The button-like flower heads and the lacy, pinnately compound stem leaves of common tansy are shown as seen at the Sandy River Delta, Troutdale, Oregon..............September 8, 2012.
Common tansy is a weedy perennial species. Plants range from 40-150 cm tall. The basal leaves are tufted and largest, while those on the stems are reduced in size upwards on the stem. The leaves are numerous, often 10-20 cm long and up to 10 cm wide. Individual leaves are sessile or short-petioled, and compound-pinnate. Leaf margins are dissected.
The yellowish flower heads are all discoid, each being about 4-10 mm wide. Typically, the inflorescence consists of from 20-200 flower heads.
Common tansy has escaped from cultivation and is commonly seen as a plant of disturbed places, such as roadsides and fields.
Common tansy is native to the Old World. In North America it may be found across much of the United States and southern Canada.
In the Columbia River Gorge it may be found between the elevations of 0'-100' between Troutdale, OR and Cascade Locks, OR.
The button-like flower heads and the lacy, pinnately compound stem leaves of common tansy are shown above.