The Jepson Herbarium
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Rhizome 0 or generally with scale-like leaves.
Stem: generally cylindric or flat.
Leaf: blade well developed and cylindric or flat, occasionally closely resembling stem, or reduced to small point; crosswalls generally present; appendages generally present at blade-sheath junction.
Inflorescence: generally terminal, appearing lateral when pushed aside by inflorescence bract; bractlets 0–2.
Flower: sepals, petals similar; stamens generally 3 or 6(2); pistil 1, ovary chambers 1–3, placentas axile or parietal, stigmas generally 3(2).
Seed: many.
315 species: worldwide, especially n hemisphere. (Latin: to join or bind, from use of stems) [Ertter 1986 Mem New York Bot Gard 39:1–90] All species with leaf crosswalls may have leaves, stems swollen, deformed by sucking insects. Fruiting time given instead of flowering time. Juncus bulbosus L., Juncus dichotomus Elliott, and Juncus elliotti Chapm. reportedly naturalized in CA.

Key to Juncus

Key to Groups

1. Annual generally < 10 cm; roots fine, fibrous; leaves narrow, generally inrolled, generally < 1 mm wide ..... Group 1

1' Perennial; plant generally larger in all respects; roots coarse or rhizomes present; leaves narrow or wide, inrolled to flat or cylindric

2. Infl bract cylindric, resembling continuation of stem; inflorescence appearing lateral ..... Group 2

2' Infl bract not cylindric, not resembling continuation of stem, or if so then channeled along inner side; inflorescence appearing terminal

3. Lf blade generally cylindric or nearly so; crosswalls generally complete ..... Group 3

3' Lf blade flat or wiry; crosswalls incomplete or 0

4. Lf blade iris-like, flattened, oriented with edge toward stem (at least from middle to tip), crosswalls generally incomplete ..... Group 4

4' Lf blade wiry or grass-like, if flattened then oriented with flat side toward stem, crosswalls 0

5. 2 bractlets subtending flower; leaves slender, generally < 1.3 mm wide, generally wiry or channeled; flowers 1 or in clusters ..... Group 5

5' 1 bractlet subtending flower; leaves broader, generally 2–7 mm wide, flat; flowers in clusters ..... Group 6

Group 1: Ann

1. St generally branched, leafy; inflorescence or flowers scattered along stem or congested in terminal cluster; stamens 3 or 6

2. Sepals 2–4 mm

3. Fls scattered along stem, 1 per node ..... J. bufonius var. occidentalis

3' Fls terminal, 3–10(25) per cluster ..... J. planifolius (2)

2' Sepals generally 4–10 mm

4. Perianth dark brown to ± black; lowest bract < inflorescence ..... J. planifolius (2)

4' Perianth green to red or pale brown; lowest bract > inflorescence ..... J. capitatus (2)

5. Fr tip generally truncate, ± = petals; petals ± blunt ..... J. ambiguus

5' Fr tip generally rounded or acute, < petals; petals acute to acuminate

6. Infl open; generally non-saline soil ..... J. bufonius var. bufonius

6' Infl congested, dense; generally saline soil ..... J. bufonius var. congestus

1' St not branched, leafless, leaves basal; inflorescence or flowers terminal; stamens 2 or 3

7. Infl bracts leaf-like, > inflorescence; sepals >>, more acuminate than petals ..... J. capitatus (2)

7' Infl bracts inconspicuous, membranous, < inflorescence; sepals, petals similar in size, shape, occasionally sepals < petals

8. Anthers >= 0.9 mm, >(=) filaments; style >= 0.9 mm, flowers outcrossing

9. Fr generally 11–17 mm, ± 3–4 × > perianth ..... J. digitatus

9' Fr 1–5 mm, < or ± = perianth

10. Perianth parts acuminate; petals colored to tip, margins narrowly scarious; seed striate at 15× ..... J. triformis

10' Perianth parts acute; petals generally not colored to tip, sepal and petal margins broadly scarious; seed not striate at 15× ..... J. leiospermus

11. Fls generally 1(2) per stem ..... var. ahartii

11' Fls generally 2–4(7) per stem ..... var. leiospermus

8' Anthers < 0.8 mm, < filaments; style < 0.6 mm, flowers generally self-pollinating

12. Perianth dark brown to ± black; generally 3–6+ flowers per stem ..... J. planifolius (2)

12' Perianth generally green to pink or red; generally 1–2 flowers per stem

13. Seed not striate; flowers 1 per stem; bracts 0 or 1–2, truncate to acute

14. Infl bractlets 0; stem thickened below flower ..... J. hemiendytus var. abjectus

14' Infl bractlets 1–2; stem not thickened below flower

15. Infl bractlet 1, tip truncate, sheathing stem; stamens 2–3 ..... J. uncialis

15' Infl bractlets 1–2, tips acute to blunt, ovate to rounded, not sheathing stem; stamens generally 2–4

