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  apomictic?
From: Mary Jane Hatfield <oneota at ames.net> on 1999.02.21 at 19:43:19(3051)
Concerning my Dracontium spruceanum inflorescence, it was suggested that
it might be setting seed. I wondered how that might be possible since I
only have the one plant with the one flower (which has been flowering
for over a month now)

I was told *Look up "apomictic"* which I did.

I found ...

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From: dave-poole at ilsham.demon.co.uk on 1999.02.22 at 08:42:15(3055)
In apomictic seed bearers, several embryos are formed within the seed
(polyembryony). One is the result of sexual reproduction and will
have shared genes from both parent plants, the remainder will have
been produced asexually and be clones of the mother plant. This is
most commonly demonstrated in several Citrus species - the clonal
seedlings being noticeable more vigorous and easily identified. When
apomictic germination occurs, it is a useful means of reproducing the
mother plant without having to worry about hybrid variation.

David Poole

From: Sue Zunino <suez at northcoast.com> on 1999.02.22 at 14:14:28(3056)
David,

Could you explain this a bit further?

>One is the result of sexual reproduction and will have shared genes from both parent plants,<

Apomixis is any form of asexual reproduction. When did sexual
reproduction occur for one of the embryos to have genes shared by both
parent plants? Is this carried in the genes of the apomictic plant so
that pollination is no longer necessary?

Sue Zunino

From: dave-poole at ilsham.demon.co.uk on 1999.02.23 at 07:55:27(3057)
>Could you explain this a bit further?

>Apomixis is any form of asexual reproduction. When did sexual
>reproduction occur for one of the embryos to have genes shared by both
>parent plants?

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From: Lewandjim at aol.com on 1999.02.23 at 08:22:06(3059)
As I suspected this discussion of apomictic reproduction may get complicated.
Like Sue Zununo, I was a little confused by David Poole's definition and
example. Perhaps there are degrees of apomixis. The most familiar example that
I know involves Hosta venticosa which I believe ONLY produces clones of itself
regardless of what the pollen parent might be.

I offer this only as further information, not as a definitive answer.

Jim Langhammer

From: Neil Carroll <zzamia at hargray.com> on 1999.02.23 at 08:32:55(3060)
Sue, I will try to answer this question about "apomictic" the way I have
always understood it. Daves answer would have left me with some questions
also.

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From: StellrJ at aol.com on 1999.02.23 at 11:49:39(3061)
In a message dated 2/23/99 7:42:43 AM Pacific Standard Time, dave-
poole@ilsham.demon.co.uk writes:

> This way, it is perfectly possibly to get a true cultivar of a

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From: dave-poole at ilsham.demon.co.uk on 1999.02.23 at 14:46:45(3064)
Neil wrote in response to Sue:

>>Apomixis is NOT any form of asexual reproduction. Apomixis is asexual
>>reproduction involving flower parts. Seeds without sex.
>

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From: dave-poole at ilsham.demon.co.uk on 1999.02.23 at 14:52:28(3065)
Jason Hernadez wrote:

>If the "normal" seedling is less vigorous than the apomictic ones--and =
would
>therefore be at a competitive disadvantage to them--why does the plant =

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From: Sue Zunino <suez at northcoast.com> on 1999.02.24 at 11:23:24(3066)
What was my original question?

Thank you all for the great lessons on asexual fertilization. After
being prompted by the wonderful and complex explainations, I mixed a bit
of searching in with them and found that (if I have this right) my
little Anthurium trinerve's genes (for which I asked the question in the
first place because it's seeds are fertile and there is not another
plant, and providing it is apomictic) has a complete set of chromozomes
within the seed embryo making it possible to reproduce, by cloning
itself, without needing another plant. I know this is a very weak
explaination. Ok, I don't get this completely, but I'm thinking.
Apomixis is ONE form of asexual reproduction. There are many types of
apomixis such as recurrent, nonrecurrent, adventitious, vegetative, and
polyembryony. But is Anthurium triverve a facultative apomict? Yes or
no.

Thank you Dave, Don, Ray, Neil, Jim, and Jason for your explainations,
and MJ for asking the original question,

Sue Z.

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From: "Toby Marsden" <tobym at beer.com> on 1999.02.24 at 11:54:14(3067)
Jason et al,

>If the "normal" seedling is less vigorous than the apomictic ones--and
would
>therefore be at a competitive disadvantage to them--why does the plant
produce
>it? Pollination/fertilization costs the plant energy, so why do it just to
>produce a disadvantaged seedling?

Unless I have missed something large indeed (not unlikely), this question is
akin to asking "Why do plants reproduce sexually when they can produce more
vigorous offspring by reproducing vegetatively (asexually)?", being as the
fertilised seedling is a product of sexual reproduction, while the
unfertilised or apomictic seedling is a product of asexual reproduction.

The answer to this question is to do with the Evolution of Species via
Natural Selection. How can a plant improve or change, if it produces
offspring identical to the parents?

Sorry if I am confusing the issue by taking it off at a tangent.
Kindest regards,

Toby

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From: mplewinska at mindspring.com (Magdalena Cano Plewinska) on 1999.02.24 at 18:54:55(3070)
On Tue, 23 Feb 1999 13:48:34 -0600, StellrJ@aol.com wrote:

>If the "normal" seedling is less vigorous than the apomictic ones--and would
>therefore be at a competitive disadvantage to them--why does the plant produce
>it?

Maybe sometimes it's a better plant (for the environment) and maybe
the plant produces lots of them "hoping" for that one superior one in
the lot. As I understand it, apomixis tends to happen in plants that
are optimally adapted to their environment, so they just produce lots
of clones of themselves on the principle that "you shouldn't argue
with success." But if conditions should change, these clones may not
be so well adapted, so it's a good idea to play it safe and make a few
plants that are different and may do better in the new environment.
--
Magda Plewinska mplewinska@mindspring.com

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From: mplewinska at mindspring.com (Magdalena Cano Plewinska) on 1999.02.24 at 18:59:50(3071)
On Tue, 23 Feb 1999 16:45:43 -0600, dave-poole@ilsham.demon.co.uk
wrote:

>relying upon literal translations from either the

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From: "George R Stilwell, Jr." <grsjr at juno.com> on 1999.02.24 at 19:32:40(3073)
Sue,

The answer is - Maybe.

Ray

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From: Neil Carroll <zzamia at hargray.com> on 1999.02.25 at 07:13:28(3074)
At 04:47 PM 2/23/99 -0600, you wrote:
>Neil wrote in response to Sue:
>
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