| Nepenthes eustachya | |
|---|---|
 | |
| A pair of upper pitchers ofN. eustachya | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: | Caryophyllales |
| Family: | Nepenthaceae |
| Genus: | Nepenthes |
| Species: | N. eustachya |
| Binomial name | |
| Nepenthes eustachya | |
| Synonyms | |
| |
Nepenthes eustachya/nɪˈpɛnθiːzjuːˈstækiə/ is a tropicalpitcher plantendemic toSumatra, where it grows from sea level to an elevation of 1,600 m. Thespecific epitheteustachya, formed from theGreek wordseu (true) andstachys (spike), refers to theracemose structure of theinflorescence.[12]
Nepenthes eustachya was probably first collected in February 1856 byJohannes Elias Teijsmann on the Sumatran coast near the port town ofSibolga. This specimen,Teijsmann 529, was designated as thelectotype ofN. eustachya byMatthew Jebb andMartin Cheek in their 1997 monograph.[13] It is deposited at the herbarium of theBogor Botanical Gardens along with twoisotypes.[12]
Nepenthes eustachya was described in 1858 byFriedrich Miquel.[2] In 1908,John Muirhead Macfarlane retainedN. eustachya as a distinct species in his revision of the genus, titled "Nepenthaceae".[14]
B. H. Danser did not support this interpretation and instead treatedN. eustachya in synonymy withN. alata in his seminal monograph, "The Nepenthaceae of the Netherlands Indies", published in 1928. He wrote:[3]
N. eustachya Miq., only recorded from Sumatra and still distinguished by Macfarlane, is united withN. alata in the above. In his monograph, Macfarlane placesN. alata in the group with carinate lid,N. eustachya among the species without keel on the lid ; yet he distinguishes aN. alata var.ecristata, without keel. For the rest there is hardly any difference to be stated between these two species and especially the inflorescences are strikingly alike.
Danser also identifiedRidley 16097 from theMalay Peninsula asN. alata, extending the species's range even further and making its apparent absence fromBorneo difficult to explain.Ridley 16097 is now thought to represent a mixed collection ofN. alba andN. benstonei.[5]
Plants belonging toN. eustachya were identified asN. alata by a number of subsequent authors, includingShigeo Kurata in 1973,[7]Mitsuru Hotta andRusjdi Tamin in 1986,[8]Mike Hopkins,Ricky Maulder andBruce Salmon in 1990,[9] and T. Sota, M. Mogi and K. Kato in 1998.[12][15]
In 1997,N. eustachya was once again elevated to species rank byMatthew Jebb andMartin Cheek, who noted a number of differences between the twotaxa.[13]Charles Clarke supported this interpretation in his 2001 monograph,Nepenthes of Sumatra and Peninsular Malaysia.[12]
The specific epitheteustachya has been misspelled several times in the literature, including once byOtto Stapf in 1886 asN. eustachys[11] and once byJacob Gijsbert Boerlage in 1900 asN. eustachia.[10][16]
Nepenthes eustachya is a climbing plant. The stem attains a length of up to 5 m and a diameter of 0.8 cm.Internodes are cylindrical in cross section and up to 12 cm long.[12]
Leaves arecoriaceous andpetiolate. Thelamina is oblong-lanceolate in shape and can be up to 20 cm long and 5 cm wide. It has a rounded toemarginate apex, which may be sub-peltate. Thepetiole iscanaliculate, notdecurrent, and generally lacks wings. It clasps the stem for around half of its circumference. Two to four longitudinal veins are present on either side of themidrib.Pinnate veins arise obliquely from the midrib.Tendrils reach 15 cm in length.[12]
Rosette and lower pitchers are ovoid in the lowermost quarter and cylindrical above, frequently widening just below the peristome. They are up to 20 cm high and 4 cm wide. On the inner surface, the glandular region covers the ovoid portion of the pitcher cup. The pitchers lack wings, bearing a pair of ribs instead. The pitcher mouth is round and has an oblique insertion. The flattenedperistome may be up to 5 mm wide. Its inner margin is lined with indistinct teeth.[12] The inner portion of the peristome accounts for around 29% of its total cross-sectional surface length.[17] The lid is sub-orbicular and lacks appendages. Thespur is up to 4 mm long and generallybifid.[12]
Upper pitchers resemble their lower counterparts in most regards. They usually attain a slightly greater size and areinfundibular in the uppermost quarter.[12]
Nepenthes eustachya has aracemoseinflorescence. Thepeduncle is up to 40 cm long, whereas therachis reaches 30 cm in length. Partial peduncles are one- or two-flowered and lackbracteoles.Sepals arelanceolate in form and up to 4 mm long.[12]
Immature parts of the plant may bear a sparseindumentum of white, mostlycaducous hairs. Mature parts areglabrous throughout.[12]
The stem and lamina are green. Pitchers are white to light pink with many red speckles. The underside of the lid is often darker than the rest of the pitcher. The peristome is usually yellowish and may bear red stripes.[12]
Nepenthes eustachya isendemic to theIndonesian provinces ofNorth Sumatra andWest Sumatra; its natural range stretches fromSibolga to thePadang Highlands. It has an altitudinal distribution of 0–1,600 mabove sea level.[12][18]
Nepenthes eustachya usually grows in open, sunny sites on cliff faces and steep slopes at theforest margin. It is restricted tosandstone substrates and often grows on bare rock.[19] Where the species does occur it is common and may form dense clumps, such as those growing beside the road from Sibolga toTarutung in North Sumatra.[12][1]
Nepenthes eustachya grows in close proximity to a number of other lowland species, includingN. albomarginata,N. ampullaria,N. gracilis,N. longifolia, andN. sumatrana.[12][20][21] It is known to hybridisewith all of these species.
