tremetol Ageratina altissima
Other Common Name(s):
Previously known as:
- Eupatorium rugosum
- Phonetic Spelling
- ah-jeh-rah-TEE-na all-TIS-see-mah
- This plant has high severity poison characteristics.
- See below
- Description
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White Snakeroot is a herbaceous perennial that can grow to 3 feet. The plant is native to woodland areas in the Eastern United States and typically occurs in rich or rocky woods, thickets, wood margins, and rocky areas. Garden uses include cottage gardens, wild gardens, woodland gardens, and naturalized areas. It may also be effective in shady corners of the border.
White Snakeroot is easily grown in average, medium to wet, well-drained soils in full sun to part shade. While it does well in dry soil, it prefers part shade in moist, organic soils. These plants have decidedly better shade tolerance than most other species of Eupatorium. The 'Chocolate' cultivar has purple leaves throughout the summer. This is one of the last wildflowers to bloom during the fall.
The root system consists of spreading rhizomes and shallow fibrous roots. This plant can spread by means of its rhizomes, or it can reseed itself into new areas. Because it spreads easily by seed, you should deadhead spent flower heads to avoid any unwanted self-seeding.
Reportedly, the erroneous belief that an extract of the roots was a remedy for snakebite led to the common name. However, settlers who drank milk from cows that fed on this plant often developed the disease called milk sickness. See information below for toxicity.
Diseases, Insects and Other Plant Problems:
The plant is susceptible to leaf miners and flea beetles may attack the foliage. Under optimum growing conditions, the plant can spread rapidly through self-seeding and rhizomes. Full sun in a dry situation can cause the leaves to turn yellow and wilt
- 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:
- Ageratina
- Species:
- altissima
- Family:
- Asteraceae (Compositae) - Aster or Sunflower Family
- Life Cycle:
- Perennial
- Recommended Propagation Strategy:
- Division
- Seed
- Country Or Region Of Origin:
- Native to woodlands in Eastern United States
- Wildlife Value:
- Flowers are attractive to butterflies, especially smaller species, and other pollinators, including leaf-cutting bees. Songbirds eat the seeds.
- Edibility:
- Toxic
- Dimensions:
- Height: 1 ft. 0 in. - 3 ft. 0 in.
- Width: 2 ft. 0 in. - 4 ft. 0 in.
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Whole Plant Traits:
- Plant Type:
- Herbaceous Perennial
- Native Plant
- Poisonous
- Wildflower
- Woody Plant Leaf Characteristics:
- Deciduous
- Habit/Form:
- Ascending
- Clumping
- Erect
- Maintenance:
- Low
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Cultural Conditions:
- Light:
- Deep shade (Less than 2 hours to no direct sunlight)
- Full sun (6 or more hours of direct sunlight a day)
- Partial Shade (Direct sunlight only part of the day, 2-6 hours)
- Soil Texture:
- Clay
- Loam (Silt)
- Soil Drainage:
- Good Drainage
- Moist
- Occasionally Dry
- Available Space To Plant:
- 3 feet-6 feet
- NC Region:
- Coastal
- Mountains
- Piedmont
- USDA Plant Hardiness Zone:
- 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
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Fruit:
- Fruit Color:
- Black
- Display/Harvest Time:
- Fall
- Fruit Type:
- Achene
- Fruit Length:
- < 1 inch
- Fruit Description:
- During autumn, each disk floret in a flowerhead is replaced by an achene with a small tuft of white hairs. These achenes are about 1/10 of an inch long, narrowly oblongoid in shape, 5-ribbed, and black; they are distributed by the wind.
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Flowers:
- Flower Color:
- White
- Flower Inflorescence:
- Corymb
- Panicle
- Flower Value To Gardener:
- Fragrant
- Long Bloom Season
- Showy
- Flower Bloom Time:
- Fall
- Summer
- Flower Size:
- 3-6 inches
- Flower Description:
- Small fluffy bright white flowers (composites with rays absent) atop smooth stems typically rising 3-5’ tall. It blooms from late summer to frost. The upper stems terminate in compound corymbs or flat-headed panicles of flowerheads that span 2 to 6 inches across. Each flowerhead is about ½" across and contains 10-30 disk florets that have brilliant white corollas and styles. There are no ray florets. Each small disk floret consists of a small tubular corolla with 5 lobes that are spreading and pointed and a divided style that is strongly exerted from the corolla. At the base of each flowerhead, there is a single series of linear floral bracts that are light green and non-overlapping. The blooming period lasts about 2 months for a colony of plants.
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Leaves:
- Woody Plant Leaf Characteristics:
- Deciduous
- Leaf Color:
- Green
- Leaf Feel:
- Prickly
- Leaf Type:
- Needles
- Leaf Arrangement:
- Opposite
- Leaf Shape:
- Cordate
- Lanceolate
- Ovate
- Leaf Margin:
- Crenate
- Serrate
- Hairs Present:
- No
- Leaf Length:
- 3-6 inches
- Leaf Description:
- White snakeroot leaves have long, nettle-like, stalks. The leaf shape ranges from lance like to elliptic-oval. The 3 to 6 inch leaves are paired along the stems and become smaller as they ascend the stems. The lower leaves are cordate to cordate-ovate, while the upper leaves are broadly lanceolate to lanceolate. All of the leaves are largely hairless and strongly serrated-crenate along their margins; they are medium to dark green on their upper surfaces and light green on their lower surfaces. There are 3 prominent veins on the upper surface of each leaf (particularly the lower ones), while the lower surface has an elevated network of veins.
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Stem:
- Stem Color:
- Brown/Copper
- Green
- Stem Is Aromatic:
- No
- Stem Form:
- Straight
- Stem Surface:
- Smooth (glabrous)
- Stem Description:
- The light green to tan stems are terete and hairless (or nearly so). Stems are upright and tall.
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Landscape:
- Landscape Location:
- Woodland
- Landscape Theme:
- Butterfly Garden
- Native Garden
- Pollinator Garden
- Rain Garden
- Shade Garden
- Water Garden
- Attracts:
- Butterflies
- Pollinators
- Songbirds
- Resistance To Challenges:
- Deer
- Problems:
- Poisonous to Humans
- Problem for Horses
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Poisonous to Humans:
- Poison Severity:
- High
- Poison Symptoms:
- The plant is highly toxic and may be fatal if eaten. Toxicity is characterized by weakness, nausea, abdominal pain, vomiting, delirium, cardiac damage, prostration and eventually, coma.
- Poison Toxic Principle:
- Tremetone, a ketone, and glycosides
- Causes Contact Dermatitis:
- No
- Poison Part:
- Flowers
- Leaves
- Roots
- Sap/Juice
- Seeds
- Stems