Glabrous herbs, generally occurring in wet places. Leaves flat or cylindric, sometimes septate. Inflorescence compound, paniculate, bracteate; bracteoles sometimes present immediately below and clasping the flower. Perianth segments free, ovate or lanceolate, entire, persistent.
Barcode of Life Data Systems (BOLD) Stats Specimen Records:681 Specimens with Sequences:857 Specimens with Barcodes:646 Species:144 Species With Barcodes:129 Public Records:278 Public Species:83 Public BINs:0
The form of the flower differentiates rushes from grasses or sedges. The flowers of Juncus comprise five whorls of floral parts: three sepals, three petals (or, taken together, six tepals), two to six stamens (in two whorls) and a stigma with three lobes. The stems are round in cross-section, unlike those of sedges, which are typically somewhat triangular in cross-section.
In Juncus section Juncotypus (formerly called Juncus subg. Genuini), which contains some of the most widespread and familiar species, the leaves are reduced to sheaths around the base of the stem and the bract subtending the inflorescence closely resembles a continuation of the stem, giving the appearance that the inflorescence is lateral.