Nepenthes izumiae is a tropical pitcher plant endemic to Sumatra, where it grows in montane forest at 1700–1900 m above sea level. It appears to be most closely related to N. lingulata and N. singalana. The specific epithet izumiae honours Izumi Davis, wife of Troy Davis, one of the describing authors. Botanical history The species was mentioned as an undescribed taxon in Charles Clarke's 2001 monograph, Nepenthes of Sumatra and Peninsular Malaysia, under the name "Nepenthes species B". Clarke considered it to be most closely allied to N. singalana, writing that "[f]urther research is required to determine whether or not this is simply an unusual variety of N. singalana, or whether it warrants description as a distinct species". Flowering-size specimens of N. izumiae, identified as N. singalana from Mount Talakmau, were already in cultivation before the species was formally published. Nepenthes izumiae was formally described by Troy Davis, Charles Clarke and Rusjdi Tamin in a 2003 issue of the botanical journal Blumea. Clarke, Davis & Tamin 1309 was designated as the holotype. This specimen was collected in the Barisan Mountains, north of Bukittinggi, on July 13, 2000. It is deposited at the Herbarium Universitas Andalas (ANDA) of Andalas University in Padang, West Sumatra. The next detailed treatment of N. izumiae appeared in Stewart McPherson's 2009 monograph, Pitcher Plants of the Old World. Description Nepenthes izumiae is a climbing plant growing to a height of 8 m. The stem ranges in colour from green to reddish. The lamina (leaf blade) varies in shape and may be linear, lanceolate, or spathulate. It measures up to 28 cm in length by 8 cm in width and may have a frilled margin. The lamina has an acute apex and narrows towards the base, widening again just before the point of attachment. Longitudinal veins are inconspicuous. Tendrils are up to 30 cm long and often have a sub-apical or even peltate insertion, joining the lamina on the underside, before the apex. The lamina is green throughout, whereas the midrib and tendril may be green to reddish. Rosette and lower pitchers are typically ovate in the basal quarter to half of the pitcher cup, becoming cylindrical and sometimes slightly infundibular above. A conspicuous hip often delimits these two parts of the trap. Terrestrial pitchers may be quite large, reaching 30 cm in height by 6 cm in width. A pair of fringed wings (≤6 mm wide)