Urodon Turcz.

Scientific Description

Family Papilionaceae. Mirbelieae.

Sometimes included in Pultenaea. Sometimes included in Leguminosae.

Habit and leaf form. Low shrubs (with stems erect, ascending or decumbent). Plants unarmed. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Self supporting. Leptocaul. Leaves small; alternate; spiral; leathery; non-sheathing; simple; epulvinate. Leaf blades dorsiventral; entire; flat, or rolled; narrowly oblong; narrowly oblong; 1 -nerved; without cross-venules. Mature leaf blades adaxially glabrous, or villous; abaxially glabrous, or villous. Leaves without stipules. Leaf blade margins entire; not prickly; flat, or involute. Leaf anatomy. Complex hairs present, or absent (? — no peltate hairs).

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

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; not crowded at the stem bases; in racemes, or in heads. Inflorescences simple. The terminal inflorescence unit racemose. Inflorescences terminal; rather dense, villous heads: the flowers ‘sessile within the last leaves, which are larger, broader, thinner and more acute than’ the vegetative leaves. Flowers subsessile, or sessile; bracteate (i.e. in the axils of modified leaves, these not trifid); (bi-) bracteolate (the bracteoles inserted a little below the calyx); small to medium-sized; very irregular; zygomorphic. The floral asymmetry involving the perianth, or involving the perianth and involving the androecium. Flowers papilionaceous; tetracyclic. Floral receptacle with neither androphore nor gynophore. Free hypanthium present, or absent. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous (not ribbed); five lobed. Calyx lobes all markedly longer than the tube. Calyx imbricate; exceeded by the corolla; bilabiate (the two adaxial lobes broader and longer); non-fleshy; persistent; non-accrescent; with the median member anterior. Epicalyx absent. Corolla present; 5; 1 -whorled; appendiculate, or not appendiculate. Standard not appendaged. Corolla polypetalous, or 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; emarginate; not sericeous. Keel 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; deciduous; non-accrescent. Petals 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, or connivent. Gynoecium 1 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium monomerous; of one carpel; superior. Carpel stylate. Style terete (subulate). Carpel 2 ovuled. Gynoecium median. Ovary sessile. Ovules shortly funicled; arillate.

Fruit and seed features. Fruit non-fleshy. The fruiting carpel dehiscent; a legume. Pods globose, or somewhat elongated; not triangular; not internally hairy. Fruit 1 celled. Dispersal unit the seed. Fruit 1–2 seeded. Seeds not mucous; non-arillate. Embryo bent (radicle inflexed). Testa non-operculate; homogeneous in colour.

Geography, cytology, number of species. Native of Australia. A genus of 2 species; 2 species in Western Australia.