Nepenthes singalana — Vorstman's Guide to the Carnivorous Plants

Nepenthes singalana — the trap in close-up — **The trap in close-up** · Photo: Shawn Mayes — CC BY-SA 3.0 · Wikimedia Commons

Nepenthes singalana — the habitat — **The habitat** · Photo: Shawn Mayes — CC BY-SA 3.0 · Wikimedia Commons

Identification

A climber with obscurely four-angled stems 3 to 6 (rarely 7) mm thick and internodes 5 to 13.5 cm. Leaves of the climbing stem are narrowly oblong to oblanceolate or spathulate, 7 to 21 cm long and 2 to nearly 4 cm wide, with a blade narrowing to the base. The leaf axils carry pubescent patches with stellate and simple hairs, and stem and leaf bear tiny red glands. Intermediate pitchers are slender, obovoid below and almost cylindrical in the upper part, 13 to 18 cm tall. Upper pitchers are usually 10 to 15 cm tall (7 to 20 cm) and 2.5 to 4.5 cm wide in the lower part, with a narrow, almost cylindrical peristome. They are reddish green streaked dull blood red, pale green inside with crimson blotches. Lower pitchers are not described in the flora used, because the herbarium material lacked them.

Similar species

The closest relatives are Nepenthes diatas and N. spathulata, sharing the combination of pitchers ventricose below and tubular above with a leaf blade narrowing to the base. N. diatas from northern Sumatra is more robust and has a woody, broad peristome to 15 mm, against the narrow, thin peristome of N. singalana. N. spathulata occurs mainly further south on Sumatra and also on Java. N. izumiae resembles N. singalana but often has a crest under the lid, broader blades with persistent marginal hairs, and usually grows epiphytically. N. pectinata and N. gymnamphora have fringed wings and a broader, strongly ribbed peristome.

The trap and how it works

A pitfall trap as in all Nepenthes: nectar on the peristome and under the lid attracts insects, the ribbed rim turns glassy when wet, and whatever falls in ends up in a digestive fluid. The pitchers of N. singalana are notably rich in infauna: mosquito larvae and other small aquatic animals live in the fluid and share in the captured prey, something that is absent in the neighbouring N. aristolochioides with its syrupy fluid. The slender upper pitchers hang free in the scrub and mainly catch flying insects; the red streaks and blotches on the inner wall heighten the contrast against the pale green background.

Habitat and ecology

Upper montane cloud forest and open scrub around the summits (B1, R5), from 1900 to 2800 m. The vegetation is low, dense and mossy, rich in ericads, and stands in cloud for much of the day; nights can be cold. The species grows terrestrially in the moss layer and climbs through the low scrub, taking advantage of openings on ridges and around craters. As in other high-mountain species the soil is a thin, acid layer of humus and moss over volcanic rock, poor in nitrogen.

Distribution and elevation

Endemic to Sumatra. According to Cheek & Jebb (2001) it is one of the most widespread montane species on the island, from the Talakmau massif (the old Mount Ophir) in the west of Sumatra south to Gunung Dempo in the south. The type locality is Gunung Singgalang near Bukittinggi. Altitude: 1900 to 2800 m; other sources give 2000 to 2900 m. The world checklist gives Sumatra as its only area.

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 cells are 8 one-degree squares — 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: the locality of poached species is obscured at source. At this scale that obscuring disappears into the noise. The cells show where it has been seen, not where it occurs: an empty square means nothing.

Forms and variation

No varieties or forms have been described from the wild. Colour varies between populations and between plants in sun and shade, from mostly green to strongly red-streaked. N. singalana crosses on many mountains with species that grow alongside it: natural hybrids are reported with N. aristolochioides, N. bongso, N. gymnamphora and N. inermis, and uncertainly with N. spathulata. On mountains with several species such intermediates can blur the picture of the 'pure' species.

Where and when to see it

Search the highest parts of the West Sumatran volcanoes, where trails run up into the summit zone. Below 1900 m you can more or less skip the species; above that line, look for slender, red-streaked pitchers hanging among the low, mossy scrub. It is cold and wet at that altitude and the weather turns quickly: set off early, as the morning is usually clearest. Because of the many crosses with neighbouring species, a plant with an odd pitcher shape is more likely a hybrid than a separate species.

Conservation status

Assessed on the Red List as Least Concern (after Clarke's 2018 assessment): the species has a long range along the Barisan chain and grows at high altitude, where little clearance takes place. As a member of the genus it is listed in CITES Appendix II. Risks are local: fire around the summits, trampling along popular climbing routes, and plant collecting.

Scientific name

Nepenthes singalana | Beccari, 1886

Nepenthes singalana was described in 1886 by Odoardo Beccari. Mount Singgalang, West Sumatra, Indonesia, at 2,000-2,900 m elevation. The specific epithet derives from Mount Singgalang, West Sumatra, to which the species is endemic.

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