Habit and leaf form. Large shrubs, or trees; evergreen. Young stems cylindrical. To 4–40 m high. Mesophytic, or xerophytic. Heterophyllous (juvenile leaves variously simple, lobed or compound). Leaves small to very large; alternate; spiral (or scattered); leathery; petiolate; non-sheathing; edgewise to the stem, or with ‘normal’ orientation; simple, or compound (in S. davallioides); epulvinate; when compound, pinnate, or bipinnate, or multiply compound. Leaf blades when simple, dissected (variously lobed), or entire; flat; ovate, or obovate, or oblong, or elliptic; when simple/dissected pinnatifid, or much-divided; one-veined, or pinnately veined, or palmately veined. Leaves without stipules. Leaf blade margins entire. Leaves without a persistent basal meristem. Stem anatomy. Secondary thickening developing from a conventional cambial ring.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous, or ornithophilous, or cheiropterophilous, or pollinated by unusual means.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. Inflorescence many-flowered. Flowers in racemes, or in umbels. Inflorescences simple, or compound; terminal, or axillary. The fruiting inflorescence not conelike. Flowers pedicellate; bracteate, or ebracteate. Bracts deciduous. Flowers small to medium-sized; very irregular; zygomorphic. The floral asymmetry involving the perianth. Flowers 4 merous; cyclic; tetracyclic. Floral receptacle developing a gynophore, or with neither androphore nor gynophore. Free hypanthium absent. Hypogynous disk present; extrastaminal; annular (well developed, horse-shoe shaped or sometimes very reduced). Perianth of ‘tepals’; 4; 1 -whorled; joined (the tube opening on lower side, all 4 segments finally separating; limb globular, recurved); hairy (outside), or glabrous; red, or cream to white, or cream to green, or white, or yellow. Androecial members definite in number. Androecium 4. Androecial members adnate; all equal; free of one another; 1 -whorled. Stamens 4; isomerous with the perianth; with sessile anthers. Anthers basifixed; non-versatile; dehiscing via longitudinal slits; introrse; four locular; tetrasporangiate. Gynoecium 1 carpelled. The pistil 1 celled. Gynoecium monomerous; of one carpel; superior. Carpel stylate; apically stigmatic. Style pollen presenter a flattened, oblique disc. Carpel 50 ovuled (i.e., ‘many’). Placentation marginal, or apical. Ovary stipitate. Ovules funicled, or sessile; in 2 rows; non-arillate; orthotropous, or anatropous, or amphitropous, or hemianatropous.
Fruit and seed features. Fruit non-fleshy; hairy, or not hairy. The fruiting carpel dehiscent; a follicle (mostly narrowly oblong or cylindrical, or flattened and semi-circular in S. reticulatus, splitting down one side). Follicles elongate (usually), or compact (in S. reticulatus); septate (septum thin, separating 2 rows of seeds). Fruit 8–50 seeded (i.e., to ‘many’). Seeds non-endospermic; highly compressed; 2- winged (the outer wing developed from the proximal part of the funicle and folded around the inner wing which is developed from the inner integument). Seed wings not encircling body (usually, wing at basal end), or encircling body (almost completely in S. reticulatus). Embryo well differentiated. Cotyledons 2(–8). Embryo straight.
Special features. Stamens inserted within a concavity near the end of a perianth segment.
Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, Northern Territory, Queensland, and New South Wales. Northern Botanical Province. Northern Australia, the Aru Islands, New Guinea and New Caledonia. N=11.
Etymology. From the Greek for "narrow" and "fruit".