5. Nepenthes Bongso KORTH., Verh., p. 19, t. 14 (1839) ; Flora, VI, p. 578 (1848) ; BL., Mus., II, p. 10 (1852) ; MIQ., Pl. Jungh., p. 167 (1852) ; Fl., I, 1, p. 1070 (1858) ; suppl., p. 151 (1860) ; Journ. Bot. Néerl., I, p. 277 (1861) ; LEMAIRE, Ill. Hort., XVI p. 42 (1869) ; MIQ., Ill., p. 6 (1870) ; HOOK, F., in D.C., Prodr., XVII, p. 101 (1873) ; BECC., Mal., III, p. 5 & 13 (1886) ; BECK Wien. Ill. Gartenz., 1895, p. 188 (1895) ; BOERL., Handl., III, 1, p. 54 (1900) ; MACF., in ENG., Pflanzenr., IV, 111, p. 47 (1908) ; non RIDL., Journ. Linn. Soc., bot., XXXVIII, p. 320 (1908).
Icon: KORTH., Verh., t. 14 (1839) optima, colorata.
Folia mediocria sessilia, lamina spathulato-lanceolata, nervis longitudinalibus utrinque 3-5, basi cordata semiamplexicauli, vagina 0 ; ascidia rosularum magnitudine mediocria, parte inferiore anguste ovata, os versus cylindrica, alis 2 fimbriatis ; peristomio operculum versus acuminato v. in collum breve elevato, applanato v. expanso, ad 8 mm lato, costis c. 1 mm distantibus, dentibus ad 4 x longioribus quam latis ; operculo suborbiculari paulum elliptico, facie inferiore plano ; ascidia inferiora et superiora parva, infundibuliformia, costis 2 prominentibus ; peristomio operculum versus acuminato, v. in collum breve elevato, applanato, costis c. 1/2 mm distantibus, dentibus c. tam longis quam latis ; operculo suborbiculari v. rotundato-elliptico, facie inferiore plano ; inflorescentia racemus parvus, pedicellis inferioribus 6-12 mm longis, omnibus 1-floris ; indumentum parcum, in partibus vegetativis velutino-tomentosum, in inflorescentiis adpresse tomentosum.
Stems climbing or prostrate, up to 2 m long, the part with adult leaves 3 to 6 mm thick, cylindrical or obtusely angular, the internodes 1 1/2 to 9 mm long ; often rosettes at the base of older plants. Leaves of the rosettes like those of the climbing stems, the tendrils hanging. Leaves of the climbing stems scattered, thin-coriaceous, sessile, lanceolate-spathulate, about 6 to 18 cm long, 1 1/2 to 4 cm broad, acute to obtuse or a little peltate at the apex, attenuate towards the base, clasping the stem with a rounded or slightly cordate base, not decurrent ; pennate nerves irregularly reticulate, the longitudinal ones usually 3 to 5 on each side, originating irregularly from the lower half of the midrib, running parallel in the outer 1/3 to 2/3 of the lamina ; tendrils mostly, but especially in the lower part of the stems not always, with curl, once to twice as long as the lamina. Pitchers of the rosettes originating with a short curve from the hanging end of the tendril, up to 10 cm high, in the lower 2/3 part narrowly ovate, up to 2 1/2 cm wide, cylindrical, slightly narrowed towards the mouth, with 2 fringed wings over the whole length, the wings 1 to l 1/2 mm broad, the fringe segments 7 mm long, 1 to 2 mm apart ; mouth very oblique, strongly acuminate or elevated to a short neck towards the lid ; peristome flattened or expanded, up to 3 mm broad on the winged side, up to 9 mm broad near the lid, the ribs about 1 mm apart, the teeth of the interior margin up to 4 times as long as broad ; interior surface of the pitcher in the lower half with minute, overarched glands (making the outer surface minutely bullate) ; lid orbicular or orbicular-elliptical, rounded at the apex, subcordate, without appendages, with many small and deepened glands on the lower surface, especially towards the base of the midrib ; spur not branched, flattened, attenuate, inserted close to the lid. Pitchers of the lower leaves like those of the upper ones, but mostly fringed like those of the rosettes. Pitchers of the climbing stems gradually or abruptly originating from the hanging end of the tendril, incurved with a 5 to 20 mm wide curve, infundibuliform, more dilated in the upper part than below, slightly contracted at the mouth, 5 to 13 cm high, 2 1/2 to 4 cm wide, with 2 prominent ribs over the whole length ; mouth horizontal at the side of the wings, incurved and acuminate towards the lid, almost elongated into a short neck ; peristome flattened-cylindrical, 2 to 3 mm broad, the ribs 1/2 to 1/3 mm apart, the teeth of the interior margin about as long as broad ; the interior surface wholly glandular with little or not overarched glands, about 200 to 300 on 1 cm2 ; lid orbicular or orbicular-elliptical, rounded at the apex, rounded or slightly cordate at the base, with small round deepened glands on the lower surface ; spur not branched, flattened, acute, inserted close to the lid, usually 