Portulaca L.

Scientific Description

Common name. Purslanes. Family Portulacaceae.

Tribe Portulaceae.

Habit and leaf form. Herbs. Plants with roots; succulent. Annual, or perennial. Helophytic to xerophytic. Leaves alternate, or opposite; when alternate, spiral; fleshy; sessile, or subsessile (rarely); non-sheathing; simple. Leaf blades entire; flat, or solid; terete; elliptic, or oblong, or ovate, or obovate, or linear, or orbicular; pinnately veined, or one-veined; cross-venulate. Leaves with stipules (stipules modified to axillary hairs, either short and inconspicuous or long and appearing woolly), or without stipules. Stipules intrapetiolar; represented by hairs. Leaf blade margins entire. Leaves without a persistent basal meristem. Leaf anatomy. Hairs present, or absent. Stem anatomy. Secondary thickening absent, or developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in heads. The terminal inflorescence unit cymose. Inflorescences terminal; flowers ephemeral, solitary or clustered in heads surrounded by a whorl of 3–30 involucral leaves, with hairs in the axils of the scarious bracts between the flowers; with involucral bracts. Flowers usually sessile, or pedicellate; bracteolate; small, or medium-sized; regular; cyclic; tetracyclic. Free hypanthium present to absent. Hypogynous disk present. Perianth with distinct calyx and corolla; 8; 2–3 -whorled; anisomerous. Calyx present; 2; 1–2 -whorled; gamosepalous; imbricate (the upper member overlapped); tubular; persistent. Corolla present; 4–6; 1 -whorled; gamopetalous (at the base); imbricate; regular; yellow, or red, or pink, or purple. Corolla lobes elliptic, or obovate. Androecium 4–25. Androecial members branched (bundled, when ‘many’), or unbranched; free of the perianth, or adnate (to the corolla base); coherent; 1 - adelphous, or 2–7 - adelphous; 1 -whorled, or 2 -whorled. Androecium exclusively of fertile stamens. Stamens 4–25; isomerous with the perianth, or diplostemonous to polystemonous; when 5, alternisepalous (opposite the petals). Anthers dehiscing via longitudinal slits; introrse; tetrasporangiate. Gynoecium 2–7 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synovarious to synstylovarious; inferior, or partly inferior. Ovary unilocular; 1 locular. Gynoecium stylate. Styles 1; apical. Stigmas 1, or 2–7 (if stigma considered entire rather than lobed); 1 - lobed, or 2–7 - lobed. Placentation basal, or free central (at maturity). Ovules in the single cavity 20–100 (‘many’); anatropous to amphitropous.

Fruit and seed features. Fruit 3–5 mm long; non-fleshy; dehiscent, or indehiscent; a capsule. Capsules circumscissile. Fruit elastically dehiscent, or passively dehiscent. Seeds non-endospermic. Perisperm present. Embryo well differentiated. Cotyledons 2(–4). Embryo curved.

Geography, cytology, number of species. Native of Australia, or adventive. Endemic to Australia, or not endemic to Australia. Australian states and territories: Western Australia, South Australia, Northern Territory, Queensland, New South Wales, Victoria, Australian Capital Territory, and Tasmania. A genus of ca 125 species; ca 12 species in Western Australia.

Economic uses, etc. P. grandiflora is a cultivated ornamental, and P. oleracea constitutes a potherb and salad green.

Etymology. From the Latin portulaca, name of the plant, purslane, from the words for "to carry" and "milk"; referring to the milky sap.