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Adaptation of Growth Form in Echium Leucophaeum (Boraginaceae)

Lems, Kornelius, Holzapfel, Christina M.
Ecology 1971 v.52 no.3 pp. 499-506
Echium, altitude, branches, branching, climate, ecotypes, evaporation, flowering, fruiting, gardens, periodicity, physiological response, rain, sea level, seedlings, temperature, wind speed, woody plants, Canary Islands
Ecotype formation in eight populations of Echium leucophaeum was studied on La Palma (Canary Islands) at 100—m intervals from sea level to 600 m elevation. Climate varied with altitude, the lower elevation having higher temperatures, evaporation, and wind velocity and lower rainfall. A method for recording growth form of individual plants was developed whereby lateral branch production and branching patterns of woody plants could readily be determined. Height growth, lateral branch production, periodicity, and number of branching cycles of Echium were all found to be significantly different in the field, plants from higher elevations having longer branches, more laterals per cycle, fewer cycles, and retarded flowering and fruiting compared with plants near sea level. Two generations of seedlings of the extreme types grown in transplant gardens showed significant differences in inherent rate of growth, indicating genetic adaptation of high and low altitude ecotypes. No significant differences could be shown in the rate of lateral branch formation and periodicity; differences observed in the field with respect to these characteristics may be physiological responses.