The cover image shows icicles formed over buds at the end of stems of a Meyer Spruce (Picea meyeri) following freeze-thaw cycles after snowfall at the Arnold Arboretum of Harvard University, in Boston, MA, USA (accession number 1341-78*B). This reflects the fluctuation between growth permissive environments with warm temperatures and below freezing temperatures that plants must endure, particularly during spring in temperate climates, and thus the duality between cold hardiness and budbreak. (See Kovaleski et al., pp. 217–224.) [Photo credit: Jacob Suissa]