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Old Dec 30 2008, 11:25 PM   #1
Danel
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Default Anatomy of a Skybroom

This first post is sort of a disclaimer. Per D.M. Domini's request I worked up my thoughts about Skybroom genisis.

However my creative juices starting flowing as I started putting those thoughts into words, and well...

It's now presented in a Perneese point of view, as if some student of Benellek's was writing an esay for a botony class

However it shouldn't be too dry of a read!
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Old Dec 30 2008, 11:27 PM   #2
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Default Re: Anatomy of a Skybroom

Anatomy of a Skybroom

The Skybroom tree is one of Pern's most interesting plant species, and if Avias accounts are correct, a native species to Pern that was not genetically altered by the original settlers to Pern.

Like many of the native flora and fauna, Skybroom trees developed over time natural defenses to the deprivations of Thread. Surprising also is that Skybroom evolved along similar lines, with some notable variations, to trees imported by the Colonists. Most notably in the ringed growth pattern of the interior soft wood, the formation of outer bark for protection, and of a similar nutrient uptake as trees brought by our ancestors.

This is where the similarities end however.

Where as trees imported by the Colonists grow by producing a new layer of wood each turn, directly under the layer of the bark, Skybroom produces it's new growth each turn in the center. This appears to be a direct consequence of the plant developing defenses against Thread, in that even if the layers of tough bark do get penetrated, the tree can still survive if the inner most central layers are undamaged.

This method of growth also leads to an interesting makeup of wood over all, in the the central most wood is the softest, and as the older rings are pushed out by new growth, they are compressed and stretched, in effect toughening the wood up. It also explains the difference in that branches on a Skybroom tree migrate upwards with it's grown, unlike the imported trees where a branch 10 hands off the ground at 7 turns, will still be 10 hands from the ground at 20 turns. With Sky broom the branches migrate upwards as the tree grows.

However this continual stretching and hardening of prior years wood has a major draw back. Skybroom trees are not very wind flexible. The tree solved that issue also by splitting into multiple trunks almost at ground level, usually two or three, sometimes more, that braid around each other in a twisting pattern. Sometimes these primary trunks also split further up during the trees growth. This twisting and braided trunk design means the tree can still grow large, but retains some flexibility against wind by dividing it's trunks.

Also the oldest branches are not the biggest. A branch reaching its growth during its first turn will not continue to grow during subsequent turn. Occasionally a first turn branch might split off a secondary branch the next turn, but this seems to be an exception, and the secondary branch becomes the larger branch, including the portion of the first turn branch it shares. In effect it becomes the primary branch, and the original branch an older offshoot. This pattern of each new turns growth being larger then the prior leads to the trees overall broom like appearance, and it's name.

Overall there appears to be no limit to how long a Sky broom can continue to grow, but on average once they reach 500 to 800 hands in height, that winds storms typically blow these ancient trees over. The twisting trunks keep it flexible, but not near as resistant to wind blow down as the imported and more flexible trees. It is uncertain how tall a Skybroom could really get, but they seem to dwarf all the imported trees but for the red wood ones, which seem to reach comparable sizes.

Additionally besides growing from the inside out, Skybroom takes up more then just nutrients. It also takes up a small portion of minerals from the soil and rock it grows around. These minerals, as each turn stretches the outer layers more, eventually become a toughness imbibing material as an outer layer becomes an inner bark layer. This is the other difference in it's method of growth as the outer rings never truly die as the inner most rings take up the fluid and nutrient flows. Instead these rings slowly lose some material to the Skybroom's leaf growth, that converts each turn some of the outer ring into cellulose, and from that into a waxy substance. This hardens a outer ring more each turn, as it will lose some amount of fiber, but retain the original minerals. When a outermost ring becomes bark, it is almost as touch as rock. Even the sharpest of axes or saws can be quickly dulled attempting to cut through the Skybroom's mineral rich hardened bark. The main reason wind fallen Skybroom trees are such a sought after prize.

The nuts of Skybroom's are also a bit unique, having shells that are far tougher then most nut shells. The main germination trigger for these seeds is for a branch or tree to fall onto these thick shelled nuts cracking them open which allows them to then sprout. They sometimes also crack open from their long drop from an tall enough tree. There are oval in shape, and three can easily fit into an adult persons palm. The shell is rough of mottled brown red and black colors, and made in a similar manner to the bark. Nut growth takes three turns, two turns of shell growth, and then one turn to grow the nut itself.

The waxy substance the leaves produce while not overly thick, is another defense against thread. Thread, heated from it's fall lands into the leaves. This melts the wax which becomes a lubricant like an oil, leading to the thread tending to slide off the leaves and hopefully to the better protected bark on the branches and twigs, before it does much damage.

