Nepenthes aristolochioides

Species of pitcher plant from Sumatra

Nepenthes aristolochioides /n//ᵻ/'/p//ɛ//n//θ//iː//z// //ær//ᵻ/,/s//t//ɒ//l//oʊ //k//i/'/ɔɪ//d//iː//z/ is a tropical pitcher plant endemic to Sumatra, where it grows at elevations of 1800–2500 m above sea level. It has an extremely unusual pitcher morphology, having an almost vertical opening to its traps. It is critically endangered by overcollection. The specific epithet aristolochioides is formed from the genus name Aristolochia and the Latin ending oides, meaning "resembling". It refers to the similarity that the pitchers of this species bear, in both shape and pigmentation, to the specialised flowers of Aristolochia. An isotype is held at Herbarium Bogoriense (BO), the herbarium of the Bogor Botanical Gardens (formerly the Herbarium of the Buitenzorg Botanic Gardens) in Java. Although labelled as "new species? ", That same year, taxonomist Jan Schlauer questioned the supposed lateral pitcher mouth of N. aristolochioides in email correspondence with botanist Matthew Jebb, who was preparing a revision of the genus at the time. Schlauer wrote that he had examined a specimen of this species (Meijer 7426) and that the seemingly vertical insertion of the pitcher mouth might be a result of the preservation process, whereby the traps had become "compressed along their longitudinal axes". Joachim Nerz wrote a detailed description of the species for an issue of the Carnivorous Plant Newsletter published the following year. Charles Clarke's Nepenthes of Sumatra and Peninsular Malaysia, also published in 2001; The pitcher lid or operculum is orbicular cordate It extends for up to 2 mm on its outer margin, In 2001, Charles Clarke wrote that the species was only known from Mount Tujuh in Jambi, although specimens collected by Herbert Christopher Robinson and Cecil Boden Kloss labelled as being taken from "Mt. Kerinci" suggested that it may be more widespread in the region. Mount Kerinci is Sumatra's highest peak and neighbours Mount Tujuh. Clarke noted that since most of the mountain remains unexplored, there is a good chance that N. aristolochioides occurs there as well. The full range of N. aristolochioides on Mount Tujuh is also unknown, since only three of the mountain's seven peaks had been climbed as of 2001. Of these, one (the type locality on Mount Tujuh) may already be extinct due to poaching by plant collectors;

No infaunal organisms have been recorded from the pitchers of N. aristolochioides. This is not due to a lack of potential inhabitants; pitchers of N. singalana, which grow alongside N. aristolochioides, support large populations of such organisms. It is thought that the structure of the traps may serve to disorientate emerging adults and so infaunal species avoid colonising them.

Nepenthes aristolochioides produces extremely thick, mucilaginous pitcher liquid, which coats the entire inner surfaces of the traps in a thin film. The pitchers of this species appear to function at least in part as flypaper traps, with the sticky inner walls trapping flying insects above the surface of the fluid. The laminar morphology of N. aristolochioides is also similar to that of N. bongso, although N. aristolochioides is easily distinguished from this species by the shape of its pitchers and the hooded nectaries of the lid. In 2001, Charles Clarke performed a cladistic analysis of the Nepenthes species of Sumatra and Peninsular Malaysia using 70 morphological characteristics of each taxon. The following is part of the resultant cladogram, showing "Clade 1", which has 51% bootstrap support. Its most strongly supported subclade is the sister pair of N. inermis and N. dubia, having 95% support. Although N. aristolochioides resembles N. klossii in some respects, the two species are geographically isolated from each other and are not thought to be closely related. The unique adaptations of these taxa might represent an example of convergent evolution, whereby two organisms that are not closely related independently acquire similar characteristics while evolving in separate, but comparable, ecosystems.

Only one natural hybrid involving N. aristolochioides is known. Nepenthes aristolochioides × N. singalana has been found in dense mossy forest on two ridges of Mount Tujuh, only one of which is populated by N. aristolochioides. It is relatively rare, which suggests that the two species flower at different times of the year. This hybrid is smaller than either of its parent species; the pitchers rarely exceed 5 cm in height. The lower pitchers resemble those of N. talangensis, but differ in having more pronounced peristome teeth. Upper pitchers are infundibular in the lower parts, ovoid in the middle, and cylindrical in the upper parts. This hybrid can be distinguished from N. aristolochioides on the basis of its narrow, cylindrical peristome and oblique mouth, as opposed to almost vertical in the latter.