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Genus Juncus Family Juncaceae

Description: Perennial or annual herbs. Culms terete or occasionally compressed.

Leaves basal or occasionally 1–3 cauline; blade flat, terete, channelled, compressed or reduced to mucro on sheath, internally septate or hollow or filled with loose pith; auricles often present. Lowest 1 or 2 involucral bracts leaf- or culm-like.

Flowers bisexual or rarely unisexual, clustered or solitary, with 1 papery bract, with or without 2 papery bracteoles. Outer whorl of tepals exceeding to shorter than inner whorl. Stamens 3–6. Ovary 1- or 3-locular or incompletely 3-septate.

Capsule smooth, shining; seeds numerous, mucilaginous when wet, occasionally tailed.


Habit
Photo L. von Richter

Flower
Photo J. & P. Edwards

Fruit
Photo L. von Richter

Distribution and occurrence: World: c. 300 species, cosmopolitan. Australia: 68 species (31 species endemic, 21 species naturalized), all States.

Text by K. L. Wilson, L. A. S. Johnson & P. Bankoff
Taxon concept:

 Key to the species 
1Leaves numerous, flat, involute, canaliculate, terete, or filiform, spread along the culms or all basal (if terete, leaves septate or spread along culms); inflorescence obviously terminal (rarely apparently lateral)2
Leaves reduced to basal sheathing cataphylls or 1 or 2 well-developed terete basal leaves similar to culms, not septate; inflorescence apparently lateral or obviously terminal, with the lowest involucral bract well-developed and appearing superficially to be a continuation of the culm27
2Leaves not septate, solid3
Leaves septate (if filiform, septa not very obvious), spread along culms, hollow or with very loose pith between septa
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15
3Flowers subtended by 2 bracteoles, solitary or loosely clustered (densely clustered in Juncus bufonius (occasionally) and in J. homalocaulis); leaves basal or both basal and cauline; auricles present or absent4
Flowers without bracteoles, more or less densely clustered; leaves all basal (except in Juncus falcatus); auricles absent
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10
4Annuals; auricles absent but often with hyaline margins narrowing abruptly at top of sheath; both cauline and basal leaves present on a plantJuncus bufonius
Perennials; auricles present; leaves all basal
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5
5Leaves flat (may be inrolled when dried)6
Leaves canaliculate or terete or filiform
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7
6Anthers 0.3–0.6 mm long, shorter than or equalling filaments; tepals 3.0–4.5 mm longJuncus tenuis
Anthers 1.2–2.0 mm long, longer than filaments; tepals 4.5–5.7 mm long
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Juncus revolutus
7Tepals no more than 3.0 mm long; base of plant with persistent fibrous remains of leaf sheaths; culms 0.2–0.5 mm diamJuncus capillaceus
Tepals more than 3.0 mm long (rarely as short as 2.8 mm in Juncus cognatus but then no fibrous remains persisting at base of plant); culms 0.5–2 mm diam
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8
8Flowers in more or less stellate, dense clusters; stamens mostly 3, occasionally 4 to 6; outer tepals 5–6(–7.5) mm long, much longer than inner (by 0.5–1 mm)Juncus homalocaulis
Flowers solitary, evenly spread along ultimate branches of inflorescence; stamens 6; outer tepals 2.8–4.2 mm long, equalling or exceeding inner tepals by less than 0.5 mm
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9
9Capsule much longer than tepals (by 1–2 mm); anthers 0.7–1.1 mm longJuncus imbricatus
Capsule about as long as tepals (slightly shorter than to slightly exceeding them); anthers 0.3–0.6 mm long
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Juncus cognatus
10Perennials (but often flowering in first year)11
Annuals
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Juncus capitatus
11Tepals less than 3.5 mm long (rarely 3.5 mm long in Juncus antarcticus, and then leaves 0.2–0.5 mm wide); leaves 0.2–11 mm wide12
Tepals longer than or equalling 3.5 mm long; leaves 1–3 mm wide
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14
12Plants dwarf, mat-forming, with a slender rhizome; culms 0.5–6 (rarely to 12) cm long; stamens 3 or rarely 6Juncus antarcticus
Plants tufted, not mat-forming, with or without a rhizome; culms mostly 15–60 cm long (occasionally as short as 5 cm); stamens 3 or 6
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13
13Stamens 3; leaves 1.5–11 mm wide; tepals with more or less narrow hyaline margins; anthers 0.3–0.5 mm long, usually shorter than filaments; capsule exceeding or occasionally equalling outer tepalsJuncus planifolius
Stamens 6; leaves 1–2 (rarely to 2.5) mm wide; inner tepals with broad whitish margins; anthers 0.4–0.8 mm long, more or less equalling filament length; capsule shorter than or equalling outer tepals
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Juncus caespiticius
