Latrobea Meisn.

Scientific Description

Family Papilionaceae. Mirbelieae.

Sometimes included in Leguminosae.

Habit and leaf form. Slender, ericoid shrubs (often with virgate branches). Plants unarmed. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Xerophytic. Leaves minute to small; alternate (or ‘scattered’); non-sheathing; simple; epulvinate. Leaf blades dorsiventral; solid (concave or channelled above); semi-terete, or solid/angular; grooved adaxially (or with involute margins), or not grooved; linear; linear. Leaves without stipules. Leaf blade margins entire, or crenate, or serrate; flat, or involute.

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, terminal; when aggregated, in heads, or in corymbs. Inflorescences terminal (or sometimes subterminal on short branchlets). Flowers pedicellate; bracteate, or ebracteate (small); bracteolate (the bracteoles small, distant from the calyx), or ebracteolate; 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; five lobed (the lobes sometimes ribbed). Calyx lobes markedly longer than the tube. Calyx exceeded by the corolla; more or less regular; non-fleshy; persistent; non-accrescent; with the median member anterior. 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. Keel about equalling the wings, or conspicuously exceeding the wings (straight or slightly incurved, almost as long as the standard); not long-acuminate/beaked; not bent and beaked. Corolla imbricate; yellow, or red, or pink, or purple; deciduous; non-accrescent. Petals shortly clawed, or sessile. 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; all alike; dehiscing via longitudinal slits; latrorse, or introrse. Gynoecium 1 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium monomerous; of one carpel; superior. Carpel stylate. Style filiform or basally thickened. Stigmatic tissue terminal. Gynoecium median. Ovary sessile to stipitate. Stigmas punctiform (minute). Ovules shortly funicled; arillate.

Fruit and seed features. Fruit stipitate; non-fleshy. The fruiting carpel dehiscent; a legume. Pods somewhat elongated to much elongated (ovate or lanceolate); not triangular; straight; not becoming inflated; more or less flat; not constricted between the seeds; not transversely septate; wingless. Fruit 1 celled. Dispersal unit the seed. Fruit 1–2 seeded. Seeds oblong to elliptic or reniform in outline; not mucous. Embryo bent (radicle inflexed). Testa non-operculate.

Geography, cytology, number of species. Native of Australia. 2n = 14. A genus of 6 species; 7 species in Western Australia; 6 endemic to Western Australia.