1	"Pair of hyaline prophylls absent from the base of each flower, though an inflorescence bract may occasionally obscure the base of the flower"	2
1	"Base of individual flowers partially covered by a pair of hyaline prophylls inserted immediately below the flower (inflorescence bracts usually also present, e.g. at the base of the pedicels)"	12
2	"Leaf-blades solid, without internal septa; leaf-sheath margins merging into blade margins (rarely with a lobe on each side) or meeting in the middle of the leaf (but not produced beyond this point into auricles)"	3
2	"Leaf-blades hollow and transversely septate (though the partitions sometimes difficult to see in fine-leaved species); leaf-sheath margins produced at the apex into small auricles that meet towards the middle of the leaf in a sinus"	7
3	"Leaf-blades terete and pungent; inflorescence appearing lateral to an erect bract"	4
3	"Leaf-blades flat or channelled, not pungent; inflorescence appearing terminal"	5
4	"Mature capsules 4–6 mm long, about twice the length of the tepals, usually golden-brown coloured, slightly darker in the upper half; seeds 1.3–2 mm long, with conspicuous hyaline appendages"	"Juncus acutus"
4	"Mature capsules 2.5–3 mm long, slightly exceeding to slightly shorter than the tepals, usually dark reddish-brown to almost black (occasionally golden-brown); seeds 0.5–1 mm long, lacking appendages or with short inconspicuous appendages"	"Juncus kraussii"
5	"Tufted non-rhizomatous annual; outer tepals twice as long as the capsule"	"Juncus capitatus"
5	"Tufted or rhizomatous perennials (occasionally annual in J. planifolius); outer tepals slightly shorter to slightly longer than the capsule"	6
6	"Stamens 6; leaf-blades to 2.5 mm wide (when flattened), channelled (except for the tip); tepals 2.2–3.2 mm long; anthers subequal in length to filaments; primary inflorescence bract usually exceeding the flower cluster(s)"	"Juncus caespiticius"
6	"Stamens 3, very rarely 4–6; leaf-blades 1–11 mm wide, flat or channelled; tepals 1.5–2.5 mm long; anthers shorter than filaments; primary inflorescence bract usually shorter than the flower cluster(s)"	"Juncus planifolius"
7	"Stamens 3"	"Juncus oxycarpus"
7	"Stamens 6"	8
8	"Mature capsules dark brown, dark reddish-brown or almost black throughout or in the upper part; tepals usually strongly tinged red-brown"	9
8	"Mature capsules green, light brown or golden-brown throughout, without a strongly contrasting darker apex; tepals ± tinged red-brown (often only towards the apex)"	11
9	"Mature capsules shorter than the outer tepals, with a broadly obtuse-truncate and mucronate apex; seeds 0.3–0.4 mm long"	"Juncus microcephalus"
9	"Mature capsules equal to or distinctly exceeding the tepals, with an acute and mucronate or beaked apex; seeds 0.4–0.6 mm long"	10
10	"Tepals 2–3 mm long; fruit clusters usually less than 8 mm diam."	"Juncus articulatus"
10	"Tepals 3.1–4.5 mm long; fruit clusters mostly 8–10 mm diam."	"Juncus oxycarpus"
11	"Outer tepals 2–3 mm long; inner tepals ovate, obtuse to acute, equal to or shorter than the outer tepals; anthers equal to or longer than the filaments; fruiting clusters 5–9 mm wide; plants commonly forming swards or sometimes tufted"	"Juncus articulatus"
11	"Outer tepals 3–4.5 mm long (rarely to 2.5 mm); inner tepals narrowly ovate, acute-acuminate, equal to or longer than the outer tepals; anthers shorter than the filaments; fruiting clusters 6–14 mm wide; plants tufted"	"Juncus holoschoenus"
12	"Culms with one or more blade-bearing sheaths"	13
12	"Culms with leaves reduced to basal cataphylls"	14
13	"Tufted non-rhizomatous annual; sheath margins of lower lamina-bearing leaves merging gradually or abruptly into blade margins, without auricles"	"Juncus bufonius"
13	"Tufted or rhizomatous perennials, sheath margins of lower lamina-bearing leaves produced at apex on either side into small auricles that ± meet in the middle of the leaf"	"Juncus imbricatus"
14	"Pith of culms at least in part interrupted by distinct small or large gaps (very rarely continuous throughout in J. australis and J. subsecundus)"	15
14	"Pith of culms continuous throughout (very rarely interrupted by a few gaps in J. pauciflorus)"	30
15	"Culms robust, most more than 3 mm diam.; striations more than 70, crowded and not strongly raised; cataphylls dark brown, dark reddish-brown, dark reddish-orange or dark purplish-brown towards the base; inflorescence branches not flexuose"	"Juncus flavidus"
15	"Culms less than 3 mm diam., or if broader then striations fewer than 70, cataphylls pale to medium brown towards the base, and/or inflorescence branches flexuose"	16
16	"Flowers scattered along the inflorescence branchlets, the density of the inflorescence varying from open (when few branchlets are present) to dense (when numerous branchlets are present)"	17
