Nepenthes villosa , or the villose pitcher-plant,Phillipps, A. & A. Lamb 1996. Pitcher-Plants of Borneo. Natural History Publications (Borneo), Kota Kinabalu. is a tropical pitcher plant endemic to Mount Kinabalu and neighbouring Mount Tambuyukon in northeastern Borneo. It grows at higher elevations than any other Bornean Nepenthes species, occurring at elevations of over . Nepenthes villosa is characterised by its highly developed and intricate peristome, which distinguishes it from the closely related N. edwardsiana and N. macrophylla.Clarke, C.M. 1997. Nepenthes of Borneo. Natural History Publications (Borneo), Kota Kinabalu.
The specific epithet villosa is Latin for "hairy" and refers to the dense indumentum of this species.
Botanical history
Nepenthes villosa was formally described in 1852 by Joseph Dalton Hooker. The description was published in Icones plantarum and accompanied by an illustration.Hooker, J.D. 1852. Nepenthes Villosa. Icones plantarum 9, t. 888.
The species was first collected in 1858 by Hugh Low when he made his second ascent of Mount Kinabalu together with Spenser St. John.
In an issue of Curtis's Botanical Magazine published in 1858, an illustration of an upper pitcher of N. veitchii was incorrectly identified as N. villosa by J. D. Hooker's father, William Jackson Hooker.Hooker, W.J. 1858. Nepenthes villosa. Curtis's Botanical Magazine 84, t. 5080.Elliot, R.R. 1993. Carnivorous Plant Newsletter 22(1–2): 22–25. That year, N. villosa was also covered in Flore des Serres et des Jardins de l'Europe by Louis van Houtte, in which the same illustration was reproduced along with the incorrect identification.Houtte, L.v. 1858. Nepenthes villosa Hook. Fil.. Flore des serres et des jardins de l'Europe 13(3): 27.
In 1859, N. villosa was again described and illustrated in J. D. Hooker's treatment of the genus published in The Transactions of the Linnean Society of London. The illustration and description were reproduced in Spenser St. John's Life in the Forests of the Far East, published in 1862.St. John, S. 1862. Life in the Forests of the Far East; or, Travels in northern Borneo. 2 volumes. London: Smith, Elder & Co.
B. H. Danser treated N. edwardsiana in synonymy with N. villosa in his seminal monograph "The Nepenthaceae of the Netherlands Indies", published in 1928. The work included a revised Latin diagnosis and botanical description of N. villosa.Danser, B.H. 1928. The Nepenthaceae of the Netherlands Indies. Bulletin du Jardin Botanique de Buitenzorg, Série III, 9(3–4): 249–438.
Danser listed four herbarium specimens that he identified as belonging to N. villosa. These include two collected by George Darby Haviland from Mount Kinabalu in 1892. One of these, Haviland 1656/1232, was collected at an elevation of . It includes male floral material and is deposited at the Herbarium of the Sarawak Museum. The second specimen, Haviland 1813/1353, was collected from the Marai Parai plateau at an elevation of ; it likely represents N. edwardsiana. It is also deposited at the Herbarium of the Sarawak Museum. It does not include floral material. G. D. Haviland explored the Mount Kinabalu area with his brother H. A. Haviland between March and April, 1892, and must have collected these specimens during this time.Stapf, O. 1894. Contribution to the flora of Kinabalu. The Transactions of the Linnean Society of London (series 2) 4: 71–76.van Steenis-Kruseman, M.J., et al. 2006. Cyclopaedia of Malesian Collectors: George Darby Haviland. Nationaal Herbarium Nederland.
Additionally, Danser lists two specimens collected by Joseph Clemens in 1915. The first, Clemens 10627, was collected on November 13 from Paka Cave to Low's Peak. It includes female floral material. The second, Clemens 10871, was collected at Marai Parai between November 22 and November 23, and does not include floral material. Both specimens are deposited at the Bogor Botanical Gardens (formerly the Herbarium of the Buitenzorg Botanic Gardens) in Java.
