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  Holes
From: "John" <criswick at spiceisle.com> on 2012.02.24 at 16:55:14(22605)
Can anyone say what
might be the biological purpose of leaves with holes in them? A typical
example would be Monstera deliciosa.

John.

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From: Hannon <othonna at gmail.com> on 2012.02.25 at 16:00:24(22613)
John,

One possibile explanation that has been suggested is that leaves with perforations look like they have been eaten and this deters a potential herbivore attack because the attacker is looking for more suitable leaf material (leaves healthier, free of competition, etc.).

Another reason could be structural-- the same leaf in 'solid' form might be too heavy or prone to wind damage, while the perforated version allows more leeway to find better light situations-- longer petioles, better wind resistance, etc.

In terms of strategies adapted for similar purposes there seems to be a gray area between lobed or compound leaves and those with actual holes. In both cases the outline of the leaf blade is larger than the actual surface area. Your example, M. deliciosa, is unusual in having both lobes and holes.

Dylan Hannon

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From: "Steve Hatfield" <moondogman at comcast.net> on 2012.02.25 at 16:38:34(22615)
Wind protection?

Steve

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From: Don Martinson <llmen at wi.rr.com> on 2012.02.25 at 17:18:32(22616)
We just had a discussion about that very thing on the Facebook/Planet Aroid group.

One of the most popular opinions was that it allows more light to penetrate to the area beneath the plant or even to lower leaves on the same plant.

Just as a side note: When I was a graduate student at Marquette University, one of the doctoral students did her thesis on what causes these “holes” or slits, and it was found to be differential cell death (just in case you’re ever on “Jeopardy”).

Don Martinson

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From: The Silent Seed <santoury at aol.com> on 2012.02.25 at 19:09:14(22617)
To confuse predators (insects, etc) and to make it more difficult to land onto them, to feed upon them, is my understanding.

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From: "Marek Argent" <abri1973 at wp.pl> on 2012.02.25 at 17:45:33(22618)
Not to be broken by wind, rain etc. Similar purpose to spokes in bike wheels.

Marek

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From: Sheldon Hatheway <sfhatheway at yahoo.com> on 2012.02.25 at 19:17:13(22619)
Interesting question! Could the holes (aren't they called fenestrations or some other big word?) possibly protect the foliage by reducing the amount of wind resistance (and possible damage) on the blade surface?

Sheldon

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From: Jason Hernandez <jason.hernandez74 at yahoo.com> on 2012.02.25 at 20:38:10(22620)
No one has figured out definitely what is the function of holes, but several ideas have been proposed in the literature. One -- which I consider the least plausible -- is to fool insects: supposedly, insects see the leaves appearing already to have been eaten and move on, as if to avoid a plant with higher concentrations of defensive compounds, or possibly competition from other insects. This theory does, however, raise questions about how important visual cues are to herbivorous insects. Another idea is that the holes increase air circulation around the leaves, possibly providing "air conditioning" or facilitating gas exchange. To me this seems more likely.

Jason

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From: Alistair Hay <ajmhay at hotmail.com> on 2012.02.25 at 22:12:07(22621)
I am not convinced any of the "ecological" explanations even begin to touch the question!

There is usually a tacit assumption that perforated leaves have evolved from unperforated leaves - hence the question 'why holes?'. But maybe they have evolved from leaves with had dissected margins - in which case the question becomes why, in their development, are these leaves dissected from within the margin instead of at the margin?

Roughly speaking, the leaf of a mature M. deliciosa has three hierarchical sets of holes - a set very big ones whose thin edges break as the leaf unfolds creating the major dissections of the leaf, a set of medium holes and a set of small holes near the midrib. Philidendron bipinnatidum on the other hand, also roughly speaking, has (up to) three sets of marginal lobes, a set of very big ones making the major divisions, which are themselves lobed (the mid-level divisions) and a few of the finest "lobes on lobes on lobes".  The leaves of these two common examples are, in a sense, 'inside out' versions of each other.... 

