Common groundsel is a low, simple to branched annual with lax to erect stems from 10-40 cm high. The herbage is typically smooth with only a few hairs at most. It has pinnately divided leaves with serrate margins. The lower stem leaves are stalked while the others are sessile.
The flower heads are small (smaller than eraser heads) with tiny disk flowers, and lacking ray flowers. The disk averages 5-10 mm wide. The 21 involucral bracts are all the same length and are black-tipped, the involucre ranging from 5-8 mm high. Common groundsel selfseeds readily so represents a weed which can spread easily.
Common butterweed is a weedy species of waste areas or disturbed places such as gardens, yards, and roadsides.
Found over much of North America (an introduction from Eurasia), common butterweed has become a pesky weed in oft-disturbed places.
In the Columbia River Gorge it may be found between the elevations of 0'-500' from Troutdale, OR east towards Lyle, WA.
Several flower heads of common butterweed as seen in weedy areas along biking and hiking trails in the Labyrinth, mid-Columbia River Gorge..............April 15, 2010. Note the black tips to the lowest involucral bracts and cobwebby hairs on the pedicels beneath each flower head.