24 September 2020

The possibly extinct Philippine pitcher plant

Time may be up for a pitcher plant only recently found to be new to science.

Mount Banahaw surrounded by clouds in the Philippines

Nepenthes is a genus of carnivorous pitcher plants that trap and digest animals – everything from ants and other insects to rats.

Their prey, attracted by sugary nectar, are captured when they slip into a pool of digestive fluid, from which they are usually unable to escape.

A few species instead trap nutrients from animal droppings, and one is mainly vegetarian.

They have long captivated the attention of botanists and tropical plant enthusiasts alike with their unusual shapes and vibrant colours.

Purple Nepenthes robcantleyi at Kew
Nepenthes robcantleyi in the Princess of Wales' Conservatory at RBG Kew © RBG Kew.

Tropical carnivores

There are currently 181 known species of Nepenthes and numbers have doubled in the last 20 years.

They are mainly found across Southeast Asia, with 59 of these in the Philippines.

Each year scientists continue to describe new Nepenthes species.

In a recent study of Nepenthes specimens, myself and Kew MSc student Charles King, discovered a species of pitcher plant, new to science, from Luzon, the most densely populated island in the Philippines. We believe it may already be extinct.

Carnivorous pitcher plant Nepenthes maxima
Indonesian pitcher plant Nepenthes maxima © Thomas Gronemeyer/Wikimedia Commons.

Herbarium finds

We came across a distinctive specimen at Kew where it was loaned from the Herbarium at the University of Pennsylvania.

The specimen was labelled as being collected from the Philippines over 100 years ago.

We originally thought the specimen was N. maxima, a species that only occurs in parts of Indonesia and thus, had been mislabelled.

However, on second inspection, we noticed features that made it clear the specimen was in fact different to N. maxima, and which placed it with one of the four major Philippine species-groups of Nepenthes

Nepenthes maximoides herbarium specimen
New to science Nepenthes maximoides © RBG Kew.

Mountain mystery

We designated this new to science species as N. maximoides.

To our knowledge, this is the only specimen of this species and it has not been seen since its collection 110 years ago, which is why we assessed it as Critically Endangered (Possibly Extinct).

We deduced that the specimen was likely collected from a forest on Mount Banahaw, a mountain considered sacred to locals and which is under “Protected Landscape” status. Therefore, there may yet be hope for this pitcher plant. 

However, land in the area has steadily been cleared for rice production and destroyed by human disturbance by visits from pilgrims and tourists so we fear N. maximoides may never be seen again. 

Sadly, this is becoming an all too familiar story where we are finding that, more often than ever before, the new species that we’re describing look like they are already probably extinct.
 

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