Low's pitcher-plant (Nepenthes lowii)

Description

Nepenthes lowii /nɪˈpɛnθiːz ˈloʊ.i.aɪ/, or Low's pitcher-plant, is a tropical pitcher plant endemic to Borneo. It is named after Hugh Low, who discovered it on Mount Kinabalu. This species is perhaps the most unusual in the genus, being characterised by its strongly constricted upper pitchers, which bear a greatly reduced peristome and a reflexed lid with numerous bristles on its lower surface. Nepenthes lowii is a climbing plant. The stem may attain a length of more than 10 m and is up to 20 mm in diameter. Internodes are cylindrical in cross section and up to 8 cm long. The leaves of this species are coriaceous in texture. The lamina or leaf blade is petiolate, oblong-lanceolate in shape, and up to 30 cm long by 9 cm wide. It has a rounded apex and an abruptly contracted base. The petiole is canaliculate and up to 14 cm long. It forms a flat sheath that clasps the stem for two-thirds to four-fifths of its circumference. Three to four longitudinal veins are present on either side of the midrib. Pinnate veins run straight or obliquely with respect to the lamina. Tendrils are up to 20 cm long and are not usually curled. The rosette and lower pitchers are bulbous in the lower part and ventricose in the middle, becoming wider towards the mouth. They are smaller than their aerial counterparts, reaching only 10 cm high by 4 cm wide. Lower pitchers are rarely seen, as the plant quickly enters the climbing stage. A pair of fringed wings runs down the front of each pitcher, although these are often reduced and only present in the upper portion of the pitcher cup. The peristome is cylindrical in cross section and widens towards the rear. It is up to 12 mm wide and bears prominent teeth and ribs. The inner portion of the peristome accounts for around 62% of its total cross-sectional surface length. On the inner surface, the glandular region covers the basal half of the pitcher; the waxy zone is reduced. The pitcher lid or operculum is approximately orbiculate in shape. On its underside it possesses a number of very dense fleshy bristles measuring up to 2 cm in length. Other than these distinctive structures, the lid has no appendages. An unbranched spur is inserted near the base of the lid. The upper pitchers of N. lowii are very distinctive, being globose in the lower part, strongly constricted in the middle, and highly infundibular above. Aerial pitchers are relatively large, growing up to 28 cm high by 10 cm wide. Wings are reduced to ribs in upper pitchers and the peristome is present only as a series of ridges on the edge of the mouth. The inner surface of the pitcher is glandular throughout and has no waxy zone. The vaulted lid is reflexed away from the mouth and is oblong-ovate in shape. It is up to 15 cm long by 9 cm wide and lacks appendages. Numerous bristles, reaching up to 2 cm in length, are present on the lower surface of the lid. As in lower pitchers, the spur is unbranched. The upper pitchers of N. lowii are extremely rigid and almost woody in texture. After drying, the pitchers retain their shape better than those of any other species in the genus.