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  Chirality
From: Theodore Held <oppenhauser2001 at gmail.com> on 2011.10.24 at 10:46:18(22229)

Dear List,

Attached here (with luck) is a picture I made of a pair of blooms from
a Cryptocoryne griffithi (identity confirmed by Peter Boyce at the
recent IAS show). Whatís interesting to me is that the outer spathe
tip (called the flag for Crypts) of the plants twists to the left for
one and to the right for the other. These plants are vegetative kin.

I have also seen the pairing of left-handed and right-handed
inflorescences on Cryptocoryne pontederifolia.

Has anyone ever noticed mirror-image flower forms like this with any
other aroids? In chemistry differences involving only mirror images
are referred to as chiral isomers and originate with subtle
molecular-level geometry. In normal life this is called ďhandedness.Ē
In a plant bloom, the differences may display as macroscopic
phenomena, but likely originate with early development, also perhaps
on a molecular level.

Please enlighten me if anyone knows about this oddity.

Ted Held.

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From: Deni Bown <denibown at googlemail.com> on 2011.10.25 at 13:23:29(22230)
Dear Ted,

Thank you for this interesting observation. It's tempting to guess
that it's just chance as what evolutionary advantage could right- or
left-handedness be to a Crypt? Given that size, color etc. are the
same, the spathe would not be held further above the water to offer
visual or olfactory signals any more effectively by twisting one way
or the other. But then who knows what happens at full moon!

Let's have more of these intriguing observations!

Deni Bown (still in Nigeria where no Crypts grow but from henceforth
will be more observant with all & any aroid inflroescences)

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From: "Tom Croat" <Thomas.Croat at mobot.org> on 2011.10.25 at 10:59:25(22231)
Dear Ted:

I was once convinced that the direction of opening was important but a
big survey we did with the way leaves opened proved that this appears to
be perhaps totally at random.

Tom

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From: Kathy <ku5 at yahoo.com> on 2011.10.25 at 17:58:10(22232)
About "handedness" with aroids, Ted: when the spathe of Amorph titanum unwraps and opens it's easy to observe this, and all the ones that have flowered for me have been left handed, and all the ones at University of Wisconsin have been right handed. I don't know the reason for this, but it's interesting.

Sent from my iPhone

On Oct 24, 2011, at 12:46 PM, Theodore Held wrote:

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From: brian lee <lbmkjm at yahoo.com> on 2011.10.25 at 18:53:53(22233)
Dear Ted,

Aloha.

I agree with Kathy. It is very interesting indeed. My favorite spiraling in Araceae are the coiled spadixes of Anthurium wendlingeri. However, I was not observant enough to notice the chirality, sinistral(left) or dextral (right). Can they have both on the same plant? List? I have no idea about molecular geometry and its influence on the chirality of Anthurium wendlingeri, nor evolutionary advantage to direction of coil. We should have Christopher comment on this...

Aloha,

Leland

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From: fschwab at nrao.edu on 2011.10.25 at 21:39:47(22235)
What do you find? Does the chirality differ between Northern and Southern
Hemisphere? Tomorrow I'll forward a reference dealing with pole beans.
:-)

- Fred Schwab

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From: Alistair Hay <ajmhay at hotmail.com> on 2011.10.26 at 00:00:13(22236)
It is presumably related to the direction of the phyllotactic spiral of the whole shoot.  It is perhaps the same phenomenon as the scars on the trunks of Philodendron Sect. Meconostigma, which are shaped either like  fat '6's or fat 'd's.

> Date: Tue, 25 Oct 2011 12:59:25 -0500
> From: Thomas.Croat@mobot.org

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From: Theodore Held <oppenhauser2001 at gmail.com> on 2011.10.26 at 09:58:56(22237)
List:

Ah, good. That means I'm not the only one to observe this sort of
growth pattern. To tell the truth, it seems to me that different
handedness might be more common than I thought, but the phenomenon is
not something one might notice, even with two specimens side-by-side.

