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

Finding a Begonia during the dry season

Dryest month during a historical drought (no rain for 4 months) and we decided to search for a Begonia - a notoriously humidity-loving plant at a little known corner of The Philippines.....a fool-hardy endeavour no doubt but we are are no beach-lovers and there were little else to do here...

We were on the road for almost a day ......

slept comfortably, then set up on a boat the next morning.

Unfortunately, the water level was too low and we had to push the boat across the pebbly bottom .....

past some curious locals .....

and eventually decided to land near a dry tributary.

The stream was totally dry and there were steep banks on both our lefts and rights - on wetter days, we would be walking with our heads under the water.

I was not claustrophobic, just hoping it wasn't raining somewhere upstream which would trigger a flash flood ......


And then, suddenly we saw it, growing flat against the steep banks .....

There are some variations in the venation. This one  ....

and this one, found deeper up along the dry stream ....

and something in between .....

 

The plant is from Section Diploclinium and is clearly related to the Begonia cleopatrae described in 2010 and yet its quite different in rosette growth form (rather than a creeper). The flowers and the seed capsules also exclude it from B. suborbiculata but there are quite a few similar looking plants here and I do not have sufficient literature to fall back on. 

....having satisfied our curiosities, we now have to plough back and get some decent food and a good bed ....

Some Southern Thailand Begonias

These Begonias from S. Thailand - Malaysian region have nicely patterned leaves but each species are also quite variable. Most of them are Begonia diversifolia or something similar - this photo was taken at my nursery.

This is likely a form of Begonia integrifolia growing at the rubber estate at the edge of a limestone hill.

Plain leaf form

This is another Begonia, a true lithophyte on limestones  - no idea what it could be though.

These plants will go completely dormant during drier months and wake up again once the rain starts falling. They are a bit tricky to grow as you need to drastically reduce watering when they go dormant or you may lose the whole lot.

Malaysian Begonias - limited and regular pressings

I had the pleasure of doing some botanising in the jungles of Peninsula Malaysia recently where I encountered some interesting Begonias. 2 of them are those that you would often expect to see in the jungle here, while the other 2 are rare and restricted in their distribution. 

 

Right up in the northern state of Kedah, there is a small little plant growing on precipitous sandstone slopes that Ruth Kiew called "Shilling Begonia". Its latin name is Begonia sibthorpiodes -  attributed to its likeness to the pennywort-  Sibthorpia.  It had very small leaves (1-2 cm diameter) and was growing on a misty vertical cliff about 15-20 m from me so if it had not been for the relatively large pink flowers, I would have dismissed it completely.

Other than being very small, it is also very rare. It has only been recorded growing on the summit of 2 mountains in Kedah, at the altitude of 700 - 1200m.

Not far from the same cliff, a population of Begonia sinuata var sinuata was growing under the shade of the bushes.  This is one of the most common Begonia here and also has a wide distribution througout SE Asia.  This plant is ephemeral and will die after 1 growing season, after setting plenty of seeds.

Way down at the southernmost state of Johore : 2 hours on tarred road (from Singapore), 1 hour of 4X4 and yet another hour of an ascending jungle track by foot took us to the locality of the only remaining habitat of the beautiful  Begonia rajah. 

This plant was discovered in 1890s where specimens from Trengganu were brought to UK from which all of the plants in the horticulture trade descended from. Although cultivated plants are readily available, the wild plants were supposedly extinct as no specimens were ever seen again.

In 2002, the plant was rediscovered at a remote location in Johore, about 300 km from its last known locality ! As you can see, not only is this plant very rare (at least in the wild), it is also very pretty, which explains its popularity amongst the hobbyists.

 

The plants we saw were growing on steep rocks close to the stream or adjacent to or even on cascades and waterfalls.This is not an easy condition to replicate in cultivation, which explains why many growers find them difficult.

 

 

Under this optimal conditions, some of the plants became quite large, certainly much larger than those I saw in cultivation ....

Along the muddy paths further away from the stream, we saw plenty of this errect Begonia barbellata, a common plant in undisturbed forests throughout S. Thailand and eastern side of Peninsula Malaysia. This plant is attractive due to its red hairy stem and pink flowers but like many Begonias here, its not easy to grow. 

 

This one is growing with some cup fungus .....

Variegated Begonia elisabethae aff

If you have a copy of Ruth Kiew's book Begonias of Peninsular Malaysia,you would probably see a plain green species with a peculiar habit of producing bulbils at the root tip. Supposedly, only  Begonia elisabethae has such a reproductive habit locally, but alas with its plain green leaves its not too eye catching.

While exploring the limestone of S. Thailand bordering the Peninsula Malaysia, I had the good fortune of finding a similar species growing on vertical cliffs, except for the intricate pattern on the leaf. I had visited the habitat during the wet and dry season, and noticed that the plant die down completely during the dry months - around December and January. 

During the wet season, which, by the way, is not a good time to scale the muddy, slippery slope, I saw the plant in its full glory ....

Strangely, the plant also produced bulbils at the leaf tip ....

Upon dislodging the plant from the cliff, I can see a rather large bulb about 2 cm in diameter. The  plain green variety also grew on the same cliff as the variegated one.

These are the male and female flowers.

At this point I can only say they are most probably similar to the Begonia elisabethae featured in the book except for their variegation. This group of closely related seasonal Begonias (which include B. variabilis and B. integrifolia) are known to be variable in their vegetative appearance so I won't be at all surprise if indeed its the same species.

And by the way, this is a very frustrating plant to grow due to its dormant habit and the ease which the elongated leaf rots.