In Letts Guide to Carnivorous Plants of the World, published in 1992, a specimen of the natural hybrid N. × kinabaluensis (N. rajah × N. villosa) is labeled as N. villosa.Cheers, G. 1992. Letts Guide to Carnivorous Plants of the World. Letts of London House, London.
In cultivation In 2004, professional horticulturist Robert Sacilotto published a summary of measured tolerances of six highland Nepenthes species, including N. villosa, based on experiments conducted between 1996 and 2001.Sacilotto, R. 2004. Experiments with highland Nepenthes seedlings: a summary of measured tolerances. Carnivorous Plant Newsletter 33(1): 26–31.
Many of the N. villosa plants in cultivation today originate from a particularly vigorous tissue culture clone introduced by Phill Mann of Australia and later sold by the Sri Lankan-based plant nursery, Borneo Exotics.Nunn, R., A.J. Lowrie, R. Sivertsen, R. Gibson, G. Bourke, C. Chiang, R. Cantley, D. Williams, B.A. Rice & E. Salvia 2014. In memory of Phillip James Mann (1951-2014). Carnivorous Plant Newsletter 43(4): 112–124.
Description
Nepenthes villosa is a weak climber, rarely exceeding in height, although the stem may grow to in length and in diameter. Internodes are cylindrical and up to long.
Leaves are coriaceous and petiolate. The lamina is spathulate to oblong and may be up to long and wide. The apex of the lamina is emarginate. The petiole is canaliculate, up to long, and bears an amplexicaul sheath. One to three longitudinal veins are present on either side of the midrib. Tendrils may reach in length.
Lower and upper pitchers are very similar. They are urceolate to ovate in shape. The pitchers grow up to high and wide. A pair of fringed wings (≤15 mm wide) runs down the front of the pitcher, although it may be reduced to ribs in aerial traps. The pitcher mouth is oblique and elongated into a neck at the rear. The glands on the inner surface are overarched and occur at a density of 200 to 1,300 per square cm (30 to 200 per square in). The peristome is cylindrical in cross section and up to wide. It bears well developed teeth and ribs. The lid or operculum is cordate and has a pointed apex. It has a pair of prominent lateral veins. Schmid-Hollinger, R. N.d. Kannendeckel (lid) . bio-schmidhol.ch. An unbranched spur, ≤ long, is inserted at the base of the lid.
Nepenthes villosa has a racemose inflorescence. The peduncle may be up to long, while the rachis grows to in length. Pedicels are filiform-bracteolate and up to long. Sepals are round to elliptic and up to long. A study of 490 pollen samples taken from two herbarium specimens (J.H.Adam 1124 and J.H.Adam 1190, collected at an elevation of ) found the mean pollen diameter to be 37.2 μm (SE = 0.2; CV = 6.7%).Adam, J.H. & C.C. Wilcock 1999. Pertanika Journal of Tropical Agricultural Science 22(1): 1–7.
The species has a dense indumentum of long, brown hairs that covers all parts of the plant.