Not being a botanist, my first guess is that there is some sort of
tiny 'kick', probably hormonal or environmental, that happens to a
meristem early in the development of a leaf or inflorescence, which is
then carried on without further chemical influence as the cells go
about their assigned roles.

In vining plants, there are some species that ALWAYS curl to the right
and others that ALWAYS curl to the left. So sometimes it is not merely
random. Offhand I cannot think of any special advantage one twist
direction might give to an aroid. Of course, in vining species I can't
think of any special advantage either; and yet they do it faithfully.

Ted Held.

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From: Christopher Rogers <branchiopod at gmail.com> on 2011.10.31 at 08:17:04(22240)
Greetings all,

I agree with Leland: Anth. wendlingeri is also my favorite aroid that spirals. When I had that plant prior to my move, I had many blooms, but I do not recall if the inflorescences all spiraled in the same direction or not. However, there was one bloom that started spiraling one way, then changed and spiralled the opposite direction!

Add to this my second favorite group of plants (after the aroids): Utricularia, the bladderworts. I used to grow U. prehensilis. This terrestrial species sends out long stems from the soil surface that tend to stick out at close to 45 degrees from the horizon. Over the course of the day they slowly swing in an arc. I the encounter a stem of another plant or a plant tag they coil around it. Some stems will then slowly uncoil and swing back in the opposite direction, again until the encounter an object, and again, they coil around it. So, here is an example of a plant that will coil both directions on the same stem.

Happy days!

Christopher

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From: "Ertelt, Jonathan B" <jonathan.ertelt at Vanderbilt.Edu> on 2011.10.31 at 12:17:22(22246)
Although I also like Anthurium wendlingeri for the spiraling infloresences, I collected an Anthurium sp. in Costa Rica back in 1992 that I have not yet sent photos to Tom Croat for i.d.ing, but the whole plant spirals as it grows, at least growing on smaller (2-3Ē diameter) tree trunks. Itís a wonderful species, with more roots growing up and out onto the leaves then grow attaching to the tree trunk host Ė one of the best non-birdís nest examples of the trash-basket root system Iíve ever seen. The inflorescence and spathe are both green initially, the spadix slowly going slightly more yellow. The fruits are light orange as they pop out, and somewhat quadrangular at the base. The leaves are wide sword-shaped, to almost two feet long on short petioles Ė thatís the best I can do without going and looking again at the plant for more detail. Iím doubtful that itís a new species, though wouldnít that be neat Ė but I do plan on taking some detailed pictures and sending them on before long. In any case, a wonderful spiral.

Jonathan

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From: Christopher Rogers <branchiopod at gmail.com> on 2011.10.31 at 12:36:54(22248)
Jonathan,

That Anthurium sound fascinating. I would enjoy seeing pictures sometime.

Christopher

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From: Bob Burns <bobburns61 at yahoo.com> on 2011.11.02 at 23:13:43(22259)
Don't know if this is germane to a discussion of chirality in aroids, but palms are distantly related. When I was living in Bangladesh, where the coconut palm is common, I discovered that most (say 19 of 20 or so) were one handed...the easiest way being to look where the flowering stalk came in relation to the leaf stalk immediately below it...to the right or to the left. I was told that below the equator, in the Southern Hemisphere, the percentages reverse, and that this is due to the way the crown of the tree captures sunlight....one "handedness" being slightly more efficient in each hemisphere. It stands to reason then, that, at the equator (provided sufficient generations from seed had gone by to reduce origin influences....which would be quite a while in the case of a coconut palm), that the percentage would be about equal, varying more and more in either direction, the further one got north
or south. I wonder if any exhaustive survey has been done on any plant about this issue, even with plants so extensively cultivated, and so obviously chiral, as the palms. Since many tropical aroids also span the equator, maybe something like this is going on with them as well...
Bob Burns
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