Ageratina adenophora
Crofton weed
Overview
Ageratina adenophora is a perennial, semi-woody plant growing 3-6 feet (0.9-1.8 m) tall, with purplish, glandular-hairy stems that branch in the upper half. The opposite leaves are triangular to diamond-shaped, 2-4 inches (5-10 cm) long, with toothed margins and a sticky surface. Flat-topped clusters of small white flower heads, each about 0.2 inch (5 mm) across and lacking ray florets, open from winter into spring. A single plant can produce tens of thousands of tiny, bristle-tufted seeds that spread on wind, water, and machinery, and the stems also root where they touch moist ground. The foliage contains toxins that cause fatal lung disease in horses and can sicken other livestock. It grows in disturbed ground, gullies, forest margins, and pasture in mild, moist climates. Native to Mexico, the species has become a serious weed in Australia, New Zealand, southern Africa, southern Asia, and parts of California and Hawaii. A limitation for any cultivation is its rapid spread and toxicity, which have led to legal restrictions on the plant in several countries.
Native Range
Ageratina adenophora, known as Crofton weed or sticky snakeroot, is native to Mexico and parts of Central America. It has spread through warm, moist regions worldwide, including Australia, New Zealand, India, China, southern Africa, Hawaii, and coastal California.Suggested Uses
Ageratina adenophora is classed as a noxious or invasive weed across its introduced range and is not planted in gardens. In affected regions it is targeted for removal from pasture, gullies, and bushland. Historic ornamental use has been replaced by control programmes using cutting, herbicide, and biological agents.How to Identify
Appearance
Size & Dimensions
Height3' - 6'
Width/Spread2' - 4'
Reaches mature size in approximately 2 years
Bloom Information
Clusters of small white flower heads open from late winter into spring, roughly July to October in the southern hemisphere and winter to spring elsewhere. Each plant carries many heads over several weeks. Large numbers of wind-borne seeds follow and disperse widely.
Detailed Descriptions
Foliage Description
greenGrowing Conditions
Sun Requirements
Requires 4-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight