Fig. 1. (A–F) Plants used in the subsequent five figures. (A, B) Nonhardened and cold-hardened plants, respectively, shown in Fig. 2. (C) Cold-hardened plant that was frozen at –11°C and allowed to recover for 3 d (Fig. 3). Note new growth at the top of the two tillers on the left. (D) Frozen plant after 10 d of recovery (Fig. 4). (E) Frozen plant at 21 d of recovery that was rated as a nonsurvivor (Fig. 5). (F) Frozen plant at 21 d of recovery that completely survived (Fig. 6). (G) Fractionated ‘Wintok’ oat crown. The whole crown is shown on the left, the crown meristem (CM) complex (I) in the center, and the lower portion of the CM complex consisting of mostly crown core tissue (J) on the right after removal of the apical region (H) from the CM complex by razor blade. Roots were trimmed as close to the base of the crown core as possible before calorimetric measurements.