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

Around Baldy Hill

It had not been raining for about 3 months at the Thai-Burmese border, near a hill the locals called Baldy Hill (translated). This region has a Tropical savanna climate, characterised by pronounced dry/wet seasons with a mean temperature no lower than 15 Deg C.

When we visited the area, we were in the middle of the hot dry season.... as we stepped out of the car, we were engulfed by the searing heat .....

40 DegC ..... now we should be assured our packet food would be kept warm for some time.

The limestone hill was brown rather than bald - quite a few of Cycads and Palms and low scrubs. The scenery at the top was nice, if rather glaring, as I had not brought my shades.

Near the summit ridge, most of the herbs were dried-up, like these clumps of a Paraboea, a relative of African Violet. They look dead but upon receiving rain, they will spring to life again.

Interestingly, we did find the rare endemic herb Campanula rosmarinifolia in a flowering mood. This is really one tough cookie.

The parched coppery fronds of a Drynaria , the basket fern. Just like most flora here, it will spring to life once the rainy season arrives.

The white strangler fig began its life as an epiphyte on its host. but once its roots touched ground, however, it grew rapidly, embraced its host in a tango of death and very soon, will over-power its host tree and send it tumbling to the ground. In a savannah like this, it does not seem to make alot of sense but in a dim, dense forest, such a strategy effectively eliminate its competitor for the precious light.

Phoenix loureiroi is a widespread relative of the date palm Phoenix dactylifera and is common in deciduous forest and seasonally burnt scrubland such as this. Like the dates,  fruits are supposed to be edible but we could not find any to try.

 

The young plants are extremely sad looking - but the deep tap roots ensure most survive the drought. Having grown them from seeds, I found that in its first year, the seedlings looked like grasses and focused its energy on strengthening the root system.

The blackened, battle-ridden  trunk shows it has been burnt by forest fires frequent during dry seasons.

This variety appears to be Phoenix loureiroi var. loureiroi from the appearance of paler leaf margin and abaxial midrib

Another prominent plant is Cycas siamensis - a palm-like plant that is actually extremely very primitive and very unrelated. Specimen plants more than a metre tall are quite frequently collected and sold in markets as horticultural subjects which is a shame as they took a few decades to reach this lofty size in the wild and may die (albeit a slow death) in the hands of inexperienced growers since cultivated plants are prone to pests like Cycad blue butterfly and scale insects.

It's blooming season for the Dendrobium orchids - this is a D. lindleyi burning spectacularly high up on a tree ...

and this appears to be Dendrobium tortile although at this distance I cannot be sure.

On a bare tree trunk, clumps of tiny Dendrobium gregulus bloomed under the scorching sun. Each pseudobulb is about an inch or so in diameter. This species is endemic to NW Thailand.

 Near the summit, a lone Amorphophallus longituberosus was about to bloom...

.... at the base of the hill, an Amorphophallus yunnanensis already did. Unlike the previous species which has a long fusiform tuber growing deep into the ground , this plant has a very round and shallow rooting tuber.

Temperature dropped quickly as the sun sets. As we were driving back to town, a forest fire threatened to stop us - fortunately not too convincingly.