Orchids on the rocks

June 22, 2019- While on a solo trek in northern Laguna I saw this clump of Pomatocalpa bicolor in full bloom. I have been seeing these plants in this location since the early 2000s and when I am here at the right time, I can expect to see the plants in flower. And this day I wasn't disappointed. 

Pomatocalpa bicolor is endemic to the Philippines and found in the provinces of Bataan, Benguet, Ilocos Norte, Laguna, Nueva Vizcaya, and Rizal on Luzon; Polillo off eastern Luzon; Busuanga and Palawan; Bolo, Leyte, Negros, and Romblon in the Visayas; and Agusan del Norte on Mindanao. Despite being widely distributed, the species appears to have very localized populations and therefore not often encountered. The stems attain lengths of more than 3 meters, with roots produced along the stem length. The branched inflorescences reach about 60 cm in length and bear fleshy flowers clustered at the rachis tips. The flowers are fragrant, 1.7 cm across by 2.3 cm high, usually off-white with purple-brown spots and changing to pale yellow as anthesis progresses.

Although the plants can be found growing on trees, they are more commonly lithophytes. This clump of plants are growing on a large boulder that gets full sun for the most part of the day- just imagine how hot it would be sitting on a bare rock under the sun! Due to the prolonged dry season, the river has become more shallow and the vines have evidently taken advantage of the situation by dominating locales exposed to the sun. Indeed, this clump of plants is currently being overrun by Dioscorea and Centrosemma that the plants themselves could hardly be seen at all. I was in this place last February and the orchids then were exposed in all their glory, with the vines seemingly being kept at bay by the overhanging shade from the trees. But the extended dry period resulted in the considerable shedding of some of the trees' leaves, resulting in sunny gaps on the forest floor that the vines have exploited. When the rains come in full force, the sometimes violent torrents will tear the recalcitrant vines away and clear the banks once more.

It is not unusual to see Pomatocalpa flowers with thickening ovaries resulting from pollination; compared to species from other genera, these plants can bear several capsules per inflorescence. As I mentioned above, P. bicolor seems to have very localized populations. But where they occur, expect to find healthy populations- unless the plants have been decimated by either habitat conversion or orchid poaching.

In more shaded locales, one can see scattered plants growing either on trees or rocks, such as this one below.

Fortunately, this place is off the orchid poachers' radar. Apart from this species, there are several more orchids that are horticulturally important but are safe in this little haven of theirs. Still, they are living on borrowed time. Charcoal producers do come here from time to time although rarely, and loggers lend their fair share of damage. In this most recent visit, I found at least three trees that were felled. Not much, but a dead tree is a dead tree. And when a tree is extracted, then the weedy vines overtake. A grim thought, but perhaps in the foreseeable future, these pomatocalpas will be struggling to survive beneath those weedy masses.