Ellison A M
Department of Biological Sciences, Mount Holyoke College, South Hadley, Massachusetts 01075-6418 USA.
Am J Bot. 2001 Mar;88(3):429-37.
Seed size and germination requirements of eight (of nine) Sarracenia species, and 13 populations of S. purpurea were studied. All species except for S. purpurea are restricted to the southeastern United States, whereas S. purpurea ranges across Canada, southward along the eastern United States into Maryland and Virginia (S. purpurea ssp. purpurea), and from New Jersey southward into northern Florida and the coast of the Gulf of Mexico (S. purpurea ssp. venosa). I tested the hypotheses that dormancy-breaking requirements vary predictably among species across a latitudinal gradient. I also sought to determine whether seed size and germination requirements were useful characters for resolving systematic and phylogenetic questions within this genus. Seed size varied significantly among species, but variability in seed size within S. purpurea exceeded the variability in seed size observed across all eight species studied. Seeds of all species are morphophysiologically dormant upon dispersal. Length of required cool, moist pretreatment varied among species, and germination in higher latitude populations is enhanced with longer pretreatment. In contrast, variability in germination requirements of subspecies, varieties, and populations of the geographically wide-ranging S. purpurea was not related clearly to geographic location (latitude or elevation). Germination requirements do not map onto a proposed phylogeny of Sarracenia, but observed differences in germination requirements of S. purpurea ssp. venosa var. burkii relative to other populations of S. purpurea support the recent proposal to elevate this variety to species status.
对9种瓶子草属植物中的8种以及13个紫瓶子草种群的种子大小和萌发需求进行了研究。除紫瓶子草外，所有物种都局限于美国东南部，而紫瓶子草分布于加拿大，沿美国东部向南延伸至马里兰州和弗吉尼亚州（紫瓶子草指名亚种），并从新泽西州向南延伸至佛罗里达州北部和墨西哥湾沿岸（紫瓶子草脉亚种）。我检验了以下假设：打破休眠的需求在不同物种间随纬度梯度呈可预测的变化。我还试图确定种子大小和萌发需求是否是解决该属内系统发育问题的有用特征。不同物种间种子大小差异显著，但紫瓶子草内部种子大小的变异性超过了所研究的所有8个物种间观察到的种子大小变异性。所有物种的种子在散播时均处于形态生理休眠状态。所需的低温、湿润预处理时间因物种而异，且高纬度种群的萌发会因更长时间的预处理而增强。相比之下，分布范围广泛的紫瓶子草的亚种、变种和种群在萌发需求上的变异性与地理位置（纬度或海拔）并无明显关联。萌发需求并不符合瓶子草属的一个拟议系统发育关系，但观察到的紫瓶子草脉亚种伯克变种相对于紫瓶子草其他种群在萌发需求上的差异支持了最近将该变种提升为物种地位的提议。
