马唐（学名：Digitaria sanguinalis）是一种禾本科植物。这种植物在中国，分布于东北、华北、华中、华东、华南及西南；全世界温带、热带地区广泛分布。

Digitaria sanguinalis is a species of grass known by several common names, including hairy crabgrass, hairy finger-grass, large crabgrass, crab finger grass, purple crabgrass. It is one of the better-known species of the genus Digitaria, and one that is known nearly worldwide as a common weed. It is used as animal fodder, and the seeds are edible and have been used as a grain in Germany and especially Poland, where it is sometimes cultivated. This has earned it the name Polish Millet.