Aeonium Webb & Berthel.
Hist.Nat.Iles Canaries (Phytogr.) 3(2,1):184-185 (1840)

Name Status: Current
Browse to the list of specimens for Aeonium Webb & Berthel.

Scientific Description
H.R. Coleman, Thursday 8 September 2016

Family Crassulaceae.

Habit and leaf form. Shrubs, or herbs (rarely); evergreen. Plants succulent. Herbs biennial, or perennial; plants with terminal rosettes of leaves. Xerophytic, or mesophytic. Leaves alternate; spiral; fleshy; sessile; non-sheathing; 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 many monochasial branches; peduncle more or less scape-like with leaves usually abruptly shortened and widely spaced below the inflorescence). The terminal inflorescence unit cymose. Flowers small to medium-sized; regular; 6–12 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; 12–24; 2 -whorled; isomerous. Calyx 6–12; 1 -whorled; gamosepalous; lobed; imbricate; regular; fleshy; persistent. Corolla 6–12; 1 -whorled; gamopetalous (basally); imbricate; regular; yellow, or white to cream, or pink to red. Androecium 12–24. Androecial members adnate (to the corolla); markedly unequal (often), or all equal; free of one another; 2 -whorled. Androecium exclusively of fertile stamens. Stamens 12–24; diplostemonous; alternisepalous. Anthers more or less basifixed; non-versatile; dehiscing via longitudinal slits; latrorse, or introrse; bilocular; tetrasporangiate. Gynoecium 6–12 carpelled. Carpels isomerous with the perianth. Gynoecium apocarpous; eu-apocarpous; 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 endospermic. Endosperm oily. Cotyledons 2. Embryo straight. Testa usually tuberculate on vertical edges. 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.

Additional characters Corolla lobes spreading.