crabgrass

plural crabgrasses

1. countableuncountableThose members of the genus Digitaria, grasses of tropical to temperate climates, which are pests of lawns, mainly from their invasive habits and the fact they die off in the fall and winter, leaving bare patches.
2. countableuncountableA marine grass of salt marshes, glasswort (Salicornia herbacea)

   The herb is also called of divers, Cali articulatum, or jointed Glassewort : in English, Crab-grasse, and Frog-grasse.

   1597, John Gerard, The Herball Or Generall Historie of Plantes