Family Pandaceae

Pandaceae Pierre

Including Centroplacaceae Doweld & Reveal, Galeariaceae Pierre

Habit and leaf form. Trees, or shrubs (of specialised growth form, with buds in the axils of the leafy short-shoots, but often not in the actual leaf axils). Plants non-succulent. Leaves alternate; distichous (on short-shoots, these simulating pinnate leaves); gland-dotted, or not gland-dotted; simple. Lamina dissected, or entire; if dissected, pinnatifid; pinnately veined; cross-venulate. Leaves stipulate. Stipules free of one another (unequally inserted). Lamina margins entire, or serrate, or dentate.

Leaf anatomy. Stomata present; anomocytic (Microdesmis), or paracytic (Galearia), or cyclocytic (Panda).

The mesophyll with sclerencymatous idioblasts; containing calcium oxalate crystals. The mesophyll crystals druses, or solitary-prismatic. Minor leaf veins without phloem transfer cells (Panda).

Stem anatomy. The cortex containing cristarque cells. Secondary thickening developing from a conventional cambial ring (?). Xylem with tracheids, or without tracheids; with fibre tracheids; without libriform fibres. Vessel end-walls scalariform, or scalariform and simple. Vessels without vestured pits. Primary medullary rays mixed wide and narrow.

Reproductive type, pollination. Fertile flowers functionally male and functionally female. Unisexual flowers present. Plants monoecious (?), or dioecious.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when solitary, axillary (or cauliflorous); when aggregated, in cymes, or in fascicles, or in panicles. Inflorescences terminal, or axillary, or cauliflorous; in axillary fascicles (Microdesmis) or cymes (Centroplacus) or in terminal (Galearia) or cauliflorous (Galearia, Panda) racemiform thyrses (Airy Shaw 1975). Flowers small; regular; mostly 5 merous; cyclic. Free hypanthium absent. Hypogynous disk present (occasionally, large only in female flowers of Centroplacus), or absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; gamosepalous; blunt-lobed, or toothed; regular; imbricate, or open in bud. Corolla 5; 1 whorled; polypetalous; imbricate, or valvate.

Androecium 5, or 10, or 15. Androecial members free of the perianth; all equal, or markedly unequal; free of one another; 1 whorled (of 5, 10 or 15 members), or 2 whorled (of five each). Androecium exclusively of fertile stamens, or including staminodes (Centroplacus). Stamens 5, or 10, or 15; isomerous with the perianth, or diplostemonous, or triplostemonous; both alternating with and opposite the corolla members. Anthers dehiscing via longitudinal slits; introrse. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate.

Gynoecium 2–5 carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil 2–5 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary 2–5 locular. Gynoecium stylate (usually), or non-stylate (sometimes, almost). Styles 2–5; free, or partially joined (basally). Stigmas 2–5. Placentation apical. Ovules 1(–2) per locule (two in Centroplacus); pendulous; when anatropous, epitropous; with ventral raphe; non-arillate (with no obturators); orthotropous (Panda only), or anatropous; bitegmic.

Fruit fleshy, or non-fleshy; dehiscent (?rarely), or indehiscent (usually); a capsule (Centroplacus only), or a drupe (usually). The drupes with one stone (the endocarp bony or stony, thin to very thick, usually tuberculate, pitted or ridged, sometimes dehiscent by valves). Fruit mostly 2–5 seeded (with as many locules and seeds as carpels). Seeds copiously endospermic. Endosperm oily. Embryo well differentiated. Cotyledons 2 (thin, flat).

Seedling. Germination phanerocotylar.

Physiology, biochemistry. Alkaloids present, or absent. Saponins/sapogenins present, or absent. Aluminium accumulation not found.

Geography, cytology. Paleotropical. Tropical. West tropical Africa, Southeast Asia. 2n = 30 (Microdesmis).

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Euphorbiales. Cronquist’s Subclass Rosidae; Euphorbiales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Malpighiales.

Species 28. Genera 5; Bhesa, Centroplacus, Galearia, Microdesmis, Panda.