A revised subgeneric classification of Trillium (Parideae, Melanthiaceae)

Abstract

Results of recent molecular phylogenetic analyses have shown that the previous separation of Trillium into two subgenera based on pedicellate or sessile flowers is untenable. An updated infrageneric classification is presented recognising four subgenera in the genus, consistent with phylogenetic analyses. The three clades of pedicellate-flowered species are recognised here as subgenera: subgen. Trillium, Delostylis and newly named Callipetalon. The fourth, Trillium subgen. Sessilia, includes all sessile-flowered species. Orthographic considerations necessitate corrections to two previously published subgeneric names: Delostylium and Sessilium should be Delostylis and Sessilia.