

Northern Cluster Sedge Carex arcta
Northern Cluster Sedge is a perennial grass native to Alaska, Canada, and the lower 48 states. It blooms Jun – Aug.
More about this plant
Carex arcta is a species of sedge known by the common name northern cluster sedge. It is native to northern North America including most of Canada and northern parts of the United States. It grows in wet areas, especially in coniferous forests. This sedge produces dense clumps of erect stems up to about 80 centimetres (31 in) high. The leaves are pale green to grayish, flat, and have reddish or purple-dotted sheaths at the base, and they are sometimes longer than the stems. The inflorescence is a dense, oblong cluster of up to 15 spikes of pointed flowers, each cluster up to 3–4 cm (1.2–1.6 in) long and each individual spike up to 1 cm (0.39 in) long. The fruit is covered in a sac called a perigynium which is greenish and veined with a reddish tip. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 5 derived from its U.S. range
- Lifespan
- Perennial
- Foliage
- Broadleaf
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~36 caterpillar species
Carex supports ~36 caterpillar species.
Native butterfly & moth caterpillars are the base of the terrestrial food web — most songbirds rear their young almost entirely on them. As a host for native Lepidoptera this is a strong genus.
Recorded feeding on Carex in North America, including:
+ 8 more species → ↑ show fewer
How we know this (2) Methods & honest limits
A recorded categorical fact: each species is tagged C3 (standard), C4 (heat/water-efficient) or CAM (succulent, night-time CO₂ uptake) — or a facultative combination. We only show a trait card for the noteworthy C4/CAM cases; C3 is the unremarkable majority, kept in the data but not surfaced as a card.
We take the plant’s U.S. county range and look up each county’s long-term climate, then summarise: native rainfall = the median annual rainfall across its counties; heat tolerance = the warm end (90th percentile) of average temperature across its range (mirroring how our cold-hardiness floor uses an extreme). Counties + medians blunt the roadside/observer bias that makes point-level climate unreliable. Needs at least five placeable counties.
Honest limits: A realized, sampling-biased niche (where it has been recorded, not its physiological optimum), and county climate is coarse — large Western counties span deserts and mountains. Derived guide, never a measured fact.
Sources for this entry (20) Open & cited
Cite this page Open data, please attribute
PlantKey’s data is open under CC BY-SA 4.0 — free to reuse and adapt, with attribution and the same licence. Photos keep their own per-image licence + credit (see Sources above).
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