Juncus acutiflorus
Juncus subg. Septati
sharpflower rush
5–6 mm diam., nodes not swollen.
erect, terete, 3 mm diam., smooth.
terete.
1, straw-colored, apex acute.
basal 1, cauline 2;
auricles 0.5 mm, apex rounded, cartilaginous;
blade 7–45 cm x 1–2 mm, terete, not scabrous.
basal and cauline: blade terete, nearly terete, or flattened, perfectly septate.
terminal panicles of 70–120 heads, 6–10 cm, branches ascending;
primary bract erect;
heads 3–5(–8)-flowered, obconic, 2–4 mm diam.
terminal panicles or racemes of 2 to –many heads, a single terminal head, or rarely a cyme of heads, sympodial;
bracts erect or ascending, flat, involute or terete;
bracteoles absent.
tepals dark reddish brown, lanceolate, apex acuminate to subulate tipte;
outer tepals 1.9–2.2 mm;
inner tepals 2–2.3 mm;
stamens 6, anthers 2 times filament length.
in multiflowered heads (rarely only 2– or 3 flowers per head).
inserted with beak exserted, straw-colored, 1-locular, narrowly ovoid, 2.3–2.4 mm, tapering to subulate tip, valves separating at dehiscence.
1- or 3-locular, beaked.
narrowly ovoid, 0.5–0.6 mm, not tailed;
body clear yellow-brown.
tailed or not tailed.
= 20.
Juncus acutiflorus
Juncus subg. Septati
NF; SPM; Europe; Asia; Africa
Worldwide
Species ca. 80 (32 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Seeds tailed, 0.7–2.6 mm, including tails; seed body covered with whitish translucent veil. | → 2 |
1. Seeds not tailed, 0.3–0.7 mm; seed body clear yellow-brown. | → 7 |
2. Seeds 1.8–2.6 mm, including tails; stamens usually 6. | → 3 |
2. Seeds 0.7–1.9 mm, including tails; stamens usually 3. | → 4 |
3. Stems and leaves scabrous; auricles 1–7.5 mm | J. caesariensis |
3. Stems and leaves smooth; auricles 0.2–0.4 mm | J. trigonocarpus |
4. Seeds 1.1–1.9 mm; heads 5–50-flowered; inflorescence branches erect to ascending | J. canadensis |
4. Seeds 0.7–1.2 mm; heads 2–8-flowered or if to 20-flowered then proximal inflorescence branches widely spreading (J. subcaudatus). | → 5 |
5. Outer tepals obtuse to nearly acute | J. brachycephalus |
5. Outer tepals acuminate to acute. | → 6 |
6. Proximal inflorescence branches widely spreading | J. subcaudatus |
6. Proximal inflorescence branches erect | J. brevicaudatus |
7. Flowers 1–2(–4) at each node, not in heads; capsules fertile only below middle. | → 8 |
7. Flowers in heads of 3–60; capsules fertile throughout or only below middle. | → 9 |
8. Culms erect, 0.3–7 dm, not forming mats | J. pelocarpus |
8. Culms decumbent, 0.1–1 dm, forming mats | J. subtilis |
9. Heads spheric or nearly spheric, 15–60-flowered | → 10 |
9. Heads obconic to hemispheric, 3–15-flowered. | → 23 |
10. Stamens 6. | → 18 |
10. Stamens 3. | → 11 |
11. Plants cespitose; tepals lanceolate | J. acuminatus |
11. Plants rhizomatous; tepals lance-subulate. | → 12 |
12. Capsules included | J. brachycarpus |
12. Capsule exserted to slightly included. | → 13 |
13. Capsules remaining united at apex after dehiscence. | → 14 |
13. Capsule valves separating at apex during dehiscence. | → 16 |
14. Leaves laterally compressed, 3–5 mm diam. | J. validus var. fascinatus |
14. Leaves terete, 1–4 mm diam. | → 15 |
15. Heads sometimes spheric, usually lobed; tepals green to stramineous, nearly equal; uppermost cauline leaf blade (below inflorescence bract) equaling or longer than its sheath | J. scirpoides |
15. Heads spheric; stramineous to reddish brown, inner tepals shorter than outer; uppermost cauline leaf blade much shorter than its sheath | J. megacephalus |
16. Tepals 4–5 mm; leaves laterally compressed | J. validus var. validus |
16. Tepals 2.9–4 mm; leaves terete. | → 17 |
17. Capsules 3.5–5 mm, exserted; culms 0.4–3 dm | J. nodosus |
17. Capsules 3–3.5 mm; equaling perianth or slightly shorter; culms 2.5–8.5 dm | J. bolanderi |
18. Tepals lanceolate to lance-ovate, light green to light pink or white or dark purplish brown; capsule ovoid to obovoid, 1.9–3.5 mm; heads 1–2 per inflorescence (15–50 for J. pervetus). | → 19 |
