescent’); dehiscent; a capsule. Capsules loculicidal. Fruit 5 celled. Dispersal unit the seed. Seeds 1 per locule, or 2 per locule.

Geography, cytology, number of species. Native of Australia, or adventive. Endemic to Australia, or not endemic to Australia. A genus of ca 12 species; ca 6 species in Western Australia.

Additional comments. Named after the French naturalist Philibert Commerson, 1727–1773, who sailed with the Bougainville expedition in 1766 and died on Mauritius.

Taxonomic Literature

  • Grieve, B. J.; Blackall, W. E. (1998). How to know Western Australian wildflowers : a key to the flora of the extratropical regions of Western Australia. Part II, Dicotyledons (Amaranthaceae to Lythraceae). University of W.A. Press. Nedlands, W.A.