Erigeron filifolius, commonly known as thread-leaf fleabane, is a perennial herb that is native to a variety of habitats including open woodlands, meadows, grasslands, and rocky slopes in western North America. Its range extends from British Columbia, Washington, Oregon, and northern California, eastward to southern Idaho and northeast Nevada. It can be found at a wide range of elevations, from sea level to 7874 feet. The plant typically grows up to 20 inches tall and has distinctive long, thin leaves that can reach up to 3 inches in length. Thread-leaf fleabane produces flower heads on each stem, either singly or in clusters of up to 10, with each head containing up to 125 white, blue, pink, or lavender ray florets encircling yellow disc florets. The flowering season is generally from late spring to early fall, and the flowers are moderately showy, attracting pollinators such as bees and butterflies.

Thread-leaf fleabane is valued for its drought tolerance and ability to thrive in poor soils, making it a suitable choice for xeriscaping and naturalized areas. It is often used in wildflower gardens, rock gardens, and borders for its delicate foliage and charming flowers. This plant prefers full sun to part shade and requires well-drained soil. It is relatively low maintenance but can be susceptible to powdery mildew in humid conditions. Thread-leaf fleabane is not known for aggressive roots or significant disease problems, making it a reliable and attractive addition to diverse garden settings.CC BY-SA 4.0