These excellent woodland plants come mainly from North America, with most species in the eastern part, some in the west (with a gap in between), and a few stragglers in Japan and China. As their name implies, they have three of everything: three large leaflets, often beautifully mottled, on each of the leaves, three sepals, and at the centre of the leaves the flower, with three petals, sometimes long and narrow and sometimes broad and showy. They are slow to raise from seed, but once established each thick rhizome gradually multiplies, eventually giving fine clumps. They are all good plants for a leafy soil in a shady places, and the best are stunning. All are well worth waiting for.

Trillium erectum f. albiflorum has plain green leaves and white flowers on short stems arising from the centre of the leaves. This is one of the quickest species to form a good clump.