Spartina hybridisation in the USA

The proliferation of invasive smooth cord-grass (Spartina alterniflora, a native of the east coast) - and its hybridization with California cordgrass (Spartina foliosa) - could grossly alter the character of San Francisco Bay and now threatens numerous newly restored tidal marshes and mudflats.

A number of approaches are recommended for dealing with this problem:

1. Control efforts need to focus on the complete extirpation of populations that contain few pure native plants since these populations export large numbers of hybrid seed;
2. Smooth cordgrass and hybrids could be selectively removed from native marshes that have not been heavily invaded;
3. New invasions should be prevented;
4. Colonisation by opening new areas of unvegetated mud to the Bay, particularly in infested areas, should be curtailed since the populations of seedlings that establish are likely to contain huge numbers of hybrids;
5. Uninvaded marshes should be regularly monitored to prevent invasion and only pure native cordgrass from uninvaded marshes should be used for restoration projects.

Personal communication: Debra Ayres [drayres@ucdavis.edu].