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1 Leaves flattened, narrowly elliptic in cross-section. |
..2 Leaves with incomplete septae; heads about 10 mm diameter; tips of dehisced capsules united; [subgenus Juncus, section Iridifolii] |
..2 Leaves with complete septae; heads about 12 mm diameter; tips of dehisced capsules split; [subgenus Juncus, section Ozophyllum] |
1 Leaves terete, not at all flattened; [subgenus Juncus, section Ozophyllum]. |
....3 Plants strictly cespitose, without any short, hard, knotty rhizomes; tepals lanceolate |
....3 Plants with at least some short, hard, knotty rhizomes; tepals lanceolate-subulate. |
......4 Capsules shorter than the tepals, clearly included within the tepals at maturity |
......4 Capsules equaling or exceeding the tepals, exserted from or only barely included within the tepals at maturity. |
........5 Capsule valves separating at the apex at maturity; stamens 6. |
..........6 Heads 6-20 flowered, 6-9 mm diameter; auricles cartilaginous, 0.5-1.0 mm long |
..........6 Heads 25-100 flowered, 10-14 mm diameter; auricles membranous, 2.5-4.0 mm long |
........5 Capsule valves remaining united at the apex after dehiscence; stamens 3. |
............ 7 Culms 4-8 mm in diameter near the base, usually > 80 cm tall; inflorescences usually > 15 cm tall, with > 25 heads; largest leaf blades > 25 cm long and > 3 mm in diameter |
............ 7 Culms 1-3 mm in diameter near the base, usually < 80 cm tall; inflorescences usually < 10 cm tall, with < 25 heads; largest leaf blades < 25 cm long and 1-2 mm in diameter. |
............ ..8 Uppermost cauline leaf blade much shorter than its sheath; tepals reddish to reddish brown; outer tepals significantly longer than the inner tepals; basal leaf sheaths and cataphylls deep reddish purple |
............ ..8 Uppermost cauline leaf blade equaling or longer than its sheath; tepals green to straw-colored; outer tepals and inner tepals of similar length; basal leaf sheaths and cataphylls straw-colored to brown. |
............ ....9 Heads lobulate; mature capsule 2.0-3.0 mm long |
............ ....9 Heads spherical, not lobulate; mature capsule 3.0-4.5 mm long |