

Oregon Goldthread Coptis laciniata
Oregon Goldthread is a perennial wildflower native to the lower 48 states. It blooms Mar – Aug.
More about this plant
Coptis laciniata is a species of flowering plant in the buttercup family known by the common name Oregon goldthread. It is native to Washington, Oregon, and northern California on the west coast of the United States, where it grows in wet habitat in the understory of mountain and coastal coniferous forests. It is a small perennial herb creeping on a yellow stolon through other vegetation and leaf litter. There are a few leaves on its short stem which are divided into leaflets subdivided into several toothed lobes. The stemlike inflorescence arises up to 19 centimeters tall from the stem at ground level. Each flower is an array of thin, threadlike petals. Six to 12 fruits arise on short stalks, arranged in a ring. The fruits are shiny, hairless follicles, each roughly a centimeter long. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 9 derived from its U.S. range
- Lifespan
- Perennial
How we know this (1) 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.
Sources for this entry (14) Open & cited
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