Plagiocarpus Benth.
Hooker's Icon.Pl. 12(3):56, Pl. 1162 (1873)

Name Status: Current
Browse to the list of specimens for Plagiocarpus Benth.

Scientific Description
Leslie Watson, Thursday 8 September 2016

Family Papilionaceae. Bossiaeae (Templetonia group).

Habit and leaf form. (Sub-) shrubs. Plants with neither basal nor terminal concentrations of leaves; to 0.4–2 m high. Mesophytic, or xerophytic. Leaves minute to medium-sized; alternate; spiral; ‘herbaceous’, or leathery; sessile; non-sheathing; compound; pulvinate; ternate. Leaves mostly palmately trifoliolate. Leaflets 3; not stipellate; pulvinate. Leaf blades dorsiventral. Leaves with stipules (inconspicuous), or without stipules. Stipules intrapetiolar; scaly, or leafy; caducous, or persistent. 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, or ornithophilous.

Inflorescence and flower features. Flowers solitary; axillary; subsessile; bracteate. Bracts small, linear. Flowers (bi-) bracteolate (the bracteoles linear); small to medium-sized; very irregular; zygomorphic. The floral asymmetry involving the perianth and involving the androecium. Flowers papilionaceous (imbricate-descending, with the posterior petal outside and forming a flag (‘standard’)); basically 5 merous. Floral receptacle developing a gynophore (slight), or with neither androphore nor gynophore. Free hypanthium present, or absent. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx 5; 1 -whorled; gamosepalous; more or less equally five lobed; toothed (the lobes acute). Calyx lobes markedly longer than the tube. Calyx hairy; not calyptrate; imbricate, or valvate; exceeded by the corolla; more or less regular, or bilabiate (the posterior pair of lobes joined a little higher); persistent; with the median member anterior. Epicalyx absent. Corolla present; 5; 1 -whorled; appendiculate (the wings conspicuously auriculate, the keel members less so). Standard not appendaged. Corolla polypetalous, or partially gamopetalous. The wings of the corolla free from the keel; laterally spurred (at least, conspicuously auriculate at the base). Standard ‘normally’ developed; not sericeous (glabrous). Keel about equalling the wings to conspicuously exceeding the wings (blunt, slightly incurved); not long-acuminate/beaked (blunt); neither coiled nor spiralled; not bent and beaked. Corolla imbricate (descending); pale yellow. Petals shortly clawed. Androecial members definite in number. Androecium 10. Androecial sequence determinable, or not determinable. Androecial members free of the perianth; all equal (more or less); coherent (into an adaxially split sheath); 1 - adelphous. The staminal tube free from the keel petals. Androecial members 1 -whorled (even though diplostemonous). Androecium exclusively of fertile stamens. Stamens 10; distinctly dissimilar in shape; diplostemonous; both opposite and alternating with the corolla members. Anthers separate from one another, or connivent; dimorphic (alternately dorsifixed and basifixed); dorsifixed and basifixed (alternately); versatile, or non-versatile (alternately); 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 (up-) curved (only towards the tip). Style filiform. Style glabrous. Stigmatic tissue terminal. Carpel 1–2 ovuled. Placentation marginal (on the ventral suture). Gynoecium median (the placenta posterior, on the ventral suture). Ovary sessile to stipitate. Stigmas punctiform (minute). Ovules pendulous to ascending; biseriate; arillate; anatropous, or campylotropous to amphitropous, or hemianatropous.

Fruit and seed features. Fruit aerial; subsessile, or sessile; non-fleshy. The fruiting carpel dehiscent; a legume. Pods somewhat elongated (obliquely ellipsoid, a little less than twice as long as broad); not triangular; straight; beaked; somewhat compressed to terete (‘turgid’); not constricted between the seeds; not transversely septate; wingless. Valves of the dehisced pod not twisted. Fruit 1 celled. Dispersal unit the seed. Fruit 1 seeded, or 2 seeded. Seeds endospermic, or non-endospermic; not mucous; somewhat compressed (prolately ellipsoid); small to medium sized; arillate (the aril collarlike, lipped). Cotyledons 2. Embryo chlorophyllous; straight. Testa non-operculate. Micropyle zigzag, or not zigzag.

Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: C3.

Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia and Northern Territory. Northern Botanical Province. A genus of 1 species; 1 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.