Theconservation status ofN. eustachya is listed asLeast Concern on the2006 IUCN Red List of Threatened Species.[1]
Nepenthes eustachya differs fromN. alata in a number of morphological features. Jebb and Cheek outlined these differences when they restored the former as a valid species.Nepenthes eustachya has alanceolate lamina with a rounded to sub-peltate apex, whereas that ofN. alata is lanceolate-ovate with an acute orattenuate apex. The petiole also serves to distinguish these species: inN. eustachya it is scarcely or not winged at all, whereas inN. alata it is broadly winged. The pitchers ofN. eustachya bear a simple orbifurcate spur, compared to the simple and acutely pointed appendage ofN. alata. Mature parts ofN. eustachya areglabrous, whileN. alata bears anindumentum of reddish or whitish hairs. Jebb and Cheek also compared the structure of the pitcher base: that ofN. eustachya is angular and woody, being gradually attenuate towards the tendril. The base ofN. alata traps, however, has a similar texture to the rest of the pitcher and is abruptly attenuate towards the tendril.[12][13]
Nepenthes alata exhibits great variability across its range and it is inevitable that some plants will deviate from the characters outlined by Jebb and Cheek. However, the overall combination of morphological differences appears to be stable and it is this that demarcates these species.[12]
Nepenthes eustachya bears a superficial resemblance toN. mirabilis. It can be distinguished from that species on the basis of its lower pitchers, which lack wings, itsfimbriate leaf margins on short shoots, andcoriaceous leaves, as opposed tochartaceous in the latter.[12]
Charles Clarke notes that the upper pitchers ofN. eustachya, which have a pronounced globose base, may resemble those ofN. clipeata fromBorneo andN. klossii fromNew Guinea. Nevertheless, it would be difficult to confuse these species as they have little else in common and are geographically isolated from each other.[12]
In 2001, Clarke performed acladistic analysis of theNepenthes species of Sumatra andPeninsular Malaysia using 70 morphological characteristics of each taxon. The following is a portion of the resultantcladogram, showing "Clade 5". It comprises the sister pair ofN. eustachya andN. mirabilis with 72% support, as well as a weakly supported subclade (69%) that includesN. longifolia and the sister taxaN. rafflesiana andN. sumatrana with 58% bootstrap support.[12]
| |||||||||||||
Nepenthes eustachya is known to hybridise with a number of otherNepenthes species with which it is sympatric.
Nepenthes albomarginata andN. eustachya grow in mixed populations at a number of locations in thePadang Highlands andTapanuli. Natural hybrids between them appear to be relatively common around the riverTjampo inWest Sumatra. A young plant ofN. albomarginata ×N. eustachya pictured inNepenthes of Sumatra and Peninsular Malaysia was observed by Charles Clarke in 1998 onBukit Kambut inWest Sumatra. It grew insecondary vegetation amongst a population ofN. eustachya at an elevation of around 900 m. This plant was subsequently destroyed, but Clarke and Troy Davis found a number of other plants onBukit Tjampo. The hybrids were growing in a dense thicket of ferns (Dicranopteris linearis andDipteris sp.) at approximately 750 m.[12]
Nepenthes albomarginata ×N. eustachya often produces reddish leaves and pitchers. The characteristic white band ofN. albomarginata is present just below the peristome. In common withN. eustachya, the indumentum is almost completely absent from the leaves, which are sub-petiolate and wider than those ofN. albomarginata. No mature plants of this hybrid have been observed and, as such, the upper pitchers and inflorescence remain unknown.[12]
Nepenthes eustachya ×N. longifolia has been recorded from a number of locations nearPayakumbuh andSibolga, where its parent species are sympatric. It is relatively rare becauseN. eustachya andN. longifolia occur in markedly different habitats; the former usually grows in exposed, sunny sites, while the latter is more common in dense, shady forest. This hybrid differs fromN. eustachya in having fringed lamina margins bearing short reddish-brown hairs. The peristome often has a distinctive raised section at the front, a characteristic inherited fromN. longifolia. It can be distinguished fromN. longifolia on the basis of its shorter tendrils and the presence of longitudinal furrows on the surface of the lamina, similar to those ofN. eustachya.[12]
In addition, putative natural hybrids withN. ampullaria,[22]N. gracilis,[22] andN. sumatrana[12] have been observed.
