Penstemon lanceolatus Benth. or P. ramosus Crosswhite in Arizona and New Mexico, a peripheral or endemic species?

Abstract

The red-flowered member of Penstemon sect. Chamaeleon from southeastern Arizona and southwestern New Mexico has been treated taxonomically both as part of the Mexican species, P. lanceolatus Benth., and as a separate species, P. ramosus Crosswhite. Under the former treatment the Arizona and New Mexico populations are peripheral populations of a primarily Mexican species; and, under the latter they represent an endemic species restricted to this area. Penstemon ramosus was distinguished from P. lanceolatus by branching below the inflorescence and by having narrow, revolute leaves. Morphological examination of herbarium specimens from Arizona, New Mexico, Texas, and Mexico, including duplicates of paratypes cited in the original publication of P. ramosus, and of field material in Arizona and New Mexico showed no consistent differences in these characters throughout the entire range. Therefore, Penstemon ramosus should be synonymized under P. lanceolatus, and Arizona and New Mexico plants that have been distinguished as P. ramosus should be treated as peripherals of P. lanceolatus.

Parent Publication

• Southwestern rare and endangered plants: Proceedings of the Fourth Conference

Citation

Anderson, J. L.; Richmond-Williams, S.; Williams, O. 2007. Penstemon lanceolatus Benth. or P. ramosus Crosswhite in Arizona and New Mexico, a peripheral or endemic species? In: Barlow-Irick, P.; Anderson, J.; McDonald, C., tech eds. Southwestern rare and endangered plants: Proceedings of the Fourth Conference; March 22-26, 2004; Las Cruces, New Mexico. Proceedings. RMRS-P-48CD. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 8-15