Family Hoplestigmataceae

Hoplestigmataceae Gilg

~ Boraginaceae

Habit and leaf form. Trees. Leaves large; alternate; chartaceous; petiolate; non-sheathing; simple. Lamina entire; obovate; pinnately veined; cross-venulate; attenuate at the base. Leaves exstipulate. Lamina margins entire.

Stem anatomy. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes. The ultimate inflorescence unit cymose. Inflorescences terminal; brown-hirsute, terminal subscorpioid cymes. Flowers ebracteate; medium-sized to large; regular; irregularly cyclic; irregularly polycyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla; 13–18; irregularly 3–5 whorled; anisomerous. Calyx 1 whorled; gamosepalous (entire and globose in bud, splitting irregularly into 2–4 lobes); persistent (at the base of the fruit). Corolla 11–14; irregularly 2–4 whorled; gamopetalous (with a short tube). Corolla lobes about the same length as the tube, or markedly longer than the tube. Corolla imbricate; regular.

Androecium 20–35. Androecial members free of the perianth; free of one another; irregularly 3 whorled. Androecium exclusively of fertile stamens. Stamens 20–35; diplostemonous to polystemonous; filantherous (with filiform filaments). Anthers dorsifixed (near the base); dehiscing via longitudinal slits; latrorse; tetrasporangiate. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate (said to resemble Ehretia).

Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary 1 locular; sessile. Gynoecium non-stylate. Styles 2; partially joined (near the base, the pair of branches incurved to form a horseshoe shape); apical. Stigmas 2; capitate. Placentation parietal (the two placentas intruded and forked). Ovules in the single cavity 4 (two per placenta); pendulous; anatropous; unitegmic.

Fruit fleshy to non-fleshy (the exocarp leathery); indehiscent; a drupe (or drupaceous). The drupes with one stone (laterally compressed, chanelled along the narrow sides, with a bony endocarp). Fruit 4 seeded. Seeds scantily endospermic. Embryo well differentiated (rather large). Cotyledons 2 (expanded). Embryo straight to curved (nearly straight).

Seedling. Germination phanerocotylar.

Physiology, biochemistry. Aluminium accumulation not found.

Geography, cytology. Paleotropical. Tropical. West equatorial Africa.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli (gamopetalous, with unitegmic ovules). Dahlgren’s Superorder Solaniflorae; Boraginales, or Solanales (?). Cronquist’s Subclass Dilleniidae; Violales. APG 3 Order unassigned to Order (as a synonym of Boraginaceae?).

Species 2. Genera 1; only genus, Hoplestigma.

This description is inadequate for reliable classification.