15. Jepsonia Small, Bull. Torrey Bot. Club. 23: 18, plate 256. 1896.
[For Willis Linn Jepson, 1867-1946, California botanist] [For Willis Linn Jepson, 1867-1946, California botanist]
Debra K. Trock
Herbs, (acaulescent, heterostylous), not rhizomatous, not stoloniferous; caudex branched or unbranched, ovoid or flat, cormlike, fleshy, without scales. Flowering stems (usually appearing in autumn or winter after basal leaves have withered), erect or ascending, leafless, 3-28 cm, stipitate-glandular, slightly viscid. Leaves in basal rosette and cauline; stipules present; petiole stipitate-glandular; blade ovate to suborbiculate or orbiculate-reniform, shallowly lobed, base cordate, ultimate margins crenate with callous-apiculate teeth, apex obtuse to rounded, surfaces hairy; venation palmate. Inflorescences cymose panicles, (origin of inflorescences not readily resolvable), 2-17-flowered, sometimes flowers solitary, bracteate, (simple or branched distally, glandular-viscid or glabrate). Flowers heterostylous; hypanthium free from ovary except at base, yellow-green to pinkish; sepals 5, yellow-green to pinkish; petals 5, white, veins prominently colored, (spatulate to elliptic, glabrous); nectary tissue not visible; stamens 10; filaments subulate, (alternate ones surpassing sepals); ovary superior, 2-locular, carpels connate to middle; placentation axile (appearing marginal); styles 2; stigmas 2. Capsules folliclelike, 2-beaked. Seeds brownish, irregular in outline with pinched, curved base, reticulate with longitudinal wings or ridges. x = 7.
Species 3 (3 in the flora): California, nw Mexico.
Jepsonia is characterized by heterostylous flowers that are produced in the autumn after summer drought; some flowers have long styles and short stamens; others have short styles and long stamens. The floral differences associated with heterostyly within populations in this genus are part of an incompatibility mechanism that prevents self-fertilization. Leaves appear after flowering and persist through the winter if moisture is available. Rarely, leaves and flowers are present simultaneously. All three species of Jepsonia also produce a secondary taproot each year. This structure begins to grow after seasonal rains and shrivels before flowering begins. It apparently acts as a contractile root. The three species in this genus are narrow allopatric endemics.
SELECTED REFERENCES Ornduff, R. 1969b. Ecology, morphology, and systematics of Jepsonia (Saxifragaceae). Brittonia 21: 286-298. Soltis, D. E. 1984c. Karyotypes and relationships of species of Jepsonia (Saxifragaceae). Syst. Bot. 9: 137-141.