Habit and leaf form. Herbs, or shrubs (rarely). Plants unarmed. Herbs annual, or perennial. Leaves basal and cauline. Plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves. Young stems cylindrical, or tetragonal. Heterophyllous (in S. atropurpurea). Leaves opposite; ‘herbaceous’; petiolate; connate, or not connate; simple, or compound; when compound, pinnate. Leaf blades when simple dissected, or entire; when dissected, pinnatifid; pinnately veined; cross-venulate. Leaves without stipules. Stem anatomy. Nodes tri-lacunar, or multilacunar. Secondary thickening developing from a conventional cambial ring.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries present. Nectar secretion around the base of the style. Entomophilous.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in heads (the receptacle elongated with receptacular bracts). The terminal inflorescence unit cymose. Inflorescences scapiflorous; pedunculate, convex; with involucral bracts. Involucral bracts leafy, in 1–3 rows. Inflorescences pseudanthial (the outermost flowers largest). Flowers bracteolate; small; very irregular; zygomorphic. The floral asymmetry involving the perianth and involving the androecium. Flowers cyclic; tetracyclic. Free hypanthium absent. Perianth with distinct calyx and corolla; 9–11; 2 -whorled; isomerous, or anisomerous. Calyx 5; 1 -whorled; partially gamosepalous (cupular); lobed; spreading; hairy (setaceous); regular; persistent. Epicalyx present (cylindric, 8-ribbed, grooved or pitted, the apex a plicate funnel shaped cup or ‘corona’). Corolla 4–6; 1 -whorled; gamopetalous; imbricate; funnel-shaped, or tubular; unequal but not bilabiate; white, or pink, or red, or purple. Androecium 4. Androecial members adnate (near the top of the tube); all equal, or markedly unequal; free of one another, or coherent; 1 -whorled. Stamens 4; becoming exserted; reduced in number relative to the adjacent perianth, or isomerous with the perianth; oppositisepalous; all alternating with the corolla members. Filaments filiform. Anthers linear; dorsifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate. Gynoecium 2 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous (but pseudomonomerous); synstylovarious to eu-syncarpous; inferior. Ovary unilocular; 1 locular. Gynoecium median. Epigynous disk present. Gynoecium non-stylate. Styles 1; apical. Stigmas 1–2; 1 - lobed, or 2 - lobed; dry type; non-papillate; Group II type. Placentation apical. Ovules in the single cavity 1; pendulous; non-arillate; anatropous.
Fruit and seed features. Fruit non-fleshy; indehiscent; achene-like. Dispersal unit the remains of the flower (with the ‘achene’ enclosed in the epicalyx and the persistent calyx limb). Fruit 1 seeded. Seeds endospermic. Endosperm oily. Embryo well differentiated. Cotyledons 2. Embryo straight. Seedling. Germination phanerocotylar.
Geography, cytology, number of species. Adventive. Australian states and territories: Western Australia, South Australia, New South Wales, Victoria, and Tasmania. South-West Botanical Province.
Economic uses, etc. Ornamentals.
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Western Australian Herbarium (1998–). FloraBase—the Western Australian Flora. Department of Biodiversity, Conservation and Attractions. https://florabase.dpaw.wa.gov.au/