Elk Thistle

Cirsium scariosum is a variable species growing in a variety of habitat types. It is made up of several geographic races, most of which have been previously classified as species. The races intergrade but their morphologies can also be quite different. This is generally a biennial or perennial herb. It takes three main forms, a stemless, flat rosette with a cluster of flower heads in the centre, a mounding form with a short, erect stem, or a fully erect form reaching up to 200 cm (79 in) in height. When there is a stem it is usually fleshy, ridged, and woolly in texture. The leaves are sharply toothed or cut into toothed lobes, lined with spines, and up to 40 centimetres (16 inches) at their longest near the base of the plant. The inflorescence holds several flower heads, each up to 4 centimeters long and 5 cm wide. The flower head is lined with phyllaries which may have spines and teeth and filled with white to purple disc florets but no ray florets. The fruit is a compressed achene a few millimetres long topped with a pappus which may be 3 centimeters in length.