14Inflorescence of 1 or 2 (rarely 4) heads; culms, bracts and tepals more or less scaberulous; capsule longer than or equalling tepals, short-apiculate; often 1 or 2 cauline leaves present as well as basalJuncus falcatus
Inflorescence diffuse, with 8–25 clusters at apex of branches; culms, bracts and tepals smooth; capsule much shorter than tepals, long-beaked; leaves all basal
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Juncus capensis
15Leaves unitubulose (i.e. with transverse septa only - determined by carefully splitting the culm) or leaves less than 1 mm diam. (and therefore not easy to determine position of septa)16
Leaves pluritubulose
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26
Seeds 0.3–0.7 mm long, not tailed
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17
16Seeds 1.3–1.9 mm long, tailed at both endsJuncus canadensis
17Stamens 318
Stamens 4–6
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19
18Slender plants with culms 6–30 cm long; leaves more or less filiform, 0.3–0.7(–1.2) mm diam., pluritubulose but septa not obvious; inflorescence 2–7 cm longJuncus bulbosus
Moderately robust plants with culms 25–60 cm long; leaves 1–2.6 mm diam., clearly unitubulose; inflorescence 9–18 cm long
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Juncus acuminatus
19Dwarf plants with culms no more than 10 cm long at maturity (rarely to 14 cm in Juncus sandwithii); leaves more or less filiform, usually less than 1.0 mm diam.; with septa often not obvious20
Plants with culms mostly 20–80 cm long (occasionally longer; if shorter, then with more or less numerous clusters and more or less numerous flowers, or inflorescence with more than 3 clusters, each with more than 4 flowers); leaves broader than filiform, 1–4 mm diam., with transverse septa usually obvious
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22
20Auricles 1–2 mm long; capsule obtuse, shortly apiculate; tuftedJuncus bulbosus
Auricles c. 0.5 mm long; capsule acuminate, long- or short-beaked; shortly rhizomatous, mat-forming
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21
21Outer tepals slightly exceeding to slightly shorter than inner tepals; inner tepals acute, with more or less narrow hyaline margins; stamens shorter than tepals; capsule longer than tepals by 0.7–1.5 mmJuncus sandwithii
Outer tepals shorter than inner tepals by up to 0.5 mm; inner tepals obtuse to broad-acute, with broad hyaline margins; stamens longer than or equalling tepals; capsule equalling or exceeding tepals by up to 0.5 mm
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Juncus thompsonianus
22Capsule tapering evenly from base into long beak, longer than tepals by 1–2 mmJuncus fockei
Capsule with short or long beak but not tapering evenly from base (body of capsule ovate, oblong or obovate in outline, contracting more or less abruptly to a beak)
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23
23Anthers longer than or equalling filaments; auricles 0.7–1.5 mm long24
Anthers shorter than filaments; auricles 1.5–3.5 mm long
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25
24Rhizome robust, 2–5 mm diam.; outer tepals usually shorter than inner; tepals with long-acuminate apices strongly reflexed at maturityJuncus acutiflorus
Rhizome absent or slender (less than 2 mm diam.); outer tepals usually longer than or equalling inner; tepals with acute to obtuse or acuminate apices erect or only slightly reflexed
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Juncus articulatus
25Capsule red-brown at least near apex, obtuse, usually shorter than tepals; tepals with usually broad whitish margins; seeds 0.3–0.4(–0.5) mm longJuncus microcephalus
Capsule golden brown, acute, subequal to tepals; tepals with broad hyaline to yellowish margins; seeds 0.4–0.6 mm long
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Juncus holoschoenus
26Leaves terete or canaliculate, 0.3–1.2 mm diam.; anthers longer than or equalling filaments; capsule obtuse, apiculateJuncus bulbosus
Leaves flattened, 1.3–3.2 mm wide; anthers shorter than filaments; capsule tapering more or less evenly to long-acuminate apex
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Juncus prismatocarpus
27Flowers without bracteoles; leaves and bracts pungent; 1 or 2 terete leaves similar to culms present, as well as several cataphylls28
Flowers subtended by 2 bracteoles; leaves and bracts acute but not pungent; leaves all reduced to cataphylls on flowering plants (vegetative shoots are long, terete leaf-like)
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29
28Capsule much longer than tepals, golden brown to chestnut-brown; anthers 1.2–1.7 mm long; seeds tailed at both ends, 1.3–1.8 mm long; inner tepals with broad whitish margins (readily deciduous) near apexJuncus acutus
Capsule slightly exceeding to slightly less than tepals, golden brown to red-brown to blackish; anthers 0.5–1.0 mm long; seeds not tailed, 0.5–0.8 mm long; inner tepals with more or less narrow hyaline margins near apex
