Prickly Sow Thistle (Sonchus asper)

Picture Notes: The picture of the plant above (Fig. 01), was taken along the hillside just above the parking lot at Red Spring in the Calico Basin of the Red Rock Canyon National Conservation Area (RRCNCA).

Description: The Sonchus asper, also know as the Sharp-fringed Sow Thistle, Prickly Sow Thistle, Spiny Sow Thistle, or Spiny-leaved Sow Thistle) is an annual weed with very spiny leaves and yellow flowers that resemble those of a dandelion. The flowers, 3/4 to 1-inch across, grow in clusters near the tip of the stems. The upper and middle leaves are bluish-green, simple, lanceolate, with wavy and sometimes lobed margins and are covered in spines on both the margins and beneath. The base of the leaf surrounds the stem. A full-grown plant can reach 5-6 feet in height. The stem is smooth and glandular hairs are absent from it and the floral bracts. They can be found in vacant lots, roadsides, fields, and other recently disturbed areas throughout most of North America.