Macroptilium (Benth.) Urb.

Scientific Description

Family Papilionaceae. Phaseoleae.

Sometimes included in Leguminosae.

Habit and leaf form. Lianas, or herbs, or herbaceous climbers; evergreen, or deciduous; not resinous. The herbs annual. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Self supporting, or climbing; the climbers stem twiners. The twiners twining anticlockwise. Mesophytic. Leaves small to medium-sized; not fasciculate; alternate; spiral, or distichous; not decurrent on the stems; ‘herbaceous’, or leathery; not imbricate; petiolate. Petioles wingless. Leaves non-sheathing; not gland-dotted; compound; pulvinate; ternate. Leaves pinnately trifoliolate. Leaves imparipinnate. Leaflets 3; 2.8–6.8 cm long. Lateral leaflets opposite. Leaflets stipellate (the stipels persistent); pulvinate; ovate, or elliptic, or triangular; cordate, or cuneate at the base, or rounded at the base; flat; with conspicuous lateral lobes. Leaf blades dorsiventral; cross-venulate. Leaves with stipules. Stipules intrapetiolar; free of the petiole; 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, or absent; 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. Pollination mechanism conspicuously specialized.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; not crowded at the stem bases; in pairs, subtended by a common bract. Inflorescences compound; axillary; racemose, with a pair of flowers at each node. Flowers pedicellate, or subsessile; bracteate. Bracts deciduous (caducous). Flowers (bi-) bracteolate. Bracteoles deciduous (caducous). 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; usually more or less cupular. Free hypanthium present, or absent. Hypogynous disk present; intrastaminal. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous; lobed; toothed. Calyx lobes markedly shorter than the tube (about a third of the total calyx length). Calyx imbricate; exceeded by the corolla; more or less regular (scarcely bilabiate, the teeth all distinct to more or less the same depth); neither appendaged nor spurred; non-fleshy; persistent; non-accrescent; with the median member anterior. Calyx lobes triangular. Corolla present; 5; 1 -whorled; appendiculate, or not appendiculate. Standard not appendaged (at least, the auricles ‘obscure’). Corolla partially gamopetalous. 2 of the petals joined, or 4 of the petals joined. The joined petals anterior (and lateral?). The wings of the corolla adherent to the keel, or free from the keel; not laterally spurred. Standard ‘normally’ developed; not sericeous. Keel conspicuously exceeded by the wings (the wings much exceeding the rest of the corolla); not long-acuminate/beaked; coiled or spiralled (twisted and incurved); not bent and beaked. Corolla imbricate (descending); glabrous abaxially; glabrous adaxially (save for the inner margin of the keel); pink and purple, or pink and black (almost), or red and pink (the standard pink, the wings red or purple to black); deciduous; non-accrescent. Petals clawed. Androecial members definite in number. Androecium 10. Androecial sequence not determinable. Androecial members free of the perianth; all equal, or markedly unequal; coherent; 2 - adelphous (the posterior stamen free of the tube, and basally geniculate). 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; filantherous. Anthers separate from one another to connivent; all alike; dorsifixed, or basifixed (depending which description one consults); versatile, or non-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 hooked (doubly bent to form a squarish hook). Style terete. Style bearded via an apical tuft, or bearded via an apical ring (below the capitate stigma). Stigmatic tissue terminal. Carpel 2–100 ovuled (‘many’). Placentation marginal (along the ventral suture). Gynoecium median. Ovary sessile. Ovary summit hairy, the hairs not confined to radiating bands (sericeous). Stigmas capitate. Ovules funicled; pendulous to ascending; biseriate; arillate; anatropous, or campylotropous to amphitropous, or hemianatropous.

Fruit and seed features. Fruit aerial; 60–105 mm long; sessile; non-fleshy; not spinose. The fruiting carpel dehiscent; a legume. Pods much elongated; not triangular; straight; not becoming inflated; somewhat compressed to terete; transversely septate between the seeds (the septa spongy); wingless; not internally hairy. Valves of the dehisced pod twisted. Fruit 1 celled; elastically dehiscent (the valves twisting). Dispersal unit the seed. Fruit 12–30 seeded. Seeds non-endospermic; not mucous; small; non-arillate; not conspicuously hairy. Cotyledons 2; accumbent. Embryo curved, or bent. Testa hard; non-operculate; smooth; conspicuously colour-patterned. Micropyle zigzag, or not zigzag. Seedling. Germination phanerocotylar (mostly), or cryptocotylar.

Special features. Calyx limb 5 lobed.

Geography, cytology, number of species. Native of Australia and adventive. 2n=22; ploidy levels recorded 2. A genus of about 20 species; 3 species in Western Australia; M. atropurpureum (DC.) Urban, M. lathyroides (L.) Urban.