Perennial sowthistle is an invasive species.
- Perennial sowthistle is found in colonies in cultivated fields, pastures, woodlands, roadsides and gardens.
- It spreads vegetatively, and by wind-borne seeds.
- While not thought to be problematic to healthy, native habitat, perennial sowthistle can reduce crop yields and increase cultivation and herbicide costs.
Perennial sowthistle should be reported. The Minnesota Department of Natural Resources provides detailed recommendations for reporting invasive species.
How to identify perennial sowthistle
- Perennial herbaceous plant, reaches heights of two to five feet.
- Vertical, single stem; branches near the top into several flower stalks.
- Stems emit a sticky, milky sap with a sour odor when broken.
- Alternate leaves up to twelve inches long; decrease in size as the leaves ascend the plant.
- Lower leaves are deeply lobed, upper leaves clasp the stem.
- Similar in appearance to dandelion leaves, but have teeth ending in small, sharp spines.
- Bright yellow, two inches-wide dandelion-like flowers develop at the tips of branches.
- Flowers open two to three hours after sunrise and close around noon.
- Blooms from June through October.
- Reddish-brown, tufted, dispersed by the wind.
- Widely spreading white brittle roots penetrating five to ten feet, produces new plants from small root pieces.
Reviewed in 2019