Family Medusagynaceae

Medusagynaceae Engl. & Gilg

~ Ochnaceae

Habit and leaf form. Small trees, or shrubs. Leaves opposite; leathery; petiolate; simple. Lamina entire. Leaves exstipulate. Lamina margins shallowly crenate.

Leaf anatomy. Stomata present; anomocytic.

Adaxial hypodermis present (mucilaginous). Lamina dorsiventral; without secretory cavities. The mesophyll containing mucilage cells; without sclerenchymatous idioblasts; containing calcium oxalate crystals (around the midrib and main vascular bundles). The mesophyll crystals druses.

Stem anatomy. Secretory cavities absent. Cork cambium present; initially superficial (subepidermally). The cortex without cristarque cells. Nodes multilacunar. Cortical bundles present. Internal phloem absent. Secondary thickening anomalous. The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones. ‘Included’ phloem absent. Xylem with tracheids. Vessel end-walls simple.

Reproductive type, pollination. Plants andromonoecious.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in panicles. The ultimate inflorescence unit cymose. Inflorescences terminal; small, lax, opposite-flowered, terminal mixed panicles. Flowers small; malodorous; regular. Free hypanthium absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; gamosepalous (connate basally). Calyx lobes markedly longer than the tube. Calyx regular; not persistent (deciduous, according to Hutchinson and Airy Shaw, though persistent according to Cronquist); imbricate. Corolla 5; 1 whorled; polypetalous; imbricate; regular; white, or red, or pink (white, becoming rose); deciduous.

Androecium 50–100 (‘many’). Androecial members free of the perianth; free of one another. Androecium exclusively of fertile stamens. Stamens 50–100 (‘many’); polystemonous; filantherous (the very slender filaments shorter than the petals, subpersistent). Anthers small, basifixed; dehiscing via longitudinal slits; bilocular (the pollen sacs often set at different heights). Pollen shed as single grains. Pollen grains aperturate; (2–)3(–4) aperturate; porate.

Gynoecium 17–25 carpelled. Carpels increased in number relative to the perianth. The pistil 17–25 celled. Gynoecium syncarpous; synovarious, or synstylovarious; superior. Ovary 17–25 locular (with as many external grooves). Gynoecium multi- stylate. Styles 17–25; free; apical to lateral (in a subapical ring, on the shoulders of the carpels — fancifully medusoid in appearance); shorter than the ovary (stout). Stigmas 17–25; capitate. Placentation axile. Ovules 2 per locule; funicled; pendulous (the lower), or horizontal (the upper); superposed; bitegmic; tenuinucellate.

Fruit non-fleshy; dehiscent and a schizocarp. Mericarps if viewed as such, 17–25; ultimately comprising follicles. Fruit viewed as a syncarp, a capsule. Capsules initially septicidal (from below, the carpels separating but remaining attached distally, the dehisced capsule becoming umbrella-shaped and the separated carpels ultimately dehiscing ventrally). Seeds winged.

Physiology, biochemistry. Aluminium accumulation not found.

Geography, cytology. Paleotropical. Tropical. Seychelles.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Theiflorae; Theales. Cronquist’s Subclass Dilleniidae; Theales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Malpighiales (as a synonym of Ochnaceae?).

Species 1. Genera 1; only genus, Medusagyna.

Fay et al. (1996) postulate relationship with Ochnaceae and Quiinaceae, on evidence of rbcL sequencing. Contributions by Dickison (1990a and b) not accounted for here.