Saturday, October 1, 2011

Rubber - Fruit and Seed

Rubber Tree (Hevea brasiliensis)
We know a lot about rubber tree, and I have seen many rubber seeds and pods strewn along the trails in Bukit Timah.  Not only are the evidence everywhere, but occasionally, one can hear the noise of "explosion" of the seed pods, before you hear the soft thud on the ground as the seeds and pods land!

Then I have never give it much thought about rubber seed, and fondly remember
a.   you can tease your friend by rubbing the rubber seed very hard on hard ground, and then applying it to your friend'ss bare skin.
b.   in our primary school, we were introduced to seed dispersion, and one of the method utilises by plants is the "explosive action".  Examples typically given by our teachers were Balsam Plant and Rubber Tree!

After the closure of the Railway Line, I decided to take a walk just like many folks here, and started my journey at Clementi Road.  Walking parallel to a big canal, I came across this fallen tree, with the rubber fruits (that has turned to rubber seed pods) still hanging onto the dead branches.

Then a thought occurred to me, why don't I write about the mechanics of the "explosive action".

Picture 1 - Dried Rubber Seed Pods
Picture 2 - Stages of Fruit to Pod (tri-lobes)
First and foremost, like all fruiting trees, the fruit does have some fleshy inedible flesh covers by green skin. And as it matured, the outer skin started to dry up, and split at certain point, till it turns brownish, and eventually strip away from the Seed Pods. This can be seen from the picture 2 and 3 below.

From picture 2, as the fruit dries, the gap between the lobe increase, until the lobes are being held at two points (at the top and bottom)

Picture 3 - Drying Process causes the skins of the fruits to split.

Picture 4 - Top View of fruit that has split skins
One interesting fact of the Rubber Tree, is that it comes in THREE.  If you observe the leaves, it comes in THREE. Likewise for the fruits, it is Tri-Lobe.
Imagine the fruit hanging on the branch, and the purpose of fruits and seeds are to propagate the species. Therefore, the design of the fruits is to ensure that the seeds that leave the pod, should be away from the parent tree!
With Tri-Lobe, at least 1 lobe will be facing away from the parent tree, and if not 2 lobes.  Thus the probability of propagation is increased.

Therefore, for the explosive action to happen, and to ensure that the seed is flung outward, the design of the Tri-Lobe and the individual seedpod are rather interesting.Now the mechanics of the explosive action, as the fruit and eventually the pod starts to dry, the weakest part of the fruit is actually the seam of a single lobe. However, the 3 lobes are connected, and will stress each other, and the explosion is usually a occurrence of all the 3 lobes, rather than individual lobe from the same pod.
  • Different thickness of the lobe around the seam
  • Connection region between lobes must be thicker than the seam of the lobe
  • Dehydration is the primary factor - which is also the stress inducer.
This drying process (dehydration) will cause the shrinkage of the lobe and is likened to the process of opening a cockle.  However, as each lobe is connected to two other lobes, and in that sense will be held in its place.
Once the stress level across the seam reaches the critical point, the shear stress or splitting pressure moves from the seams of the lobes to the TWO connecting points between lobes.

At the critical moment, and very fast, the final split occurred almost simultaneously in all the six connecting joints, and at the same time the seam of the lobe split open, and by virtue of the seed being connected to the inner wall, the seed is flung outward, awayfrom the centre of the tri-lobe.

Picture 5 - Individual Pod with Seed

Picture 6 - Purposely saw the Seed Pod to separate them.  The Blue marking from the saw, also indicates the connecting parts of the  lobes.  There are 2 connecting points between lobes.

Picture 7 - Notice the whitish colour seed pod, the bigger lobe has extra seam!
To summarise the explosive action,
  1. Different thickness of the lobe.  It is thicker at the side, and thinner at the top and bottom.  This is to facilitate the initial crack propagation. Cracks will occur at the top or bottom, and slowly creep to the centre.
  2. The connecting region is thicker between lobes than at the seam.  This is to ensure the the "in between lobe" fails at the last point.  Otherwise it will be shooting out individual lobe, instead of seed.
  3. All these "tearing" or "shear stress" is the result of dehydration, by design, water will not be fed to the fruit, but slowly dried under the sun.
Another observation, immediately after the lobe has opened and dropped to the ground, both halves can be easily put back (just like cockle shell), but through time, it will continue to deform due to dehydration.

Finally, this is my observation from my collections of fruits, pods, seeds, and experimenting with them, as it is very difficult to catch the explosive actions on film.  And if there is any mistake or correction, kindly feedback to me.

