In experiment 2 where one chamber was maintained at 4 °C above normal for the entire growing season there were differences in the phenological development. There was no significant difference in the number of total leaf collars for the different temperature regimes, only the rate of leaf appearance was different. The same response was observed for both experiments (Fig. 3). In experiment 2, we measured the leaf area on each leaf as it reached maximum size and observed no significant difference in cumulative leaf area between temperature treatments and the same total leaf area was observed for the two experiments (Fig. 4). The effect of warm temperatures was observed only in the rate of development of the plants until the beginning of the reproductive stage. Similar leaf area and number of leaves produced the same amount of total vegetative biomass with no significant differences in