This annual is widespread in marshy wetlands of southeastern states, often colonizing edges of artificial ponds. In Ky. it is generally associated with oligotrophic waters, and rare to absent in calcareous landscapes. The names Scirpus smithii Gray or S. smithii var. williamsii (Fern.) Beetle have been erroneously applied to some Ky. plants in the past (BT, M). Those names belong to more northern taxa with 2n = 40, versus 38 in typical pungens (FNA 23).