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The families of flowering plants.                                                                                                                                                                

Davidsoniaceae Bange

                        

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~Cunoniaceae

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. Leaves without a persistent basal meristem.

Leaf anatomy. Hairs present. Urticating hairs present.

Minor leaf veins without phloem transfer cells.

Stem anatomy. Secondary thickening developing from a conventional cambial ring (?). Vessel end-walls scalariform and simple.

Reproductive type, pollination. Fertile flowershermaphrodite. 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).

Perianthsepaline; 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. Ovules5–7 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, biochemistry. Not cyanogenic. Iridoids not detected. Proanthocyanidins probably present. Ellagic acid absent. Aluminium accumulation not found.

Geography, cytology. Tropical. Northeast Australia.

Taxonomy.Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rosiflorae; Cunoniales. Cronquist’s Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; unplaced at Superordinal level; Order Saxifragales (as a synonym of Cunoniaceae).

Species 1. Genera 1; only genus, Davidsonia

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