The Tropical Pitcher Plants of Philippines

Reprinted from the Journal Trifid No. 3/2005:

V. RYBKA & R. RYBKOVÁ 1)
Philippines, with its 14 Nepenthes species, are the third richest region within the Nepenthes habitation area. Compared to Borneo and Sumatra, the centre of the species richness of genus, 14 species in Philippines is markedly lower quantity. It’s substantially compensated by traps size, colour and shape so that they are, in my opinion, ranked among the most beautiful of all.

The fact that 13 of 14 species is endemic growing within a rather small area points out the significance of this region. In Philippines the pitcher plants grow from lowlands to mountainous locations and most of the major islands of this extensive archipelago host some of Nepenthes species. Though we can allocate the area of higher species richness represented the northeast part of Mindanao island as well as the small Sibuyan and Palawan islands. Unfortunately we have not visited the third mentioned island so vicarious information is only provided.

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Nepenthes alata na lokalitě na Mindanao
© VLASTIK RYBKA, ROMANA RYBKOVÁ

The only non-endemic species is N. mirabilis. It covers the larger part of Philippines but has surprisingly not been located in Palawan. It can be found in lowland warm areas, very often close to water reservoirs, sometimes slightly flooded.

As regards a taxonomy the most complex species is N. alata. It results from its areal spread in the major part of the Philippines archipelago. No wonder that isolated populations have the series of anomalous attributes, whereas many of them could be classified as a subspecies. The significant difference is between a mountainous population of Luzon and lowland one of Mindanao, different plants grow in the mountains of the same island and even more different ones in Sibuyan island. Many other forms are apparently still unknown. Closely related to N. alata are in particular N. copelandii and N. philippinensis. First mentioned mainly grows in the southern part of Mindanao island, for instance, in the highest mountain massif of Philippines, Mt. Apo. The main diference from N. alata are upper opened funnel shaped traps. The validity of this earlier described species has to be else certified. N. philippinensis originates from the lower sites of Palawan. Its traps are obviously light-colored and do not have the typical appendage on the lower surface of the pitcher lid (typical for N. alata). A nomenclatural complication is allied to the species name. The species was described in 1908 but a type item became charred in Manila herbarium. In 1998 Cheek a Jebb described the species N. wilkiei. Then, however, they discovered the different item of N. philippinensis species and found out a conformity with their N. wilkiei – now classified as the synonym of N. philippinensis species.

Next three interesting species originate from the lowlands of Mindanao island. Due to its bulky traps one cannot omit N. merrilliana species. It is the main candidate for species with the biggest traps; also a very long lid encourages attention. Regarding the size, an antipode is N. bellii with the traps reaching maximum 8-10 cm, very thin stems, extremely long trailings and very narrow leaves. That all makes this species unique and waiting for frequent integration into the collections of growers. Both species grow in a sparse lowland vegetation on ultramafic soils in the northeast of Mindanao island. This area is a host of other species – N. truncata – one of the most beautiful pitcher plants. This species has the traps of extreme tall size of 40 cm but relatively slender. Hence the volume of the traps is smaller as compared with other candidates for a size primacy.

It does not grow too high and produces commonly branched under shrubs. Besides lowland form also mountain richly colored and distinctly haired populations (more attractive than lowland ones) are known. Poorly known species from the same area is N. mindanaoensis. It grows in middle altitudes and was for a long time being confused with N. petiolata occurring on Mt. Hilonghilong. This species was unavailable for a long time and was recently spread into collections by Robert Cantley.

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Nepenthes argentii na lokalitě na ostrově Sibuyan
© VLASTIK RYBKA, ROMANA RYBKOVÁ
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Nepenthes sibuyanensis na lokalitě na ostrově Sibuyan
© VLASTIK RYBKA, ROMANA RYBKOVÁ

In the last decade two new mountainous species were described in Sibuyan little island. Both grow on the mountain rising in the centre of the island up to altitude of 2000 m. N. sibuyanensis grows in the shrubby vegetation and has attractive bulkily traps. The smallest known Nepenthes in the world - N. argentii – is absolute unique. When mature, the stem typically grows to only 30 cm, the rosettes have the maximum average diameter of only 10 cm and the traps average 4.5 cm tall. The mountains of Mindoro island host N. burkei, the species closely allied to N. sibuyanensis but even more to N. ventricosa occurring in Luzon. The relationship between these two species is not fully obvious. N. burkei was described on the basis of plants growing in a culture and the currently growing plants are very similar to those offering as N. ventricosa. This situation has a few explanations. Either N. ventricosa is very variable and true N. burkei is not grown at all or N. ventricosa can be distinguished by very light and markedly necked traps from N. burkei with darker and bulbous traps. The third possible explanation is that both supposed species are only the extreme forms of the variability of one species boring, according to the rules of priority, the name N. ventricosa. It is necessary to carry out the detailed research of wild populations to elucidate the issue mentioned above.

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Nepenthes ventricosa na lokalitě na Luzonu
© VLASTIK RYBKA, ROMANA RYBKOVÁ

The highest sites of Palawan island host an interesting species N. mira noted for its bulky traps. Jebb and Cheek refer this species to giant Bornean N. rajah. There is another indefinite species in Palawan, namely N. deannian. It is either the synonym of some well-known species or different recondite species. The pitcher plants of Philippines are being searched less than those of Borneo and Sumatra and there are relatively enough issues to settle. The certain part of unexplained variability can be caused by the hybridization of some species. One can expect the discovery of new species but it is however necessary to point out that the exploitation of the nature of Philippines is very fast and extensive so there is a short time to discover unknown and conserve an extant natural assets. The Philippine Nepenthes growing is generally easy. More tricky species to grow are N. mira and particularly N. mindanoensis. The most difficult species is N. argentii that strictly requires a cool humid microclimate as well as a nocturnal cooling.

TRANSLATION BY R. PICHL


1)
Vlastimil Rybka is an ecologist, a nature conservationist and a CP´s grower with a special interest in the Nepenthes genus. He is a worker of The Prague Botanical Garden (Fata Morgana), the Czech Republic.
Romana Rybková is employed in The PBG (The Fata Morgana management) as her husband above.