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TT: Re: Nodes

please no more plant physiolgy. i still have nightmares and upset stomachs
from the torture. its my version of post traumatic stress syndrome. maybe
someone can get a grant to study it.
> From: Fink, Clayton R. <FinkCR1@central.SSD.JHUAPL.edu>
> To: 'Tree Town' <TreeTown@Majordomo.Flora.Com>
> Subject: TT: Nodes
> Date: Thursday, January 08, 1998 5:02 PM
>  -----------------------------------------------------------------------
> I checked up on branching last night and here's what I took away from
> it:
> Shoot growth occurs in the apical meristem and this tissue is flanked by
> microscopic leaf primordia. One or both of the primordia will become a
> leaf at a node while the meristem continues to grow away from the node.
> The leaf branching pattern is species specific - the leaves at
> successive nodes will be in planes that are at a predictable angle to
> each other.  Auxiliary buds form in the leaf axils, but will not
> necessarily begin to grow into a branch due to apical dominance - their
> growth is inhibited by the hormonal influence of the apical meristem.
> The shoot apex is a source of the plant hormone auxin.  Auxin has been
> shown to inhibit the growth of the auxiliary buds in shoots where the
> apical meristem has been removed, when applied exogenously.  According
> to the plant physiology text I have, just how the auxilliary buds are
> released from apical dominance is not clear.  Cytocynin, another plant
> hormone, and auxin are mutual antagonists - they exert an inhibitory
> effect on each other.  It's thought that cytocynin might have something
> to do with inhibiting apical dominance.  It was also mentioned that both
> ethylene and absisic acid,  other important plant hormones, may play a
> role in various ways.
> That's my basic understanding of it though there is much, much more to
> it.  Maybe Tom Kimmerer could shed some light on this.
> CF
>  ==============================(TreeTown)===============================