SEED PRODUCTION AND GERMINATION IN LONG'S BITTERCRESS (CARDAMINE LONGII) OF MASSACHUSETTS

Abstract

Abstract Cardamine longii (Brassicaceae), long's bittercress, is an imperiled plant confined largely to freshwater tidal marshes of the eastern U.S. To better understand possible causes of rarity in the species, its reproductive output was studied in two southeastern Massachusetts populations. Plants were found to produce about 10 fruits per individual (five per inflorescence), with the majority of a population fruiting in July. About 78% of the flowers produced in the two populations set fruit, with each fruit yielding nine seeds on average. Seeds were viable as indicated by their ability to germinate in the laboratory. Without any prior cold treatment, germination levels reached 87% over a four-week period yet were markedly reduced when seeds were allowed to dry prior to incubation. We suggest that fruit and seed production and viability are not important factors in limiting C. longii's population sizes and growth.