Looking at it primarily as an evolution of development (interior functional) question rather than an adaptive-ecological (exterior functional) question leads one off in a rather different direction [see Hay & Mabberley in Bot. Jahrb. Syst. 113 (1991) 339-428] :-)

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From: Zanezirklejr at aol.com on 2012.02.26 at 11:02:12(22623)
There isn't a purpose, its just a genetic factor they have. Plants like monstera have huge leaves and with the wind it allows the plant to pass air through the leaf without ripping it apart. My monstera has 2 and 3 foot wide leaves on it but its inside.

In a message dated 2/25/2012 5:37:17 P.M. Eastern Standard Time, criswick@spiceisle.com writes:

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From: "E.Vincent Morano" <ironious2 at yahoo.com> on 2012.02.26 at 18:16:47(22626)
If these are tropical plants then perhaps is is so they dont get destroyed in tropical storms. If the plants have a weak root system and coulds easily bee uprooted then I think this is the likely reason. But now another question arises; Were they created like this or were the leaves full and somewhere along they line developed holes in them to adapt?

From: aroid-l-bounces@www.gizmoworks.com [mailto:aroid-l-bounces@www.gizmoworks.com] On Behalf Of John
Sent: Friday, February 24, 2012 7:55 PM
To: ' Discussion of aroids '
Subject: [Aroid-l] Holes

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From: =?iso-8859-1?B?ZGF2aWQgYnL2ZGVyYmF1ZXI=?= <david_dav44 at hotmail.com> on 2012.02.27 at 00:18:31(22630)
There is a famous article dealing with structures and their supposed functions from Gould and Lewontin, which might be interesting in context of the holes and Alistair's comment:

The Spandrels of San
Marco and the Panglossian Paradigm: A Critique of the Adaptationist
Programme

The article can be found on the internet.

Yours,

David Broederbauer

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From: Kyle Baker <kylefletcherbaker at yahoo.com> on 2012.02.27 at 01:33:01(22631)
And it is out of doors exposed to the elements?

Mr. Kyle Fletcher Baker, MCN
Maine Zone 5

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From: Jason Hernandez <jason.hernandez74 at yahoo.com> on 2012.02.27 at 09:11:39(22632)
The difficulty I have with the "tropical storms" idea is that some fenestrated Monstera spp. occur in regions not subject to tropical storms, e.g. the premontane cloud forest of the Pacific coast of Ecuador. I will let growers address the matter of whether scandent Monstera with fenestrated leaves are any easier to pull away from the substrate than, say, scandent Philodendron with entire leaves.

I am not sure what you mean by "created." We may suppose that the primeval leaf was linear, like the branches of Equisetum or the needles of a conifer (think also of Lycopodium and Araucaria), and that the next evolutionary step was a broadening, so as to capture more sun. All the variations in leaves we see are developments in response to the requirements of different niches. The juvenile-stage leaves of a
Monstera probably approximate the ancestral leaves, in parallel with the way various organisms' embryonic development hints at their evolutionary stages.

Jason Hernandez

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From: hermine <hermine at endangeredspecies.com> on 2012.02.29 at 18:34:58(22633)
>
>I am not sure what you mean by "created." We may suppose that the
>primeval leaf was linear, like the branches of Equisetum or the
>needles of a conifer (think also of Lycopodium and Araucaria), and
>that the next evolutionary step was a broadening, so as to capture
>more sun. All the variations in leaves we see are developments in
>response to the requirements of different niches. The
>juvenile-stage leaves of a Monstera probably approximate the
>ancestral leaves, in parallel with the way various organisms'
>embryonic development hints at their evolutionary stages.

I always thought that wind passage had something to do with it as a
FAR better idea than Banana foliage, which shreds HIDEOUSLY in the
wind. But ultimately I feel this is a question like "Who made G-d?".

hermine

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From: Peter Boyce <phymatarum at googlemail.com> on 2012.02.29 at 19:11:23(22634)
Hi Jason,

On what basis must the 'primeval' leaf be linear? Some of the most complex leaves of extant plants are those of fern and fern-allies, the lineages of which well-predate "modern" families as the aroids.

