Cotyledon L.
Sp.Pl. 2:429 (1753)

Name Status: Current
Browse to the list of specimens for Cotyledon L.

Scientific Description
H.R. Coleman, Friday 3 October 2008

Family Crassulaceae.

Habit and leaf form. Herbs, or shrubs; evergreen. Plants succulent. Perennial; plants with terminal rosettes of leaves. Xerophytic, or mesophytic. Leaves opposite; fleshy; petiolate, or sessile; simple; not peltate. Leaf blades entire; flat (more or less); one-veined, or pinnately veined; cross-venulate, or without cross-venules. Leaves without stipules. Leaf blade margins entire. Leaves without a persistent basal meristem. Leaf anatomy. Hydathodes present. 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. Floral nectaries present. Nectar secretion seemingly from the gynoecium (each carpel with a nectariferous scale-like appendage abaxially near the base). Entomophilous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in cymes, or in panicles (a thyrse, usually with several dichasia each one ending in monochasial branches; peduncle scape-like with 1 or 2 pairs of small bracts; flowers borne well above the leaves). The terminal inflorescence unit cymose. Inflorescences terminal. Flowers small to medium-sized; regular (mainly pendulous); 5 merous; cyclic; pentacyclic. Floral receptacle not markedly hollowed. Free hypanthium present, or absent. Hypogynous disk seemingly absent (i.e. the nectariferous appendages being interpreted as gynoecial). Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx 5; 1 -whorled; gamosepalous; imbricate; regular; fleshy; persistent. Corolla 5; 1 -whorled; gamopetalous; lobes twisted in bud; urceolate, or tubular (with the apices of the lobes recurved or recoiled); regular; yellow, or orange, or red. Androecium 10. Androecial members adnate (to the corolla); markedly unequal; free of one another; 2 -whorled, or 1 -whorled (rarely). Androecium exclusively of fertile stamens. Stamens 10. Staminal insertion near the base of the corolla tube. Stamens becoming exserted, or remaining included; diplostemonous; alternisepalous. Filaments glabrous except for a tuft of hairs where filaments are fused to the tube. Anthers more or less basifixed; non-versatile; dehiscing via longitudinal slits; latrorse, or introrse; bilocular; tetrasporangiate. Gynoecium 5 carpelled. Carpels isomerous with the perianth. Gynoecium apocarpous, or syncarpous; eu-apocarpous, or semicarpous (when the carpels slightly united at base); superior. Carpel apically stigmatic; 20–50 ovuled (i.e. ‘numerous’). Placentation (sub) marginal. Stigmas wet type; papillate; Group III type. Ovules pendulous to horizontal; biseriate; non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy; an aggregate. The fruiting carpels not coalescing. The fruiting carpel dehiscent; a follicle. Seeds with distinct vertical edges; endospermic. Endosperm oily. Cotyledons 2. Embryo straight. Seedling. Germination phanerocotylar.

Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: CAM.

Geography, cytology, number of species. Adventive. Australian states and territories: Western Australia and South Australia.