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  flowering 'juvenilies'
From: "Peter Boyce" p.boyce at rbgkew.org.uk> on 2000.06.15 at 14:45:46(4787)
Dear All

The newly raised issue of juvenile monsteroids flowering is
interesting because, while the production of flowers by a plant
vegetatively in a juvenile phase does occur in the monsteroids,
notably Monstera tuberculata, Rhaphidophora hayi, R. latevaginata,
R. pachyphylla, R. parvifolia, R. okapensis and Scindapsus lucens,
this 'M. dubia' thing is that the plants are flowering with very small
leaves and BENEATH the leaves, whereas in all of those listed
above while the juvenile growth morphology is retained into
flowering in most instances the leaves of flowering individuals are
considerably larger than those of youngsters and the
inflorescences are carried clear of the leaves either at the tips of
clinging shoots or on free shoots arising from the leaf axils. If the
description of this 'dubia' plant is correct it would appear that
inflorescences are arising directly from the leaf axils. Because
aroids ALWAYS flower at the shoot apex it would mean that in this
plant each inflorescence is carried at the tip of a very short shoot
arising in the leaf axil (the same situation as in Pothos scandens) -
a feature not yet recorded in the Monstereae.

Pete

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From: "Eduardo Goncalves" edggon at hotmail.com> on 2000.06.15 at 19:41:04(4796)
Dear Aroiders,

The production of sexual parts in juvenile individuals is a
morphogenetic "accident", but it is usually explored by the evolutionary
history of many groups. There are two morphogenetic processes associated to
this aspect: Paedomorphosis and Neoteny. Both concern juvenile individuals
with mature sexual parts or juvenile structures that are kept active in
adult individuals. These phenomenons occur in both plants and animals. Some
evolutionists say that humans are just neotenic apes, because our brain
continues to develop for a long time after birth! Anyhow, theses processes
are also know in plants and maybe they are a good natural method to "make"
new species. Juvenile (or poorly diferenciated) organs are usually very
plastic and can adapt to different conditions. If this ability to be
morphologically plastic is important for the effective survival of a quoted
species, it can be kept or even "improved" by natural selection.
I have one possible example. One of the most morphologically variable
genus in the tribe Spathicarpeae is Spathicarpa. It is small, with poorly
differenciated ground tissues and have usually the simplest leaf type in the
tribe (I mean the same type we find in seedlings of almost all genera of
the tribe). One of my hypothesis (still in test) is that Spathicarpa is a
neotenic genus in Spathicarpeae. The same for Urospathella wurdackii
G.S.Bunting (now currently recognized as Urospatha wurdackii (G.S.Bunting)
Hay). It is a Urospatha that flowers with the leaves of seedlings!!!! Maybe
this kind of leaf is useful in those savannas this species occurs. Or maybe
it is just an accident that soon will be erased by natural selection!
In the case of the supposed M. dubia that flowers with juvenile
flowers, we can make some free speculation about this. In the "normal"
environment of the species, maybe it is not a good idea flowering this way,
because pollinators may not be able to find the flowers. Meanwhile, if this
plant spread to new areas, maybe with smaller trees and different potential
pollinators, it can prove to be successful (in evolutionary aspects), so it
can diverge from the main species and become ANOTHER species. If evolution
can be so creative than me (I don't think so), it is really possible to
occur in nature!

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From: Don Burns donburns at macconnect.com> on 2000.06.16 at 17:36:39(4800)
>Date: Fri, 16 Jun 2000 19:25:30 -0500 (CDT)
>Reply-To: webmaster@plantapalm.com
>Originator: aroid-l@mobot.org
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From: Jody Haynes webmaster at plantapalm.com> on 2000.06.16 at 17:49:40(4806)
Eduardo,
Yours was an interesting post. I, too, have some knowledge (and an astute
interest) of paedomorphosis and neoteny--but only in animals. I was not
aware of
the process in plants.

I feel that these terms should be clarified. Although they both refer to the
"possession in the adult stage of features typical of the juvenile stage of the
organism's ancestor", neoteny specifically refers to sexual maturation of the
'juvenile' stage: "heterochronic evolution whereby development of some or all
somatic features is retarded relative to sexual maturation, resulting in
sexually mature individuals with juvenile features" (Futuyma, D. J. 1986.
Evolutionary Biology. Sinauer Associates, Inc. Sunderland, MA.).

Thus, paedomorphosis refers to the simple possession of juvenile traits in an
adult organism, but does not specify a process; conversely, neoteny is the
process by which somatic maturation is retarded relative to sexual maturation.

Does this make sense? Anyone else care to comment on this interesting topic?
Jody

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From: StellrJ at aol.com on 2000.06.18 at 19:22:57(4832)
In a message dated Fri, 16 Jun 2000 8:50:17 PM Eastern Daylight Time, Jody
Haynes writes:

Thus, paedomorphosis refers to the simple possession of juvenile traits in an

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From: Jody Haynes webmaster at plantapalm.com> on 2000.06.19 at 14:26:39(4843)
> So, what you are saying is, paedomorphosis is when an adult looks or acts
> like a juvenile, while neoteny is when a juvenile is capable of reproducing?

Yes and no. Neoteny is the *process* of retardation of somatic maturation
relative to sexual maturation, whereas paedomorphosis is the *possession* of
juvenile traits in an adult.

> So, in human terms, certain males of our species are behaviorally

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From: Lewandjim at aol.com on 2000.06.19 at 14:28:05(4847)
In a message dated 06/18/2000 10:23:21 PM Eastern Daylight Time was written:

<< So, what you are saying is, paedomorphosis is when an adult looks or acts
like a juvenile, while neoteny is when a juvenile is capable of reproducing?

So, in human terms, certain males of our species are behaviorally
paedomorphic, while teenage mothers are cases of neoteny.

Jason Hernandez

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From: "Eduardo Goncalves" edggon at hotmail.com> on 2000.06.20 at 18:59:48(4867)
Dear Jody,

Thanks for your comments. In my post, I just forgot to include a good
definition of both terms. You did it with precision! I hope someone have
other possible examples with other groups in this marvelous family.

Best wishes,

Eduardo.

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From: StellrJ at aol.com on 2000.06.20 at 19:59:48(4868)
In a message dated Mon, 19 Jun 2000 5:33:21 PM Eastern Daylight Time, Jody
Haynes write:

> So, what you are saying is, paedomorphosis is when an adult looks or acts

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From: Jody Haynes webmaster at plantapalm.com> on 2000.06.20 at 20:11:21(4871)
Thank you, Eduardo. I, too, look forward to more information on this topic.

Eduardo Goncalves wrote:

> Dear Jody,

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