Ecological and genetic status of the purple pitcher plant, Sarracenia purpurea L., in Maryland and Virginia.

摘要

Sarracenia purpurea is a rare wetland plant in Virginia and a threatened species in Maryland, with two potential subspecies in the region. I utilized restriction fragments from the intron of the chalcone synthase gene to compare S. purpurea populations and determine whether the subspecies concept was supported. I performed a census of existing populations, compiled all known historical data on the species, and investigated the reasons for the species demise and predicted dates of extinction. Bloom phenology was examined to see if climate change may have influenced bloom period. Soil, vegetation, and climatic information was obtained to determine if taxonomic differences correlated with environmental variables. I found no genetic difference in the intron of the chalcone synthase gene in mid-Atlantic S. purpurea populations while I did find differences with other Sarracenia species and S. purpurea varieties. These results suggest that a single taxon of S. purpurea occurs in Maryland and Virginia. Only 31% (4 of 13) of the sites are extant on the western shore of Maryland and District of Columbia while 33% (14 of 42) of the sites remain in Virginia with respective populations of 46 and 513 clumps. Causes of regional extirpation include beaver flooding, succession, and development. Predicted pitcher plant population extinction dates, based on trend line from 130 years of data, are 2015 (Maryland) and 2055 (Virginia). Disturbance, especially natural fire, played an essential role in maintaining purple pitcher plant historically in Maryland and Virginia. Sarracenia purpurea blooms May 8--June 12 in Maryland and Virginia with a peak May 18--20. Peak bloom period of S. purpurea may have shifted as much as a week from historical dates, perhaps due to climate change. Purple pitcher plant soils in Maryland and Virginia met expected conditions of low pH (3.5--4.9) and were low in almost all macro- and micro-nutrients. Perturbed or polluted sites exhibited elevated levels of exchangeable cations magnesium, calcium, and sodium. Climatic data disclosed that southern Virginia purple pitcher plant sites are both warmer and wetter than those in Maryland. Maryland pitcher plant bogs had greater species richness than Virginia bogs but the latter had more state rare plants.