18. Tepals lance-subulate, green to stramineous; capsule lance-subulate, 3.2–6.5 mm; heads 1–23 per inflorescence. | → 21 |
19. Heads 15–50 | J. pervetus |
19. Heads 1–2. | → 20 |
20. Tepals dark purplish brown to black; anthers 1/4 to equal filament length | J. mertensianus |
20. Tepals light green, or light pink to white; anthers 2–3 times length of filaments | J. chlorocephalus |
21. Outer tepals 2.4–4.1 mm, equaling inner tepals; auricles 0.5–1.7 mm | J. nodosus |
21. Outer tepals 4–6 mm, outer and inner tepals unequal in length; auricles 1–4 mm. | → 22 |
22. Outer tepals longer than inner; capsule 4.3–5.7 mm | J. torreyi |
22. Outer tepals shorter than inner; capsules 5.2–6.5 mm | J. texanus |
23. Stamens 3. | → 24 |
23. Stamens 6. | → 31 |
24. Stems creeping or floating, capillary; filiform, submersed leaves often formed before flowering; inflorescences with 1–9 heads. | → 25 |
24. Stems erect, not floating; filiform leaves absent; inflorescences with 3–200 heads. | → 26 |
25. Capsule rounded at apex, 2.5–4 mm; tepals 2–3.6 mm, obtuse to acute | J. bulbosus |
25. Capsule acute to acuminate at apex, 3.5–6.1 mm; tepals 2.8–5.5 mm, acute to acuminate-subulate | J. supiniformis |
26. Capsule much longer than perianth, 1.3–2 times perianth length. | → 27 |
26. Capsule equaling or just exceeding perianth. | → 29 |
27. Capsules beaked; plants often decumbent or matted | J. supiniformis |
27. Capsules not beaked; plants erect. | → 28 |
28. Capsule 1/3 longer than perianth, 2.8–4.2 mm | J. debilis |
28. Capsule twice as long as perianth, 4–5.2 mm | J. diffusissimus |
29. Heads 5–50; tepals 2.6–3.5 mm, nearly equal; capsules 2.8–3.5 mm | J. acuminatus |
29. Heads 30–250; tepals 1.7–2.9 mm, inner tepals shorter than outer tepals; capsules 1.9–2.9 mm. | → 30 |
30. Leaf blade with prominent and conspicuous ringlike bands at position of cross partitions; roots without terminal tubers; inner tepals 1.7–2.1 mm | J. nodatus |
30. Leaf blade with faint ringlike bands at position of septa; roots often with terminal tubers; inner tepals 2.4–2.8 mm | J. elliottii |
31. Stems creeping or floating, capillary; filiform, submersed leaves often formed before flowering; inflorescences with 1–9 heads. | → 32 |
31. Stems erect; filiform submersed leaves not formed except in J. militaris; heads 1–66. | → 34 |
32. Auricles 0.8–2.1 mm; capsules 3.5–6.1 mm | J. supiniformis |
32. Auricles 0.4–1 mm; capsules 2.5–4 mm. | → 33 |
33. Capsules exserted about 1 mm beyond perianth; apex acute below beak; outer tepals acute to acuminate | J. articulatus |
33. Capsules as long as tepals or exserted to 0.5 mm beyond tepals, apex obtuse below apex; outer tepals acute to obtuse | J. bulbosus |
34. Proximal culm leaf overtopping inflorescences, distal culm leaf usually inflated, bladeless sheath; often developing filiform (hairlike) leaves off rhizome in running water | J. militaris |
34. Proximal culm leaf shorter than inflorescence, distal culm leaf usually with blade, sheath not inflated; not developing filiform leaves off rhizome. | → 35 |
35. Tepals 1.6–3 mm; apex obtuse to acuminate, usually not subulate mucronate; anthers shorter than to equaling filaments. | → 36 |
35. Tepals 2.3–6.2 mm; apex usually acuminate with subulate mucro (acute in J. acutiflorus); anthers equaling or longer than filaments. | → 37 |
36. Inner tepals obtuse; inflorescence stiffly erect | J. alpinoarticulatus |
36. Inner tepals acuminate; inflorescence spreading | J. articulatus |
37. Capsule abruptly contracted at apex, usually not exserted | J. nevadensis |
37. Capsule narrowed to beak, exserted at least slightly. | → 38 |
38. Heads 2–9; tepals 2.8–5.5 mm | J. supiniformis |
38. Heads 25–66; tepals 2.5–3.5 mm. | → 39 |
39. Tepals nearly equal; heads with 6–10 flowers | J. dubius |
39. Tepals unequal, outer shorter than inner; heads with 5–8 flowers | J. acutiflorus |
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