Richardia L.

Scientific Description

Family Rubiaceae.

Habit and leaf form. Herbs (usually with a taproot, prostrate to decumbent or rarely erect). Annual, or perennial. Young stems tetragonal. Helophytic, or mesophytic, or xerophytic. Leaves opposite; petiolate to sessile; connate (via the stipules), or not connate; gland-dotted, or not gland-dotted; simple; epulvinate. Leaf blades entire; pinnately veined; cross-venulate. Leaves with stipules. Stipules sheathing, bearing bristles; with colleters (secreting mucilage), or without colleters. Leaf blade margins entire, or serrate. Leaves without a persistent basal meristem. Domatia recorded, or not recorded; represented by pits, or pockets, or hair tufts. Leaf anatomy. Hairs present, or absent. Stem anatomy. Nodes unilacunar, or tri-lacunar. Secondary thickening developing from a conventional cambial ring.

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

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. Inflorescence many-flowered. Flowers in heads. The terminal inflorescence unit cymose. Inflorescences terminal; pedunculate; with involucral bracts. Involucral bracts 2–4, leafy. Flowers small to medium-sized; regular; 3–8 merous; cyclic; tetracyclic. Free hypanthium present, or absent (depending on interpretation). Perianth with distinct calyx and corolla; 7–14; 2 -whorled; the two whorls isomerous, or anisomerous. Calyx 4–8; 1 -whorled; gamosepalous; lobed; open in bud; turbinate or subglobose; regular; persistent (eventually falling from top of mature fruits). Corolla 3–6; 1 -whorled; gamopetalous; imbricate, or valvate, or contorted; shortly funnel-shaped; regular; hairy adaxially (narrow area of hairs near base of tube); white, or pink, or purple. Fertile stamens present, or absent (when flower female). Androecium 4, or 6. Androecial members adnate (to the corolla tube); free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 4, or 6. Staminal insertion in the throat of the corolla tube. Stamens usually becoming exserted; isomerous with the perianth; oppositisepalous. Anthers dehiscing via longitudinal slits; introrse; tetrasporangiate. Pollen shed in aggregates, or shed as single grains; if aggregated, in tetrads. Fertile gynoecium present, or absent (when flower male). Gynoecium 3 carpelled, or 4 carpelled. The pistil 3 celled, or 4 celled. Carpels reduced in number relative to the perianth, or isomerous with the perianth. Gynoecium syncarpous; synstylovarious; inferior. Ovary plurilocular; 3 locular, or 4 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; becoming exserted. Stigmas 3–4; linear or spathulate; wet type, or dry type; papillate, or non-papillate; Group II type and Group IV type. Placentation axile. Ovules 1 per locule; horizontal, or ascending; anatropous, or hemianatropous.

Fruit and seed features. Fruit non-fleshy; a schizocarp. Mericarps 3, or 4; comprising achenes, or comprising nutlets, or comprising drupelets. Fruit 3 seeded, or 4 seeded. Seeds 1 per mericarp. Seeds endospermic. Endosperm ruminate, or not ruminate; 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. Adventive. Australian states and territories: Western Australia, Queensland, and New South Wales. Northern Botanical Province and South-West Botanical Province.

Etymology. After Richard Richardson (1663–1741), English botanist.