Verbatim text: Todsen, T. K. 1998. Penstemon metcalfei (Scrophulariaceae), a valid species. Sida 18: 621–622.
Author: Todsen, T.K.
Year: 1998
Title: Penstemon metcalfei (Scrophulariaceae), a valid species
Journal: Sida
Volume: 18
Pages: 621–622