About Cirsium scariosum Nutt.
Cirsium scariosum Nutt. is a variable plant species that grows across a wide range of habitat types. It is divided into several geographic races, most of which were previously classified as separate species. These races intergrade with one another, but can also show very distinct morphological differences. It is generally a biennial or perennial herb, and grows in three main forms: a stemless flat rosette with a cluster of flower heads at its center, a mounded growth form with a short erect stem, or a fully erect form that reaches up to 200 cm (79 in) in height. When a stem is present, it is typically fleshy, ridged, and woolly in texture. Its leaves are sharply toothed or cut into toothed lobes, edged with spines, and reach up to 40 centimetres (16 inches) in length at their longest point near the base of the plant. The inflorescence bears several flower heads, each growing up to 4 centimeters long and 5 centimeters wide. Each flower head is lined with phyllaries that may have spines and teeth, and filled with white to purple disc florets; it does not produce ray florets. The fruit is a compressed achene a few millimeters long, topped with a pappus that can reach 3 centimeters in length.
