Plumbago L.

Scientific Description

Family Plumbaginaceae.

Habit and leaf form. Herbs, or herbaceous climbers, or shrubs, or lianas; evergreen. Perennial; plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves. Self supporting, or climbing; stem twiners. Twining clockwise. Helophytic, or mesophytic, or xerophytic. Leaves alternate; spiral; ‘herbaceous’; petiolate (often stem-clasping). Petioles winged, or wingless. Leaves sheathing, or non-sheathing; simple; epulvinate. Leaf blades entire; pinnately veined, or palmately veined to parallel-veined. Leaves with stipules, or without stipules; without a persistent basal meristem. Stem anatomy. Nodes tri-lacunar. Secondary thickening developing from a conventional cambial ring, or anomalous.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants heterostylous. Entomophilous; via hymenoptera, via lepidoptera, and via diptera.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in racemes, or in spikes. The terminal inflorescence unit cymose, or racemose. Inflorescences scapiflorous, or not scapiflorous; terminal; sometimes arranged in a leafy panicle. Flowers uni- bracteate; bi- bracteolate; small to medium-sized; regular; 5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx 5; 1 -whorled; gamosepalous (forming a 5 ribbed tube, often with stalked or sessile glands); shortly lobed; erect; plicate in bud; exceeded by the corolla; tubular; regular; persistent. Corolla 5; 1 -whorled; gamopetalous; imbricate, or contorted; funnel-shaped; regular; white, or blue; not fleshy; persistent, or deciduous. Androecium 5. Androecial members free of the perianth, or adnate (to the corolla); free of one another, or coherent; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; isomerous with the perianth; alternisepalous; all opposite the corolla members. Anthers dorsifixed, or basifixed; versatile, or non-versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate. Gynoecium 5 carpelled. The pistil 1 celled. Carpels isomerous with the perianth. Gynoecium syncarpous; synovarious, or synstylovarious (depending on interpretation of the branched style); superior. Ovary unilocular; 1 locular. Styles 1; filiform, 5-branched; apical. Stigmas 5; dry type; papillate; Group II type. Placentation basal. Ovules in the single cavity 1; pendulous (from a long, basally attached funicle); anatropous (or circinnotropous).

Fruit and seed features. Fruit dehiscent; a capsule (completely enclosed by the persistent calyx). Capsules circumscissile (at the base, the caducous part often splitting towards the apex with 5 valves). Seeds endospermic, or non-endospermic; winged. Embryo well differentiated. Cotyledons 2. Embryo straight. Seedling. Germination phanerocotylar.

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

Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, Northern Territory, Queensland, and New South Wales. Northern Botanical Province and Eremaean Botanical Province.

Additional characters Stigmas the stigmatic area linear (covering entire length of style branches). Corolla lobes spreading.