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Juncus kraussii
29Inflorescence branches, upper culms and mid-region of tepals finely scabrousJuncus radula
Plants not scabrous
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30
30Plants unisexual (rudimentary parts of the other sex present)31
Plants bisexual
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32
31Culm striations 35–60; culms 65–125 cm long, 1.6–3.2 mm diam.; stomates sunken below surface of culmJuncus psammophilus
Culm striations 100–200; culms 120–400 cm long, 4–9 mm diam.; stomates superficial
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Juncus ingens
32Pith continuous (may be dense or more loose, but without distinct lacunae) at least in middle portion of culms33
Pith interrupted (with obvious lacunae in the pith) at least in middle portion of culms
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50
33Stamens usually 6 (occasionally fewer in some flowers in an inflorescence)34
Stamens usually 3 (occasionally more in some flowers in an inflorescence)
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38
34Culm striations greater than 40; culms greater than or equalling 2.5 mm diam.; cataphylls more or less lax35
Culm striations 40 or less; culms less than 2.5 mm diam.; cataphylls more or less tight
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36
35Capsule without red-brown flecks on adaxial surface, usually exceeding tepals (occasionally equalling them); flowers loosely clustered or solitary and spread out along the branches of the inflorescence (rarely densely clustered but if so then not in several discrete clusters)Juncus pallidus
Mature capsule with red-brown flecks on adaxial surface, usually shorter than tepals (occasionally equalling them); flowers in dense, distant clusters at apex of branches
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Juncus vaginatus
36Flowers in dense distant clusters at apex of branches; culms 1.5–4.5 mm diam.; mature capsule with red-brown flecks adaxiallyJuncus vaginatus
Flowers solitary and spread out along the branches of the inflorescence; culms 0.5–1.7 mm diam. (rarely to 2.5 mm in Juncus pauciflorus); capsule without red-brown flecks adaxially
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37
37Outer tepals 2.0–2.8 mm long; culms mid-green, very glossyJuncus pauciflorus
Outer tepals 2.9–3.1 mm long; culms grey-green, dull
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Juncus dolichanthus
38Striations 10–20; culms 15–45 cm long, 0.6–1.2 mm diam.; inflorescence shorter than or equalling 3 cm long and flowers in 1–several dense discrete clustersJuncus filicaulis
Striations 20–120; culms 50–170 cm long, 1.3–8.5 cm diam.; inflorescence longer than 3 cm long (occasionally culms and inflorescences slightly smaller in Juncus usitatus but then flowers solitary and spread along branches, and culms yellow-green to mid-green)
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39
39Inflorescence reddish overall (capsules red-brown to dark red-brown and tepals with red-brown sides)Juncus phaeanthus
Inflorescence straw-coloured to golden brown overall (although either capsules or tepals may occasionally be red-brown)
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40
40Inflorescence with flowers in discrete dense clusters at apex of branches41
Inflorescence with flowers solitary and spread along the branches or loosely clustered towards apex of branches
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44
41Stomates deeply sunken below culm surface in straight-sided pitsJuncus australis
Stomates superficial or slightly sunken below culm surface
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42
42Culms yellow-green to mid-green, not glaucousJuncus alexandri
Culms grey-green to blue-green, often glaucous
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43
43Culms 55–110 cm long, 2.2–5 mm diam.; stomates slightly sunkenJuncus firmus
Culms 90–160 cm long, 3.5–8.5 mm diam.; stomates superficial
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Juncus semisolidus
44Culms grey-green to blue-green, often glaucous45
Culms yellow-green to mid-green, not glaucous
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46
45Culms 55–110 cm long, 2.2–5 mm diam.; stomates slightly sunkenJuncus firmus
Culms 90–160 cm long, 3.5–8.5 mm diam.; stomates superficial
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Juncus semisolidus
46Cataphylls coppery to dark golden brown adaxially, lax or tightly enclosing culm; culms soft or more or less hard47
Cataphylls silvery to pale golden brown adaxially, more or less tightly clasping culm; culms more or less soft
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49
47Cataphylls dull, tightly enclosing culm; culms soft; capsule mostly shorter than outer tepalsJuncus effusus
Cataphylls glossy at least near base, lax; culms more or less hard; capsule mostly exceeding outer tepals
