Burtonia R.Br.
Hort.Kew. 3:12 (1811)

Name Status: Current

Scientific Description
Leslie Watson, Friday 3 October 2008

Family Papilionaceae. Mirbelieae.

Sometimes included in Gompholobium. Sometimes included in Leguminosae.

Habit and leaf form. Shrubs (and undershrubs). Leaves alternate; spiral; non-sheathing; simple, or compound; when compound, unifoliolate, or ternate, or pinnate, or palmate. Leaves when trifoliolate, palmately trifoliolate. Leaves imparipinnate (the terminal leaflet always sessile). Leaflets not stipellate. Leaf blades dorsiventral. Leaves with stipules (minute), or without stipules. Stipules intrapetiolar; free of one another.

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

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; not crowded at the stem bases; when solitary, axillary (in the upper axils); when aggregated, in racemes, or in corymbs. Inflorescences simple. The terminal inflorescence unit racemose. Inflorescences terminal. Flowers pedicellate; bracteate, or ebracteate. Bracts persistent. Flowers bracteolate, or ebracteolate (‘with four persistent bracts or bracteoles’). Bracteoles persistent. Flowers very irregular; zygomorphic; papilionaceous; tetracyclic. Floral receptacle developing a gynophore, or with neither androphore nor gynophore. Free hypanthium present, or absent. Hypogynous disk present; intrastaminal; annular. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous; lobed. Calyx lobes markedly longer than the tube (the tube very short). Calyx valvate; exceeded by the corolla; somewhat bilabiate (the upper pair of lobes somewhat broader), or regular; non-fleshy; persistent; non-accrescent; with the median member anterior. Corolla present; 5; 1 -whorled; appendiculate, or not appendiculate. Standard not appendaged. Corolla partially gamopetalous. 2 of the petals joined. The joined petals anterior (the keel members). The wings of the corolla free from the keel; not laterally spurred. Standard ‘normally’ developed; entire, or emarginate. Keel conspicuously exceeded by the wings, or about equalling the wings, or conspicuously exceeding the wings; not long-acuminate/beaked; neither coiled nor spiralled; not bent and beaked. Corolla imbricate; yellow, or orange, or red, or purple, or blue; deciduous; non-accrescent. Petals very shortly clawed. Androecial members definite in number. Androecium 10. Androecial sequence determinable, or not determinable. Androecial members free of the perianth; all equal to markedly unequal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 10; all more or less similar in shape; diplostemonous; both opposite and alternating with the corolla members; filantherous. Anthers separate from one another to connivent; all alike; dehiscing via longitudinal slits; latrorse, or introrse; tetrasporangiate. Gynoecium 1 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium monomerous; of one carpel; superior. Carpel stylate. Style (in-) curved (dilated basally). Style glabrous. Carpel 2 ovuled (by contrast with Gompholobium). Placentation marginal. Gynoecium median. Ovary shortly stipitate, or sessile to subsessile. Ovules long funicled (one curved upwards, the other downwards); pendulous and ascending; biseriate.

Fruit and seed features. Fruit shortly stipitate, or subsessile to sessile; non-fleshy. The fruiting carpel dehiscent; a legume. Pods globose; not triangular; becoming inflated, or not becoming inflated; somewhat compressed to terete; not constricted between the seeds; not transversely septate; wingless. Fruit 1 celled. Dispersal unit the seed. Fruit 2 seeded. Seeds not mucous; non-arillate. Embryo bent (radicle inflexed). Testa non-operculate.

Geography, cytology, number of species. 2n = 18. A genus of about 12 species; 10 species in Western Australia.