This is widespread on wet medium-acid soils in humid temperate regions of North America. In gross morphology, it is a strictly cespitose species (without rhizomes or tubers), generally moderate in its degree of inflorescence branching and head size. J. acuminatus typically has semi-globose heads, which are unusual among Ky. species of Juncus, and similar only to articulatus. But F noted: "In members of this section [Ozophyllum] the inflorescence is often changed to masses of horn-like galls." Psyllid insects are often involved (Hodkinson & Bird 2000). In acuminatus such inflorescences are frequent and sometimes interpreted as "pseudo-viviparous." This phenomenon has not been noted much within floras, and deserves more research in this and other wetland species (e.g. Leck & Leck 2005).