Tropical pitcher plant

Description

Nepenthes merrilliana is a tropical pitcher plant endemic to the Philippines. It produces some of the largest pitchers in the genus, rivalling those of N. rajah. The species is native to northern and central Mindanao as well as neighbouring Dinagat and Samar. Its presence in southern Mindanao is uncertain. It inhabits coastal forest areas on steep slopes at elevations of 0–1100 m above sea level. Nepenthes surigaoensis is closely related to N. merrilliana and was for a long time considered a heterotypic synonym of this species. Nepenthes samar is another closely allied species. Nepenthes species usually consist of a shallow root system and a prostrate or climbing stem, often several metres long and up to 15 m (49 ft) or more, and usually 1 cm (0.4 in) or less in diameter, although this may be thicker in a few species (e.g. N. bicalcarata). From the stems arise alternate, sword-shaped leaves with entire leaf margins. An extension of the midrib (the tendril), which in some species aids in climbing, protrudes from the tip of the leaf; at the end of the tendril the pitcher forms. The pitcher starts as a small bud and gradually expands to form a globe- or tube-shaped trap. The shapes can evoke a champagne flute or a condom. The trap contains a fluid of the plant's own production, which may be watery or more viscous, and is used to drown the prey. This fluid contains viscoelastic biopolymers that may be crucial to the retention of insects within the traps of many species. The viscoelastic fluid in pitchers is especially effective in the retention of winged insects. The trapping efficiency of this fluid remains high, even when significantly diluted by water, as inevitably happens in wet conditions.