Trilliums are a group of rhizome perennials - normally herbaceous in that they die down each year. As you would expect by its name, the Trilliums have their foliage grouped in three leaves, and of course the various flower parts similarly grouped in three. Three petals, three sepals etc.
All of the Trilliums do well in woodland situations and will also tolerate full sun - though prefer moist soil. A shaded border is ideal, and the early growth and flower will do much to create additional interest to the early spring garden.
Trillium grandiflorum - image below - is well suited to providing a carpet of white flowers in spring - to be followed by lush foliage for most of the summer. Most of the Trilliums form a dense carpet of foliage, but should not simply be considered as ground cover plants. However, once established, they will smother out any weeds that dare to compete.
Trilliums normally flower in early to mid spring - rising from bare soil as a pleasant surprise year after year. They are relatively trouble free - other than the universal slug problem in the early spring.
Some of the better known Trilliums are listed for your convenience, but there is quite a wide range, which we will try to cover once we get suitable images.
Raising Trilliums from seed is a laborious procedure and you will need to be patient, with very little to see for around two years, and no flower for a further three or four years.
Rhizomes are the natural form of propagation of Trilliums - so go with the flow on this. Divide the plants, or cut sections of rhizomes and replant. A different approach, is to cut out the growing point of the rhizomes (and discard0 which will then induce the plant to product small offsets or plantlets. These can be removed replanted where necessary. They take a little time to get re-established.