Merremia Endl.

Scientific Description

Family Convolvulaceae.

Habit and leaf form. Herbs, or herbaceous climbers, or shrubs; laticiferous, or non-laticiferous and without coloured juice. Autotrophic. Plants with neither basal nor terminal concentrations of leaves. Often climbing, or self supporting; stem twiners. Helophytic, mesophytic, and xerophytic. Leaves alternate; spiral; petiolate; non-sheathing; simple, or compound; when compound, palmate. Leaf blades dissected, or entire (often lobed or dentate); when dissected, palmately lobed; pinnately veined, or palmately veined; cross-venulate; cordate, or hastate. 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 to many-flowered. Flowers in cymes. The terminal inflorescence unit cymose. Inflorescences axillary; sometimes umbel-like; with involucral bracts, or without involucral bracts. Flowers pedicellate (pedicels often thickened upwards); bracteate; bi- bracteolate. Bracteoles persistent, or 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 (subequal or unequal); persistent; usually slightly accrescent, or non-accrescent; with the median member posterior. Corolla 5; 1 -whorled; gamopetalous; entire, or lobed. Corolla lobes markedly shorter than the tube. Corolla funnel-shaped, or campanulate; regular; white to yellow. Androecium 5. Androecial members adnate (to the corolla); markedly unequal (often), or all equal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; remaining included; oppositisepalous. Anthers straight or spirally twisted when dehisced; dehiscing via longitudinal slits; introrse; tetrasporangiate. Pollen grains psilate. Gynoecium 2–4 carpelled. The pistil 2–4 celled. Gynoecium syncarpous; synstylovarious; superior. Ovary plurilocular; 2–4 locular. Locules secondarily divided by ‘false septa’, or without ‘false septa’. Gynoecium median. Styles 1; simple (filiform); apical; not becoming exserted. Stigmas 2; dry type; papillate (the papillae clavate or cylindrical); Group II type. Placentation basal. Ovules 1 per locule, or 2 per locule; ascending; apotropous; non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal (via 4 valves). Fruit 1–4 locular; 1–4 seeded. Seeds ovoid-trigonous, rounded to truncate apically; 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 3–12- colpate. Stigmas the stigmatic area globose.