Family Medusandraceae

Medusandraceae Brenan

~ Peridicaceae

Habit and leaf form. Trees; with coloured juice (yellow, throughout the plant including the xylem). Leaves deciduous; alternate; petiolate; non-sheathing; ostensibly simple, or compound (on the evidence of complex vascularization and a pulvinus at the distal end of the petiole); reasonably interpreted as unifoliolate. Leaflets pulvinate. Lamina entire; ovate, or obovate; pinnately veined; cross-venulate; attenuate at the base, or cuneate at the base. Leaves stipulate. Stipules very caducous (small). Lamina margins distantly, slightly crenate to serrate.

Leaf anatomy. Stomata present; anomocytic. Hairs present (of an unusual, thick-based type, abaxially).

Lamina with secretory cavities (associated with the veins). Secretory cavities containing yellow juice.

Stem anatomy. Secondary thickening developing from a conventional cambial ring, or anomalous. Vessel end-walls oblique; scalariform. Wood parenchyma paratracheal (and diffuse).

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes. The ultimate inflorescence unit racemose. Inflorescences axillary; paired or solitary, dense, pendent, catkinlike racemes. Flowers bracteate (the bracts tiny, caducous); small; regular; pentacyclic. Free hypanthium absent. Hypogynous disk absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous, or gamosepalous (then basally connate); regular; persistent; more or less accrescent; open in bud. Corolla 5; 1 whorled; polypetalous (the petals small); imbricate; regular.

Androecium 10. Androecial members free of the perianth; markedly unequal; free of one another; 1 whorled, or 2 whorled (?). Androecium including staminodes. Staminodes 5; non-petaloid (oppositisepalous, elongate and much exceeding the petals, serpentine and very densely pubescent above the base, tipped by vestigial anthers). Stamens 5; isomerous with the perianth; alternisepalous; opposite the corolla members; erect in bud. Anthers dehiscing by longitudinal valves (the outer, abaxial loculi by an outwardly recurved valve, the inner adaxial locules by inwardly recurved valves); latrorse; four locular; tetrasporangiate. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate.

Gynoecium 3(–4) carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium syncarpous; synovarious; superior. Ovary 1 locular; sessile. Gynoecium stylate. Styles 3(–4); free (short); apical; shorter than the ovary (remote, conical divergent). Stigmas 3(–4); small. Placentation apical (but very peculiar, there being a slender placental column extending from the base of the ovary to its top, to which the ovules are attached). Ovules in the single cavity 6(–8); pendulous (from the top of the placental column); epitropous; anatropous.

Fruit leathery, non-fleshy; dehiscent; a capsule (subtended by the reflexed, accrescent calyx). Capsules three valvular. Fruit 1 seeded. Seeds copiously endospermic. Endosperm slightly ruminate. Seeds large. Embryo well differentiated (small, near the edge of the endosperm). Cotyledons 2. Embryo straight.

Seedling. Germination cryptocotylar.

Geography, cytology. Paleotropical. Tropical. West tropical Africa.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli (?). Dahlgren’s Superorder Corniflorae (?); Cornales (?). Cronquist’s Subclass Rosidae; Santalales. APG 3 core angiosperms; core eudicot; unplaced at Superordinal level; Order Saxifragales (as a synonym of Peridiscaceae?).

Species 1. Genera 1; only genus, Medusandra.