Family Desfontainiaceae

Desfontainiaceae Endl.

~ Columelliaceae, Loganiaceae

Habit and leaf form. Glabrous shrubs (with shiny, dark green, prickly, holly-like leaves), or trees (rarely, small); leptocaul. Leaves evergreen; small to medium-sized; opposite; flat; leathery; petiolate; not gland-dotted; simple; epulvinate. Lamina dissected to entire (holly-like); oblong, or ovate; pinnately veined; cross-venulate. Leaves stipulate to exstipulate. Stipules interpetiolar to intrapetiolar (the small stipules connected by a transverse line). Lamina margins dentate (prickly-dentate and holly-like). Leaves without a persistent basal meristem.

Leaf anatomy. Extra-floral nectaries absent. Stomata present; anomocytic. Hairs present, or absent; when present, eglandular. Complex hairs absent.

Lamina dorsiventral. Minor leaf veins without phloem transfer cells.

Stem anatomy. Young stems cylindrical. Cork cambium present; initially deep-seated (arising near the phloem). Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem with tracheids (a few); with fibre tracheids; without libriform fibres; with vessels (narrow, hard to distinguish from the other elements in T.S.). Vessel end-walls very oblique; scalariform (with many bars). Vessels without vestured pits (intervascular pitting partly scalariform, partly rounded and bordered). Primary medullary rays very narrow (predominantly uniseriate, of upright cells). Wood ring porous; not storied; parenchyma apotracheal (mainly diffuse).

Reproductive type, pollination. Fertile flowers hermaphrodite. Plants hermaphrodite; homostylous.

Inflorescence, floral, fruit and seed morphology. Flowers mostly solitary; axillary (in opposite axils); small to medium-sized; regular to somewhat irregular. The floral irregularity when detectable involving the perianth (the calyx only). Flowers 5 merous; tetracyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; gamosepalous (basally only); blunt-lobed (the oblong lobes ciliate); unequal but not bilabiate, or regular; non-fleshy; persistent; non-accrescent; strongly imbricate. Corolla 5; alternating with the calyx; gamopetalous. Corolla lobes markedly shorter than the tube. Corolla imbricate, or contorted (but not twisted); funnel-shaped, or hypocrateriform to tubular; regular; yellow and red (the tube crimson, the lobes yellow); fleshy.

Androecium 5. Androecial members adnate (in the throat of the corolla); all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; inserted in the throat of the corolla tube; isomerous with the perianth; oppositisepalous; alternating with the corolla members; filantherous (the filaments short and thick). Anthers basifixed; dehiscing via longitudinal slits; introrse. Pollen grains aperturate; 3 aperturate; colporate.

Gynoecium (3–)5 carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil (2–)5 celled (i.e., diminishing from 5 above). Gynoecium syncarpous; eu-syncarpous; superior. Ovary (3–)5 locular, or 1 locular (i.e., becoming unilocular above); sessile. Gynoecium stylate. Styles 1 (the style persistent); apical. Stigmas 1; capitate. Placentation above, where unilocular, parietal (the mushroom-shaped placentas intruding deeply); below, where plurilocular, axile. Ovules differentiated; 15–50 per locule (‘many’); anatropous (?); unitegmic; crassinucellate. Endothelium differentiated. Endosperm formation cellular.

Fruit fleshy; indehiscent; a berry (white or yellow). Dispersal unit the fruit. Seeds endospermic (the endosperm starchy). Embryo well differentiated (but minute). Cotyledons 2. Embryo straight.

Physiology, biochemistry. Alkaloids present, or absent (only weak positives recorded — no isoquinoline alkaloids). Iridoids detected; ‘Route I’ type. Arthroquinones not detected. Verbascosides not detected. Cornoside detected. Saponins/sapogenins absent.

Geography, cytology. Andes, Costa Rica to Cape Horn. 2n=14. Supposed basic chromosome number of family: 7. Ploidy levels recorded: 2.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Corniflorae; Dipsacales (re-assigned). Cronquist’s Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; campanulid; Order Bruniales (as a synonym of Columelliaceae).

Species 1. Genera 1; only genus, Desfontainia.

Leeuwenberg (1980); but Desfontainea seems related to Dipsacales rather than Gentianales in terms of both the available descriptive data and rbcL sequence analyses (cf. Bremer et al., 1994). Its nearest neighbour as assessed from the present descriptions is Caprifoliaceae.

Economic uses, etc. A cultivated ornamental.