Idaho goldthread
Coptis occidentalis
Family: Ranunculaceae
What it is like
Coptis occidentalis is an evergreen Perennial growing to 0.2 m (0ft 8in). See above for USDA hardiness. It is hardy to UK zone 4. It is in leaf all year, in flower from April to May. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.
Height (m): 0.2
Where it is found
Moist coniferous woods at elevations of 500-2000 metres in the Rocky Mountains.
Western N. America - Idaho, Montana and Washington.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 0
Medicine
Rating: 0
Other
Rating: 2
A yellow dye is obtained from the root. Can be grown as a ground cover plant in the peat garden.
Dye: Plants that provide dyes.
Ground cover: Ground Cover
How it is grown
Requires a light moist humus-rich slightly acidic soil with a northerly aspect or light shade. This species is closely related to C. laciniata.
Propagating it: Seed - best sown in a greenhouse as soon as it is ripe in an ericaceous compost. Seal the pot in a polythene bag until germination takes place, which is usually within 1 - 6 months at 10°c. Stored seed should be sown as early in the year as possible. Four weeks cold stratification may be beneficial. Prick out the seedlings into individual pots when they are large enough to handle and grow on in a shady part of the greenhouse for at least their first winter. Plant them out in mid-autumn or in spring. Division in spring.
Best place to grow: Woodland Garden Dappled Shade; Shady Edge; Ground Cover;
Habit: Perennial
Hardiness: 4-8
Growth:
Soil: Light (sandy), medium, heavy (clay)
Shade: Semi-shade, no shade
Moisture: Moist
Things to keep in mind
Although no specific mention of toxicity has been found for this species, it belongs to a family that contains many species that are mildly toxic and so it is wise to treat this plant with some caution.