TULIG, MELISSA* AND CURTIS CLARK. Biological Sciences, California State Polytechnic University, Pomona, CA 91768. - Morphological Variation in Mimulus section Diplacus (Scrophulariaceae).
Mimulus section Diplacus consists of erect or prostrate shrubs
found throughout California in many habitats. The group has a history
of disagreement in taxonomic treatments, including its separation as a
separate genus and the recognition of various species, subspecies, and
varieties. Recent treatments describe as many as fourteen species or
as few as two. Taxonomic boundaries between species and subspecies
are obscured by hybridization, especially in southern California where
there is overlap in the distributions of six taxa. Measurements of
twenty-one floral and vegetative characters have been made from
samples of all taxa throughout the range of the section to delineate
morphological gaps. Principal components analysis shows a clear
separation between species based on variation in the morphology of
corolla, calyx, and pedicel features. Hybrid populations are variable
in floral features and show an intermediacy between their putative
parents. Although hybrids are problematic for the taxonomy of the
group, they appear to be geographically limited and confined to
disturbed areas.
Key words: hybridization, Mimulus, phenetics, Scrophulariaceae