They are biennial or perennial plants, rarely annuals or subshrubs, growing to 0.5 to 3 metres (1.6 to 9.8 ft) tall. The plants first form a dense rosette of leaves at ground level, subsequently sending up a tall flowering stem. Biennial plants form the rosette the first year and the stem the following season. The leaves are spirally arranged, often densely hairy, though glabrous (hairless) in some species. The flowers have five symmetrical petals petal colours in different species include yellow (most common), orange, red-brown, purple, blue, or white. The fruit is a capsule containing numerous minute seeds.