Ecology, Morphology, and Systematics of Jepsonia (Saxifragaceae)

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Abstract
Aspects of flowering, leaf production, caudex and contractile root morphology, edaphic preferences, and systematics ofJepsonia (Saxifragaceae) are discussed. Although other authors have recognized as few as one species ofJepsonia, various lines of evidence suggest that three allopatric species can be recognized, which are morphologically distinct and separated from each other by barriers to hybridization. These species areJ. heterandra of the Sierra Nevada foothills of California,J. malvifolia of southern California’s offshore islands and the Mexican Guadalupe Island, andJ. parryi of mainland southern California and adjacent Baja California. Plants flower from late summer to early winter in response to environmental factors that have yet to be clearly identified. Flowers are heterostylous, and the species are self-incompatible. Pollination is by syrphid flies and halictid bees. Leaves are produced during or after flowering in response to rain. They persist through the winter until the onset of the dry season in the subsequent late spring. Plants perennate by a starchy underground structure, which is hypocotylar in origin and best termed a caudex. Young plants and many old ones also produce one or more very large, whitish, starch-free contractile roots that are annual in duration.Jepsonia heterandra characteristically is restricted to the crevices of slatelike rocks, although the other two species occur in a wider range of edaphic situations. Moisture and temperature conditions, as well as rodent predations, may determine the general and local distribution of the species. The relationships of the genus are briefly considered, and interspecific differences are described.

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