While not a major source of wax, a wind fallen Skybroom tree, when all the leaves are briefly boiled to melt the wax off, can yield quite a substantial and surprisingly clearer amount of wax then most other methods of wax production. A single family cothold can produce candles for near twenty turns from the wax off the leaves of a full sized fallen Skybroom.

The few holds that do cultivate both Skybroom's for wax production along with their regular farming, tend to bring in many more marks into their holds overall. Large scale Skybroom cultivation has not seem to have caught on however. This can be accounted for by fact that no Lord Holder would really want to use arable land for Skybroom production instead of food production. Perhaps after this final pass of Thread is over, holds dedicated to Skybroom farming for wax and wood will become more common place.
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Old Dec 31 2008, 02:38 AM   #3
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Default Re: Anatomy of a Skybroom

An interesting idea for the skybrooms. I'd think that instead of them being nut bearing though, the trees would be colony based. Root system grows stalks, like Aspen trees. It would work better than a tree trying to grow nuts through what you've described as bands of increasingly dense mineral growths. Forestry could consist of harvesting saplings instead of full grown trees. They'd be less dense, on a level of terran oak, but able to be worked.
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Old Dec 31 2008, 08:59 PM   #4
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Default Re: Anatomy of a Skybroom

I went with a tough nut/seed, as shoots and roots close to the ground would be very vulnerable to thread.
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Old Jan 1 2009, 12:34 AM   #5
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Default Re: Anatomy of a Skybroom

okay, so how does the tree get materials through its multiple rings of mineral hardened materials? Since all the growth is on the internal side, how does it pass the product of photosynthesis from the leaves through all the external layers to the growth areas of the branches and trunk, and form the nuts by passing the same materials back out?
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Old Jan 1 2009, 01:06 AM   #6
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Default Re: Anatomy of a Skybroom

Hmm, I just had a bit of thought, would the wax be the type used on slate? Seals and such?

As for wind potection "knees" come to mind here, above suporting the tree in questions. Somewhere a dry cedar or something or other? Or Fig?
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Old Jan 1 2009, 02:32 AM   #7
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Default Re: Anatomy of a Skybroom

ghost8772

Well i'm no botonist, but I have explaination for your questions too!

A Leaf bring in nutrients from the inner most center wood of its twig, which continues down to the inner most center wood of it's branch, and to the trunk. The Outer rings end at a leaf growth.

So you haver one central nutrient uptake channel through the center of the tree, and several downward waste/food channels through the the outer rings. The oldeest (and less numerous) branches and leaves on them, send the waste/food down what would be the outmost ring layer, because of this growth patern, a leaf/twig would be overgown after one turn, in escence, the next years growth causes it to be pushed off it's twig when it's waste/food channel (outer ring) becomes a bark layer. A new leaf will grow from the current two turns of rings at the end of each twig.

So a leaf is part of the current turn of growth, which connects it's waste channel to a prior year of growth. When a outer layer Ring layer no longer has any leaves connected to it, that ring layer is then 'dead' and becomes a bark layer. In the case of a twig, that would be the layer of two turns prior to the leaf growing. When a branch or trunk layer has no more viable twigs that proccess waste/food connected to it, that layer becomes the inner most bark layer.

Nut growth would behave similar to a leaf expect that the nut does not need to send out waste/food. It's attached at the point where a leaf meats the thrid turn bark on a twig, and migrates up the twig each turn of growth, untill the point of it's fourth year, where it's attachment point become a new branch split, which pushes the nut off the tree.
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Old Jan 1 2009, 02:39 AM   #8
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Default Re: Anatomy of a Skybroom

Ginny,

I was thinking the Braiding/Twisting intertwining of the trunks and branches would account for enough flexibility.

A solid 12 gage copper wire does not bend very easily, and infarct breaks quite easily if forced to bend to far. However a 12 gage wire made of smaller gage braided or twisted strands, has much more flexibility and can bend much further then it's solid counterpart.

