Rarotonga’s very own rare ground-orchid

Thursday September 17, 2020 Written by Published in Environment
The Rarotonga Ground-Orchid Habenaria amplifolia that is only found on Rarotonga. PC: Joseph Brider. 20091630. The Rarotonga Ground-Orchid Habenaria amplifolia that is only found on Rarotonga. PC: Joseph Brider. 20091630.

Orchid lovers will be pleased to know that Rarotonga has its very own rare ground-orchid that is native (endemic) to the island and found nowhere else in the world.

It is known as the Rarotonga Ground-Orchid and its scientific name is Habenaria amplifolia.

The small delicate plant grows to about 30cm in height and has deep, glossy green leaves.

Its many green, fragrant flowers form on a long stem with a length of about 30cm.

The orchid is not found everywhere and at areas where they are discovered, other plants are often established there.

Joseph Brider, the research officer at the Cook Islands Natural Heritage Trust says “the plant is found in the inland forest, typically in the bottom of a valley or on flat terraces on the valley slopes where the forest is fairly open and the ground is moist and bog.”

The orchid grows out of the soil, “as opposed to living on a branch, coconut husk or other plants, like most of the orchids that are grown in home gardens”.

The orchid belongs to the Orchidaceae family (Orchids) and nested within that family, it belongs to the Genus Habenaria.

For most of the year the plant is dormant underground, and Brider says “it grows from a corm like many other members of the Habenaria genus”.

“From June to August, the corm comes out of dormancy and starts growing its leaves and flower stalk. The plant usually flowers in September and then returns to its dormant state for next year.”

The plant was first discovered by New Zealand botanist, Thomas Frederic Cheeseman in 1901 from plants he collected in 1899.

Cheeseman was the first person to publish the plants of Rarotonga in a book “The Flora of Rarotonga, the chief Island of the Cook Group”. The 1903 book is still a useful resource today.

The Habenaria genus has about 600 different species that appear in the tropical and sub-tropical regions of the world with some species found in temperate climates.  

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