16. Perianth parts generally 6, shiny, incurved, generally > fruit ..... J. bryoides

16' Perianth parts generally 4, dull, erect or outcurved, generally < fruit ..... J. hemiendytus var. hemiendytus

13' Seed striate; flowers 1–2(7) per stem; bracts 2, acute to acuminate

17. Perianth parts generally 4

18. Fr much paler than perianth; seed 0.5–0.8 mm, < 4 per row, < 10 per capsule; fruit generally ± spheric to obovoid, < perianth ..... J. capillaris (2)

18' Fr, perianth both pale green or pink; seed 0.3–0.5 mm, > 4 per row, > 10 per capsule; some fruit ± ellipsoid or oblong, >= perianth ..... J. tiehmii

17' Perianth parts generally 6

19. Perianth generally > and darker than capsule; < 10 seeds per capsule; seed 0.5–0.8 mm, striations generally faint at 30× ..... J. capillaris (2)

19' Perianth generally < and same color as capsule; > 40 seeds per capsule; seed 0.3–0.6 mm, striations obvious at 30×

20. Fls generally (1)2–3(4) per stem; fruit, perianth generally ± dark red in age; seed 0.4–0.6 mm ..... J. kelloggii

20' Fls 1(2) per stem; fruit, perianth generally pale green to pale red in age, perianth midvein tips dark red; seed 0.3–0.4 mm ..... J. luciensis

Group 2: Per; infl bract erect and st-like

1. Rhizomes long, creeping; stem scattered or in lines, in loose colonies

2. Blades well developed on some upper sheaths, > 5 cm, stem-like ..... J. mexicanus

2' Blades 0 or < 1 cm, not stem-like

3. Perianth < 5.5(6) mm; inflorescence open

4. St smooth, not stiff, generally dark green; fruit acute below beak; stem generally < 1.1 m ..... J. balticus subsp. ater

4' St ridged, stiff, gray-green; fruit ± obtuse below beak; stem to 2 m ..... J. textilis

3' Perianth generally > 6 mm; inflorescence open or a dense head

5. Infl dense, branches obscured; older sheaths shiny, dark brown; stem generally flattened, generally arching, twisted ..... J. breweri

5' Infl generally open, branches obvious; sheaths dull to ± shiny, pale to dark brown; stem cylindric, erect, generally not twisted ..... J. lescurii

1' Rhizomes short; stem cespitose, in dense tufts like bunchgrass

6. Stamens 6

7. Infl < 6 flowers

8. Fr notched or truncate; leaf blades 0 or vestigial; moist ground ..... J. drummondii

8' Fr acute or acuminate; leaf blades > 2 cm, stem-like; ± dry ground ..... J. parryi

7' Infl > 10 flowers

9. Sheaths bladeless; stem slender, blue-green ..... J. patens

9' Sheaths with blades 5–100 cm, stem-like, tip sharp; stem coarse, dark green

10. Perianth 2–4 mm; fruit >> perianth; fresh sepals rounded or notched with short awn, thin, not stiff; stem smooth, base fibrous ..... J. acutus subsp. leopoldii

10' Perianth 4–6 mm; fruit ± = perianth; fresh sepals spiny, acuminate, thick, firm; stem with 6–11 low wide ridges per side, base not fibrous ..... J. cooperi

6' Stamens 3

11. Petals blunt, perianth << fruit; pith generally chambered ..... J. usitatus

11' Petals acuminate, perianth ± >= fruit; pith generally solid

12. Upper sheath tip generally strongly asymmetrical on fertile stem

13. Sheath tip thickened, with a raised rim; sheath generally dark brown to black ..... J. effusus subsp. pacificus

13' Sheath tip thin with broad membranous wings; sheath green when fresh to pale or mid-brown when dry

14. Perianth dark brown- to black-striped; fertile stem slender, generally 0.8–2 mm diam above sheath; NCo, KR, CCo, SCoRO ..... J. hesperius

14' Perianth pale brown; fertile stem stout, generally 2–3.7 mm diam above sheath; SW, DSon ..... J. effusus subsp. austrocalifornicus

12' Upper sheath tip ± symmetrical on fertile stem

15. Fertile stem slender, 0.8–2 mm diam above sheath; perianth with mid- to dark-brown stripes; stem striations 8–12 per side, coarse, best seen on dry stem; montane natives

16. Upper 1/2 of sheath green to pale brown, thin, dull, veins prominent, tip thin, ± inrolled towards stem ..... J. exiguus

16' Sheath generally dark brown to ± black throughout, thick, glossy, veins obscure, tip thickened, not inrolled ..... J. laccatus

15' Fertile stem stout, generally 2–5 mm diam above sheath; perianth generally pale brown; stem striations 14–26 per side, slender; rare introduced subspp. ..... J. effusus

