Galactia P.Browne

Scientific Description

Family Papilionaceae. Phaseoleae.

Sometimes included in Leguminosae.

Habit and leaf form. Shrubs, or lianas, or herbaceous climbers (‘twining or trailing vine’, or ‘prostrate or scrambling perennial herb’!); not resinous. Perennial. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Climbing (or prostrate); when climbing, stem twiners, or scrambling. Mesophytic. Not heterophyllous. Leaves small to medium-sized; alternate; spiral, or distichous; ‘herbaceous’, or leathery; not imbricate; petiolate. Petioles wingless. Leaves non-sheathing; not gland-dotted; compound; pulvinate; ternate. Leaves pinnately trifoliolate. Leaves imparipinnate. Leaflets 3; 2–8 cm long. Lateral leaflets alternate, or opposite. Leaflets stipellate (the stipels persistent). Leaflets without swollen, glandlike stipels. Leaflets pulvinate; elliptic, or oblong, or ovate, or orbicular; cuneate at the base, or oblique at the base, or rounded at the base; flat; without lateral lobes. Leaflet margins flat. Leaf blades dorsiventral, or isobilateral, or centric; cross-venulate. Mature leaf blades adaxially glabrous (rarely), or pubescent; abaxially glabrous (rarely), or pubescent. Leaves with stipules. Stipules intrapetiolar; free of one another; scaly, or leafy; persistent. Leaf blade margins entire; not prickly; flat. Leaves without a persistent basal meristem. Leaf anatomy. Hairs present; glandular hairs absent; complex hairs absent. Branched hairs absent. Stem anatomy. Secondary thickening developing from a conventional cambial ring, or anomalous.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the disk. Entomophilous; via hymenoptera.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; not crowded at the stem bases. Inflorescence few-flowered. Flowers (pseudo-) in racemes. Inflorescences compound; axillary; pseudoracemes, with small clusters or solitary flowers at the thickened nodes. Flowers pedicellate; bracteate. Bracts deciduous. Flowers (bi-) bracteolate. Bracteoles persistent (at the base of the calyx). Flowers small to medium-sized; very irregular; zygomorphic. The floral asymmetry involving the perianth and involving the androecium. Flowers papilionaceous (imbricate-descending); basically 5 merous; tetracyclic. Floral receptacle with neither androphore nor gynophore. Free hypanthium present, or absent. Hypogynous disk present; intrastaminal. Perianth with distinct calyx and corolla; (9–)10; 2 -whorled; isomerous to anisomerous. Calyx present; 5 (basically), or 4 (the two components of the upper lip being almost completely fused); 1 -whorled; gamosepalous; lobed; blunt-lobed and toothed. Calyx lobes about the same length as the tube to markedly longer than the tube. Calyx imbricate; exceeded by the corolla; bilabiate (the lower lip with three lobed with the median longer, the upper with its two components connate to form one broad lobe); neither appendaged nor spurred; non-fleshy; persistent; non-accrescent; with the median member anterior. Epicalyx present (representing the bracteoles). Corolla present; 5; 1 -whorled; appendiculate to not appendiculate (the standard slightly auriculate). Standard appendaged (with small auricles). Corolla partially gamopetalous. 2 of the petals joined, or 4 of the petals joined. The joined petals anterior. The wings of the corolla adherent to the keel (according to Bentham); not laterally spurred. Standard ‘normally’ developed; emarginate; not sericeous. Keel conspicuously exceeded by the wings, or about equalling the wings; not long-acuminate/beaked; neither coiled nor spiralled; not bent and beaked. Corolla imbricate (descending); glabrous abaxially; glabrous adaxially; pink, or purple, or blue; deciduous. Petals clawed (the standard shortly so). Androecial members definite in number. Androecium 10. Androecial members free of the perianth; markedly unequal (alternately long and short); coherent; 2 - adelphous (the posterior stamen free of the rest, whose filaments are united into a tube); 1 -whorled. Androecium exclusively of fertile stamens. Stamens 10; remaining included; 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; dorsifixed; versatile; dehiscing via longitudinal slits; latrorse, or introrse; tetrasporangiate. Pollen shed as single grains. Gynoecium 1 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium monomerous; of one carpel; superior. Carpel stylate; apically stigmatic. Style filiform, curved. Style glabrous. Stigmatic tissue terminal. Carpel 7–10 ovuled (or ‘many’!). Placentation marginal (along the ventral suture). Gynoecium median (the placenta posterior, on the ventral suture). Ovary sessile. Ovary summit hairy, the hairs not confined to radiating bands. Styles becoming exserted; hairless. Ovules pendulous to ascending; biseriate; arillate; anatropous, or campylotropous to amphitropous, or hemianatropous.

Fruit and seed features. Fruit aerial; 30–55 mm long; non-fleshy; sparsely hairy; not spinose. The fruiting carpel dehiscent; a legume. Pods much elongated; not triangular; straight, or curved; shortly beaked; not becoming inflated; somewhat compressed; irregularly constricted, or not constricted between the seeds; more or less transversely septate between the seeds; wingless; not internally hairy. Valves of the dehisced pod not twisted. Fruit 1 celled; elastically dehiscent. Dispersal unit the seed. Fruit 7–8 seeded. Seeds non-endospermic; not mucous; small; arillate to non-arillate; wingless. Cotyledons 2; accumbent. Embryo curved, or bent. Testa hard; non-operculate; smooth; conspicuously colour-patterned (mottled). Micropyle zigzag, or not zigzag.

Special features. Calyx limb 4 lobed. Upper lip of calyx entire to lobed; 1–2 lobed. Lower lip of calyx lobed; 3 lobed.

Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, South Australia, Northern Territory, Queensland, and New South Wales. 2n=20; ploidy levels recorded 2. A genus of about 50 species; 1 species in Western Australia; G. tenuiflora (Klein ex Willd.) Wight & Arn.; 0 endemic to Western Australia.

Additional comments. Note marked differences in the Kimberly and Northern Territory descriptions of G. tenuiflora, extending even to the nomenclatural authority.