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The families of flowering plants

L. Watson and M.J. Dallwitz

Sphenostemonaceae P. van Royen & Airy Shaw

~ Aquifoliaceae, more recently Paracryphiaceae.

Habit and leaf form. Trees and shrubs. Mesophytic. Leaves persistent; alternate, or opposite, or whorled; leathery; non-sheathing; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire, or dentate. Leaf development not ‘graminaceous’.

Axial (stem, wood) anatomy. The axial xylem with tracheids.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes. The ultimate inflorescence units 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 (then short), or latrorse (then 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 III core angiosperms; core eudicot; Superorder Asteranae; campanulid. APG IV Order Paracryphiales (as a synonym of Paracryphiaceae).

Species 7. Genera 1; only genus, Sphenostemon.

General remarks. The comparative descriptive data compiled here show Sphenostemon differing from Paracryphia(ceae) (q.v.) in at least ten conspicuous characters representing vegetative, floral and fruit morphology, in addition to the wingless seeds with ruminate endosperm.

Illustrations. • Sphenostemon papuanus: Fl. Malesiana 10 (Van Steenis, 1950-).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 15th April 2018.’.