This is the true species and NOT the plant of books and gardens. The imposter is usually one of two or three other species, most likely the large species chloropetalum or kurabayashi or sometimes the slightly smaller cuneatum. There is a massive amount of confusion amongst garden journalists, 90% of whom are simply repeating the errors of earlier writers with no actual experience of the plants, hence the mistake has passed down the generations.
True Trillium sessile is quite a rare, dwarf plant, only 12-15cm tall at most. It has delightfully clouded and silvered leaves held below small, deep red-brown stemless flowers. This has a quiet charm and is a good conversation point as well! Different and distinct. Easily grown under standard Trillium conditions sited as befits quite a dwarf plant. Fully hardy although it is early into growth. This will not usually be available on Spring after the end of February!