The families of flowering plants
Habit and leaf form. Small, slender trees; leptocaul. Mesophytic, or xerophytic. Leaves large (about 1 m long); alternate; spiral; petiolate; non-sheathing; compound; pinnate. Lamina pinnately veined; cross-venulate. Leaves stipulate (the stipules large, reniform, palmately veined). Lamina margins of the leaflets serrate to dentate. Leaf development not graminaceous.
Leaf anatomy. Hairs present. Urticating hairs present. Minor leaf veins without phloem transfer cells.
Axial (stem, wood) anatomy. Secondary thickening developing from a conventional cambial ring (?).
The vessel end-walls scalariform and simple.
Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in panicles. Inflorescences axillary. Flowers regular. Hypogynous disk present; of separate members (scales, alternating with the stamens).
Perianth sepaline; 4(–5); joined; 1 whorled. Calyx 4(–5); gamosepalous (connate into a tube as long as the lobes). Calyx lobes about the same length as the tube. Calyx valvate (thick).
Androecium 8, or 10. Androecial members free of the perianth; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 8, or 10; diplostemonous; filantherous (the filaments more or less tumid below). Anthers dorsifixed; versatile; dehiscing via pores to dehiscing via short slits to dehiscing via longitudinal slits (the initial apical pores becoming slits); introrse. Pollen grains aperturate; 3 aperturate; colporate.
Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium syncarpous; synovarious; superior. Ovary 2 locular. Styles 2 (these filiform, geniculate above); free; apical. Stigmas 2. Placentation axile, or apical. Ovules 5–7 per locule; pendulous; non-arillate; anatropous; bitegmic.
Fruit fleshy; indehiscent; a drupe. The drupes with separable pyrenes (two-pyrened). Seeds non-endospermic. Cotyledons 2 (these large).
Seedling. Germination cryptocotylar.
Physiology, phytochemistry. Not cyanogenic. Iridoids not detected. Proanthocyanidins probably present. Ellagic acid absent. Aluminium accumulation not found.
Geography, cytology. Tropical. Northeast Australia.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Rosiflorae; Cunoniales. Cronquists Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; unplaced at Superordinal level; Order Saxifragales (as a synonym of Cunoniaceae).
Species 3 (D. jerseyana, D. johnsonii, D. pruriens). Genera 1; only genus, Davidsonia.
General remarks. Seemingly differing from Cunoniaceae sensu stricto (q.v.) in the non-endospermic seeds, micropyle not zig-zag, and cryptocotylar seed germination, as well as in possessing urticating hairs.
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: 24th October 2017. delta-intkey.com/angio’.