Eco-Physiology of Geum turbinatum and Implications Concerning Alpine Environments

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Abstract
Field and controlled-environment studies were made of G. turbinatum Rydb. This perennial herb, though almost ubiquitous throughout the Rocky Mountain alpine, is seldom encountered below timberline. High viability among the seeds tested indicated that sexual reproduction may be important in the dispersal and maintenance of the species, but there were no apparent environmental requirements for germination which would restrict Geum to the alpine. Vegetative growth was favored by low average temperatures (<15 C)[long dash]particularly soil-temperature conditions. No treatment consistently caused Geum plants to initiate flower ing-shoot primordia at lower elevations. Development of alpine-initiated flowers continued, however, if temperatures averaged 10-14 C, but above 15 C development was almost completely inhibited. Dormancy in Geum seems to be regulated by relative changes in soil temperatures with at least 5 weeks of freezing temperatures required to break dormancy completely. The dormancy response is primarily regulated by the roots. Because of its importance to Geum-functioning, low soil temperature is probably an essential factor in the distribution of this species and consequently may also operate in determining the lower limits of western American alpine tundra. Low soil temperature may likewise be important in setting the upward limit of tree distribution, that is, in the formation of alpine timber lines.

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