Root lifespan and overwintering strategies for two wetland species, Sagittaria latifolia wild. (Alismataceae) and Carex crinita lam (Cyperaceae), in contrasting climate zones.

Abstract

In northern wetlands, roots of some perennial wetland plant species senesce in the autumn, while other species maintain their roots over the winter. Some of these species extend in their distribution to warmer climates. This research investigates the effects of growing season length on root phenology of two species with such contrasting overwintering patterns. Sagittaria latifolia (autumn-senescing roots) and Carex crinita (overwintering roots) were investigated near the northern (46°N) and southern (35°N) edges of their distribution in North America. C. crinita maintained >75% of its roots alive in both locations, without changing its overwintering strategy. Roots of S. latifolia senesced completely in the autumn in the north, whereas, in the south some roots (~10%) remained alive throughout the winter. This suggests that complete root senescence before the winter is an adaptation to long winters, and may be unnecessary under short mild winters. Nevertheless, the species maintains the short-lived root strategy regardless of the winter severity.