At-least thats what I thought of when Anne described the twisted trunk nature of Skybrooms.
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Old Jan 12 2009, 12:03 AM   #9
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Default Re: Anatomy of a Skybroom

These are interesing points, considering the talk is about a non-terrestrial plant. In another sci-fi story I read, the trees were plyable till cut in a needed shape and then allowed to dry out. This caused the wood to shrink into itself and become exceedingly hard. Also don't for get that species of NE oak that was used on the early revolutionary warship (nick name "Old Ironsides"). When the British shot at it, the cannon balls were bouncing off the hull.
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Old May 20 2009, 03:44 PM   #10
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Default Re: Anatomy of a Skybroom

just a quick note. my grandson got a booklet in a kid's meal the other day about the outdoors one comment made me think of this thread....It was stated that trees can "warn" other trees about insects. Releases chemicals so surrounding trees make wood harder and leaves more difficult to digest,,,thought it could help explain skybroom (native to Pern and warned of thread) as well as the trees in southern being self healing....
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Old May 25 2009, 04:10 PM   #11
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Default Re: Anatomy of a Skybroom

Fantastic post about skybrooms, Danel! I really enjoyed reading your 'essay' LOL I've often wondered about skybroom (I think I posted about it's evolution somewhere around here a few years ago), and how it must've already had some kind of heightened hardness that was only increased by the intense selective pressure applied by the arrival of Thread.

Emeraldrose, the "self-healing" aspect of vegetation from the South is due, in some unexplained part, to the grubs that were developed and not due to a constitutive defense mechanism of the plant already. (Possibly the grub impregnates the soil with some kind of intense organic compound that the plants uptake and use in the same way as a secondary metabolite to highly increase their recuperative systems.)

But the point about Thread-attacked flora releasing some kind of semiochemical (whether it be an allomone or some other pheromone) which in turns induces an "extra-hardening" response from native flora, seem to make a lot of sense!
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Old May 26 2009, 04:04 PM   #12
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2cent Re: Anatomy of a Skybroom

Quote:
Originally Posted by Emeraldrose View Post
just a quick note. my grandson got a booklet in a kid's meal the other day about the outdoors one comment made me think of this thread....It was stated that trees can "warn" other trees about insects. Releases chemicals so surrounding trees make wood harder and leaves more difficult to digest,,,thought it could help explain skybroom (native to Pern and warned of thread) as well as the trees in southern being self healing....
Hmm, a twig of an idea, perhaps the grubs have a way to send something to help the southern plants be self-healing, its written into the bio-coding of the plants.
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Old Jun 28 2009, 07:15 AM   #13
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Default Re: Anatomy of a Skybroom

Quote:
Originally Posted by Gidget2 View Post
But the point about Thread-attacked flora releasing some kind of semiochemical (whether it be an allomone or some other pheromone) which in turns induces an "extra-hardening" response from native flora, seem to make a lot of sense!
It makes more sense to me than "grubs" actually, because without it Pern would not have any indigenous flora. It seems logical that whatever process Southern flora uses to survive thread has existed as long as thread has. Maybe "grubs" enhance something that was already happening naturally?
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Old Jul 8 2009, 05:00 PM   #14
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Quote:
Originally Posted by vyon View Post
It makes more sense to me than "grubs" actually, because without it Pern would not have any indigenous flora. It seems logical that whatever process Southern flora uses to survive thread has existed as long as thread has. Maybe "grubs" enhance something that was already happening naturally?
That's exactly what I was thinking, yes! There had to be something pre-existing that came to the fore courtesy to the intense selective pressure bought about by Thread's arrival. I know that Thread doesn't attack ALL the planet ALL at the same time, and we've seen from The PERN Survey that the bare patches were recovered very quickly, but there clearly was intense pressure for plants (and animals, although looking at the lack of large native fauna on Pern, they clearly didn't do that well LOL) to evolve and survive.

I think that it's this that the grubs kick into some kind of super overdrive, plus the natural healing chemicals that plants have (I can't think what they're called off the top of my head, apologies).
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Old Mar 6 2010, 06:30 PM   #15
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Red face Re: Anatomy of a Skybroom

at myself got right area wrong sub-forum.
Ok here is a question. and I am going to copy to here
X-posted from another unmaped area of Pern.
just had a twig of a thought the Igen Caves where the holdless stay RoP, GWHD and got a question for you, don't know if this idea would work or not. In RoP. HC USA Del Ray edtion
Quote:
a tangle of young sky-broom sapling, they partly covered the entry pg. 111
could they be transplanted or not?
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Last edited by GinnyStar; Mar 6 2010 at 06:34 PM. Reason: Two differnt question on same thing.
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Old Mar 28 2010, 07:49 AM   #16
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Default Re: Anatomy of a Skybroom

More likely used as cuttings, like willow or poplar, since the roots would be too intertwined to dig out a single one and transplant it.

That might solve the wind problem too - while the trees would be vulnerable to wind if they grew alone, the intertangled roots would help support a clump of trees.

Californian Redwood grows comparitively quickly here, and I notice that it looks happier growing in a clump than singly or in a row or hedge.
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