closely, and itself has close relatives with similar floral features. However, trillium speciation in this group of Asian species is characterized by differences in chromosome number, with hybrids more definitively distinguishable from parent species by karyotype. T. apetalon T. camschatcense T. channellii T. × hagae T. smallii T. tschonoskii Taxonomy Trillium erectum was first described by the Swedish botanist Carl Linnaeus in 1753. The specific epithet erectum means "upright, erect", a reference to the erect pedicel of some forms of this species. In many populations, however, the pedicel leans or declines, sometimes declining beneath the leaves, making the name somewhat inappropriate. In 1803 André Michaux introduced the name Trillium rhomboideum to describe a form of T. erectum with black fruit in "the high mountains of North Carolina". The specific epithet rhomboideum refers to the broadly rhombic leaves of this (and all) forms of T. erectum. Michaux also described Trillium rhomboideum var. atropurpureum, a variety with large, dark purple petals. A decade later in 1813, Frederick Traugott Pursh referred to Michaux's variety more simply as Trillium erectum var. atropurpureum. Perhaps unaware of these taxonomic developments, other botanists subsequently described Trillium atropurpureum. The epithet atropurpureum means "dark-purple coloured", a reference to the petal color of certain forms of T. erectum. Indeed, in some locales T. erectum is commonly known as the purple trillium. Infraspecies , Plants of the World Online (POWO) accepts two infraspecific names: Trillium erectum var. album Trillium erectum var. erectum POWO lists 30 synonyms for variety erectum and 3 synonyms for variety album. Michaux introduced the term album in 1803 by describing Trillium rhomboideum var. album, a variety with a smaller flower and white petals. Pursh gave a similar description for Trillium erectum var. album in 1814. The word album means "bright, dead-white", a reference to the variety's white petals, a distinctive feature noted by both Michaux and Pursh. John Kunkel Small raised T. rhomboideum var. album to species rank in 1903. In his description, he added long anthers to the list of characters cited by Michaux while expanding the range of the taxon to include North Carolina, Tennessee, and Georgia. In 1917, R.R. Gates recognized the existence of two distinct forms of T. erectum with white petals, one of which was represented by the previously mentioned Trillium album . This prompted Ralph Hoffmann to propose Trillium erectum f. albiflorum, a white-flowered form of T. erectum that occurs occasionally