TAXONOMY OF THE GENUS CARDARIA WITH PARTICULAR REFERENCE TO THE SPECIES INTRODUCED INTO NORTH AMERICA

摘要

In the opinion of the authors, the genusCardariacontains five species. They are described and a key is given. Two taxa are transferred fromLepidiumtoCardaria, asC.PROPINQUUMand its varietyAURICULATUM. Chromosome numbers reported forC. chalepensis, 2nensp;=ensp;80 andC. pubescens, 2nensp;=ensp;16, are new, as are those of naturally occurring and previously unrecognized hybrids betweenC. chalepensisandC. draba, 2nensp;=ensp;64. Three species,C. draba, C. chalepensis, andC. pubescens, are introductions to North America, where they have become prominent agricultural weeds. The morphological and specific limits of these three species are discussed in detail.