Waltheria L.

Scientific Description

Family Sterculiaceae.

(Subfamily Byttnerioideae), Tribe Hermannieae.

Habit and leaf form. Herbs, or shrubs, or trees (rarely); non-laticiferous and without coloured juice. ‘Normal’ plants. Leaves well developed. Plants with roots; non-succulent. Leaves cauline. To 0.5–1.5 m high. Self supporting. Mesophytic. Not heterophyllous. Leaves small, or medium-sized; alternate; with blades; petiolate. Petioles wingless. Leaves with ‘normal’ orientation; simple; not peltate. Leaf blades neither inverted nor twisted through 90 degrees; dorsiventral; entire; flat; oblong, or obovate (and ‘fasciculate’ in W. virgata); pinnately veined; cross-venulate. Mature leaf blades adaxially glabrous, or pubescent (less densely than lower surface); abaxially glabrous, or pubescent (very densely). Leaves with stipules. Stipules persistent. Leaf blade margins entire, or serrate, or dentate, or crenate. Leaf anatomy. Hairs present. Unicellular hairs present. Complex hairs present. Complex hairs stellate.

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

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; not crowded at the stem bases. Inflorescence many-flowered. Flowers in cymes (or in dense clusters). Inflorescences simple; terminal, or axillary. Flowers pedicellate; bracteate, or ebracteate. Bracts deciduous. Flowers bracteolate, or ebracteolate; small; regular; not resupinate; neither papilionaceous or pseudo-papilionaceous; 5 merous; cyclic; tetracyclic. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous; lobed. Calyx lobes markedly shorter than the tube, or markedly longer than the tube. Calyx hairy (on the outside), or glabrous (to sparsely hairy inside); exceeded by the corolla, or more or less equalling the corolla; turbinate or obtuse; regular; neither appendaged nor spurred; red. Calyx lobes triangular. Epicalyx absent. Corolla present; 5; 1 -whorled; not appendiculate; polypetalous; contorted; yellow, or orange, or pink, or purple, or blue; withering but persistent. Petals spathulate. Androecium present. Fertile stamens present. Androecial members definite in number. Androecium 5. Androecial members free of the perianth; free of the gynoecium; markedly unequal; coherent (connate at the base); 1 - adelphous; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; all more or less similar in shape; isomerous with the perianth; alternisepalous; all opposite the corolla members; filantherous. Anthers separate from one another; all alike; dehiscing via longitudinal slits; bilocular. Fertile gynoecium present. 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 straight, or curved. Style hairy on basal part, or with long ascending hairs. Carpel 2 ovuled (one of which develops into a seed).

Fruit and seed features. The fruiting carpel dehiscent. Dispersal unit the seed. Seeds 1 per locule. Seeds small.

Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia, Northern Territory, and Queensland. Northern Botanical Province and Eremaean Botanical Province. A genus of ca 50 species; 2 species in Western Australia; 0 endemic to Western Australia.