Carex laxa

Wahlenberg

Kongl. Vetensk. Acad. Nya Handl. 24: 162. 1803.

Treatment appears in FNA Volume 23. Treatment on page 428. Mentioned on page 425, 427.

Plants colonial, long-rhizomatous. Culms 15–40 cm, smooth distally. Leaves: proximal sheaths greenish to pale brownish, ± spongy and septate-nodulose; ligules 1.4–3.5 mm, longer than wide; blades green, ± flat, 2–25 cm × 1–2.5 (–3.5) mm, those of fertile and vegetative shoots similar. Inflorescences 4–12 (–20) cm, 1.25–2.75 times longer than proximal bract; proximal bracts 1.8–7 (–13) cm, sheaths 0.9–2.2 (–3.5) cm, blades 0.9–5 (–9.5) cm; pistillate spikes 1–2, short cylindric, 0.6–1.5 cm × 4–6 mm; lateral spikes nodding on flexible peduncles. Pistillate scales reddish-brown tinged, ovate, broadly acute or obtuse. Perigynia (3–) 5–18, dense, glaucous-green, finely many-veined, 2.8–4 × 1.2–1.5 mm, apex gradually tapered to entire orifice, papillose; beak absent or poorly defined, to 0.3 mm. Achenes light to dark-brown, 1.5 –1.9 × 1–1.2 mm.


Phenology: Fruiting early–mid summer.
Habitat: Fens
Elevation: 900–1100 m

Discussion

Carex laxa superficially resembles C. limosa in size and habit; it is easily distinguished by its sheathing proximal inflorescence bracts, by its rhizomatous habit, and by its roots lacking a dense covering of root hairs. Carex limosa has sheathless inflorescence bracts, is stoloniferous, and has roots densely covered with yellowish orange root hairs. Carex laxa may well be overlooked in the north, being mistaken in the field for the more common C. limosa.

Selected References

None.

Lower Taxa

None.
... more about "Carex laxa"
light +  and dark-brown +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.19 cm1.9 mm <br />0.0019 m <br />) +
trigonous +
smaller +
1mm;1.2mm +
not septate-nodulose +
not +  and beaked +
papillose +
Paul E. Rothrock +  and A. A. Reznicek +
Wahlenberg +
shortened +
tapering +
0.18 cm1.8 mm <br />0.0018 m <br /> (0.22 cm2.2 mm <br />0.0022 m <br />) +
0 cm0 mm <br />0 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
5 cm50 mm <br />0.05 m <br /> (9.5 cm95 mm <br />0.095 m <br />) +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
2 cm20 mm <br />0.02 m <br /> (25 cm250 mm <br />0.25 m <br />) +
m--shaped +
0.9 cm9 mm <br />0.009 m <br /> (?) +  and 5 cm50 mm <br />0.05 m <br /> (?) +
1mm;2.5mm +
glumaceous +  and foliaceous +
2-ranked +  and arranged +
ascending +  and appressed +
scale-like +  and leaflike +
parallel +  and divergent +
terete +, rolled +  and plicate +
purple +  and brown +
round +  and trigonous +
15 cm150 mm <br />0.15 m <br /> (40 cm400 mm <br />0.4 m <br />) +
Yukon +, Alaska +  and Eurasia +
900–1100 m +
open +, pistillate +  and staminate +
hypogynous +  and subtending +
biconvex +  and trigonous +
12 cm120 mm <br />0.12 m <br /> (20 cm200 mm <br />0.2 m <br />) +
1.25-2.75 times longer than proximal bract +
4 cm40 mm <br />0.04 m <br /> (12 cm120 mm <br />0.12 m <br />) +
prophyllate +, pedunculate +  and pistillate +
multi-ranked +, 2-ranked +, 3-ranked +  and alternate +
basal +  and cauline +
longer than wide +
0.14 cm1.4 mm <br />0.0014 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
bidentate +  and entire +
with (1-)3-6(-30) bristles and/or scales +
glaucous-green +
0.28 cm2.8 mm <br />0.0028 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
ascending +  and spreading +
0.12 cm1.2 mm <br />0.0012 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
Fruiting early–mid summer. +
2-3(-4)-carpellate +
3 (?) +  and 1 (?) +
long-sheathing +  and leaflike +
7 cm70 mm <br />0.07 m <br /> (13 cm130 mm <br />0.13 m <br />) +
1.8 cm18 mm <br />0.018 m <br /> (7 cm70 mm <br />0.07 m <br />) +
septate-nodulose +
Kongl. Vetensk. Acad. Nya Handl. +
adventitious +
reddish-brown tinged +
basal +  and proximal +
obtuse;acute;ovate +
2.2 cm22 mm <br />0.022 m <br /> (3.5 cm35 mm <br />0.035 m <br />) +
cylindric +
0.9 cm9 mm <br />0.009 m <br /> (2.2 cm22 mm <br />0.022 m <br />) +
vegetative +  and fertile +
0.6 cm6 mm <br />0.006 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
cylindric +
0.4 cm4 mm <br />0.004 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
1 (?) +  and 3 (?) +
septate +, hollow +  and solid +
compressed +, terete +  and trigonous +
papillate +
deciduous +
2-3(-4)-fid +
Carex laxa +
Carex sect. Paniceae +
species +
plant +  and colonial +
0 cm0 mm <br />0 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +