Luzula arctica
Luzula subg. Luzula
arctic wood rush
densely cespitose, 5-20 cm.
sheaths brown to straw-colored;
basal leaves to 10 cm × 4 mm;
cauline leaves usually 2, reduced.
apex generally callous.
glomerules 1-3, sessile;
proximal inflorescence bract inconspicuous, brown, much shorter to ± equaling inflorescence, apex often clear, dentate;
bracts deep brown, margins dentate;
bracteoles deep brown, margins dentate.
spikelike or umbellate.
tepals deep brown with narrow clear margins and apex, 1.7-2.1 mm;
anthers ± equaling filament length.
in glomerules.
dark reddish to blackish, shining, spheric, 1.8-2.1 mm, usually exceeding tepals.
translucent, clear brown, broadly elliptic, with few entangled hairs, 1-1.2 mm.
usually without tuft of hairs;
caruncle conspicuous to barely visible.
= 24.
Luzula arctica
Luzula subg. Luzula
AK; BC; LB; MB; NT; NU; QC; YT; Greenland; Eurasia
Temperate and arctic regions and tropical mountains
Species ca. 50 (15 species in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Inflorescences dense, spikelike, though often interrupted, nodding | L. spicata |
1. Inflorescences of distinct glomerules, not spikelike, sometimes lax but not nodding. | → 2 |
2. Inflorescences of sessile glomerules only or with smaller glomerules on short branches. | → 3 |
2. Inflorescences with central glomerule(s) sessile or nearly sessile, always with other pedunculate glomerules. | → 8 |
3. Proximal inflorescence bract conspicuous, usually well-exceeding inflorescence. | → 4 |
3. Proximal inflorescence bract inconspicuous. | → 7 |
4. Seeds 1.3 mm, caruncle absent. | L. subcapitata |
4. Seeds 0.8–1.5 mm, with caruncle. | → 5 |
5. Seeds 0.8 mm, caruncle 0.2 mm | L. orestera |
5. Seeds 0.9–1.5 mm, caruncle either barely visible or at least 0.3 mm. | → 6 |
6. Capsules ovoid; caruncle barely visible. | L. groenlandica |
6. Capsules spheric; caruncle 0.3-0.8 mm | L. comosa |
7. Tepals shorter than capsule; bracteoles deep brown, dentate | L. arctica |
7. Tepals and capsule about equal; bracteoles clear to deep brown, conspicuously fimbriate | L. confusa |
8. Inflorescence branches straight. | → 9 |
8. Inflorescence branches arching. | → 14 |
9. Inflorescence branches mostly erect; glomerules mostly cylindric. | → 10 |
9. Inflorescence branches divergent as much as 90°; glomerules not cylindric. | → 12 |
10. Tepals pale or with brown central area at maturity; seeds 0.7–1 mm; caruncle 0.2–0.3 mm | L. pallidula |
10. Tepals pale brown to chestnut brown to blackish at maturity; seeds 0.9–1.7 mm; caruncle 0.2–0.7 mm. | → 11 |
11. Seeds 1.1–1.7 mm; caruncle 0.2–0.6 mm | L. multiflora |
11. Seeds 0.9–1.3 mm; caruncle 0.5–0.7 mm | L. bulbosa |
12. Leaves with callous apex; glomerules sessile to congested to spreading. | → 13 |
12. Leaves without callous apex, glomerules on elongate peduncles | L. echinata |
13. Stolons slender and short, conspicuous rhizomes present | L. campestris |
13. Stolons or conspicuous rhizomes absent. | L. comosa |
14. Inflorescence branches arching in all directions; basal leaf sheaths bluish green | L. subcongesta |
14. Inflorescence branches arching in 1 direction; basal leaf sheaths variously colored. | → 15 |
15. Basal leaf sheaths dull brown-gray to green; cauline leaves as large or larger than basal leaves | L. kjellmaniana |
15. Basal leaf sheaths shining reddish to brown to purple; cauline leaves usually smaller than basal leaves. | → 16 |
16. Basal and cauline leaves not reaching inflorescence | L. arcuata subsp. unalaschkensis |
16. Basal and especially cauline leaves often reaching or exceeding inflorescence | L. confusa |
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