Key to the genera of Juncaceae

1a Auricles lacerate ............................................................................................................................................................ 1. Oreojuncus

1b Auricles absent or entire.....................................................................................................................................................................2

2a Leaf margin hairy, at least sparsely near the sheath opening; seeds 3 ..................................................................................2. Luzula

2b Leaf margin not developed (leaves round, glabrous), or glabrous; seeds many ................................................................................3

3a Leaf margin minutely serrulate............................................................................................................................................ 3. Patosia

3b Leaf margin not developed (leaves round) or smooth........................................................................................................................4

4a Flowers in inflorescence; anthers connective, not mucronate (if flowers occasionally solitary then tepals shorter than 10 mm) ....5

4b Flowers solitary and anthers mucronate (if anthers not mucronate then outer tepals at least 15 mm long) ....................................12

5a Inflorescence racemose, a pair of floral bracteoles absent, flowers usually in heads or clusters, rarely borne ± singly ...................6

5b Inflorescence cymose, a pair of floral bracteoles present below each flower, flowers usually borne singly or in loose groups ......... .......................................................................................................................................................................................10. Agathryon

6a Leaves terete, stem-like, pungent, basal, not septate, vascular bundles scattered over most of the transversal section, the lower bract apparently forming a prolongation of stem .......................................................................................................................... 4. Juncus

6b Leaves flat, compressed, canaliculate, or if terete, then usually septate, not stem-like, basal or cauline, vascular bundles usually in a subepidermal position, lower bract usually not in a position of stem prolongation....................................................................... 7

7a Leaves unitubulose or pluritubulose, perfectly septate; if pluritubulose and imperfectly septate then terete, flattened or laterally compressed ..................................................................................................................................................................... 5. Verojuncus

7b Leaves flat or with raised margins, not septate, or bitubulose and septate; if unitubulose and perfectly septate then anthers distinctly exserted...............................................................................................................................................................................................8

8a Annuals............................................................................................................................................................................ 6. Juncinella

8b Perennials ...........................................................................................................................................................................................9

9a Anthers distinctly to at least partly exserted from the perianth in later stages of flowering................................................................ .......................................................................................................................... 7. Alpinojuncus (previously Juncus sect. Stygiopsis)

9b Anthers not exserted .........................................................................................................................................................................10

10a Seeds with two distinct appendages. Sino-Himalayan region.....................................................................................7. Alpinojuncus

10b Seeds without appendages, if appendages present, then W North America.....................................................................................11

11a Plants with 1–6 (or more) cauline leaves. Dominantly occurring in Northern Hemisphere. If cauline rosette is present, then B. repens ............................................................................................................................................................................9. Boreojuncus

11b Plants without cauline leaves, if cauline leaves present, then A. cyperoides. Occurring only in Southern Hemisphere ..................... ................................................................................................................................................................................. 8. Australojuncus

12a Plants cushion-forming, upper part of stem densely covered with leaves, flower lateral (subterminal, axillary) ...........................13

12b Plants not cushion-forming, upper part of stem leafless, flower terminal........................................................................................14

13a Leaves regularly distichous; gynophore developed, elongating during capsule ripening............................................... 11. Distichia

13b Leaves ± spirally arranged; gynophore absent ................................................................................................................12. Oxychloë

14a Flower bracts 2, the lower one herbaceous, conspicuously longer than perianth, upper bract ± equalling perianth, capsule suborbicular to obovoid, obtuse, to c. 5 mm long, seeds without conspicuous appendages..........................................13. Rostkovia

14b Flower bracts 1 or 2, membranous, much shorter than perianth, capsule oblong to ellipsoidal, trigonous, acuminate, at least 7 mm long, seeds with two distinct appendages........................................................................................................ 14. Marsippospermum