Many species of grasses, legumes, and other forbs can be used as cover and green manure crops, sometimes called living mulches. For quick cover and abundant roots, grasses are a good choice. To increase soil fertility, nitrogen fixing legume species are popular. For reducing nematodes in crop rotations or "flash grazing" applications, brassica species can be helpful, either alone or in combination with annual ryegrass.
To learn more about the individual species, choose the species of interest from the following drop-down menu or click on the species grouping of interest from the left-hand menu (Grasses, Legumes, or Other Forbs).
The UC-Davis Cover Crop Database also has links to additional species http://www.sarep.ucdavis.edu/ccrop/)