Herbs, annual or perennial, perennials rhizomatous. Stems terete. Leaves basal or cauline; blade flat or terete and channeled, not septate. Inflorescences terminal panicles or racemes of 2–many heads or single terminal head, sympodial; bracteoles absent below perianth. Flowers solitary or in heads. Capsules 1-locular or usually 3-locular. Seeds usually not tailed.

Distribution

North America and south temperate areas of the world

Discussion

The relationships of both the perennial and annual species in this subgenus are poorly understood as evidenced by the variety of opinions expressed in numerous floras. The need for a multidisciplinary investigation of this subgenus, including morphometric and chromosomal evaluations, became painfully obviously evident during the preparation of this manuscript.

Species ca. 25 (20 in the flora).

Selected References

Ertter, B. 1986. The Juncus triformis complex. Mem. New York Bot. Gard. 39: 1--90.

Lower Taxa

Juncus bryoides, Juncus capillaris, Juncus capitatus, Juncus covillei, Juncus falcatus, Juncus filipendulus, Juncus hemiendytus, Juncus howellii, Juncus kelloggii, Juncus leiospermus, Juncus longistylis, Juncus luciensis, Juncus macrophyllus, Juncus marginatus, Juncus orthophyllus, Juncus regelii, Juncus repens, Juncus tiehmii, Juncus triformis, Juncus uncialis

Key

1	Plants annual.	> 2
1	Plants perennial.	> 11
2	Proximal bracts foliose, clearly surpassing inflorescence; outer tepals acute, 2 times as long as delicate obtuse inner tepals	Juncus capitatus
2	All bracts commonly inconspicuous, membranous; inner and outer tepals similar in size and shape.	> 3
3	Style and anthers more than 1 mm; culms to 13(–17) cm.	> 4
3	Style and anthers less than 0.5(–0.8) mm; culms rarely to 6.5 cm.	> 5
4	Culms capillary, 0.1–0.4 mm diam.; capsules usually shorter than perianth	Juncus triformis
4	Culms stouter, (0.2–)0.4–0.8 mm diam.; capsules usually nearly equal to tepals	Juncus leiospermus
5	Flowers mostly several per culm; bracts acute to acuminate.	> 6
5	Flowers uniformly solitary; bracts acute to truncate or absent.	> 9
6	Capsules usually shorter than perianth, greenish or tan	Juncus capillaris
6	Capsules usually nearly equal to or longer than perianth, brownish.	> 7
7	Flowers 2-merous; capsules longer than tepals	Juncus tiehmii
7	Flowers usually 3-merous; capsules nearly equal to perianth.	> 8
8	Flowers several per culm; capsules and tepals commonly turning dark reddish; seeds 0.4–0.5 mm	Juncus kelloggii
8	Flowers solitary; capsules and tepals commonly remaining pale yellow-green until seeds ripen; seeds 0.3–0.4 mm	Juncus luciensis
9	Tepals turning inward to enwrap shorter capsule at maturity, mostly less than 2.3 mm; flowers usually 3-merous; culms 0.1–0.2 mm diam.	Juncus bryoides
9	Tepals erect to recurved at maturity, nearly equal to or shorter than capsule; flowers 2- or 3-trimerous; culms usually more than 0.2 mm diam.	> 10
10	Flowers 3-merous; bracts solitary, truncate, completely sheathing culm	Juncus uncialis
10	Flowers 2-merous; bracts 0–2, rounded to ovate, not sheathing culm	Juncus hemiendytus
11	Culms arcuate-stoloniferous and creeping or floating	Juncus repens
11	Culms erect, never rooting at nodes.	> 12
12	Seeds not tailed.	> 12
12	Seeds tailed.	> 13
13	Auricles absent or essentially so; anthers 1–1.5 mm	Juncus regelii
13	Auricles 1–3 mm, rounded to acutish; anthers 1.8–2.6 mm	Juncus howellii
14	Culms borne in tufts, rhizomes poorly developed.	> 15
14	Culms borne singly or in small groups along creeping rhizome.	> 17
15	Stamens 6	Juncus macrophyllus
15	Stamens 3.	> 16
16	Tepals staw-colored; capsules yellowish to light brown; glomerules mostly 1–5(–10) per culm	Juncus filipendulus
16	Tepals dark brown; capsules brown; glomerules more than 10 per culm	Juncus marginatus
17	Stamens 3	Juncus marginatus
17	Stamens 6.	> 18
18	Auricles absent or rudimentary, less than 1 mm.	> 19
18	Auricles rounded or acute, 1–3 mm.	> 21
19	Anthers 1.6–2.4 mm	Juncus orthophyllus
19	Anthers 0.8–1.5 mm.	> 20
20	Tepals 3–4 mm	Juncus covillei
20	Tepals 4.5–6 mm	Juncus falcatus
21	Tepals 3–4 mm	Juncus covillei
21	Tepals 5–6 mm.	> 22
22	Tepals with broad clear margins	Juncus longistylis
22	Tepals without clear margins	Juncus orthophyllus