Xerophytic Begonia from Palawan

The northern part of Palawan is a beach bum paradise. It is also dominated by  prominent limestone karsts which understandably see much less human traffic than the beaches. The cliffs are very photogenic and instalgrammable when observed from afar but the treacherous steep slopes can be daunting.

 

 

Fortunately there was a cliff which can be accessed through a cave. The stalagtites and unusual geological patterns of the walls were interesting, but they were sideshows. Actually we were also unsure what to expect, we just need to climb some limestone cliff and check out the flora offerings... 

 .... the cave opened into a west facing cliff face and we were blinded by the intense sun.


the first thing I noticed as my eyes acclimatised to the light was high quantity of Dioscorea seed capsules sprayed all over the ground and this Euphorbia antiquorum which can be found all over seaside limestone from Indochina to Malaysia. I remembered saying to my mate not to expect any Begonia in this type of habitat, when he interrupted "looked behind you".....

.... is this a Begonia I see before me .... or an alien ?
Actually its the recently described Begonia elnidoensis which is named after El Nido the beach enclave that is full of beautiful bodies of water and humans. It is one of the most xeric Begonias I have seen. Some Begonias in seasonally dry area will become dormant, leaving behind a tuber in the ground to wait for the next favourable growing season but this Begonia keeps growing even in the dryest season.

Growing on near vertical cliffs, they have more stems than leaves. This being the dry season (there was no rain for 3 months or so) and with little shade from the sun on the vertical cliffs, leaves are very few and the dominant feature was the thick gnarled stems, some longer than 2 feet, growing out and almost perpendicular to cliff faces. Plants supposedly grow on and on - old stems die out but new ones appear from the thick clump. It does not has prominent tuber or caudex. 

Another similar Palawan endemic, Begonia wadei, differs from having a hairy petiole, amongst other characteristics.

At another locality, less exposed and more humid, we saw more leafy specimens with brilliant red-veined leaves, even flowering specimens, which was surprising in this dry period. There are also some seedlings peeping from crevices. The seeds are reported to be dispersed by wind.

 

Reference  : Hughes, Mark; Peng, Ching-I et al, May 2018, PLoS One 13(5) e194877