Date of Award:

5-1971

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Plant Ecology

Committee Chair(s)

I. G. Palmblad

Committee

I. G. Palmblad

Abstract

The response of Mimulus guttatus DC. to its unusual thermal habitat in Yellowstone Park is described. Although populations within the park are usually observed in thermal areas, no evidence indicates that they are restricted to thermal soils. The median temperature for soils of natural populations is about 26 C. Populations are distributed in both acidic and basic thermal areas. Success of the species in the thermal soils is facilitated by rapid vegetative growth, allowing fluctuation in population size or position with changes in soil temperature. Water availability is a critical limiting factor in distribution and lack of water tends to affect morphology more severely than does extreme temperature. Dwarf plants taken from decomposed sinter sites attained a morphology similar to other thermal plants when grown under greenhouse conditions.

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