Update 22nd July 2014
Today I chance upon a "freak" rubber fruit.  One that has 4 pods instead of normal 3s.
 I would assume the explosive action will not be as effective as 3, for the angle of throw is now greatly reduced!

Sunday, July 17, 2011

Gunung Rinjani of Lombok

Gunung Rinjani
The 3rd highest mountain in Indonesia at 3,726 m, is also one of the toughest mountain to be climbed.  Located on the island of Pulau Mutiara (translated to means Pearl Island, for this island is also famous for pearls), it is commonly known as Lombok both locally as well as globally.  Separated by a straits from the more famous island of Bali,  this is an Island, which is a good alternative to the bustling island of Bali for vacation, not as cosmopolitan but definitely still preserves all the charm of a rustic with spartan lifestyle. 

Gunung Rinjani itself is at the north of the island, and the bustling activities tends to be located as far away from this live volcano, which will be in the west and south.  The island by the Indonesian archipelago standard is not big, and is dominated by this big lively volcano that can be seen from any part of this island with an unobstructed view.

Gunung Rinjani which is an active volcano that last erupted about a year ago.  It so happened I was on this very mountain when it was spewing lava in July 2009, that I stood at the rim of this volcano witnessing the magmatic event, then we were not allowed to climb to the summit nor go down to the crater lake as the volcano was rumbling and whistling like a runaway steam locomotive with the escaped steam. This year (2011) it was different, this volcano is at peace within itself; just some steam spewing out from its vents, and one has to look very closely to notice these plumes.
Gunung Rinjani (July 2009)  the centre black streak - that was caused by the lava flow.

Gunung Rinjani (July 2011) - the volcano is at peace
To climb to the rim, there are typically two routes, the easier one which we did in 2009 was to start and end via the Senaru Village, or the harder route which is by Sembalun Lawang. We chose the harder route for our climb, and did a crossover to the Senaru Village.  For doing a crossover, this would entail the fact that you had to bring all your gears with you in your trekking.

Climbing Profile of the track.  The "valley" is the crater, where we have decended, and again the upward climb to the rim before heading down to Senaru Village.
We arrived at Lombok international airport at Mataram, and were driven for hours to the Sembalun Lawang Lodge. By the time we arrived, it was almost midnight, this location is about 1200 m above sea level, and is surprisingly chilly!
One thing I have noticed about Rinjani, is that the weather is like the desert, hot in the daytime, and cold at night. This very night, the temperature dipped below 10 deg C.  Though we had a long day, very few of us were in the mood for shower, after all there were no hot water in the rooms, and worse some of us had no water at all!  We retired quickly for the night, as the trekking began at 5 am, as we need to reach the campsite at the rim early so as to secure a good location, for good space is limited.

Day 1 (Sembalun Lawang to Plawangan 2)
Having to start off at 5 am, and with a few winks of sleep, we were thankful that this was the beginning of the climb which is less dangerous, after all our alertness had been compromised by tiredness and lack of sleep; and one false steps can lead to the abandonment of the climb.

The journey to this campsite is most scenic, as the path crosses many interesting points.
We walked in path with long grasses; crossed bridge over gully; seen the effect of the hot weather as we saw many dried riverbed; and most majestic will be the views of the volcano itself.
Day 1 - still at the foot of the volcano, but we were already 1,100 m high.  Walking through long grasses, despite the seemingly hot sensation, it was still quite cold in this early hour.
Another shot of the journey through the long grass track. (Picture courtesy of Loh CH)
Walking across dried up river bed. (Picture courtesy of Loh CH)

The beautiful scenery of valley and gorge. (Picture courtesy of Loh CH)
The second part of this day journey is an incessant long climb up. Incessant as in having round one corner, one is faced with another round of climbing, and this would go on for hours as the path will zigzag up the volcano slope till finally one reaches flat ground, and that would also be the rim of the volcano, with one side leading to the crater, and the other side the foot of the volcano.

By the time, we reached the rim, and the campsite at Plawangan 2 (2,639 m), we were so glad that the tents had been set up, and all we have to do was to plonk ourselves into the tent. But, the view here and at this hour of twilight was most fantastic. As the sun began to set, the particles in the air caused the sunlight to split from its pure form to produce the beautiful array of multiple hue of the light spectrum to give us this magnificent of dusk.
Day 1 Campsite.  Though we may have started early on this day, there were many people having the same idea, and we were not the first on the rim. (picture courtesy of Loh CH)

After the last light, and the campsite was enveloped in veil of darkness, and then one lifted one's eyes to heaven, the heaven was speckled with dots of light and more amazingly the river of stars (milky way).  We were witnessing our home in space, as the solar system joins the myriads of stars in our galaxy.
The sun may have set, but we were still having some of the remnants of the sun light.  As can be seen, at this altitude, we were above the cloud.
Finally the last light, and the moon can be seen at the top.  (This is the exact colour, picture has not been edited)
Before we retired for the evening in the unusual time of 8 pm, we were told that we would be setting off at 1:30 in the morning to catch the sunrise on the summit. This meant that we were going to have a long climb ahead of us! 

