Herbs, perennial, rarely annual, perennials rhizomatous. Stems terete. Leaves basal and cauline; blade usually flat, involute, rarely nearly terete, channeled, not septate. Inflorescences terminal cymes, usually sympodial (monopodial in J. trifidus); bracts erect or ascending, flat, involute, or terete; bracteoles 2, at base of perianth. Flowers borne singly, not in heads. Capsules 1-locular (placentae 1/2–3/4 distance to central axis) or 3-locular, rarely beaked. Seeds not tailed (except J. vaseyi).

Distribution

Worldwide.

Discussion

Species 25 (18 in the flora).

Selected References

Brooks, R. E. 1989. A Revision of Juncus Ssubgenus Poiophylli (Juncaceae) in the Eastern United States. Ph.D. dissertation. University of Kansas.

Catling, P. M. and K. W. Spicer. 1987. The perennial Juncus of section Poiophylli in the Canadian prairie provinces. Canad. J. Bot. 65: 750--760.

Wiegand, K. M. 1900. Juncus tenuis Willd., and some of its North American allies. Bull. Torrey Bot. Club 27: 511--527.

Lower Taxa

Juncus anthelatus, Juncus brachyphyllus, Juncus bufonius, Juncus compressus, Juncus confusus, Juncus coriaceus, Juncus dichotomus, Juncus dudleyi, Juncus georgianus, Juncus gerardii, Juncus greenei, Juncus interior, Juncus occidentalis, Juncus secundus, Juncus squarrosus, Juncus tenuis, Juncus trifidus, Juncus vaseyi

Key

1	Plants annual	Juncus bufonius
1	Plants perennial.	> 2
2	Leaves minutely serrulate; auricles deeply lacerate	Juncus trifidus
2	Leaves entire; auricles not lacerate.	> 3
3	Auricles at summit of leaf sheath 3–6 mm, membranous, transparent; capsules never 3-locular.	> 4
3	Auricles absent or merely short, scarious or cartilaginous projections less than 2 mm.	> 5
4	Capsules less than 3/4 length of tepals, borne widely spaced along usually diffuse branches of inflorescence; plants mostly 7–9 dm	Juncus anthelatus
4	Capsules 3/4 or more length of tepals, borne congested or branch internodes ca. as long as tepals; plants mostly less than 7 dm	Juncus tenuis
5	Leaf blade channeled to terete.	> 6
5	Leaf blade flat.	> 10
6	Inflorescence falsely lateral, overtopped by terete bract that looks to be continuation of culm	Juncus coriaceus
6	Inflorescence terminal, involucre bract flat or much shorter than inflorescence.	> 7
7	Perianth segments obtuse	Juncus squarrosus
7	Perianth segments acute to acuminate.	> 8
8	Seeds distinctly tailed, tail at least 1/2 length of seed body; capsules golden tan	Juncus vaseyi
8	Seeds not tailed; capsules chestnut brown or paler.	> 9
9	Capsules 1-locular or pseudo-3-locular, widely elliptic to rounded, apex rounded; seeds 0.3–0.4 mm	Juncus dichotomus
9	Capsules 3-locular, elliptic, apex somewhat truncate; seeds 0.48–0.7 mm	Juncus greenei
10	Capsules chestnust brown or darker; tepals apically obtuse or rounded.	> 11
10	Capsules tan or light brown; tepals acute to acuminate.	> 12
11	Anther 1–2 times length of filament, less than 1 mm; capsule usually exceeding perianth	Juncus compressus
11	Anther 2–4 times length of filament, longer than 1 mm; capsule usually nearly equal to perianth	Juncus gerardii
12	Capsules 3-locular.	> 13
12	Capsules 3-locular or pseudo-3-locular.	> 16
13	Tepals 2.5–3.5 mm; capsule nearly globose.	> 14
13	Tepals 4–5.5 mm; capsule ellipsoid to narrowly so.	> 15
14	Tepals green; flowers chiefly arranged along inner side of branches; plants of e North America	Juncus secundus
14	Tepals usually with brownish midstripe; flowers not secund; plants of w North America	Juncus confusus
15	Anthers 0.6–0.9 mm; auricles scarious, lobes 0.5 mm; plants of c United States	Juncus brachyphyllus
15	Anthers 1.2–1.5 mm; auricles scarious to membranous, 0.2–0.3 mm; plants endemic to s Appalachian Piedmont	Juncus georgianus
16	Auricles 0.5–1(–1.5) mm, membranous	Juncus occidentalis
16	Auricles 0.1–0.3(–1) mm, scarious to leathery.	> 17
17	Auricles leathery, yellowish; tepals spreading in fruit, nearly equal to or exceeding capsule; anthers 0.6–1 mm	Juncus dudleyi
17	Auricles scarious, whitish or sometimes purplish tinged, not leathery; anthers 0.4–0.6 mm.	> 18
18	Mature capsules light brown or darker; plants of coastal plain of e, se North America	Juncus dichotomus
18	Mature capsules light tan; plants of interior continent	Juncus interior