Juncus sect. Ozophyllum, Dumortier, 1827

Knapp, Wesley M., 2014, (Juncaceae), a new combination in sect. and notes on morphologically similar species, Phytotaxa 174 (5), pp. 243-260 : 258

Key to morphologically similar species of Juncus sect. Ozophyllum and J. polycephalos (sect. Iridifolii) of North America, north of Mexico.

1 Leaves with incomplete septate bands; auricles poorly developed, <0.5 mm ................................... Juncus polycephalos Michaux

- Leaves with complete septate bands; auricles well developed,> 0.5 mm, forming a distinct ligule..................................................2

2 Capsules separating at maturity into three distinct portions...............................................................................................................3

- Capsules remaining united at apex at maturity, forming a prominent beak of> 0.5 mm. .................................................................5

3 Largest tepals 4–5 mm long; leaves laterally compressed ............................................................................. Juncus validus Coville

- Largest tepals 2.9–4 mm long; leaves terete.......................................................................................................................................4

4 Capsules 3.5–5 mm long, exceeding tepals; culms 0.4–3 dm............................................... Juncus nodosus Linnaeus (1762: 466)

- Capsules 3–3.5 mm long, slightly included within or equaling tepals; culms 2.5–8.5 dm .................................................................. ......................................................................................................................................... Juncus bolanderi Engelmann (1868: 470)

5 Leaves laterally compressed, flattened, elliptical in cross-section, septate bands of leaves often externally obscure ........................ ................................................................................................................................. Juncus fascinatus (M.C. Johnston) W. Knapp

- Leaves strictly terete, rounded or channeled, circular in cross-section, septate bands of leaves often prominent and ring-like.......6

6 Culms 4–8 mm in diameter near base, usually> 80 cm tall; inflorescence usually> 15 cm tall with> 25 heads; longest leaf blade> 25 cm long and> 3 mm wide......................................................................................... Juncus paludosus E.L. Bridges & Orzell

- Culms 1–3 mm in diameter near base, usually <80 cm tall; infl. usually <10 cm tall, with <25 heads; longest leaf blades <25 cm long and <2 mm in diameter...............................................................................................................................................................7

7 Uppermost leaf blade well developed, equaling to longer than its sheath; heads spherical to lobed; tepals green to straw-colored, nearly equal in length; basal leaf sheaths and cataphylls straw-colored to brown................................ Juncus scirpoides Lamarck

- Uppermost leaf blade poorly developed, much shorter than its sheath; heads strictly spherical; tepals reddish to reddish brown, the inner tepals somewhat shorter than outer; basal leaf sheaths and cataphylls deep reddish purple................................................. .......................................................................................................................................... Juncus megacephalus Curtis (1835:132)