The families of flowering plants

L. Watson and M.J. Dallwitz

Curtisiaceae (Harms) Takht.

~ Cornaceae.

Habit and leaf form. Trees. Leaves opposite; leathery (shining above, rusty-tomentose below); simple. Lamina entire. Leaves exstipulate. Lamina margins coarsely dentate.

General anatomy. Plants without ‘crystal sand’.

Leaf anatomy. The leaf lamina dorsiventral (with a single palisade layer). Stomata present; mainly confined to one surface (abaxial); anomocytic. Hairs present (and sometimes forming an abaxial tomentum); exclusively glandular (and no 2-armed hairs present). Lamina without secretory cavities. The mesophyll containing crystals. The crystals exclusively solitary-prismatic (these very large, abutting on the upper epidermis). Main veins vertically transcurrent.

Axial (stem, wood) anatomy. Secretory cavities absent. Primary vascular tissues probably in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring.

The wood diffuse porous. The vessels small. The vessel end-walls scalariform. The vessels without vestured pits. The axial xylem with fibre tracheids; without libriform fibres; without septate fibres. The fibres without spiral thickening. The parenchyma apotracheal. ‘Included’ phloem absent. The wood not storied.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in panicles. The ultimate inflorescence units cymose. Inflorescences terminal; many-flowered, dichotomous, tomentose thyrses. Flowers minute; regular.

Perianth with distinct calyx and corolla; 8; 2 whorled; isomerous. Calyx 4; 1 whorled; gamosepalous; funnel-shaped (turbinate); valvate. Corolla 4; 1 whorled; polypetalous; valvate.

Androecium 4. Androecial members free of the perianth; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 4; isomerous with the perianth; oppositisepalous; alternating with the corolla members. Anthers introrse; tetrasporangiate. Pollen grains aperturate; 3 aperturate; colporate.

Gynoecium 4 carpelled. Carpels isomerous with the perianth. The pistil 4 celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; inferior. Ovary 4 locular. Epigynous disk present (densely barbate). Gynoecium stylate. Styles 1; apical; short, subconical, glabrous. Stigmas 1, or 4; if regarded as single, 4 lobed. Placentation apical. Ovules 1 per locule; pendulous; epitropous (the micropyle turned outwards); with ventral raphe; anatropous; unitegmic; crassinucellate. Endosperm formation cellular.

Fruit fleshy; indehiscent; a drupe (small, subglobular). The drupes with one stone (4-locular). Fruit 4 seeded. Seeds copiously endospermic. Endosperm oily. Embryo well differentiated. Cotyledons 2. Embryo straight.

Physiology, phytochemistry. Not cyanogenic. Iridoids detected; ‘Route I’ type (+seco).

Geography, cytology. Cape. Temperate, sub-tropical. South Africa.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli (?). Dahlgren’s Superorder Corniflorae; Cornales. Cronquist’s Subclass Rosidae; Cornales. APG III core angiosperms; core eudicot; Superorder Asteranae. APG IV Order Cornales.

Species 1 (Curtisia dentata). Genera 1; only genus, Curtisia.

General remarks. This family exemplifies the well known difficulties in distributing certain Dicot families between Dahlgren’s Araliiflorae and Corniflorae. It is equally hard to assign them with confidence to the higher level groupings Crassinucelli and Tenuinucelli, although the latter evidently represent a major divergence in the Dicot line of descent (cf.Young and Watson 1970, Chase et al. 1993).

Illustrations. • Curtisia dentata (as C. faginea): Harvey, Thesaurus Capensis 2 (1863). • Curtisia dentata (as C. faginea): inflorescence and floral structure (with Corokia: Das Pflanzenreich, 1910).

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: 5th March 2018.’.