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48
48Pith usually slightly interrupted near apex or base; cataphylls usually dark yellow-brown to dark red-brown abaxially, rarely black at very baseJuncus laeviusculus
Pith always continuous; cataphylls mostly dark red-brown but usually black at very base
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Juncus alexandri
49Cataphylls yellow to dark yellow-brown abaxially; striations 35–80Juncus continuus
Cataphylls red-brown or occasionally golden brown; striations 20–40
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Juncus usitatus
50Culms no more than 2.5 mm diam. (about halfway along culm)51
Culms more than 2.5 mm diam. (about halfway along culm)
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75
51Culm striations less than 2552
Culm striations at least 25
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56
52Culms grey-green to blue-green, occasionally glaucous53
Culms yellow-green to mid-green, never glaucous
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55
53Stomates sunken in sloping-sided pits; cataphylls golden brown to coppery adaxially, usually dark red-brown to black abaxially; striations widely spaced; inflorescence 6–15 cm longJuncus sarophorus
Stomates superficial; cataphylls silvery to pale golden brown adaxially, straw-brown to dark yellow-brown abaxially; striations closely packed; inflorescence mostly 1.5–7 cm long
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54
54Inflorescence head-like or occasionally with 1 or 2 extra dense clusters; striations longer than or equalling 0.1 mm wide; tepals frequently red-tingedJuncus filicaulis
Inflorescence with flowers spread out along the branches or clustered; striations mostly less than 0.1 mm wide; tepals occasionally red-tinged
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Juncus subsecundus
55Cataphylls red-brown to golden brown abaxially; culms more or less softJuncus usitatus
Cataphylls pale yellow to pale golden brown abaxially; culms more or less hard
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Juncus ochrocoleus
56Inflorescence reddish overall (capsules red-brown to dark red-brown and tepals with red-brown sides)Juncus phaeanthus
Inflorescence straw-brown to dark golden brown overall (although either capsules or tepals may occasionally be at least partly red-brown)
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57
57Stomates deeply sunken below surface of culm58
Stomates superficial
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60
58Stomates in sloping-sided pits; striations 20–40, widely separated; anthers 0.3–0.5 mm longJuncus sarophorus
Stomates in straight-sided pits; striations 35–90, more or less closely packed; anthers 0.5–1.0 mm long
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59
59Cataphylls dark yellow-brown to red-brown; tepals with narrow hyaline marginsJuncus australis
Cataphylls yellow to dark golden brown; tepals with more or less broad hyaline margins
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Juncus flavidus
60Outer tepals longer than 2.5 mm long61
Outer tepals less than or equalling 2.5 mm long
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63
61Culms hard; striations usually 15–30, rarely to 40; inflorescence usually 1–5 cm longJuncus subsecundus
Culms soft; striations 25–115; inflorescence 7–19 cm long
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62
62Cataphylls yellow to dark yellow-brown; capsule shorter than or equalling outer tepals; lowest involucral bract often shorter than inflorescenceJuncus remotiflorus
Cataphylls usually pink-brown to red-brown; capsule longer than outer tepals; lowest involucral bract longer than inflorescence
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Juncus aridicola
63Inflorescence of several dense discrete clusters of flowers at the apex of branches64
Inflorescence diffuse, with flowers evenly spread along branches or loosely clustered towards the apex of the branches
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67
64Culms yellow-green to mid-green, not glaucousJuncus gregiflorus
Culms grey-green to blue-green, often glaucuous
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65
65Cataphylls straw-brown to dark yellow-brown, more or less tight; striations mostly less than 30; culms mostly less than 1.4 mm diam.; outer tepals mostly 2.5–4 mm longJuncus subsecundus
Cataphylls mostly red-brown to black (rarely yellow-brown), more or less lax; striations 30–60; culms mostly 1.4–2.5 mm diam.; outer tepals 1.8–2.6 mm long
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66
66Culms hard; inflorescence 4–15 cm longJuncus subglaucus
Culms soft; inflorescence usually 1–5 cm long
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Juncus amabilis
67Culms grey-green to blue-green, often glaucous68
Culms yellow-green to mid-green, not glaucous
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71
