Nepenthes platychila — Vorstman's Guide to the Carnivorous Plants

Identification

A climber to about four metres, growing both on the ground and epiphytically in moss on trees. The stem is terete and 5 to 8 mm thick. The leaves are coriaceous, oblong-elliptic, 10 to 18 cm long and only 4 to 4.5 cm wide, dark greyish green, clasping the stem at their base. The upper pitchers are the point of recognition: narrow below, rapidly widening into a broad funnel from halfway up, 12 to 16.5 cm tall, with a flattened and greatly expanded peristome up to 3.3 cm wide. The lid is ovate to orbicular, almost 5 cm long. The pitchers are light green to yellow-green with numerous red or purplish-red stripes, especially on the peristome. The lower pitchers were unknown at description and no good account of them has been published since. The difference between lower and upper pitchers is linked to growth stage: young plants and rosettes form lower pitchers, and only when the stem begins to climb do upper pitchers appear, their tendrils often coiling around a support.

Similar species

The describer's closest relative is Nepenthes fusca in its old, broad sense, a widespread epiphytic species of the Bornean mountains; it has funnel-shaped upper pitchers with a narrow, cylindrical peristome and a narrowly triangular lid. The broad, flat peristome of N. platychila separates it at once. Nepenthes ephippiata is also known from the Hose Mountains, but has a toothed peristome and saddle-shaped leaf bases. N. platychila is placed in the N. maxima complex.

The trap and how it works

A pitfall whose most conspicuous part is the peristome. In Nepenthes the peristome is a ribbed rim with nectar glands; with a film of water on it, it becomes glass-smooth, so that insects coming for nectar slide into the pitcher. A broad, flat peristome like this one enlarges the area on which a visitor can land and then slip, but whether that increases this species' catch has not been studied. There are nectar glands under the lid, and digestive fluid at the bottom. Nothing has been published on the prey of this species.

Habitat and ecology

Mossy mountain forest and steep sandstone slopes between about 900 and 1400 m (B1). The plant grows epiphytically in the moss of the cloud forest, or on the ground on steep sandstone slopes among ferns of the genera Dicranopteris and Dipteris, which often form dense mats on open, impoverished ground. The latter points to open, sunny spots on poor, fast-leaching soil.

Distribution and elevation

Endemic to Borneo and, as far as is known, confined to the Hose Mountains in Kapit Division, central Sarawak, where it has been collected from a few summits. That is narrower than the broad 'Borneo' in the guide's own species list. The range is little explored, so the species may occur elsewhere along the same chain. Borneo is the centre of diversity of the genus, with more than forty species, most of them endemic and many confined to a single mountain or range.

Recorded (one-degree cells)

Distribution based solely on records at GBIF (Global Biodiversity Information Facility), not on TDWG regions — those are often far larger than the actual range. The light halo is the area around a record, the dark core the record itself. The darker square is the only one-degree cell — roughly a hundred and ten kilometres — in which the species has been recorded, from all GBIF records. This is coarser than for most species because hardly any record of this plant carries an accurate coordinate. It shows where the species has been seen, not where it occurs: an empty square means nothing.

Forms and variation

No varieties or wild colour forms have been described. The pitchers vary in the density and colour of their stripes, from yellow-green with little red to heavily red-striped. No natural hybrids are recorded in the literature, though crossing with other species of the Hose Mountains, such as N. ephippiata, cannot be ruled out.

Where and when to see it

The Hose Mountains lie far in the interior of Sarawak and can only be reached by river and long treks through undisturbed forest; a visit requires permits and local guidance. Once there, search open, steep slopes among ferns and the moss of the cloud forest along the ridges; the broad peristome of the upper pitchers can be recognised from a distance. Lower pitchers remain barely described: a good photograph with a scale is valuable information.

Conservation status

There is no IUCN assessment of this species (Not Evaluated). What is known: it comes from one remote mountain range, has been collected at few sites, and grows in an area kept relatively intact by its inaccessibility. Logging and infrastructure are advancing in central Sarawak, however, and the restricted range makes the species vulnerable. As a member of Nepenthes it is listed in CITES Appendix II, so international trade in wild plants requires a permit.

Scientific name

Nepenthes platychila | Lee, 2002

Nepenthes platychila was described in 2002 by Ch'ien C. Lee, in "Nepenthes platychila (Nepenthaceae), a new species of pitcher plant from Sarawak, Borneo" (The Gardens' Bulletin Singapore 54: 257-261). The species had earlier, in a 2002 report on Nepenthes species from this mountain range, been designated with the provisional name "Nepenthes sp. 'B'". The Hose Mountains, central Sarawak, Borneo — the same mountain range as N. glandulifera (golf 22) and N. appendiculata (golf 18). The specific epithet derives from Greek, meaning "flat-lipped", referring to the plant's distinctive smooth peristome (the rim of the pitcher opening).

World Checklist of Vascular Plants (WCVP), via Plants of the World Online (POWO), Royal Botanic Gardens, Kew.