Greyiaceae (Gürke) Hutch.
Habit and leaf form. Small or medium sized trees, or shrubs (with somewhat bare branches). Leaves deciduous; alternate; spiral; flat; petiolate; sheathing (the expanded, sheathing bases congenitally united with the stem, forming pseudo-cortex); simple; somewhat peltate. Lamina dissected; pinnatifid (lobulate, somewhat Pelargonium-like); pinnately veined (subpalmate at the base); cross-venulate. Leaves exstipulate. Lamina margins serrate, or dentate.
Leaf anatomy. Stomata present; anomocytic.
The mesophyll containing calcium oxalate crystals. The mesophyll crystals raphides, or raphides and druses. Minor leaf veins without phloem transfer cells.
Stem anatomy. Nodes multilacunar. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem with libriform fibres; with vessels. Vessel end-walls simple. Wood parenchyma scanty paratracheal (and a few diffusely scattered cells). Pith heterogeneous.
Reproductive type, pollination. Fertile flowers hermaphrodite. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes. The ultimate inflorescence unit racemose. Inflorescences terminal. Flowers bracteate; medium-sized (conspicuous, protandrous); regular to somewhat irregular; if irregular, slightly zygomorphic; 5 merous; cyclic; pentacyclic (including the staminodes, the ten stamens seemingly in one cycle). Free hypanthium absent. Hypogynous disk present; extrastaminal; annular (fleshy, cupular, connected by five interstaminal ridges with the ovary, 10-lobed, the lobes crowned by 10 small glandular staminodes alternating with the stamens, the whole constituting a nectariferous, more or less persistent corona).
Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; very shortly gamosepalous, or polysepalous. Calyx lobes markedly longer than the tube. Calyx persistent; imbricate. Corolla 5; 1 whorled; polypetalous; imbricate; red; deciduous. Petals sessile (cuneate-obovate); ciliolate.
Androecium 15 (including the staminodes on the corona). Androecial members free of the perianth; markedly unequal (the staminodes much shorter); free of one another; 2 whorled. Androecium including staminodes. Staminodes 10 (on the disk, 5+5 in one whorl); external to the fertile stamens. Stamens 10 (5+5 in one whorl); diplostemonous; alternisepalous; both alternating with and opposite the corolla members; long filantherous (the anthers exserted). Anthers basifixed; non-versatile; dehiscing via longitudinal slits; latrorse to introrse. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate.
Gynoecium (4–)5(–6) carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth to increased in number relative to the perianth. The pistil 1 celled, or 5(–6) celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 1 locular, or 5 locular (deeply five lobed, the carpellary lobes distinct except for the common, central placental column, or united by their ventral margins around a central hollow); sessile. Gynoecium stylate. Styles 1; attenuate from the ovary; apical. Stigmas 1; 5 lobed; wet type; non-papillate. Placentation when unilocular, intrusive parietal; when 5-locular, axile. Ovules in the single cavity 50–100 (‘many’); 30–50 per locule (‘numerous’); biseriate; anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Embryo-sac development Polygonum-type.
Fruit non-fleshy; a schizocarp. Mericarps 5; comprising follicles (the mature carpels separating from the central column or hollow, and opening ventrally). Fruit many seeded. Seeds copiously endospermic; minute. Embryo well differentiated (small). Cotyledons 2. Embryo straight.
Physiology, biochemistry. Not cyanogenic. Iridoids not detected. Proanthocyanidins absent. Flavonols present; quercetin. Ellagic acid present. Saponins/sapogenins absent.
Geography, cytology. Cape. Temperate to sub-tropical. Southeast South Africa. X = 16, 17.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rosiflorae; Saxifragales. Cronquist’s Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Geraniales (as a synonym of Melianthaceae).
Species 3. Genera 1; only genus, Greyia.