Herbs, perennial, rhizomatous. Culms terete. Leaves basal; blade usually absent, rarely present (J. hallii and J. parryi), if present terete, channeled, not septate. Inflorescences lateral cymes, sympodial; bracts erect, terete, appearing to be continuation of culms; bracteoles 2, at base of perianth. Flowers borne singly, not in heads. Capsules 3-locular. Seeds usually not tailed.

Distribution

Worldwide.

Discussion

Species ca. 25 (11 in the flora).

Selected References

Ahti, L. 1980. The Juncus effusus aggregate in eastern North America. Ann. Bot. Fennici 17: 183--191.

Fernald, M. L. and K. M. Wiegand. 1910. The North American variation of Juncus effusus. Rhodora 12: 81--93. Hamet-

Stace, C. A. 1970. Anatomy and taxonomy in Juncus subgenus Genuini. Bot. J. Linn. Soc. 63(suppl. 11): 75--81.

Lower Taxa

Juncus arcticus, Juncus drummondii, Juncus effusus, Juncus filiformis, Juncus gymnocarpus, Juncus hallii, Juncus inflexus, Juncus lesueurii, Juncus parryi, Juncus patens, Juncus textilis

Key

1	Flowers 1–3(–5); seeds tailed.	> 2
1	Flowers more than 5.	> 4
2	Leaf blade reduced to bristle	Juncus drummondii
2	Leaf blade well developed.	> 3
3	Perianth 6–9 mm; capsules oblong, acute	Juncus parryi
3	Perianth 4–5 mm; capsules ovoid, retuse	Juncus hallii
4	Culms well spaced along sparingly branched creeping rhizomes.	> 5
4	Culms tufted on short, densely branching rhizomes.	> 8
5	Anthers shorter than filaments; tepals greenish; capsules green to light brown	Juncus filiformis
5	Anthers equal to or longer than filaments.	> 6
6	Fruits acute.	> 7
6	Fruits obtuse	Juncus textilis
7	Perianth usually 3–6 mm	Juncus arcticus
7	Perianth (5–)6–8 mm	Juncus lesueurii
8	Stamens 3	Juncus effusus
8	Stamens 6.	> 9
9	Plants cespitose, stooling; capsules 3–4 mm	Juncus inflexus
9	Plants cespitose, not stooling; capsules less than 3 mm.	> 10
10	Perianth much shorter than capsule; seeds 0.7–1 mm	Juncus gymnocarpus
10	Perianth equal to or exceeding capsule; seeds 0.4–0.5 mm	Juncus patens