Nepenthes angasanensis is a tropical pitcher plant species endemic to Sumatra, where it grows at an altitude of to above sea level.McPherson, S.R. & A. Robinson 2012. Field Guide to the Pitcher Plants of Sumatra and Java. Redfern Natural History Productions, Poole. The status of this taxon is controversial as it is similar in morphology to N. mikei and N. tobaica. It has even been suggested that the taxon might represent a natural hybrid between N. densiflora and N. tobaica.Schlauer, J. Nepenthes angasanensis . Carnivorous Plant Database.

The specific epithet refers to Mount Puncak Angasan, from which the type specimen was collected. No forms or varieties of N. angasanensis have been described.

Taxonomy

+ Differences between N. angasanensis, N. mikei and N. tobaica (Salmon & Maulder, 1999) Character N. angasanensis N. mikei N. tobaica Habit Produces offshoots from underground rhizomes No rhizomes No rhizomes Spur Forked Fasciculate Filiform Inner margin of peristome Teeth to to long Teeth to to long Teeth < Stem cross section Cylindrical Cylindrical Cylindrical to obtusely triangular Bracteoles Sometimes near base of lowest pedicel only Half way up every pedicel At base or slightly below pedicel attachment, few Pitcher glands 300 / cm2 (1900 per sq in) 150–180 / cm2 (1000 to 1200 per sq in) 200–250 / cm2 (1300 to 1600 per sq in) Pedicels 1-flowered 1-flowered 2-flowered Inflorescence (female) to long, 9–17 flowers to long, 4–10 flowers to long, 30–50 flowers

In 2001, Charles Clarke performed a cladistic analysis of the Nepenthes species of Sumatra and Peninsular Malaysia using 70 morphological characteristics of each taxon. The following is a portion of the resultant cladogram, showing part of "Clade 6". The sister pair of N. angasanensis and N. mikei has 79% support.Clarke, C.M. 2001. Nepenthes of Sumatra and Peninsular Malaysia. Natural History Publications (Borneo), Kota Kinabalu.

Natural hybrids

The following natural hybrids involving N. angasanensis have been recorded.

N. angasanensis × N. densiflora

References

Hernawati & P. Akhriadi 2006. A Field Guide to the Nepenthes of Sumatra. PILI-NGO Movement, Bogor.

External links Photographs of N. angasanensis at the Carnivorous Plant Photofinder