Morphological variation of Phacelia secunda J.F. Gmel. (Hydrophyllaceae) along an altitudinal gradient in central Chile

Abstract

Phacelia secunda J.F. Gmel. (Hydrophyllaceae) is a perennial herb that both, in Chile and Argentina, shows a wide distributional range, inhabiting from Parinacota (18°S) to Tierra del Fuego (54°S), and from the sea level up to the high Andes. In this study some morphological variations along an altitudinal gradient from 1600 to 3400 m in Andes of central Chile (33°S) are reported. The diameter of the rosettes significantly increased with elevation, as well as the number of inflorescences per individual and the longitude of pubescence. In contrast, the height of inflorescences decreased with elevation. Tendencies for privileging vertical growth at lower elevations and horizontal growth at higher elevations would be adaptations to the cold and harsh climate of high mountain habitats. In a similar vein, the increase in the longitude of pubescence with elevation would be an adaptation in order to maintain positive thermal balances and avoid the excesses of radiation in those habitats.