Blue Cohosh Caulophyllum thalictroides
- Phonetic Spelling
- kaw-loh-FILL-um thal-ik-TROY-deez
- This plant has low severity poison characteristics.
- See below
- Description
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Blue Cohosh is a perennial herbaceous wildflower typically found in woodlands of oaks or maples where the native ground flora is still intact. Blue Cohosh is valued for its lacy, blue-green foliage and clusters of blue, fruit-like seeds. Leaves appear at mid-stem, blue in spring and turning bluish-green at maturity. Young plants are covered with a waxy bloom. Flowers give way in summer to attractive blue berry-like seeds (outer seed coating turns fleshy and blue as seeds mature) which resemble small grapes and provide ornamental interest into fall.
The genus name comes from the Greek words kaulos meaning a stem and phyllon meaning a leaf. The species name recognizes that the foliage is similar to meadow rue (Thalictrum).Blue Cohosh prefers dappled sunlight and shady woodland with average moisture and fertile, slightly acidic, loamy soil containing organic matter from decaying leaves and other plant materials. The soil should be consistently moist and not dry out. The large seeds are difficult to germinate and the plant is slow to spread on its own, but it can be divided just after flowering. However, once it becomes established at a favorable site, Blue Cohosh is long-lived and established plants are generally best left undisturbed. It can also spread very slowly by rhizomes to form colonies.
Diseases, Insect Pests, and Other Plant Problems:
No known diseases or insect pests.
- See this plant in the following landscape:
- Cultivars / Varieties:
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- Tags:
- Cultivars / Varieties:
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- Tags:
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Attributes:
- Genus:
- Caulophyllum
- Species:
- thalictroides
- Family:
- Berberidaceae
- Life Cycle:
- Perennial
- Recommended Propagation Strategy:
- Division
- Seed
- Country Or Region Of Origin:
- Central and Eastern Canada to North Central Eastern United State
- Distribution:
- New Brunswick south to South Carolina, west to Arkansas and north to North Dakota and Manitoba.
- Wildlife Value:
- Pollen and nectar attract insects, foliage attracts caterpillars, and mice feed on the berries.
- Play Value:
- Wildlife Food Source
- Edibility:
- Seeds are toxic.
- Dimensions:
- Height: 1 ft. 0 in. - 2 ft. 0 in.
- Width: 0 ft. 6 in. - 1 ft. 0 in.
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Whole Plant Traits:
- Plant Type:
- Herbaceous Perennial
- Native Plant
- Poisonous
- Woody Plant Leaf Characteristics:
- Deciduous
- Habit/Form:
- Ascending
- Erect
- Growth Rate:
- Slow
- Maintenance:
- Medium
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Cultural Conditions:
- Light:
- Dappled Sunlight (Shade through upper canopy all day)
- Deep shade (Less than 2 hours to no direct sunlight)
- Partial Shade (Direct sunlight only part of the day, 2-6 hours)
- Soil Texture:
- High Organic Matter
- Loam (Silt)
- Sand
- Soil pH:
- Acid (<6.0)
- Alkaline (>8.0)
- Neutral (6.0-8.0)
- Soil Drainage:
- Good Drainage
- Moist
- NC Region:
- Mountains
- Piedmont
- USDA Plant Hardiness Zone:
- 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b
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Fruit:
- Fruit Color:
- Blue
- Gold/Yellow
- Green
- Fruit Value To Gardener:
- Showy
- Display/Harvest Time:
- Fall
- Fruit Type:
- Berry
- Fruit Length:
- < 1 inch
- Fruit Width:
- < 1 inch
- Fruit Description:
- After flowering, berry-like seeds appear, 1/3 of an inch across. These seeds are initially green, but they later become bright blue at maturity during the summer. The seed coat is fleshy. Because of the bright blue seed coats, woodland birds disperse the seeds, which are known to be toxic to humans.
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Flowers:
- Flower Color:
- Gold/Yellow
- Green
- Flower Inflorescence:
- Panicle
- Flower Bloom Time:
- Spring
- Flower Shape:
- Radial
- Flower Petals:
- 6 petals/rays
- Colored Sepals
- Flower Size:
- < 1 inch
- Flower Description:
- On a flowering plant, the central stem terminates in a round floral panicle about 1 to 3 inches long; each panicle has 5 to 30 flowers. Individual flowers are about 1/3 of an inch across, consisting of 6 petaloid sepals, insignificant petals, 6 stamens, and an ovoid ovary with a beak-like style. Underneath each flower, there are 3 to 4 green bractlets that resemble sepals. The blooming period occurs in spring before the leaves have fully developed.
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Leaves:
- Woody Plant Leaf Characteristics:
- Deciduous
- Leaf Color:
- Green
- Leaf Value To Gardener:
- Showy
- Leaf Type:
- Compound (Pinnately , Bipinnately, Palmately)
- Leaf Arrangement:
- Alternate
- Leaf Shape:
- Oblong
- Obovate
- Ovate
- Leaf Margin:
- Entire
- Hairs Present:
- No
- Leaf Length:
- 1-3 inches
- Leaf Width:
- 1-3 inches
- Leaf Description:
- On a flowering plant, a compound leaf is located at the middle of the central stem, where it is divided into a whorl of 3 compound leaflets. Each leaflet is divided into 9 simple subleaflets arranged in groups of 3. The subleaflets are 1 to 3 inches long and ¾ to 2 inches across, broadly ovate-oblong to obovate-oblong, and smooth along their margins. The surface of the subleaflets is glabrous and green. The upper compound leaf of a flowering plant is located under the inflorescence. This compound leaf resembles the lower compound leaf, except its 3 compound leaflets are smaller in size.
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Stem:
- Stem Color:
- Green
- Purple/Lavender
- Stem Is Aromatic:
- No
- Stem Form:
- Straight
- Stem Surface:
- Smooth (glabrous)
- Stem Description:
- Unbranched erect central stem is light green to pale purple, terete, glabrous, and often glaucous.
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Landscape:
- Landscape Location:
- Naturalized Area
- Woodland
- Landscape Theme:
- Native Garden
- Shade Garden
- Attracts:
- Bees
- Small Mammals
- Resistance To Challenges:
- Deer
- Problems:
- Contact Dermatitis
- Poisonous to Humans
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Poisonous to Humans:
- Poison Severity:
- Low
- Poison Symptoms:
- Low level toxin if eaten. Can result in vomiting and diarrhea. If eaten in excess, can cause high blood pressure and symptoms similar to nicotine poisoning.
- Poison Toxic Principle:
- Alkaloids and saponins
- Causes Contact Dermatitis:
- Yes
- Poison Part:
- Roots
- Seeds
