菖蒲属为单子叶植物菖蒲目下唯一科菖蒲科的唯一属。全世界共2种，分布于亚洲、北美洲的温带、亚热带地区，以及热带亚洲，欧洲引进栽培。根茎具气味，可供药用(药用植物)。

菖蒲科虽然自1820年即被确立，但传统上，菖蒲属植物大部份被纳入天南星科里，直到最近才广被接受自成一科。

它具有数个不同于天南星科的特征：单面叶 (unifacial)，花梗的维管束为分离的2束，无针簇状结晶 (天南星科植物普遍有)，种子具perisperm(自珠心组织发育，能提供种子养份的二倍体组织，天南星科植物绝不具此)，珠孔具毛，具特殊的精油细胞等等之解剖学特征；分子分类学的研究里，菖蒲科植物是所有的其他单子叶植物之姊妹群，亦即其与天南星科植物的亲缘关系并不算很近。

Acorus is a genus of monocot flowering plants. This genus was once placed within the family Araceae (aroids), but more recent classifications place it in its own family Acoraceae and order Acorales, of which it is the sole genus of the oldest surviving line of monocots. Some older studies indicated that was placed in a lineage (the order Alismatales), that also includes aroids (Araceae), Tofieldiaceae, and several families of aquatic monocots (e.g., Alismataceae, Posidoniaceae). However, modern phylogenetic studies demonstrate that Acorus is sister to all other monocots. Common names include Calamus and Sweet Flag.