Gardenia Ellis

Scientific Description

Common name. Gardenias. Family Rubiaceae.

Habit and leaf form. Small trees, or shrubs; facultatively deciduous. Plants unarmed, or spiny. Young stems tetragonal. Helophytic, or mesophytic, or xerophytic. Leaves small to large; opposite, or whorled; leathery; 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, forming an intrapetiolar cone or dome; with colleters (secreting mucilage), or without colleters. Leaf blade margins entire, or serrate. Leaves without a persistent basal meristem. Domatia recorded, or not recorded (then absent); represented by pits (domatia large, conspicuous ciliated pits below and domes above in secondary midvein angles, or small and inconspicuous). 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’, or solitary; terminal. Inflorescence few-flowered. Flowers in fascicles. The terminal inflorescence unit cymose. Inflorescences pseudo- axillary, or terminal. Flowers pedicellate to sessile; small to large; fragrant; regular; 4–12 merous; cyclic; tetracyclic. Free hypanthium present, or absent (depending on interpretation). Perianth with distinct calyx and corolla; 9–21; 2 -whorled; the two whorls isomerous, or anisomerous. Calyx 4–9; 1 -whorled; gamosepalous (the tube initially enclosing the corolla); entire, or lobed; open in bud; cylindric, tubaeform or crateriform; regular; coriaceous. Calyx lobes linear. Corolla 5–12; 1 -whorled; gamopetalous; contorted (to the left); tube cylindric, tubaeform or crateriform; regular; white. Androecium 5–9. Androecial members adnate (to the corolla tube); free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5–9. Staminal insertion in the throat of the corolla tube. Stamens remaining included, or becoming exserted (partially); isomerous with the perianth; oppositisepalous; with sessile anthers. Anthers medifixed in upper part of tube; dehiscing via longitudinal slits; introrse; tetrasporangiate. Pollen shed in aggregates; in tetrads. Gynoecium 2 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; eu-syncarpous; inferior. Ovary unilocular; 1 locular (with 2–9 parietal placentas). Epigynous disk present. Gynoecium stylate. Styles 1; simple (elongate, clavate at apex); 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; hairy, or hairless. Stigmas 1; 2–9 - lobed (the stigmatic lobes connate, linear, almost as long as the anthers); wet type, or dry type; papillate, or non-papillate; Group II type and Group IV type. Placentation parietal. Ovules in the single cavity 6–100 (i.e. ‘numerous’, partially embedded in the placenta); pendulous, or horizontal, or ascending; anatropous, or hemianatropous.

Fruit and seed features. Fruit fleshy; green to yellow; indehiscent; a berry, or a drupe; numerous seeded. Seeds lenticular; endospermic, or non-endospermic. Endosperm ruminate, or not ruminate; if present, oily. Seeds compressed (stuck together in a soft placental mass). Cotyledons 2. Embryo straight, or curved. Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Aluminium accumulation 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 and Eremaean Botanical Province. X = 11.

Etymology. After Alexander Garden (1730–91), physician and botanist, of Charleston, South Carolina, who later moved to England; correspondent of Linnaeus.