[A gradient in cold-resistance of ash bud sequences]

Terminal buds of ash (Fraxinus ornus L.) twigs are more developed than the two additional subterminal buds and the axillary buds inserted lower on the twig. The lateral buds gradually decrease in size from the tip to the base of the twig.A gradient of cold-resistance was established in the bud sequence of ash twigs. The terminal bud is the most frost-sensitive, and the inactive substitutional buds are the most resistant. As soon as the trees become active at the beginning of spring, the high degree of cold-resistance achieved during winter is reduced first in those buds which are the earliest to burst. The subterminal and the most basal buds, which, as a rule, do not open, partially lose their cold-resistance in spring and summer, however they remain markedly more resistant during this time than growing buds.

InFraxinus ornus the more a bud is developed, the less it becomes cold-resistant and the sooner it loses the resistance it had.