As a Chicagoan and long-time volunteer with the Chicago Wilderness Habitat Project, I became interested in the dune communities along Chicago's lake shore through the Chicago Wilderness Plants of Concern Program. This program monitors the presence of rare plant populations in the six-county area that encompasses the Chicago Wilderness Region.

POC and the Illinois Department of Natural Resources list Great Lakes sea-rocket, Cakile edentula ssp. edentula var. lacustris Fernald (Brassicaceae) as a threatened species in Illinois. An annual plant, it colonizes beaches in the early stages of dune community succession. This variety, known more commonly as American sea-rocket, is believed to have diverged approximately 9,000 years ago from its ancestral lineage, Cakile edentula ssp. edentula var. edentula during the last glacial retreat (Rodman, 1974). According to Rodman, the ancestral lineage var. edentula originated on the Atlantic coast but was accidentally brought to the Great Lakes Region in the 19th century through shipping ballast, where it may have begun to hybridize with the locally adapted variety. For this reason the Wisconsin Department of Natural Resources lists C. edentula as special concern.

I am working with Dr. Nyree Zerega, plant systematist and Director of the Masters' in Plant Biology and Conservation Program, to investigate hybridization between lacustris and edentula from three different approaches: morphological, genetic, and biological. First I will sample populations of both varieties to ask: Do Chicago Region lacustris have morphological characters suggesting they have hybridized with edentula? Second, through AFLP and microsatellite analysis I ask: is there genetic evidence indicating hybridization between lacustris and edentula in the Chicago Region? Third, a controlled cross of parental varieties will determine whether lacustris and edentula can produce fertile offspring.

Among those who have studied Cakile edentula and its congeners, it is suspected though not currently known that lacustris will readily outcross with edentula in sympatric populations. In her work on the effects of inbreeding on seed dispersal, Donohue (1998) found that although the selfing rate of lacustris is intermediate to high, it will outcross with its own variety. This past summer I witnessed pollination of both types by the Cabbage white butterfly (Pieris rapae). Evidence of genetic swamping or lack thereof could impact the conservation status of lacustris in Illinois and Wisconsin.

I am fortunate to have a portion of my study site so close at hand. The City of Evanston has several small beaches where in August of 2006, I found evidence of C. edentula and two other locally rare species as a volunteer monitor for Plants of Concern. Through such monitoring programs, we are finding that early succession plant communities are taking hold along the sand beaches. Because of its unique mix of grassland, hardwood forest, wetland and duneland, the Chicago Region is naturally rich in biodiversity. This is one of many reasons Chicago has become a hotspot for successful conservation programs.