I recently saw this plant growing on the corner of my street. Sow Thistle is native to Eurasia, but has spread to other countries. In the United States, grows in areas such as pastures, roadsides, bushlands and the shorelines of lakes, rivers, and sea coast.
Many people tend to confuse Sow Thistle with Dandelions. Sow Thistle usually has many flowers sprouting out on each stalk, while Dandelion only has one flower per stalk. Sow Thistle leaves grow all the way up the stalk, as well as at the base of the plant. Dandelion leaves are only at the base.
Sow Thistle’s flowers are grouped in loose clusters at the end of stalks. A plant may have up to 20 flower heads, with only a few blooming at once. The flowers open two to three hours after sunrise and close around noon.
The flowerheads mature to form fluffy spheres that are three to four inches diameter and comprised of seeds with long, slender beaks on white, umbrella-like structures that aid in their dispersal by wind. The fluffy sphere of seeds looks similar to that of a Dandelion, only much larger.
This plant’s leaves are alternate, simple, and are the broadest near or above the middle – they can be up to a foot long. They are deeply lobed along the margin and the spiny toothed, lobed leaf bases clasp Sow Thistle’s stem. Its stems are filled with milky white sap.
This plant is also known as Field Milk Thistle, Field Sow Thistle, Perennial Sow-thistle, Corn Sow Thistle, Dindle, Gutweed, Swine Thistle, or Tree Sow Thistle.