Range: Newfoundland to Florida and Texas, westward to California. Habitat: Yards, roadsides, waste places.
Grazing cattle usually avoid plants with a disagreeable odor, but they seem to make an exception of the Mustards. The smell of this weed is suggestive of a pigsty, whence its name of Swine Cress; it is occasionally the cause of damaged dairy products. (Fig. 123.)
Stems four inches to a foot in length, prostrate, diffusely branched, hairy, spreading on all sides from the root. Leaves very deeply pin-natifid, some but once, others with the segments also cut; upper ones sessile but those near the base having slender petioles. Flowers white, extremely small, in slender axillary racemes on short, threadlike pedicels. Autumn plants flower earliest, coming into bloom as soon as uncovered from winter snows. Silicles small, wrinkled, warty, the two valves separating readily into two ovoid nutlets, each containing one seed.
Fig. 123. - Swine Cress (Corono-pus didymus). X 1/4.
Carpet Cress usually grows in patches, which should be hoed out very early in spring before any seeds are developed. Successive crops will probably appear from seeds that have lain dormant in the soil, and these should be given like treatment.