(Subfamily Byttnerioideae), Tribe Lasiopetalae.
Habit and leaf form. Shrubs; non-laticiferous and without coloured juice. ‘Normal’ plants. Leaves well developed. Plants with roots; non-succulent. Leaves cauline. To 1.5 m high. Self supporting. Mesophytic. Not heterophyllous. Leaves small, or medium-sized; alternate; with blades; petiolate (shortly); simple; not peltate. Leaf blades neither inverted nor twisted through 90 degrees; dorsiventral; entire; flat; linear, or ovate, or oblong; pinnately veined; cross-venulate; cordate. Mature leaf blades adaxially pubescent (densely stellate hairy), or glabrous; abaxially pubescent (densely to tomentose stellate hairy). Leaves with stipules, or without stipules (rarely). Stipules intrapetiolar; free of the petiole; free of one another; leafy. Leaf blade margins entire (or slightly irregular); revolute (to recurved). Leaf anatomy. 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 few-flowered. Flowers in cymes. Inflorescences simple, or compound (rarely); leaf-opposed. Flowers pedicellate (pedicels (and peduncles) with a red epidermis and densely stellate hairy, sometimes with glands, peduncles persistent on stem from previous year); bracteate. Bracts 2 at apical pedicel node, none at basal node, one at remainder. Flowers 3 bracteolate. Bracteoles persistent (densely tomentose, valvate ovoid when enclosing the bud, recurved from the flower and then broadly ovate lanceolate when enclosing the extruding fruiting calyx). Flowers small; regular; not resupinate; neither papilionaceous or pseudo-papilionaceous; 6 merous; cyclic; tetracyclic, or tricyclic. Perianth with distinct calyx and corolla; 12, or 6 (rarely); 2 -whorled, or 1 -whorled; isomerous. Calyx present (‘petaloid’); 6; 1 -whorled; gamosepalous (‘divided almost to the base’); lobed. Calyx lobes markedly longer than the tube. Calyx prominently 3 veined (5 at the base); hairy (fine simple and 2 celled hairs inside, longer, denser stellate hairs on ribs, and shorter, sparser white stellate between ribs on the outside); exceeding the corolla; regular; neither appendaged nor spurred; pink, or purple; persistent. Calyx lobes ovate, or elliptic. Epicalyx absent. Corolla present, or vestigial, or absent; 6; 1 -whorled; polypetalous; regular; glabrous abaxially; glabrous adaxially; dark red. Petals obovate (or obcordate). Androecium present. Fertile stamens present. Androecial members definite in number. Androecium 6, or 12 (rarely). Androecial members free of the perianth; free of the gynoecium; all equal, or markedly unequal (rarely, when staminodes present); free of one another; 1 -whorled. Androecium exclusively of fertile stamens, or including staminodes (rarely). Staminodes 6 (when present, minute, triangular, relictual). Stamens 6; all more or less similar in shape; isomerous with the perianth; alternisepalous; all opposite the corolla members; filantherous. Filaments filiform. Anthers all alike; introrse; bilocular. Fertile gynoecium present. Gynoecium 3 carpelled. The pistil 3 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; eu-syncarpous; superior. Ovary plurilocular; 3 locular; sessile. Gynoecium stylate. Styles 1; apical; hairy (basally to 1/3 of length with white stellate hairs), or hairless (at apex). Stigmas 1; 1 - lobed. Placentation axile.
Fruit and seed features. Fruit ca 3 mm long; stellate hairy; dehiscent; a capsule. Capsules loculicidal. Dispersal unit the seed. Seeds endospermic.
Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia. South-West Botanical Province. A genus of 4 species; 4 species in Western Australia; 4 endemic to Western Australia.
Additional comments. Named from the Greek lysios (loosening), and the Latin sepalum (sepal), in reference to the dissected calyx lobes.