In general, the leaves are 50â250 millimetres (2â10 in) long or longer, simple, lobed, and form a basal rosette above the central taproot. The flower heads are yellow to orange coloured, and are open in the daytime, but closed at night. The heads are borne singly on a hollow stem (scape) that is usually leafless and rises 10â100 millimetres (3â8â3+7â8 in) or more above the leaves.