Cirsium horridulum var. horridulum

A variety of the Bull Thistle, the Common Yellow Thistle is a biennial plant in the Asteraceae (daisy) family that is native to North America on the Coastal Plain from southern Maine to Florida and west to Texas as well as Mexico, Belize, Guatemala, Honduras and the Bahamas. In North Carolina, it is rarely seen in the mountains, but it is the most often seen thistle in the Piedmont. It differs from the typical variety in having densely wooly hairs on the stems, leaf undersides, and bracts surrounding the flower head. The plant is spiny all over with a tall branching stem that contains large yellowish or red-purple flower heads. The plant often grows 2 to 5-1/2 feet tall (sometimes as high as 8 feet) with clasping leaves that are 8 to 24 inches long. It is often found in disturbed areas, roadsides and woodlands. The genus name comes from the Greek kersion which means thistle.

Bull Thistle prefers sunny, open areas. It grows in all types of soils from moist to dry conditions, but it doesn't do well sitting in salt or brackish water. It grows best in sandy soil.  It is self-pollinated via seed but expect it to take two years until it flowers.

It is a high-value nectar plant for bees and butterflies and the songbirds eat the seeds and use the tufts of the seeds for their nests. The seeds are rich in oil, an important food source for seed-eating birds. It is the host plant for the Little Metalmark butterfly (Calephelis virginiensis), which has three to five broods from March-October, and Painted Lady Butterfly (Vanessa cardui) which have one to three flights in the east from May-October and three to four flights in south Texas from October-April. Flowers are also attractive to hummingbirds. Members of this genus support the following specialized bees: Thistle Long-horned bee Melissodes desponsus, plus Osmia (Helicosmia) chalybea and Osmia (Helicosmia) texana.

Bull thistle is a great option in your meadow garden or naturalized area when looking for native host plants for the Little Metalmark butterfly or the Painted Lady butterfly. Select with care, as this species may spread into areas (such a lawns and flower beds) where thistles are not wanted. Some gardeners object to their spininess.

Quick ID Hints:

• White densely wooly stems and underside of the leaves.

Insects, Diseases, and Other Plant Problems: No significant problems.

More information on Cirsium horridulum.