Mount Ilas Bungaan is a limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 hill near Berau, East Kalimantan

East Kalimantan

East Kalimantan is the second largest Indonesian province, located on the Kalimantan region on the east of Borneo island. The resource-rich province has two major cities, Samarinda and Balikpapan...

, Borneo

Borneo

Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....

. It is also known as Flowering Rock, a literal translation of its Indonesian name (ilas = rock, bungaan = flowering). The hill is located "on a remote stretch of the Karangan River" and its base lies at an altitude of around 300 m.

Botanist A. J. G. Kostermans

André Joseph Guillaume Henri Kostermans

Dr. André Joseph Guillaume Henri 'Doc' Kostermans was a botanist. He was born in Purworejo, Java, Dutch East Indies, and educated at Utrecht University, taking his doctoral degree in 1936 with a paper on Surinamese Lauraceae.He spent most of his professional life studying the plants of...

 explored Mount Ilas Bungaan between September 8 and September 19, 1957, as part of an expedition to northeastern Borneo. During this time, Kostermans made the first known collection of the rare pitcher plant

Pitcher plant

Pitcher plants are carnivorous plants whose prey-trapping mechanism features a deep cavity filled with liquid known as a pitfall trap. It has been widely assumed that the various sorts of pitfall trap evolved from rolled leaves, with selection pressure favouring more deeply cupped leaves over...

 Nepenthes campanulata

Nepenthes campanulata

Nepenthes campanulata , the Bell-Shaped Pitcher-Plant, is a tropical pitcher plant endemic to Borneo.Forest fires destroyed the only known population of N. campanulata in 1983 and it was uncertain whether the species had survived elsewhere or was in fact extinct. It was rediscovered in 1997,...

, which grew on the "sand and limestone walls" of the hill's 100 m high rock face. He wrote the following account of his discovery:

I was working for the Forestry Department at that time in Sangkulirang

Sangkulirang

Sangkulirang is a town and sub district of East Kalimantan, Indonesia. The town lies in the northern part of the Makassar Strait.Sangkulirang is situated in the delta of the Karangan River, which forms the Sangkulirang bay on the east coast of Borneo. Most of the regency is vegetated with mangrove...

 and when I had finished I wanted to find out about a flowering rock, Ilas Bungaan, upriver. After 10 days walking I saw the yellowish rock for the first time. When we were there we discovered that the yellow colour was that of the leaves of a Nepenthes

Nepenthes

The Nepenthes , popularly known as tropical pitcher plants or monkey cups, are a genus of carnivorous plants in the monotypic family Nepenthaceae. The genus comprises roughly 130 species, numerous natural and many cultivated hybrids...

completely covering the steep face of the 50 m high rock. We cut a tree that fell to the rock and acted as a ladder and climbed up. The Nepenthes was not in flower or fruit, but we found caves in the rock and in the caves a couple of boat-like coffins with sculptured dog-head ends which contained decapitated skeletons.

The population of N. campanulata originally discovered on Mount Ilas Bungaan was destroyed during the widespread Borneo forest fires of 1983–1984 and the species is thus locally extinct

Local extinction

Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...

. It has since been rediscovered in Gunung Mulu National Park

Gunung Mulu National Park

Gunung Mulu National Park near Miri, Sarawak, Malaysian Borneo, is a UNESCO World Heritage Site that encompasses incredible caves and karst formations in a mountainous equatorial rainforest setting...

 in Sarawak

Sarawak

Sarawak is one of two Malaysian states on the island of Borneo. Known as Bumi Kenyalang , Sarawak is situated on the north-west of the island. It is the largest state in Malaysia followed by Sabah, the second largest state located to the North- East.The administrative capital is Kuching, which...

, more than 400 km from Mount Ilas Bungaan.