

Toothed Flatsedge Cyperus dentatus
Toothed Flatsedge is a perennial grass native to Canada and the lower 48 states. It blooms Aug – Sep.
More about this plant
Cyperus dentatus, also known as toothed flatsedge, is a species of flowering plant in the sedge family Cyperaceae. It is native to eastern North America, from Nova Scotia in Canada southward to Virginia in the United States. Disjunct populations occur in western Virginia, southeastern Tennessee, and northwestern Indiana south of Lake Michigan. In the early 19th century, botanists formally described the species based on plants found on the banks of the Susquehanna River in Pennsylvania, in the pine barrens of New Jersey, and in New England. Its range was once thought to extend into the southern U.S. states of Georgia, South Carolina, and North Carolina but some botanists believe these reports may actually be based on Cyperus lecontei, a close look-alike. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 5 derived from its U.S. range
- Lifespan
- Perennial
- Flower colour
- Green AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~5 caterpillar species
Cyperus supports ~5 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 modest genus.
Recorded feeding on Cyperus in North America, including:
+ 4 more species → ↑ show fewer
How we know this (2) Methods & honest limits
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.
McKenzie et al. assigned each species a flower colour with a GPT-4V vision model over iNaturalist photos. We use the confident tier plus a separately-labelled lower-confidence top-up (mostly inconspicuous green/brown flowers), and render it as a small tint — never as an asserted fact, and kept out of the written synopsis.
Honest limits: AI image inference (~87% expert agreement on the confident tier); a decorative, confidence-tiered indicator, not a measured trait.
Sources for this entry (18) 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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