17. Perianth spreading or curving away from fruit; sheaths 5–14 cm, margins generally dark-banded; sheath clasping stem, margins overlapping 2–4 cm from tip ..... subsp. effusus

17' Perianth erect, pressed to fruit; sheaths generally 15–27 cm, margins generally pale; sheath not clasping stem, margins generally loose, flattened or unrolled ..... subsp. solutus

Group 3: Per; lf blades with regular crosswalls, gen tubular, scarcely flattened

1. Plant matted, submerged, early leaves hair-like; stem capillary ..... J. supiniformis (3)

1' Plant not matted, generally not submerged; leaves and stem generally wider

2. Most or all flowers with 3 stamens

3. Plant long-rhizomatous; inflorescence dense, clusters 1–3(5), > 20-flowered ..... J. bolanderi

3' Plant cespitose; inflorescence open, clusters > 5, < 15–flowered

4. Fr generally <= perianth ..... J. acuminatus

4' Fr > perianth

5. Perianth 3.4–5.4 mm; inflorescence bulblets occasionally present; fruit dark ..... J. supiniformis (3)

5' Perianth 2.3–3.2 mm; inflorescence bulblets 0; fruit pale ..... J. diffusissimus

2' Most or all flower with 6 stamens

6. Lf, stem surfaces conspicuously wrinkled ..... J. rugulosus

6' Lf, stem surfaces smooth

7. Rhizome nodes tuberous

8. Sepals > petals; inflorescence bracts spreading; fruit ± = perianth; inflorescence clusters generally 1–1.5 cm wide ..... J. torreyi

8' Sepals ± = petals; inflorescence bracts ascending; fruit > perianth; inflorescence clusters generally < 1 cm wide ..... J. nodosus

7' Rhizome tubers 0

9. Anthers > filaments

10. Infl clusters 1–3

11. Perianth white to pink or ± green ..... J. chlorocephalus

11' Perianth ± brown-black ..... J. mertensianus (2)

10' Infl clusters generally > 5

12. Fr abruptly narrowed to beak; fruit generally <= perianth ..... J. nevadensis var. nevadensis

12' Fr gradually tapered to beak; fruit generally > perianth

13. Petals generally blunt, tips hooded; fruit generally dark brown to black ..... J. articulatus subsp. articulatus (2)

13' Petals acuminate, bristle-tipped; fruit light brown to red or dark red ..... J. dubius

9' Anthers <= filaments

14. Infl clusters > 5; fruit > perianth; inflorescence bulblets occasionally present; stem occasionally rooting at nodes

15. Infl clusters > 10; perianth 1.9–3.1 mm; pale petal margins wide, flat, tips generally blunt, hooded ..... J. articulatus subsp. articulatus (2)

15' Infl clusters < 10; perianth 3.4–5.4 mm; pale petal margins narrow, generally inrolled, tips acuminate ..... J. supiniformis (3)

14' Infl clusters generally 1–3; fruit generally <= perianth; inflorescence bulblets 0, stem not rooting at nodes

16. Fr abruptly tapered to distinct beak; leaves ± to strongly flattened, hollow, blue-green; stem with 1–3(4) heads; n NCo ..... J. nevadensis var. inventus

16' Fr generally notched or truncate, ± beakless; leaves tubular, hollow, green; stem with 1(2) heads; montane

17. Perianth generally < 2.8 mm; perianth brown, stiff; inflorescence bract narrow, generally not sheathing; SW ..... J. duranii

17' Perianth generally > 3.1 mm; perianth ± purple-black, not stiff; inflorescence bract wide, generally sheathing; not SW ..... J. mertensianus (2)

Group 4: Per; lf blades flattened, iris-like, crosswalls often incomplete

1. Fr gradually tapered to long beak

2. Perianth green, tips red or purple; inflorescence generally > 15 cm, clusters generally <= 8-flowered ..... J. oxymeris

2' Perianth generally dark brown to dark purple-brown or ± black; inflorescence generally < 10 cm, clusters > 8-flowered ..... J. phaeocephalus

3. Infl 10+ few-flowered clusters; clusters generally 5–10 mm wide ..... var. paniculatus

3' Infl 1–10 many-flowered clusters; clusters generally > 10 mm wide ..... var. phaeocephalus

1' Fr abruptly tapered to beak

4. Anthers generally 1–1.5 mm, >> filaments; styles >= 1 mm; flowers outcrossing ..... J. macrandrus

4' Anthers 0.5–1 mm, generally <= filaments; styles <= 1 mm; flowers generally self-pollinating

