ABSTRACT
The decision tree key arranges major genera of North American forest trees functionally according to their environmental requirements for germination after natural dispersal. It classifies genera into the three broad dormancy categories: nondormant, conditional dormancy, and primary dormancy. A dormancy model describes the morphological/physiological features of a seed and how they interact with environment to produce germination at an ecologically appropriate time. Betula seed has classical conditional dormancy involving interaction of light, chilling, and incubation temperature. Most of the red oaks have primary dormancy which is broken by winter chilling, a requirement for both radicle and epicotyl growth. After seed of most conifers have been released from dormancy via chilling, they may be dried and stored at a low temperature without losing their capability for rapid, uniform germination. Light's promotive effect is frequently greater at higher temperatures than at lower ones, and chilling after imbibition almost always results in development of the capacity for complete germination in the dark.
