Family Sphenostemonaceae

Sphenostemonaceae P. van Royen & Airy Shaw

~ Aquifoliaceae, more recently Paracryphiaceae

Habit and leaf form. Trees and shrubs. Mesophytic. Leaves evergreen; alternate, or opposite, or whorled; leathery; non-sheathing; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire, or dentate. Leaves without a persistent basal meristem.

Stem anatomy. Xylem with tracheids.

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 (sub-) terminal; racemes. Flowers bracteate (the bracts caducous); regular; cyclic; tetracyclic, or polycyclic. Free hypanthium absent. Hypogynous disk absent.

Perianth with distinct calyx and corolla, or sepaline (corolla sometimes absent); 8, or 4; 4 whorled, or 2 whorled; isomerous. Calyx 4; 2 whorled; polysepalous; regular; not persistent (caducous); imbricate. Corolla when present, 4; 2 whorled; polypetalous; regular; fleshy; deciduous.

Androecium 4–12. Androecial members free of the perianth; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 4–12; isomerous with the perianth to triplostemonous; petaloid, or filantherous, or with sessile anthers (the filaments short and thick or obsolete, the connective thick, the anther elongate or thick and petaloid). Anthers introrse (short), or latrorse (elongate). Pollen grains aperturate; 3 aperturate; porate, or colporate (?).

Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 2 locular. Gynoecium non-stylate. Stigmas 1; capitate. Ovules 1 per locule; pendulous; non-arillate.

Fruit fleshy; indehiscent; a drupe (asymmetrically ovoid). The drupes with separable pyrenes, or with one stone (with 1–2 bony pyrenes). Seeds endospermic. Endosperm ruminate.

Geography, cytology. Tropical. Eastern Malaysia, Queensland, New Caledonia.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli (?). Dahlgren’s Superorder Corniflorae; Cornales. Cronquist’s Subclass Rosidae; Celastrales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; campanulid; Order Paracryphiales (?).

Species 7. Genera 1; only genus, Sphenostemon.