TERRESTRIAL ORCHID HABENARIA GIBSONII VAR. FOETIDA THRIVES ON PANAY ISLAND PLANT DIMENSIONS AND SEASON

INSIDE the campus of the University of the Philippines Visayas (UPV) in Miagao, Iloilo, a terrestrial orchid, Habenaria gibsonii var. foetida

Blatt. & McCann, thrives. Researcher Maria Celia D. Malay found the flowering Habenaria gibsonii var. foetida plants while hiking on campus.

This terrestrial orchid variety has previously been recorded in India, East Himalaya, Myanmar, Thailand, Laos, Cambodia, and Vietnam.

Habenaria is one of the largest genera in the orchid family, which contains about 890 species of predominantly terrestrial (those that grow on the ground) and rarely epiphytic orchids (those that grow on or are anchored to trees or other plants).

The genus is distributed across pantropical and subtropical regions. Today, there are 20 species of Habenaria recorded from the Philippines, 12 (or 60%) of which are endemic to the country.

So far, Habenaria gibsonii var. foetida was discovered in two forest patches within the UPV Miagao campus, including the collection site. There, approximately 150 mature plants, which grow individually or in groups of three to five plants, were spotted at the sampling site in July 2021.

This new Philippine distribution record is said to be the first one in the Malesian region.

In a journal article published in Check List last August 2, 2022, the authors wrote, “Habenaria gibsonii var. foetida was observed at low elevations in a hilly area that was used for agriculture before infrastructure for the UPV campus was built around it in the early 1980s.”

The authors of this study include Malay, Ma. Regina B. Altamirano, and Rene Alfred Anton Bustamante. The collaboration between these researchers from the University of the Philippines Visayas and the Philippine Taxonomic Initiative led to the completion of the study.

Compared with the herbarium samples from other Asian countries, H. gibsonii var. Foetida plants from Panay Island have longer petal

lengths than those from Thailand and Vietnam. Specimens from India, on the other hand, “have larger dimensions of bracts, ovary pedicel, dorsal and lateral sepals, and spur…”

The researchers added, “In all specimens examined, the labellum sidelobes were shorter than the midlobe however, our estimates of sidelobe-to-midlobe length ratios varied from 0.6 to 0.8, and we consider this, together with varying leaf shapes, as part of the natural variation of populations of H. gibsonii var. foetida, given the taxon’s wide distribution.”

The flowering season of H. gibsonii var. foetida lasts from July to August, followed by the fruiting period from September to November. The plant becomes dormant and loses its above-ground parts from November to April, when the dry season falls.

Although the orchid’s habitat at the university provides a certain level of protection, it is not totally guarded against the risk of being walked over by hikers, locals who sometimes collect firewood and buri palm, as well as animals that graze around the location.

Further threats that could adversely impact the H. gibsonii var. foetida populations in the campus include (1) future development plans, which could expose the plants to foot traffic and ground clearing operations, as well as (2) heavy rains, which could cause slope erosion and wash away the plants.

The survey was only conducted on the UPV campus, which is one of the study’s limitations. Further botanical research on the distribution and conservation status of this orchid in other parts of the Philippines is necessary.

To end, the study’s authors stated, “Our new occurrence records of H. gibsonii var. foetida [highlight] the importance of the island of Panay in floristic studies of the Philippines.”

“The fact that H. gibsonii var. foetida was discovered in a largely built environment supports the idea that the island flora is undersurveyed.”

Photos courtesy of M.R.B. Altamirano