The leaves are dark green with a broad final lobe and narrower irregular lobes along the sides. Each lobe ends in a short spine. In late spring an erect stem develops which grows up to 1.5m high. When this happens the rosette leaves die off. The stem has whitish-green ribs, it is usually branched about half way up.
Mature plants are stiff and spiny.
There are at least two forms of saffron thistle in Western Australia. The narrow leaf form appears to germinate more readily than the broad. There are also distinct differences in the shape of the seed and rate of stem growth. In early summer, single yellow compound flowers form at the end of each stem or branch. Lance-like spines surround each flower.