Operculina Silva Manso

Scientific Description

Family Convolvulaceae.

Habit and leaf form. Herbaceous climbers (the stems, petioles and peduncles often narrowly winged); laticiferous, or non-laticiferous and without coloured juice. Autotrophic. Annual, or perennial; plants with neither basal nor terminal concentrations of leaves. Climbing; stem twiners. Helophytic, mesophytic, and xerophytic. Leaves alternate; spiral; petiolate; non-sheathing; simple. Leaf blades entire; pinnately veined, or palmately veined; cross-venulate; cordate. Leaves without stipules; without a persistent basal meristem. Stem anatomy. Nodes unilacunar. Secondary thickening anomalous, or developing from a conventional cambial ring; via concentric cambia, or from a single cambial ring.

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

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’. Inflorescence few-flowered. Flowers in cymes. The terminal inflorescence unit cymose. Inflorescences axillary; with involucral bracts, or without involucral bracts. Flowers pedicellate (pedicels thickened upwards in fruit); bracteate; bi- bracteolate. Bracteoles deciduous. Flowers small to large; regular to somewhat irregular. The floral asymmetry (when noticeable) involving the perianth (K only). Flowers 5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present; annular. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx 5; 1 -whorled; polysepalous; imbricate; regular to unequal but not bilabiate (then subequal); persistent; accrescent (and often lacerate in fruit); with the median member posterior. Corolla 5; 1 -whorled; gamopetalous; campanulate, or funnel-shaped; regular; glabrous abaxially, or hairy abaxially (on mid-petaline bands); white, or yellow. Androecium 5. Androecial members adnate (to the corolla); all equal to markedly unequal (actually slightly unequal); free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; remaining included; oppositisepalous. Anthers often spirally twisted after dehiscence; dehiscing via longitudinal slits; introrse; tetrasporangiate. Pollen grains psilate. Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary plurilocular; 2 locular. Gynoecium median. Styles 1; simple (filiform); apical; not becoming exserted. Stigmas 1; 2 - lobed; dry type; papillate; Group II type. Placentation basal. Ovules 2 per locule; ascending; apotropous; non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy; not hairy; dehiscent; a capsule. Capsules circumscissile (with the upper part of the epicarp forming an operculum and separating from the endocarp and lower half of the epicarp, the endocarp scarious at length splitting irregularly). Fruit 2 locular; 4 seeded. Seeds trigonous to globular; endospermic. Endosperm oily. Seeds conspicuously hairy, or not conspicuously hairy. Cotyledons 2. Embryo chlorophyllous; straight, or curved. 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, and Queensland. Northern Botanical Province and Eremaean Botanical Province.

Additional characters Pollen grains colpate. Stigmas the stigmatic area globose.