3 to 5 mm long. Male inflorescence a raceme, mostly seemingly lateral, the peduncle 3 to 7 cm long, 1 mm thick at the top, the axis 4 to 16 cm long, irregularly angular, the lower pedicels 6 to 12 mm long, the upper ones little shorter, all of the 1-flowered, with a filiform bract few mm above the base. Tepals elliptical, about 3 mm long. Staminal column 3 to 31/2, mm long, including the uniseriate anthers. Female inflorescence almost like the male one, somewhat shorter and more robust on the average. Tepals oblong to lanceolate. Ovary sessile. Fruit 10 to 25 mm long, the valves acute or hardly acuminate towards both ends, 3 to 5 mm broad. Seeds filiform, about 6 to 12 mm long, the nucleus longitudinally, but hardly transversely wrinkled. Indumentum of the stems and the leaves thin but dense, velvety-tomentose in youth, soon diminishing or disappearing, very densely velvety tomentose on the pitchers in youth, later thin-woolly, forming a tomentose ribbon below the peristome ; inflorescences very densely stellate-hairy when young, later less densely appressedly and often a little woolly-haired, the perigone outside like the inflorescence, the staminal column sparingly haired at the base, glabrous for the rest, the ovary very densely tomentose, the fruit with deepened points and very sparingly haired. (Colour of the young stems greyish-green, of the older ones dark-grey ; young leaves light-green, tendril grey-haired, pitchers grey-haired when young, later light-green, with irregular purple spots, on the inner surface yellow at the bottom, gradually merging into red towards the top;) colour of herbarium specimens usually blackish, sometimes fallow-dun to dark-brown. (Description after all the plants seen by the author, the part between brackets after KORTHALS.)
SUMATRA. Res. Tapiannoeli: G. Loeboekraja, "in silvis cacuminis supremi scandens, repens", 1990 m, XI 1840 or 1841, JUNGHUHN, H. L. B. 908,155-870 (m) ; H. A. R. T. 000252 (m) ; Res. West Coast: G. Singgalang, 1700 m, VI-VII 1878, BECCARI, piante sumatrane 183, H. L. B. (m) ; 222, H. L. B. (0) ; 268, H. L. B. (m) ; G. Marapi, 2500 m, KORTHALS, H. L. B. 908,155-867 (f) ; type of N. Bongso KORTH.; G. Talang, 2200 m, 2 XI 1918, BÜNNEMEIJER 5398, H. B. (0) ; H. L. B. (0) ; 2400 m, 2 XI 1918, BÜNNEMEIJER 5397, H. B. (0): 2500 m, 7 XI 1918, BÜNNEMEIJER 5521, H. B. (m, f) ; H. L. B. (f) ; Bt. Gombak, 2330 m, 16 XI 1918, BÜNNEMEIJER 5748 bis, H. B. (0).
MIQUEL is certainly wrong when recording N. Bongso also from Bangka (Ill., p. 6).
This species is related to, and not always easily to be distinguished from, a number of species from Sumatra and the Malay Peninsula, such as N. singalana, N. pectinata and N. Macfarlanei. See under N. Bongso x pectinata and the general discussions.
N. Bongso is restricted to the mountains of central Sumatra ; here it is only found on high summits in the forest and the alpine scrub ; the elevations recorded vary between 1700 and 2500 m. KORTHALS discovered it on Mt. Marapi in the upmost 100 m, "on ridges, covered with burnt stone blocks".
This species varies little ; only the dimensions of the leaves and the number of the longitudinal nerves are rather inconsistent in the specimens seen by me and this is one of the causes that N. Bongso may be confounded with related species.
? Nepenthes Bongso x pectinata.
SUMATRA. Gov. Atjèh & Dependencies: Galo Loeëus, Weuïh ni Kis, 6 III 1904, PRINGGO ATMODJO (exp. VAN DAALEN) 176, H. B. (0) ; H. L. B. (0).
The above specimen seems to be intermediate between N. Bongso and N. pectinata. With the latter it has in common the coarser stems, the lanceolate leaves up to 20 cm long or still longer, strongly attenuate towards the base, and with 5 distinctly parallel longitudinal nerves on each side, and the coarse peristome with long teeth on the interior margin. The only upper pitcher seen by me (H. B..) is infundibuliform and the teeth of its peristome are distinctly shorter than those of N. pectinata. It is not unlike the upper ones of N. Macfarlanei, but on the underside of the lid there is no trace of hairs or bristles. The other pitcher (H.L.B.) is broadest in the middle and therefore differs both from those of N. Bongso and N. pectinata. As both species have been found only much more to the South, the above plant is probably not a hybrid between them. The species from the gymnamphora group being too insufficiently known, I have thought it better not to describe a new species on the imperfect material at hand. See also the general discussions.