Aidia Lour.

Scientific Description

Family Rubiaceae.

Habit and leaf form. Trees, or shrubs; evergreen. Young stems tetragonal. Self supporting, or climbing, or epiphytic (rarely). Helophytic, or mesophytic, or xerophytic. Leaves medium-sized to large; opposite; leathery; petiolate; 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 interpetiolar; triangular with a medial rib tapering into an acumin; with colleters (secreting mucilage), or without colleters. Leaf blade margins entire, or serrate. Leaves without a persistent basal meristem. Domatia recorded (ciliated domatia commonly present in secondary midvein angles). 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’; in cymes. The terminal inflorescence unit cymose. Inflorescences at alternate nodes; pseudo-monopodial, of terminal thyrsoid cymes with repeating monochasial or dichasial branching; subtended by unequal leaves, these often reduced to leaf-spurs. Flowers pedicellate; small to medium-sized; fragrant; regular; 4–6 merous; cyclic; tetracyclic. Free hypanthium present, or absent (depending on interpretation); conic, smooth, without ridges. Perianth with distinct calyx and corolla; 8–12; 2 -whorled; the two whorls isomerous. Calyx (4–)5–6; 1 -whorled; gamosepalous; entire, or lobed (minutely); glabrous; open in bud; tubular; regular; coriaceous; persistent, or not persistent (leaving a circular scar on fruit). Corolla (4–)5–6; 1 -whorled; gamopetalous; contorted (overlapping to the left); tubular; regular; hairy adaxially (with a bearded throat); green, or white to cream, or yellow. Corolla lobes narrowly ovate. Androecium 4–6. Androecial members adnate (to the corolla tube); free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 4–6. Staminal insertion in the throat of the corolla tube. Stamens becoming exserted; isomerous with the perianth; oppositisepalous. Anthers sagittate; basifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate. Pollen shed as single grains. Gynoecium 2(–3) carpelled. The pistil 2(–3) celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious to eu-syncarpous; inferior. Ovary plurilocular; 2(–3) 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 1; 2 - lobed (the stigmatic lobes connate, equalling the anthers in length); wet type, or dry type; papillate, or non-papillate; Group II type and Group IV type. Placentation axile. Ovules 5–50 per locule (i.e. ‘few’ to ‘many’); pendulous, or horizontal, or ascending; anatropous, or hemianatropous.

Fruit and seed features. Fruit fleshy; indehiscent; a berry (globular to ellipsoid, smooth); 5–50 seeded (i.e. ‘few to numerous’ seeded). Seeds angular (embedded in the firm placental mass); 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.

Additional characters Corolla lobes spreading (reflexed).