To persist (without immigration) in habitats with unpredictable environmental conditions, annuals must produce seeds each year or have a seed bank. Thus, we predicted that compared to perennials, annuals have a wider germination temperature range (GTR, the difference in temperature between the week with the highest and the week with the lowest germination during the natural germination season). We determined the GTR via germination phenology data for 350 herbaceous species in 59 families from the eastern USA: summer annuals (SA), 63; winter annuals (WA), 83; monocarpic perennials (MP), 28; and polycarpic perennials (PP), 176. There was no significant phylogenetic signal for the GTR. The width of the GTR during the first spring germination season was 9.6, 8.7 and 8.8°C for MP, PP and SA, respectively, and during the first autumn germination season 12.8, 11.8 and 12.4°C for MP, PP and WA, respectively. Annuals did not have a wider GTR than perennials in either the spring or the autumn germination season. Our data suggest that selection for early germination in either spring or autumn has resulted in only small differences in the GTR. We predict that global warming will have little or no effect on reshaping the germination phenology of herbaceous species of temperate eastern North America.

为了在环境条件不可预测的栖息地中坚持（没有移民），一年生植物必须每年生产种子或拥有种子库。因此，我们预测，与多年生植物相比，一年生植物的发芽温度范围更广（GTR，自然发芽季节发芽最高的一周和最低发芽的一周之间的温差）。我们通过美国东部 59 科 350 种草本植物的萌发物候数据确定了 GTR：夏季一年生植物（SA），63；冬季一年生植物（WA），83；单果多年生植物（MP），28；和多果类多年生植物（PP），176。GTR 没有显着的系统发育信号。MP、PP 和 SA 在第一个春季发芽季节的 GTR 宽度分别为 9.6、8.7 和 8.8°C，MP、PP 和 WA 在第一个秋季发芽季节分别为 12.8、11.8 和 12.4°C。在春季或秋季发芽季节，一年生植物没有比多年生植物更宽的 GTR。我们的数据表明，在春季或秋季选择早期发芽仅导致 GTR 的微小差异。我们预测全球变暖对重塑北美东部温带草本植物的萌发物候几乎没有影响。