Ecology Nepenthes villosa is endemic to the upper slopes of Mount Kinabalu and neighbouring Mount Tambuyukon in Sabah, Borneo. It generally grows at 2,300–3,240 m above sea level,McPherson, S.R. 2009. Pitcher Plants of the Old World. 2 volumes. Redfern Natural History Productions, Poole. the highest elevation of all Bornean Nepenthes species; only N. lamii from New Guinea is found at greater elevations.Robinson, A., J. Nerz, A. Wistuba, M. Mansur & S. McPherson 2011. Nepenthes lamii Jebb & Cheek, an emended description resulting from the separation of a two-species complex, and the introduction of Nepenthes monticola, a new species of highland pitcher plant from New Guinea. In: McPherson, S.R. New Nepenthes: Volume One. Redfern Natural History Productions, Poole. pp. 522–555. On Mount Kinabalu, N. villosa is common along the Mesilau Trail (between Pondok Magnolia and the meeting point with the old summit trail) and almost all the way up to the Laban Rata rest house;Thong, J. 2006. Victorian Carnivorous Plant Society Journal 81: 12–17. a particularly large population has been reported at around 3047 m.Toyoda, Y. 1972. Carnivorous Plant Newsletter 1(4): 62–63. On Mount Tambuyukon, an altitudinal inversion has been noted, whereby N. villosa is more common at much lower elevations of 1600–1900 m, being replaced by N. rajah towards the summit. The exposed, uppermost slopes of Mount Tambuyukon can become very hot during the day and this might explain the inability of N. villosa to colonise them. Plants from Mount Tambuyukon generally produce slightly more elongated pitchers.Fretwell, S. 2013. Back in Borneo to see giant Nepenthes. Part 2: Mt Tambuyukon and Poring. Victorian Carnivorous Plant Society Journal 108: 6–15.
Nepenthes villosa often grows in mossy forest and sub-alpine forest dominated by species of the genera Dacrydium and Leptospermum, particularly Leptospermum recurvum. It has also been recorded growing among shrubs, grass, and boulders in open areas. Here the soil may become relatively dry, although relative humidity is usually close to 100% as the slopes are often enveloped in clouds. Like many Nepenthes from the Mount Kinabalu area, it is endemic to ultramafic soils.
Although many plants grow along Mount Kinabalu's summit trail and are easily accessible to climbers, all known populations of the species grow within Kinabalu National Park and so their collection is illegal. In 1997, Charles Clarke suggested a revised assessment of Conservation Dependent based on this. Clarke writes that N. villosa "has a secure future", although he adds that climbers have had a significant impact on populations of the species growing along the summit trail, with the number of plants having declined in recent years. A 2002 study found 1,180 individual N. villosa growing in 11 plots, each measuring 0.01 hectares, at elevations of between and on Mount Kinabalu. This number constituted 94% of the pitcher plants recorded from the plots, the rest being N. × kinabaluensis.
Related species
Nepenthes villosa is most closely related to N. edwardsiana and N. macrophylla. There has been much taxonomic confusion surrounding the status of these three taxa.
Joseph Dalton Hooker, who described both N. edwardsiana and N. villosa, noted the similarity between the two species as follows:
This most remarkable plant [N. villosa] resembles that of edwardsiana in so many respects, especially in the size, form and disposition of the distant lamellae of the mouth, that I am inclined to suspect that it may be produced by young plants of that species, before it arrives at a stage when the pitchers have elongated necks.
Günther Beck von Mannagetta und Lerchenau was the first to treat N. edwardsiana in synonymy with N. villosa when he published his monograph on the genus in 1895. Beck, G. 1895. Die Gattung Nepenthes. Wiener Illustrirte Garten-Zeitung 20(3–6): 96–107, 141–150, 182–192, 217–229.
In his 1908 monograph, John Muirhead Macfarlane wrote the following with regards to the two species: "Examinatione microscopica probatur, illas species distinctas esse".Macfarlane, J.M. 1908. Nepenthaceae. In: A. Engler Das Pflanzenreich IV, III, Heft 36: 1–91. This is probably "based on the old belief that plants, which differ anatomically, can not be forms of the same species".
B. H. Danser united the species "[w]ith some hesitation" in his 1928 monograph "The Nepenthaceae of the Netherlands Indies". He suggested that N. villosa is a stunted form of N. edwardsiana from higher elevations, which flowers at a "juvenile stage of development". Danser acknowledged that the indumentum of N. villosa is more dense than that of N. edwardsiana, but noted that it "is a difference only of degree".
The two taxa differ considerably in their altitudinal distributions. Nepenthes villosa usually occurs at ultrahighland elevations, , whereas N. edwardsiana is found between . Where their altitudinal distributions overlap, they are still identifiable as distinct species.