68Tepals acute to obtuse; cataphylls adaxially coppery to golden brownJuncus polyanthemus
Tepals acuminate to acute, often mucronate; cataphylls adaxially silvery to occasionally golden brown
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69
69Striations mostly 15–30Juncus subsecundus
Striations 35–115
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70
70Culms hard; striations 35–55; inflorescence branches more or less straightJuncus subglaucus
Culms soft; striations 40–115; inflorescence branches often strongly flexuous
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Juncus aridicola
71Cataphylls abaxially pale yellow to pale golden brownJuncus ochrocoleus
Cataphylls abaxially dark yellow-brown to pink-brown, red-brown or black
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72
72Cataphylls tightly enclosing culms; tepals with broad hyaline margins73
Cataphylls lax; tepals mostly with narrow hyaline margins
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74
73Culms less than 2.0 mm diamJuncus usitatus
Culms 2.1–4 mm diam
                       Back to 72
Juncus mollis
74Culms hard; inflorescence 3–10 cm long; anthers longer than or equalling filamentsJuncus laeviusculus
Culms more or less soft; inflorescence 1–5 cm long; anthers shorter than or equalling filaments
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Juncus gregiflorus
75Inflorescence reddish overall (capsules red-brown to dark red-brown and tepals with red-brown sides)Juncus phaeanthus
Inflorescence straw-brown to dark golden-brown overall (although either capsules or tepals may occasionally be at least partly red-brown)
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76
76Stomates sunken below culm surface77
Stomates superficial
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79
77Stomates in sloping-sided pits; striations 20–40, widely separated; anthers 0.3–0.7 mm longJuncus sarophorus
Stomates in straight-sided pits; striations 35–90, more or less closely packed; anthers 0.5–1.0 mm long
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78
78Cataphylls dark yellow-brown to red-brown; tepals with narrow hyaline marginsJuncus australis
Cataphylls yellow to dark golden-brown; tepals with more or less broad hyaline margins
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Juncus flavidus
79Culms grey-green to blue-green, often glaucous80
Culms yellow-green to mid-green, not glaucous
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82
80Culms more or less hard; cataphylls abaxially dark red-brown to blackJuncus semisolidus
Culms more or less soft; cataphylls abaxially pink-brown to red-brown
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81
81Cataphylls golden brown to coppery adaxially; seeds 0.4–0.5 mm longJuncus polyanthemus
Cataphylls silvery to pale golden brown adaxially; seeds 0.3–0.4 mm long
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Juncus aridicola
82Inflorescence of discrete dense clusters of flowers at the apex of branches83
Inflorescence diffuse, with flowers spread evenly along branches or in loose clusters towards apex of branches
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85
83Culms hard; lowest involucral bract mostly shorter than or equalling inflorescenceJuncus brevibracteus
Culms more or less soft; lowest involucral bract mostly longer than inflorescence
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84
84Culms 3–10 mm diam.; striations 65–160; outer tepals 2.0–3.0 mm long, with more or less broad hyaline marginsJuncus procerus
Culms 1–3 mm diam.; striations 30–65; outer tepals 1.6–2.2 mm long, with narrow hyaline margins
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Juncus gregiflorus
85Cataphylls abaxially pale yellow to pale golden brownJuncus ochrocoleus
Cataphylls abaxially dark yellow-brown to pink-brown, dark red-brown or black
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86
86Culms soft87
Culms hard
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88
87Flowers in loose to dense clusters; cataphylls laxJuncus gregiflorus
Flowers solitary along branches of inflorescence; cataphylls tightly enclosing culms
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Juncus mollis
88Tepals with narrow hyaline margins89
Tepals with broad hyaline margins
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90
89Anthers longer than or equalling filaments; capsule golden brownJuncus laeviusculus
Anthers shorter than filaments; capsule dark golden brown to red-brown
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Juncus brevibracteus
90Capsule longer than or equalling outer tepals; lowest involucral bract mostly shorter than or equalling inflorescence; culms 1.7–2.9 mm diamJuncus laeviusculus
Capsule shorter than or equalling outer tepals; lowest involucral bract mostly longer than inflorescence; culms 3–10 mm diam
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Juncus procerus

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