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[Arisaema Enthusiast Group (AEG) Discussion List (and other=]

hardy  Aroids)" <ARISAEMA-L at NIC.SURFNET.NL> Aroids)" <ARISAEMA-L at NIC.SURFNET.NL>
Sender: "Arisaema Enthusiast Group (AEG) Discussion List (and other=
From: pbruggeman at TISCALI.NL
Subject: Betr: Re: Arisaema dilatatum germination quandary
In-Reply-To: <002601c50403$bdbb9f50$5ad8fea9 at FAMILY>
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Dear Adam,

As far as I know what causes an Arisaema species to show this behavior st==
ill
remains a little bit of a mystery and the behavior is not always a stable==

characteristic within a species. Some species can be induced to show this==

behavior. Older seed of A. nepenthoides for instance sometimes shows a mi==
xture
of hypogeal and epigeal germination for a species that usually produces a==

seedleaf in the first season. It is however closely related to a species
that has several clones that exclusively produce a seedleaf only in their==

second season (A. lobatum). It therefore might be influenced by ecologica==
l
circumstances which would make the production of the seedleaf unfavourabl==
e
in the first year. One might think, for instance, that high altitude spec==
ies
with a relatively short growing season, would prefer this type of germina==
tion
more but I have tried to analyze the species that show this type of germi==
nation
and the habitat they come from and thusfar I have not been able to make a==
ny
correlation. It seems to occur random throughout the genus and, at best,
would suggest it is a trade aquired by species independant from one anoth==
er
(convergent evolution) in a similar way that members of section Tortuosa
all have the same spadix appendix type but do not all seem to have the sa==
me
ancestor. The species that do show a certain characteristic can be relate==
d
to eachother but only because the common ancestor has developed the trade==
=2E
The possibility of this type of germination is there but only few actuall==
y
have developed it.

Also what the small tuber is is hard to say. The use of the term "protoco==
rm"
is strictly speaking false because that only applies to the relatively un==
structured
mass of cells formed by orchids after germination that have interaction w==
ith
mycorrhiza. There seems to be some structure in the small Arisaema tubers==

and usually the size of the little tuber at the the end of the first seas==
on
is twice the size of the initial seed but can they already take up nutrie==
nts
without photosynthesis? Would it be an advantage to store nutrients the f==
irst
year and produce bigger growth the next year? It definitely is not meant
to place the young tuber deeper in the soil because the roots formed by s==
pecies
that produce a seedleaf in the first season do that job much better than
the distance the young tuber is formed away form the initial seed. Fascin==
ating
stuff but I am afraid more questions than answers.

Pascal
>-- Oorspronkelijk bericht --
>Date:         Wed, 26 Jan 2005 18:04:15 -0600
>Reply-To:     "Arisaema Enthusiast Group (AEG) Discussion List (and othe==
r
>hardy              Aroids)" <ARISAEMA-L at NIC.SURFNET.NL>
>From:         Adam Fikso <irisman at AMERITECH.NET>
>To:           ARISAEMA-L at NIC.SURFNET.NL
>Subject: Re: Arisaema dilatatum germination quandary
>
>
>OK, one person's experience (yours) was  enough to certainly confirm tha==
t
>something unusual was going on.  Maybe there's no data in the literature==

>on
>how this was established as fact.  Sort of lost in the mists of history?==

>


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