Nepenthes albomarginata

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Nepenthes albomarginata (Latin: albus = white, marginatus = margin) is a pitcher plant of the genus Nepenthes found on the island of Borneo.

N. albomarginata is notable for specializing in termites; most of the species in the genus Nepenthes are unselective about their prey. According to botanist Marlis A. Merbach and coworkers, this specialization to a single prey taxon is unique amongst carnivorous plants.

N. albomarginata has a unique morphological feature: a rim of living white trichomes directly below the peristome. The rim's hairs tend to be missing from pitchers that had caught termites. Merbach says: "For several days, nothing would happen, then — after a single night — pitchers would fill with termites and their rim hairs would disappear".

Merbach investigated this phenomenon by placing fresh intact pitchers, together with pitchers with their white rims removed, near to the head of foraging columns of the termite Hospitalitermes bicolor. When the column found the pitcher, termites grazed on the rim.

While grazing, many termites (both workers and soldiers) fell into the pitchers. Once in the pitcher, they were unable to climb out. Merbach counted up to 22 individuals per minute falling into the pitchers and noted that the capture rate could easily exceed this for denser columns. After about an hour, the hairs were all gone and the pitcher was evidently no longer attractive to termites (and was filled with termites trying to escape).

It is not known how the trichomes lure termites to the plant. Merbach detected no long-range olfactory attraction during his experiments and noted that "all contacts seemed to happen by chance, with termites often missing pitchers less than 1 cm away from them".

Merbach also points out that N. albomarginata is the only plant species to offer its tissue as a bait.

Forms and Varieties

• "var. typica (Lobb ex Lindl.)"
• * f. sanguinea (Toyoda ex Hinode-Kadan.)
• * "typ. green" (G & G)
• * "typ. Penang red" (G & G)
• * "typ. striated" (G & G)
• * "f. striata"
• * "f. black/purple"
• * "f. spotted"

Gallery

Image:Nep alb265.jpg|Upper pitcher, Bako National Park Image:Nep alb323.jpg|Small plant of green form, Bako N. P. Image:Nep alb328.jpg|Lower pitcher, Bako N. P. Image:Nep alb340.jpg|Purple form, Bako N. P. Image:Nep alb325.jpg|Red form, Bako N. P.

References

• Clarke et al (2000). [Nepenthes albomarginata]. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006.
• Nature vol 415, pp 36-37 (3 January 2002); doi:10.1038/415036a.
• Clarke, C. 1997. Nepenthes of Borneo. Natural History Publications (Borneo), Kota Kinabalu, pp. 62-64.
• [Termite Prey Specialization in the Pitcher Plant Nepenthes albomarginata - Evidence from Stable Isotope Analysis]