Aeschynomene L.
Sp.Pl. 2:713 (1753)

Name Status: Current
Browse to the list of specimens for Aeschynomene L.

Scientific Description
Leslie Watson, Thursday 8 September 2016

Family Papilionaceae. Aeschynomeneae.

Habit and leaf form. Ours(sub-) shrubs, or herbs (with glandular based hairs). Perennial; plants with neither basal nor terminal concentrations of leaves; to 0.2–2 m high. Mesophytic, or xerophytic. Leaves small to large; alternate; spiral; ‘herbaceous’, or leathery; not imbricate; petiolate. Petioles wingless. Leaves non-sheathing; compound; pulvinate (and more or less sensitive); in ours, pinnate; paripinnate. Leaflets 10–60. Lateral leaflets alternate (to sub-opposite). Leaflets not stipellate; pulvinate, or epulvinate; flat, or folded; without lateral lobes. Leaf blades dorsiventral. Leaves with stipules. Stipules intrapetiolar. Stipules more or less peltate. Stipules free of one another; leafy (large, narrowly ovate and basally extended); persistent. Leaf blade margins entire. Leaves without a persistent basal meristem. Stem anatomy. Nodes tri-lacunar, or penta-lacunar. Secondary thickening developing from a conventional cambial ring.

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

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in racemes. The terminal inflorescence unit racemose (the flowers solitary in the bract axils). Inflorescences terminal, or axillary, or leaf-opposed; in ours, few-flowered racemes. Flowers pedicellate; (bi-) bracteolate; small; very irregular; zygomorphic; resupinate (sometimes, in pendulous inflorescences or in association with bird pollination), or not resupinate. The floral asymmetry involving the perianth and involving the androecium. Flowers papilionaceous (imbricate-descending, with the posterior petal outside and forming the ‘standard’); basically 5 merous. Floral receptacle developing a gynophore. Free hypanthium present, or absent. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous; (five) lobed; imbricate, or valvate; bilabiate (upper lip 2-lobed, lower 3-lobed); persistent; non-accrescent; with the median member anterior. Corolla present; 5; 1 -whorled; appendiculate (the wings auriculate), or not appendiculate. Standard not appendaged. Corolla polypetalous (the keel petals often more or less free), or partially gamopetalous. When partially gamopetalous, 2 of the petals joined (the two ventral petals connivent to form the ‘keel’). The joined petals of the papilionate corolla anterior. The wings of the corolla free from the keel; not laterally spurred. Standard ‘normally’ developed; entire, or emarginate; not sericeous. Keel conspicuously exceeded by the wings to conspicuously exceeding the wings; not long-acuminate/beaked; neither coiled nor spiralled; not bent and beaked. Corolla imbricate (descending); yellow, or pink to purple, or yellow, orange, purple, and brown; deciduous. Petals clawed, or sessile. Androecial members definite in number. Androecium 10. Androecial sequence determinable, or not determinable. Androecial members free of the perianth; markedly unequal (the filaments alternately long and short); coherent; 2 - adelphous (5+5, in two bundles). The staminal tube free from the keel petals. Androecial members 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. Anthers separate from one another, or connivent; all alike; dorsifixed; versatile; dehiscing via pores, or 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 glabrous. Stigmatic tissue terminal. Carpel 3–9 ovuled. Placentation marginal (along the ventral suture). Gynoecium median (the placenta posterior, on the ventral suture). Ovary sessile to stipitate. Stigmas capitate. Ovules pendulous to ascending; biseriate; arillate, or non-arillate; anatropous, or campylotropous to amphitropous, or hemianatropous.

Fruit and seed features. Fruit aerial; in ours, 12–45 mm long; stipitate; non-fleshy; hairy to not hairy; not spinose. The fruiting carpel indehiscent; a loment (with 3–9 segments). Pods much elongated; not triangular; more or less straight; not becoming inflated; somewhat compressed, or terete (the segments globular or cuboid); regularly constricted between adjacent seeds (the upper margin straight, the lower lobed); transversely septate between the seeds; wingless. Loment segments rounded or cuboid. Fruit 1 celled; elastically dehiscent, or passively dehiscent; 3–9 seeded. Seeds reniform (asymmetric); endospermic, or non-endospermic; not mucous; compressed; small; non-arillate. Cotyledons 2; accumbent. Embryo curved, or bent. Testa non-operculate. Micropyle zigzag, or not zigzag. Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Nitrogen-fixing root nodules present. Aluminium accumulation not found. Photosynthetic pathway: C3.

Geography, cytology, number of species. Native of Australia and adventive. 2n= 16, 20, 40. A genus of about 150 species; 3 species in Western Australia.

Taxonomic Literature

  • Wheeler, J. R.; Rye, B. L.; Koch, B. L.; Wilson, A. J. G.; Western Australian Herbarium (1992). Flora of the Kimberley region. Western Australian Herbarium. Como, W.A.
  • Reynolds, S. T. (1990). Aeschynomeneae (Benth.) Hutch. (Leguminosae) in Australia.