Nepenthes angasanensis
# Nepenthes angasanensis

Nepenthes angasanensis /nɪˈpɛnθiːz ˌæŋɡəsəˈnɛnsɪs/ is a tropical pitcher plant species endemic to Sumatra, where it grows at an altitude of 1,400 metres (4,600 ft) to 3,100 metres (10,200 ft) above sea level. 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.

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 1.5 millimetres (0.06 in) to 2 millimetres (0.08 in) long | Teeth to 0.2 millimetres (0.01 in) to 0.4 millimetres (0.02 in) long | Teeth < 0.2 millimetres (0.01 in) |
| 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) | 5.5 centimetres (2 in) to 12.5 centimetres (5 in) long, 9-17 flowers | 4 centimetres (2 in) to 8 centimetres (3 in) long, 4-10 flowers | 19.5 centimetres (8 in) to 40 centimetres (16 in) 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.

## Natural hybrids

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

* N. angasanensis × N. densiflora
