Spermacoce L.

Scientific Description

Family Rubiaceae.

Habit and leaf form. Small shrubs, or herbs (prostrate to erect). Herbs annual, or perennial. Young stems tetragonal. Helophytic, or mesophytic, or xerophytic. Leaves opposite, or whorled (falsely); petiolate to sessile; connate (via the stipules), or not connate; gland-dotted, or not gland-dotted; simple; epulvinate. Leaf blades entire; one-veined, or pinnately veined; cross-venulate. Leaves with stipules. Stipules connate and adnate with base of petiole to form a fimbriate sheath; with colleters (secreting mucilage), or without colleters. Leaf blade margins entire, or serrate. Leaves without a persistent basal meristem. Domatia not recorded (absent). Stem anatomy. Nodes unilacunar, or tri-lacunar. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants homostylous, or heterostylous. Entomophilous. Pollination mechanism conspicuously specialized (with passive pollen presentation involving stylar modification), or unspecialized.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; usually in sessile clusters, sometimes the axillary clusters very compact and forming a spike-like inflorescence. The terminal inflorescence unit cymose. Inflorescences terminal, or axillary. Flowers bracteolate (the filiform bracteoles intermixed with the flowers within the clusters); minute to small; regular; 4 merous; cyclic; tetracyclic. Free hypanthium present, or absent (depending on interpretation); obovoid to obconic. Perianth with distinct calyx and corolla; 5–12; 2 -whorled; the two whorls isomerous, or anisomerous. Calyx (2–)4(–8); 1 -whorled; gamosepalous; lobed; open in bud; regular; usually persistent. Corolla (3–)4; 1 -whorled; gamopetalous. Corolla lobes markedly shorter than the tube to markedly longer than the tube. Corolla valvate; funnel-shaped or salver-shaped; regular; hairy adaxially (throat bearded), or glabrous adaxially; blue, or purple, or white. Androecium 4. Androecial members adnate (to the corolla tube); free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 4. Staminal insertion near the base of the corolla tube, or in the throat of the corolla tube. Stamens becoming exserted, or remaining included; isomerous with the perianth; oppositisepalous. Anthers elliptic to narrowly oblong; dorsifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate. Pollen shed in aggregates, or shed as single grains; if aggregated, in tetrads. Gynoecium 2 carpelled. The pistil 2 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious to eu-syncarpous; inferior. Ovary plurilocular; 2 locular. Gynoecium transverse. Epigynous disk present. Gynoecium stylate. Styles 1; attenuate from the ovary, or from a depression at the top of the ovary; apical; shorter than the ovary at anthesis to much longer than the ovary at anthesis; usually becoming exserted, or not becoming exserted. Stigmas 1; 1 - lobed, or 2 - lobed (lobes short); when simple, capitate; wet type, or dry type; papillate, or non-papillate; Group II type and Group IV type. Placentation axile. Ovules 1 per locule; pendulous, or horizontal, or ascending; amphitropous.

Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule (with a partial septum). Capsules dehiscing via 2 longitudinal valves. Fruit 1 locular, or 2 locular; 1–2 seeded. Seeds oblong to ellipsoid or ovoid, grooved on one face; endospermic, or non-endospermic. Endosperm ruminate, or not ruminate; if present, oily. Cotyledons 2. Embryo straight, or curved. Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Aluminium accumulation demonstrated, or not found.

Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, Northern Territory, and Queensland. Northern Botanical Province.

Etymology. From the Greek for "seed" and "point"; said to refer to the capsule being surrounded by the calyx points.