Trilliaceae
Trilliaceae was a family of flowering plants first named in 1846; however, most taxonomists now consider the genera formerly assigned to it to belong to the family Liliaceae. The APG IV system, of 2016, does not recognize such a family either and assigns the plants involved to family Melanthiaceae, tribe Parideae.
Nevertheless, some taxonomists still recognize a separate family Trilliaceae. The most important genus in North America is Trillium, and the taxonomy of that genus has always been controversial.
A recent treatment stated that the family Trilliaceae, which exhibits an arcto-tertiary distribution, comprises six genera. Three of these exhibit a wide distribution:Paris from Iceland to Japan,Daiswa from eastern Asia, andTrillium from North America and eastern Asia
Three are monotypic, endemic genera:Trillidium govanianum, with a tepaloid inflorescence, from the Himalayan Mountains;Kinugasa japonica, with petaloid sepals, from Japan; andPseudotrillium rivale, newly segregated, with spotted petals, from the Siskiyou Mountains of California and Oregon.
Within Melanthiaceae, these are consolidated into three genera;
;ParideaeParis L. Pseudotrillium S.B.FarmerTrillium L.