Day 2 (Plawangan 2 to Summit, and then back to Plawangan 2 to Lake Segara)
We awoke with stiff muscles and back, as we had been sleeping on gravels, which is the primary substrate covering a live volcano.

Once again the climb of the previous day was to be repeated, except that the intensity had increased, as the slope is covered with loose gravels and every steps on the gravels cause one to slip!  Thus the saying of for every 3 steps, you slip 2 steps.  At this juncture of the climb, it was more of 3 steps with 1 slippage!  Still in such environment, one's muscle must be strong for climbing on such terrain, as the ground shifts under our weight.
Initial Climb in the middle of the night.  It was cold, and we were sored, but we were determined.
(Picture courtesy of Loh CH)
Final push to the summit.  At this time, the sun was breaking out from the horizon. (Picture courtesy of Loh CH)
Proceeding to climb, this part of the trek is made up of 3 parts.  The first part is a steep climb, and subsequently a comforting flat terrain to be followed by the final summit assault which is most demanding with steep slop.  On this final slope to the 3,726 m summit, the paths are covered with loose gravels and this time the effect of 3 steps up and 2 steps slippage became a reality. But like most loose substrate, the trick of climbing with minimal slippage is to do it fast, just like walking in the swamp, the moment one stops, one will start to sink, and this is the same with such loose gravels, sinking is equivalent to slippage as one is also on a slope of acute angle (estimated to be between 45 deg to 60 deg),

Having strived, panted and possibly cursing under our breath, we arrived at the summit.  At this vantage point, we were presented with a beautiful view of the island of Lombok of which this volcano sits.  And even the neighbouring Bali highest peak, Gunung Agung can be seen.
A clearer view of the terrain as we pushed for the summit.  Notice the loose earth and rocks.  (Picture courtesy of Loh CH)
The unexpected highlight of the day was the surprise move of the proposal of a man to his beloved, at 3,726 m up and surrounded by clouds, this occasion, a rarity and most endearing to us who witnessed it.  We wish the happy couple - Blessed Togetherness in the near further.

Congratulations and Best Wishes to this Happy Couple
After enjoying the view on the summit, the descent was most challenging, tiredness compounded with the unstable substrate assured a few falls for most of us.  But we got the hang of it, by doing a dig, heel and slide motion.  Digging into the gravels with the heel, and leaning backward as we slid downward, and thus saving energy in the process, to be repeated once the sliding stopped.  Sliding has a downside and that is it is harder to control the direction of descent, and one would like to control the direction if the ridge is only about 1 to 1.5 m across. As it would be the crater or the foot of the volcano, a nasty slide of about 1,000 m on either sides. Not a comforting thought!
Observe that our foot sunk into the earth. (Picture courtesy of Loh CH)

Downward trek to our camp at the rim.  At this point, the crater that we have passed during the night became obvious.
In the crater, rise another "hill", this is where the real activity of the volcano takes place. The local called this Gunung Anak Baru (the young/child mountain).
We managed to return to our campsite, and had our brunch before making another arduous descent to the crater (Senaru Lake). Today, the journey will be longer than the previous day, as we had to combine both the summit ascent as well as this descent.
Walking down towards the crater.  Honestly, it was much harder going down than going up! (Picture courtesy of Loh CH)
Arriving at a good time, we enjoyed ourselves by the lake.  In as much as the water was warm and inviting, we were hesitant to go into the water for it was polluted with rubbish that has been carelessly discarded.  The pollutants came in many forms, and the description is best left to the imagination of the readers.  However, along the shoreline, there were many avid fishermen, hoping to land themselves a carp or two!

Day 3 (Lake Segara to Pos 2)
Waking up at the normal hour unlike the last 2 days, we had to ascend from the lake and up to the rim to our next campsite. Once again, it was an incessant climb up, but definitely not as bad as the journey to the summit, or the journey down.

