三芒草属（学名：Aristida）是禾本科下的一个属，为一年生或多年生草本植物。该属共有约15O种，分布于温带和热带地区。

Aristida is a very nearly cosmopolitan genus of plants in the grass family.

Aristida is distinguished by having three awns (bristles) on each lemma of each floret. The genus includes about 300 species found worldwide, often in arid warm regions. This genus is among those colloquially called three-awns wiregrasses, speargrasses and needlegrasses.