Penstemon grinnellii

Photo by: Andrea D. Wolfe©
Location: Kern County, California

Penstemon grinnellii is a member of Penstemon subg. Penstemon sect. Peltanthera subsect. Spectabiles (Bennett et al. 1989). It occurs in the coastal, transverse and Sierra Nevada ranges of California. Typical habitats are sandy and rocky soils along roadsides from 800 to 2,900 m in elevation. It is primarily pollinated by large carpenter bees.

Several studies of hybridization and hybrid speciation have focused on P. grinnellii (Straw 1955, 1956a,b; Wolfe and Elisens 1993, 1994, 1995). P. grinnellii and P. centranthifolius were proposed as parental species of P. spectabilis based on morphological and artificial crossing evidence (Straw 1955, 1956a,b). Wolfe and Elisens (1993, 1994, 1995) used allozyme, chloroplast DNA and nuclear ribosomal DNA data to demonstrate that hybrid speciation was not supported, but that introgression of markers from P. centranthifolius to P. spectabilis, P. clevelandii, and P. grinnellii has occurred.

Bibliography and suggested readings

Bennett, R. W., K. Lodewick, and R. Lodewick. 1987. Penstemon nomenclature. Eugene, OR: American Penstemon Society.

Grant, K. A. and V. Grant. 1968. Hummingbirds and their flowers. New York: Columbia University Press.

Grant, V. 1994. Modes and origins of mechanical and ethological isolation in angiosperms. Proceedings of the National Academy of Sciences, U.S.A. 91: 3-10.

Keck, D. D. 1937. Studies in Penstemon V. The section Peltanthera. American Midland Naturalist 18: 790-829.

Mitchell, R. J. 1988. Is Penstemon centranthifolius truly hummingbird pollinated? Crossosoma 15: 1-9.

Straw, R. M. 1955. Hybridization, homogamy, and sympatric speciation. Evolution 9: 441-444.

Straw, R. M. 1956a. Adaptive morphology of the Penstemon flower. Phytomorphology 6: 112-118.

Straw, R. M. 1956b. Floral isolation in Penstemon. American Midland Naturalist 90: 47-53.

Wolfe, A. D. and W. J. Elisens. 1993. Diploid hybrid speciation in Penstemon revisited. American Journal of Botany 80: 1082-1094.

Wolfe, A. D. and W. J. Elisens. 1994. Nuclear ribosomal DNA restriciton-site variation in Penstemon section Peltanthera (Scrophulariaceae): An evaluation of diploid hybrid speciation and evidence for introgression. American Journal of Botany 81: 1627-1635.

Wolfe, A. D. and W. J. Elisens. 1995. Evidence of chloroplast capture and pollen-mediated gene flow in Penstemon sect. Peltanthera (Scrophulariaceae). Systematic Botany 20: 395-412.

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Please send your suggestions, comments, and corrections to wolfe.205@osu.edu
Last updated December 13, 1996.