Habit and leaf form. Trees. Leaves alternate; spiral, or distichous (?); leathery; not gland-dotted; simple. Lamina entire. Leaves stipulate. Stipules free of one another; caducous (and minute). Lamina margins entire.
General anatomy. Plants with silica bodies (?).
Leaf anatomy. Stomata present; mainly confined to one surface (abaxial); anisocytic.
Lamina dorsiventral, or isobilateral. The mesophyll with sclerencymatous idioblasts.
Stem anatomy. Cork cambium present; initially superficial. The cortex without cristarque cells. Cortical bundles present (with normal orientation). Secondary thickening developing from a conventional cambial ring. Vessel end-walls scalariform, or simple.
Reproductive type, pollination. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers solitary; axillary; large; regular. Free hypanthium absent. Hypogynous disk present (large, plicate, dentate, membranous, representing connate staminodes); extrastaminal.
Perianth sepaline (the anthoecial tube within it constituting a pseudocorolla); disciform; joined; 1 whorled. Calyx disciform; 1 whorled; gamosepalous (leathery); entire, or lobulate to blunt-lobed (by tearing during anthesis); persistent; accrescent (constituting a flotation device for the fruit).
Androecium 50–100 (or more). Androecial members branched, or unbranched (?); maturing centrifugally; free of the perianth; coherent (the filaments of the stamens adnate basally to one another and to the pseudocorolla); 2 whorled (comprising an outer staminodal whorl, and the stamens in a single, dense ring, not resolvable into series). Androecium including staminodes. Staminodes 24–28 (connate); external to the fertile stamens; petaloid (connate to form the large, membranous, plicate pseudocorolla, which opens umbrella-like at anthesis). Stamens 40–100 (?—‘many’); polystemonous; filantherous (the filaments slender). Anthers basifixed; non-versatile; dehiscing via longitudinal slits; introrse. Pollen grains aperturate; 3 aperturate; colpate (colpate).
Gynoecium 6–8 carpelled. The pistil 6–8 celled. Gynoecium syncarpous; eu-syncarpous; partly inferior. Ovary 6–8 locular. Gynoecium stylate. Styles 1 (filiform); attenuate from the ovary; apical; about as long as the ovary to much longer than the ovary. Stigmas 1; 6–8 lobed; capitate. Placentation axile to apical. Ovules (3–)4(–6) per locule; funicled; pendulous to horizontal; anatropous; bitegmic; tenuinucellate.
Fruit non-fleshy; dehiscent, or indehiscent; a capsule, or capsular-indehiscent. Capsules loculicidal (6–8 valved and ribbed, pyramidal, crustaceous, surrounded by the persistent calyx). Seeds copiously endospermic. Endosperm ruminate. Seeds without starch. Seeds with amyloid. Cotyledons 2 (but small and reduced). Embryo straight to curved (somewhat hooked).
Geography, cytology. Neotropical. Tropical. Northern Brazil.
Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Theiflorae; Theales. Cronquist’s Subclass Dilleniidae; Lecythidales. APG (1998) Eudicot; core Eudicot; Asterid; unassigned to Euasterid I or Euasterid II.
Species 1. Genera 1; only genus, Asteranthos.
Appel (1966) favoured inclusion of Asteranthos in Scytopetalaceae rather than Lecythidaceae. Morton et al. (1998) refer it to subfamily Scytopetaloideae of their expanded Lecythidaceae, based on an assessment ‘using both molecular and morphological data’.