5. Stamens 3; perianth generally dark brown to black ..... J. ensifolius

5' Stamens 6; perianth generally green to red-tipped or brown

6. Lvs generally 2–5 mm wide; perianth brown ..... J. saximontanus

6' Lvs generally 5–14 mm wide; perianth green, red-tipped ..... J. xiphioides

Group 5: Per; lf blades wiry or slightly flattened and channeled, < 1.3 mm wide

1. Perianth black-striped, tips blunt, hooded, incurved; anthers >> filaments; rhizomatous; coastal salt marshes ..... J. gerardii subsp. gerardii

1' Perianth green, brown, or red, tips acute or acuminate, not incurved or hooded; anthers < to > filaments; cespitose; inland wetlands

2. Lf sheath appendages stiff, thick, plastic-like, rounded, shiny, ± yellow ..... J. dudleyi

2' Lf sheath appendages not stiff, thin, rounded to acuminate, dull, white or translucent

3. Fr chambers 3, partitions straight, united except at tip

4. Sepals > petals; style (0.3)0.4–0.8 mm; anthers > filaments; perianth generally green or light brown, pale margins narrow; inflorescence open ..... J. brachyphyllus

4' Sepals ± = petals; style 0.1–0.2 mm; anthers < filaments; perianth with thick, darker brown stripes, pale margins broad; inflorescence generally compact ..... J. confusus

3' Fr chamber 1, partitions concave, separated except at base

5. Fr ridged, truncate or notched; perianth green or with thick dark brown stripes ..... J. occidentalis

5' Fr ridges 0 or obscure, fruit rounded or acute; perianth green or ± red, pale brown in age

6. Lf sheath appendages generally rounded, ± opaque below, 0.2–0.6 mm; bractlets acuminate, generally bristle-tipped; stem with 2–6 strong ridges per side; DMtns ..... J. interior

6a. St with 2–6 strong ridges per side; fruit < 2.5 mm, < 75% perianth; inflorescence generally orange-red; flower < internodes ..... [J. anthelatus]

6a' St with generally 0–1 strong ridges per side; fruit generally > 2.5 mm, > 75% perianth; inflorescence generally green; flower generally > internodes ..... J. tenuis

6' Lf sheath appendages generally acute to acuminate, ± translucent, generally 1–8 mm until late in season when generally smaller or absent; bractlets generally acute to blunt; stem with or without strong ridges per side; widespread

7. St with 2–6 strong ridges per side; fruit < 2.5 mm, < 75% perianth; inflorescence generally orange-red; flower < internodes ..... [J. anthelatus]

7' St with 0–1 strong ridges per side; fruit generally > 2.5 mm, > 75% perianth; inflorescence generally green; flower generally > internodes ..... J. tenuis

Group 6: Per; lf blades flattened, grass-like, gen 2–7 mm wide

1. Stamens 3

2. Plant base with knobby tubers; anthers ± purple-red; cespitose ..... J. marginatus

2' Tubers 0; anthers yellow; rhizomatous or cespitose ..... J. planifolius

1' Stamens 6

3. Seeds slender, 1–2 appendages >= 1/2 seed body

4. Seed body > both appendages; petals generally > sepals; inflorescence clusters generally 5–20, clusters generally 2–5-flowered; leaves <= 4.5 mm wide ..... J. howellii

4' Seed body < 1–2 appendages; petals generally = sepals; inflorescence clusters 1–5, clusters generally 10–30-flowered; leaves < 3 mm wide ..... J. regelii

3' Seeds plump, appendages 0 or short points, << seed body

5. Perianth generally 2–3.6 mm; fruit >= perianth

6. Fr blunt or notched, petals blunt or acute; heads 1–6, branches erect, inflorescence narrow; leaves blue-green ..... J. covillei

6' Fr, petals acuminate; heads 10–50, branches spreading, inflorescence diffuse; leaves green ..... J. cyperoides

5' Perianth generally 4–6 mm; fruit generally <= perianth

7. Lf sheath appendages well developed, generally rounded, > 1 mm

8. Rhizomatous; sepals generally = petals; inflorescence clusters 1–4(5); perianth midveins smooth to occasionally papillate, green ..... J. longistylis

8' Loosely cespitose; sepals < petals; inflorescence clusters 8–30; perianth midveins smooth, generally red-streaked ..... J. macrophyllus

7' Lf sheath appendages 0 or obscure, generally pointed, < 1 mm

9. Perianth parts < 1.5 mm wide; fruit brown; heads 3–12; generally montane ..... J. orthophyllus

9' Perianth parts > 1.5 mm wide; fruit ± black; heads 1–3(5); coastal ..... J. falcatus

10. Petals acuminate, generally > 5 mm; anthers generally > 1.7; fruit tip acute to truncate, inconspicuous, << perianth, generally ellipsoid to oblong; CCo ..... subsp. falcatus

10' Petals acute to blunt, generally < 4.5 mm; anthers < 1.5 mm; fruit tip notched, conspicuous, ± = perianth, generally spheric to broadly ellipsoid; NCo ..... subsp. sitchensis

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Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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