16	"Flowers clustered on the inflorescence branchlets (rarely somewhat scattered in J. gregiflorus), inflorescences composed of one to many clusters"	25
17	"Tepals 2.5 mm or less long"	18
17	"Tepals more than 2.5 mm long"	23
18	"Cataphylls pale to medium brown towards the base"	19
18	"Cataphylls dark brown to dark reddish-brown towards the base"	22
19	"Culms 0.5–2 (–2.3) mm diam., with less than 40 moderately strongly to strongly raised striations"	20
19	"Culms 1–6 mm diam., with more than 40 weakly raised striations"	21
20	"Tepals 2–4 mm long; capsules 2–3.5 mm long"	"Juncus subsecundus"
20	"Tepals 1.3–2 mm long; capsules 1.5–2 mm long"	"Juncus usitatus"
21	"Culms dull green to greyish-green or glaucous; at least some inflorescence branches curving downwards"	"Juncus aridicola"
21	"Culms bright light green; inflorescence branches erect"	"Juncus continuus"
22	"Culms readily splitting longitudinally when compressed; pith very open, consisting mainly of air spaces; capsules 2–2.5 mm long; culm striations 30–80"	"Juncus amabilis"
22	"Culms not easily split longitudinally when compressed; pith with air spaces and partitions often ± equal; capsules 1.5–2 mm long; culm striations 25–40 (rarely to 45)"	"Juncus usitatus"
23	"Culm striations fewer than 35, very rarely to 40, strongly raised, coarse and easily counted"	"Juncus subsecundus"
23	"Culm striations more than 40 or if fewer then striations fine and not strongly raised"	24
24	"Culm striations very crowded and often difficult to distinguish from adjacent tissue when culm is examined just above the apex of the longest cataphylls; cataphylls usually reddish-brown to dark brown towards the base; stomates sunken in pits"	"Juncus flavidus"
24	"Culm striations fine but easily distinguished from adjacent tissue; cataphylls usually pale to medium brown towards the base; stomates superficial"	"Juncus aridicola"
25	"Tepals with conspicuous brown to red-brown longitudinal bands on either side of the stramineous midrib or deep brown to red-brown throughout; pith loose and cobweb-like, usually scarcely interrupted"	"Juncus continuus"
25	"Tepals stramineous or with very faint brown to red-brown longitudinal bands; pith various"	26
26	"Cataphylls pale to medium brown towards the base; stomates superficial"	27
26	"Cataphylls dark brown to dark red-brown towards the base, or if paler (as rarely the case in J. flavidus and J. australis) then stomates sunken in pits"	28
27	"Culms bright light green with 40–80 weakly raised striations; tepals brown (later turning stramineous) 1.6–2.5 mm long; longest cataphyll to 22 cm long"	"Juncus continuus"
27	"Culms dull green to greyish- or bluish-green with fewer than 40 strongly raised striations; tepals stramineous or rarely faintly reddish-tinged, 2–4 mm long; longest cataphyll to 12 cm long"	"Juncus subsecundus"
28	"Culms bright green; capsules usually with a somewhat flattened top; tepals acute, 1.6–2.4 (rarely to 2.7) mm long; stomates superficial"	"Juncus gregiflorus"
28	"Culms dull green to greyish- or bluish-green; capsules usually with an obtuse to subacute top; tepals acute to acuminate, 1.5–3.5 mm long; stomates superficial or sunken in pits"	29
29	"Culms readily splitting longitudinally when compressed; capsules equal to or exceeding tepals, with a reddish-brown apex; culm striations fine, moderately strongly raised and fairly crowded; stomates superficial"	"Juncus amabilis"
29	"Culms less easily split longitudinally when compressed; capsules equal to or shorter than sepals, with a golden-brown apex; culm striations either coarser and less crowded or very crowded and often difficult to distinguish from adjacent tissue; stomates sunken in pits"	"Juncus flavidus"
30	"Upper part of culm and primary bract minutely scabrous; inflorescence branches and tepals usually also minutely scabrous"	"Juncus radula"
30	"Upper part of culm, primary bract, inflorescence branches and tepals not scabrous"	31
31	"Cataphylls stramineous to pale brown towards the base"	32
31	"Cataphylls dark brown, reddish-brown or reddish-purple towards the base"	33
32	"Tepals 1.6–2.5 mm long; stamens usually 3 (rarely 4–6)"	"Juncus continuus"
32	"Tepals 2.6–3.8 mm long; stamens usually 6 (rarely 3)"	"Juncus pallidus"
33	"Stamens usually 3, rarely 4, 5 or 6; capsules 1.5–2.7 mm long"	"Juncus continuus"
33	"Stamens 6; capsules 2.2–3.5 mm long"	34
34	"Culms usually dull green to bluish-green, 2.5–8 mm diam., with 50–100 striations; flowers not widely spaced, inflorescence branches erect"	"Juncus pallidus"
34	"Culms bright green, 0.4–2.2 mm diam., with 20–50 striations; flowers widely spaced on lax inflorescence branches"	"Juncus pauciflorus"