Nepenthes merrilliana

Nepenthes merrilliana

Synonymy

Nepenthes merrilliana Macfarl. in Trans. Proc. Bot. Soc. Pennsylv. 3(3): 208, t. 1. 1911 sec. McPherson 2009
  • Nepenthes merrillii Elmer in Leafl. Philipp. Bot. 8: 2787. 1915 syn. sec. McPherson 2009 [non Nepenthes merrilliana Macfarl. 1911]
    • Type: Philippines, Mindanao, Surigao Province, Dinagat Island, alt. 20 m, 1907, Hutchinson 7545 (PNH).

Description

Scrambling or climbing branched stems up to 10 m long.
The lamina is linear or slightly lanceolate, up to 40 cm long and 7 cm wide. The apex of the leaf is acute or obtuse and the base is attenuate, clasps the stem and is slightly decurrent. The lamina often meets the tendril unequally on either side of the midrib, and one side may be up to 4 mm shorter than the other. The lamina is also often slightly broader on one side of the midrib than the other. The stem and tendril are green or yellow and the midrib is orange or red, particularly close to the stem. The lamina is green but young or developing leaves may be bright orangey-red or purple, gradually turning green as they age. Thus each plant usually bears two or three red leaves, and all remaining foliage is green. Exceptions were encountered on Dinagat, where a small population of plants was identified in which all parts of the foliage were pure red. In some populations of N. merrilliana, both on Dinagat and Mindanao, the lower surface of the leaves may be uniformly flushed red. The stems and leaves are glabrous, but the pitchers may be sparsely covered in minute hairs less than 1 mm long.
The lower pitchers are typically up to 35 cm tall and 14 cm wide, though sometimes larger, and are wholly, broadly cylindrical or ellipsoidal. In some populations, the lower half of the pitcher may be slightly swollen and expanded, and the upper half may taper towards the pitcher opening. Wings up to 24 mm wide, fringed with filaments up to 18 mm long, typically run down the front of the lower pitchers, but these wings are often reduced or only partly expressed. The peristome is loosely cylindrical, up to 3 cm wide, and is expanded towards the sides and back of the pitcher opening. The peristome is lined with ribs up to 2 mm high, spaced up to 3 mm apart. The ribs are elongated on the inner edge of the peristome to form narrow, needle-like teeth up to 1.5 mm long. The peristome is slightly raised and elongated just below the lid. The outer margin of the peristome is recurved and sometimes slightly crenellated, and the inner margin extends into the pitcher opening for several millimetres. A gap of a few millimetres is often present at the back of the peristome, below the lid. The lid is elliptic or ovate, up to 12 cm long and 7.5 cm wide, and lacks an appendage. The spur is unbranched and up to 16 mm long and 3 mm wide.
The lower pitchers of N. merrilliana are among the largest of all Nepenthes. The largest trap that I encountered was 42 cm long, 16 cm wide and had a total volume of 2.3 litres, but pitchers up to 45 cm long have been recorded (Volker Heinrich, pers. comm.), with volumes up to three litres (Geoff and Andrea Mansell, pers. comm.). This immense pitcher size may rival that of N. rajah, although on average, the pitchers of N. merrilliana are not quite as large. During my observations of N. merrilliana across Dinagat and Mindanao, during June and July 2007, and July 2008, it was evident that in all populations, the very largest pitchers had withered and died a few month earlier, suggesting that the production of the largest lower pitchers may be seasonal.
The lower pitchers are very variable in colouration. The exterior of the trap is usually yellowish green or orange, but may be flushed red, pink or brown, sometimes mottled with faint, dark red blotches. The interior of the pitcher is yellow or orange and usually lined heavily with small, dark purple or black flecks. The peristome may be dark red, brown or purple, and the lid is pure yellow, orange or red. In some populations, all parts of the pitcher may be yellowish green or pure red. An unusual colour form exists on Dinagat, in which the pitchers are consistently bright pink, with peristomes of bright yellow (Stewart McPherson, pers. observ.).
The upper pitchers are wholly infundibular, often broadly so, up to 35 cm tall and 14 cm wide. Wings are reduced to narrow ridges. All other parts are consistent with the lower pitchers. Colouration is comparable and similarly variable, but usually, the upper pitchers are entirely yellowish green.
The inflorescence is a raceme, to 50 cm long by 3.5 cm at the widest point. The peduncle is up to 15 cm long and up to 6 mm in diameter at the base, the rachis to 35 cm long. Flowers are mainly borne on loosely arranged 2-flowered partial peduncles lacking bracts, with pedicels to 15 mm long. Tepals are ovate-elliptic and 4 mm long and the anther head is borne on a column up to 5 mm long. Fruits are up to 18 mm long.A

Notes

The large pitchers of N. merrilliana distinguish it from most other Nepenthes. Only N. attenboroughii, N. insignis, N. rajah, N. truncata and the giant variety of N. rafflesiana produce pitchers of comparable volume. Of these species, N. merriliana only bears similarity to N. insignis, but is easily distinguished from that species by its lower pitchers which are very distinct; those of N. merrilliana are broad and cylindrical, whereas those of N. insignis are comparatively narrow, often with a slender waist.B
N. surigaoensis Elmer, a species that was treated as a synonym of N. merrilliana by Jebb & Cheek (1997) and Cheek & Jebb (2001) is here considered as a separate species. C

Distribution (General)

Philippines, Mindanao and DinigatA

Etymology

The specific epithet honours American botanist, Dr. Elmer Merrill, who undertook extensive studies of the flora of the Philippines and the Asia-Pacific region during the first decades of the 20th century. A

Habitat

Lowland heath forest, degraded or recovering secondary vegetation, logged lowland dipterocarp forest, on exposed, inland cliff and landslide areas, and in stunted, lower montane forest.A

Bibliography

A. McPherson, S. R. 2009: Pitcher Plants of the Old World 2
B. McPherson, S. R. 2009: Pitcher Plants of the Old World 1
C. Berendsohn, W.G. 2017+: Compilation of Nepenthes data for the Caryophyllales taxonomic backbone.

Specimens

CountryDateCollector + collecting numberHerbariaTypeScanDerivatives
1907-��-��Hutchinson, W.J. 7545PNH
Citation: Philippines, Mindanao, Surigao Province, Dinagat Island, alt. 20 m, 1907, Hutchinson 7545.

Specimen summary: PNH
Type for: Nepenthes merrilliana Macfarl.