I urge everyone to read: Hay & Mabberly (1991). Transference of function and the origins of the aroids - Botanische Jahrbcher fr Systematik 113(23), 339-428]. I can send the pdf to anyone unable access it on-line.

Peter

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From: "E.Vincent Morano" <ironious2 at yahoo.com> on 2012.02.29 at 19:33:44(22635)
What I mean by created was is in made that way originally by God. I dont believe we evolved from apes thru evolution. Buy I do believe plants and animals adapt not evolve. Because evolution implies that they eventually turn from one genus to another over time. I do believe that thinks were created with the ability to adapt to changing environments. So Im wondering were these plant alway with holes in the leaves or at onetime did they have full leaves and slowly adapted or perhaps through a freak genetic expression shat happens to be good caused them to have holes in the leaves.

When you look at DNA its clearly a viable code and it simply isnt possible for these complex codes to be in existence with out a writer. If you are familiar with mathematics and
probabilities then you know that if the odds of something happening is is low enough past a certain point then its considered impossible. The possibility in which certain conditions are wight where in the primordial soup can spontaneously spawn life are so incredibly low that according to mathematical probabilities its impossible, cant happen. You have higher odds what while you are sitting at your desk reading this that a pot of petunias could spontaneously come into existence and sit on your desk....just to put it into some perspective for you.

Take for example one cell in your liver and the thousands of complex functions that go on inside that cell ever day just in that one cell. You have a higher chance of getting struck by lightning 27 times in the same day then for this to be a result of evolution.

Now I do believe in creation but I dont
believe what these "creationists" believe that the earth was made in 7 day. Its not possible, I prefer to think of these creative days as creative time periods or epochs. Although there were probably a few more then 7.

From: Jason Hernandez

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From: "Sherry Gates" <TheTropix at msn.com> on 2012.03.02 at 06:01:05(22636)
Very well said, Mr. Morano!!!

Sherry Gates

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From: Kyle Baker <kylefletcherbaker at yahoo.com> on 2012.03.04 at 04:45:39(22640)
I have always leaned towards an initial creation that was followed by evolution. But the argument for both sides is as endless as the myriad of snowflakes that fall from the sky...

Mr. Kyle Fletcher Baker, MCN
Maine Zone 5

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From: Jason Hernandez <jason.hernandez74 at yahoo.com> on 2012.03.08 at 07:55:45(22648)
I will address several respondants at once.

hermine: "ps why is broccoli like that?"

Broccoli is a highly domesticated form of sea kale, as are kale, collard, cabbage, and cauliflower. If you look at a broccoli plant growing, you see the big, collard-like leaves, with the broccoli head coming up in the middle. Let that broccoli head grow without picking it, and it will turn into a flower stalk much like those of various wild mustards. Broccoli is like that because over the years, people selected for a thickened flower stalk with buds packed tightly together and taking longer to open.

Peter Boyce: "On what basis would the primeval leaf be linear?"

I was thinking of such fern allies as Equisetum and Lycopoduim, as well as quillworts, all of which have various combinations of linear structures which function as leaves. It seems to me these would have been derived from the strings of cells in filamentous algae, but I could be wrong about that.

Vincent: "What I mean by created was is in made that way originally by God."

I am familiar with all of this, as I was raised a creationist. I found it left too much unexplained, and had to do a lot of interpretation to make the science fit the foregone conclusion: as you do admit, organisms have the capacity to adapt, and this is the essence of evolution. As to the origin of DNA and its authorship, I never have understood molecular biology, so I refrain from comment.

---1723283206-2087545813-1331222145=:96077--

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From: "John" <criswick at spiceisle.com> on 2012.03.11 at 06:12:24(22656)
This was written to me
by Kirsten Llamas, author of Tropical Flowering Plants, and she has given me
permission to post it.

John.

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