The beginning of this journey was most challenging, as we had to negotiate narrow walkway around the lake, holding onto roots and branches for support. As we struggled to maneuver these obstacles, the porters with their heavy load were making us looked bad as they skillfully and agilely negotiated every turns without even using their hands.  Must be the poles they used for balancing!
Negotiating the narrow walkway around the lake. (Picture courtesy of Loh CH)
Having given the choice of camping at Plawangan 1 or Pos 2, we decided to choose a longer journey to Pos 2 (1,500 m) for today, as it is located at a lower altitude which provides a more hospitable environment of milder climate.  Plawangan 1 (at 2,641 m) is still at the rim, and we realised that it will be cold and may be plagued with water problem.
The ultimate reason for us, is that the following day, we would have a shorter walk to Senaru village, which would be the end of this trek.
The difficult climb began after we circumvent the lake. (Picture courtesy of Loh CH)

But we were rewarded with the majestic view surrounding us.

And still we have to climb some more before we reached the rim. (Picture courtesy of Loh CH)
Day 4 (Pos 2 to Senaru Village)
Final day of trekking, we walked from Pos 2 to our lodge in Senaru Village.
But before the start of our trek, we thanked our porters, guides, and cooks for making this trip possible.  After all, we were carrying our daypacks which only weighed between 5 to 12 kg, but the porters were easily handling loads of between 25 to 40 kg easily, and they still managed to walk faster than us.
Porters with the heavy load. (Picture courtesy of Loh CH)
As we reflected on this climb, most of us who had climbed various mountains, mountains that are higher than Rinjani have to admit that this is one tough mountain. On the other hand, we felt a certain triumph of being able to reach the summit.  Many had harboured thoughts of giving up as the ways were tough, but for those who made it to the summit, there were much psyching of our mind over body, and possessing the ever pressing on attitude to reach the goal.
Such is our determination, and on further thoughts, we will be using this same determination with God's grace to overcome whatever challenges in any of our endeavours.  

A special thanks to Lois for proof reading my draft.
And a big thank you to Loh CH, my colleague and fellow climber for sharing the pictues.

Tuesday, February 22, 2011

Agaricus Mushroom in Bukit Timah

Why oh why are mushrooms so hard to ID!
Coming down from my trekking, near to the beginning of the Summit Trial, one can find 2 logs, and on a good damp day, it will be covered with mushrooms.

Today is no exception, I find it intriguing that one log was covered with these white fungus, and somehow the other log was pretty much spared.

Taking some close up, I believe these are the Lepiota (sp), or commonly called the Parasol Mushroom.
(somehow I can hear some giggling over this name, isn't it obvious that mushrooms usually look like parasol. Good Question which I have no answer)

So these are some of the close-ups of this species.
From the pictures, one can see the various stages of development.
With the young mushrooms with undeveloped caps just emerging from the log, to the fully bloom mature adults.

The cap of this species is rather thin, that the gills from the underside can be seen.
The stipe itself is relatively thin, with the annulus forming at midpoint.
I thought this could be a Marasmius, but then the stipe is quite long!
Or a Hygrophorus, but then the stipe is too thin!
So my conclusion that this is probably a Leipiota.

Taken from underneath, the annulus on the right specimen is pretty obvious, and the evidence of the thin cap to produce this highlighted shot.

A side view of this same specimen.

Alas, from experience, these mushrooms will disappear in about a week time, leaving behind brownish patches, and nutrients for the next generation to sprout!

Thursday, February 10, 2011

Another Giant Agaricus in Bukit Timah

Where there is dead log and plenty of moisture, one is guaranteed to see fungi.
Today, having finished my climb in Bt Timah, and returning to the Dairy Farm Car Park, I chanced upon this Giant Agaricus in the male toilet.

From initial observation,

  • it has a rather deep depression in the centre where the stipe (stem) is located 
  • the cap is very unusual, in that it flows down like a skirt
  • the stipe is very short for such a big pileus (cap)

Again, I tried to ID this specimen, and the only conclusion I have is that it is a gilled mushroom of the Agaricales Order.
Initial ID seems to place this in the family of the Brittle Cap, but those have long stipes, whereas this does not!

Does this specimen belongs to the Brittle Cap family?  To me, it is more like a bottle cap!

Placing a ruler, the cap spread across almost 13 cm!

Taking the underside, shows that the gills reach to the end of the cap.

Naturally, how does one justify a 13 cm size specimen to be a giant, well I looked around and saw couple of the same species growing around, and the spread of the cap was about 5 cam.

Two specimens here, with one already badly damaged.  Otherwise, the cap spread is about 5 cm.

 Once again, if anybody can ID this species, please do let me know.