The Differential Temperature Responses of the Growth of Certain Plant Species From Different Altitudes. I. Growth Analysis of Phleum Alpinum L., P. Bertolonii D. C., Sesleria Albicans Kit. And Dactylis Gloerata L.

Summary The growth rates of Dactylis glomerata L. and Phleum bertolomii D.C., which ale essentially lowland species in Britain, show a large response to an increase in day temperature from 10 to 20 ° C. while those of Sesleria albicans Kit. which occurs from sea‐level to 900 m, and Phleum alpinum L. (600 to 1200 m) show little response. These differences can be attributed to the greater leaf‐area ratio, and to the increased rates of both leaf‐initiation and leaf‐expansion of the lowland species at higher temperatures. Net assimilation rates are scarcely affected by temperature. The differences are therefore due to morphogenetic effects and not to differences in the rates of physiological processes.