Nepenthes izumiae

Species of pitcher plant from Sumatra

Nepenthes izumiae /n//ᵻ/'/p//ɛ//n//θ//iː//z// //i/'/z//uː//m//i//aɪ/ 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. Nepenthes izumiae was formally described by Troy Davis, Charles Clarke and Rusjdi Tamin in a 2003 issue of the botanical journal Blumea. The next detailed treatment of N. izumiae appeared in Stewart McPherson's 2009 monograph, Pitcher Plants of the Old World. Tendrils are up to 30 cm long

The typical habitat of N. izumiae is upper montane mossy forest, where conditions are moist and the plants experience diffused sunlight. At one location, the vegetation is dominated by ferns of the genera Dicranopteris and Dipteris. The species is most commonly epiphytic, often being found on moss covered branches, but it can also grow terrestrially over a layer of moss. Nepenthes izumiae is naturally sympatric with N. dubia and N. gymnamphora, and a natural hybrid with the former has been recorded. The only known populations of N. izumiae lie outside the boundaries of national parks. Stewart McPherson considers the species to be "at significant risk of being poached and over collected" and cites the "rapid demise" of N. aristolochioides, another highly sought after Sumatran plant, as an example of the possible fate of this species. Nepenthes izumiae is also threatened by forest and shrub fires as well as land development.

Nepenthes izumiae is thought to be most closely allied to two other Sumatran endemics: N. lingulata and N. singalana. With the former, N. izumiae shares the general morphology and colouration of its pitchers. However, it can be easily distinguished from that species as it lacks the highly developed filiform appendage that gives N. lingulata its name. It also differs in typically having an orbicular lid, as opposed to the triangular lid of N. lingulata, as well as broader pitchers with more highly developed peristome ribs and an unbranched spur. In addition, N. lingulata completely lacks nectar glands on the underside of the lid and has a very dense woolly indumentum. Nepenthes izumiae differs from N. singalana in that it often possesses a basal crest on the underside of the lid; this structure is never found in N. singalana. Nepenthes izumiae also differs in several other vegetative features: it has broader laminae with persistent hairs on the margins, longer and narrower terrestrial traps, and a thinner peristome with finer ribs and teeth. In addition, whereas N. izumiae is typically epiphytic in growth habit, N. singalana is mostly terrestrial. Nepenthes izumiae may also bear a resemblance to N. bongso and N. ovata, but both of these species have entirely infundibular upper pitchers and often have spathulate laminae with glabrous margins. Nepenthes spathulata could also be confused with N. izumiae, but it can be distinguished on the basis of its wider laminae and pitchers, the latter typically also being lighter in colouration.

In the wild, N. izumiae is known to form natural hybrids with N. dubia and N. jacquelineae. A single mature female plant of N. dubia × N. izumiae grows along the summit trail on Mount Talakmau. It produces infundibular upper pitchers that are yellowish green in colouration. The pitchers are relatively small, reaching only around 10 cm in height. As in N. dubia, the stem and tendrils are purplish red. The lamina is green with a red midrib. Nepenthes dubia × N. izumiae differs most obviously from N. dubia in having an ovate lid that is never reflexed beyond 180 degrees. This hybrid is listed as N. dubia × N. singalana in Charles Clarke's 2001 monograph, Nepenthes of Sumatra and Peninsular Malaysia, because at the time of its publication it was uncertain whether N. izumiae represented a distinct species.