"P van Rijckevorsel" wrote in message
...
"mel turner" schreef
Well, I do get the impression they have more leaves than normal.
[Perhaps twice as many?]

***
If they have twice as many leaves as normal, maybe it is not that the
leaves
have an unusual position, but that the leaves have their normal postion,
but
twice in each position?

I confess that I'm not quite sure what "twice in each position" means.
There are two leaves at each node of the stem, but they are on
opposite sides of the stem.

It may be that these opposite-leaved plants form approximately the
same number of nodes as their alternate-leaved brethren, which
would of course give them twice as many leaves.

I was just told that there is an already published, known mutation
of corn that causes this morphology. I'll pass on the reference
when I get it.

The thing that struck me as most interesting about these plants is
that this isn't a case of them showing various irregular phyllotaxies.
They are either just as regularly opposite-decussate as any mint plant,
or completely normal and alternate/distichous.

I've also seen the reverse change in some other plant species that are
normally opposite-decussate: some tropical Acanthaceae shrubs in which
individual branches would grow out with what appeared to be a
perfectly regular spiral alternate phyllotaxy.

It's as if the two phyllotaxies aren't all that far apart in terms of
developmental controls.

There of course has to be more to it, or there wouldn't be so many
major taxonomic groups that are all one or all the other. There'd
likely be many more species in which phylltaxy is variable and
irregular on the same plant [Broussonetia papyrifera comes to mind as
being very plastic from opposite to alternate, and I've seen many
Aristotelia shoots go from whorls of 3 or 4 down to opposite and
finally to alternate leaves].

cheers