Callistachys Vent.

Scientific Description

Family Papilionaceae. Mirbelieae.

Sometimes included in Oxylobium lanceolatum. Sometimes included in Leguminosae.

Habit and leaf form. Tall shrubs (the young branches with appressed, silky hairs). Plants unarmed. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Leptocaul. Leaves medium-sized (5–14 cm long); whorled (mostly), or alternate to opposite (some, sometimes); mostly 3 per whorl; leathery; simple; epulvinate. Leaf blades dorsiventral; entire; flat; lanceolate to ovate, or oblanceolate, or oblong; narrowly ovate, or obovate, or oblong to elliptic; cross-venulate. Leaves with stipules. Stipules intrapetiolar; free of one another; filiform or subulate. Leaf blade margins entire; not prickly; flat to revolute. 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’; dense in racemes. Inflorescences simple. The terminal inflorescence unit racemose. Inflorescences terminal. Flowers pedicellate (the pedicels 3–6 mm long); bracteate. Bracts deciduous (caducous, trifid). Flowers ebracteolate (according to Crisp and Weston, 1995); 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 developing a gynophore. Free hypanthium present, or absent. Hypogynous disk present; intrastaminal; annular (short). Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous; five lobed. Calyx lobes about the same length as the tube to markedly longer than the tube. Calyx densely hairy (golden or darkly sericeous); imbricate; exceeded by the corolla; bilabiate (the lobes of the upper lip connate to above the middle, slightly curved); 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, or 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; not sericeous. Keel about equalling the wings; not long-acuminate/beaked; neither coiled nor spiralled; not bent and beaked. Corolla imbricate; yellow to 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. Filaments glabrous. Anthers separate from one another to connivent; all alike; dorsifixed; versatile; 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 curved. Style glabrous. Carpel 6–12 ovuled. Placentation marginal. Gynoecium median. Ovary shortly stipitate. Ovules arillate.

Fruit and seed features. Fruit stipitate; non-fleshy; hairy (sericeous). The fruiting carpel dehiscent; a legume (but dehiscing only in the upper third). Pods much elongated; not triangular; straight; not becoming inflated; somewhat compressed; not constricted between the seeds; partially transversely septate between the seeds, or not transversely septate; wingless; not internally hairy. Fruit 1 celled. Dispersal unit the seed. Fruit 6–12 seeded. Seeds reniform; not mucous; minutely arillate. Embryo bent (radicle inflexed). Testa non-operculate; homogeneous in colour.

Geography, cytology, number of species. 2n = 16. A genus of 1 species; 1 species in Western Australia, or 2 species in Western Australia.