Germination ecology of the perennial Centaurium somedanum, a specialist species of mountain springs

Abstract

To better understand how a rare endemic species of Centaurium adapts to a specialized ecological niche, we studied the germination ecology of the mountain spring specialist C. somedanum, a perennial species restricted to a habitat unusual in the genus. We conducted laboratory experiments with fresh seeds collected from two populations for three consecutive years, to investigate (1) the effect of temperature and light in germination, (2) the existence of seed dormancy and (3) inter-population and inter-annual variation in germinability. Germination occurred only in the light and at relatively low temperatures (15-22 ºC) with no differences between constant and alternate regimes, and a significant decrease at high temperatures (25 ºC and 30 ºC). We found non-deep simple morphophysiological dormancy and variation in seed germinability depending on the year of seed collection. C. somedanum diverged from the common germination characteristics of the genus in (1) its germination at lower temperatures, which contrasts with what is generally expected in wetland species but could be adaptive in the spring habitat; and (2) its morphophysiological dormancy, which we report here for the first time in the genus and which could be an adaptation to its mountain habitat.