Ageratina occidentalis, commonly known as Western Snakeroot, is a deciduous perennial herb or subshrub native to mountainous regions, forest clearings, and streambanks in the Western United States. It typically grows to a height of approximately 70 centimeters with fuzzy green or purple stems. The leaves are distinctive for their glandular texture and triangular shape with serrated edges. From late summer to fall, it produces a dense cluster of fuzzy flower heads with long, protruding disc florets in shades of white, pink, and blue, although the flowers are not particularly showy. The fruit is an achene with a rough, bristly pappus that aids in wind dispersal.

Western Snakeroot is valued for its adaptability to a range of soil conditions and its ability to thrive in both full sun and partial shade. It is often used in native plant gardens, restoration projects, and as a component of pollinator-friendly landscapes. While it is not known for aggressive growth, it can spread through rhizomes and self-seeding, which should be considered in garden planning. It is relatively low-maintenance, requiring medium amounts of water and tolerating various drainage speeds. There are no significant disease issues, but it can occasionally suffer from rust or mildew in overly moist conditions.CC BY-SA 4.0