Dysphania R.Br.

Scientific Description

Common name. Crumbweeds. Family Chenopodiaceae.

Sometimes included in Chenopodiaceae.

Habit and leaf form. Small, prostrate herbs. Plants unarmed. Short lived perennial, or annual. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Stems not ‘jointed’. Stem internodes solid. Mesophytic, or xerophytic. Leaves small; alternate; petiolate; non-sheathing; simple; epulvinate. Leaf blades dissected to entire; flat; ovate, or obovate, or oblong, or elliptic; when incised, pinnatifid; pinnately veined; cross-venulate; attenuate at the base, or cuneate at the base, or rounded at the base. Leaves without stipules. Leaf blade margins entire. Leaves without a persistent basal meristem. Leaf anatomy. Hairs present; glandular hairs present. Extra-floral nectaries absent. Stem anatomy. Secondary thickening developing from a conventional cambial ring, or anomalous; when anomalous, via concentric cambia.

Reproductive type, pollination. Fertile flowers hermaphrodite and functionally female, or hermaphrodite, functionally male, and functionally female. Unisexual flowers absent. Plants gynomonoecious, or polygamomonoecious.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in fascicles, in spikes, and in glomerules. Inflorescences terminal, or axillary; fasciculate and crowded, or spicate. Bisexual flowers fewer, terminal or to each side of a glomerule, female flowers more numerous and lateral. Flowers pedicellate; ebracteate; ebracteolate; minute. Hypogynous disk absent. Perianth sepaline; (1–)3–4; 1 -whorled; basally joined, or free; accrescent (the perianth being so interpreted). Calyx present; not replaced by accrescent bracteoles; (1–)3–4; polysepalous, or gamosepalous (basally); valvate; galeate; non-fleshy; persistent; accrescent (surrounding the fruit, becoming winged). The fruiting calyx not berrylike; winged. Corolla absent. Fertile stamens present, or absent (from female flowers). Androecial members definite in number. Androecium 1(–2). Androecial members free of the perianth; all equal; free of one another (exserted); 1 -whorled. Androecium exclusively of fertile stamens. Stamens 1, or 2; all more or less similar in shape; reduced in number relative to the adjacent perianth to isomerous with the perianth; oppositisepalous. Anthers dehiscing via longitudinal slits; introrse. Fertile gynoecium present, or absent (assuming occurrence of male flowers). Gynoecium (2–)3 carpelled. The pistil 1 celled. Gynoecium syncarpous; synovarious, or synstylovarious; superior. Ovary unilocular; 1 locular; sessile. Gynoecium stylate. Styles 1–2; apical. Stigmas 1–2. Ovules in the single cavity 1; non-arillate; hemianatropous.

Fruit and seed features. Fruit non-fleshy (the pericarp smooth to papillate, usually diaphanous); indehiscent; a nut (surrounded by the broadly winged perianth); 1 celled; 1 seeded. Seeds non-endospermic. Perisperm present. Embryo well differentiated; curved (‘circular, surrounding the endosperm’).

Geography, cytology, number of species. World distribution: Australia. 5 species.

Etymology. From the Greek for "dark, obscure, scarcely visible"; refers to the small flowers.