Roots of the coal-swamp Lycopods, Stigmaria.

James Mahaffy (mahaffy@mtcnet.net)
Sat, 04 Sep 1999 16:06:09 -0500

> Arthur V. Chadwick (chadwicka@swau.edu) wrote
> Fri, 03 Sep 1999 07:35:46 -0700
[snip]
> Also, Stigmarian rootlets seem to be incapable of penetrating soil by
> growth, as they are blunt ended and have no supporting tissues to enable
> the penetration of resistant substrates. Furthermore, they grow from a
> large terminal bud, rather than from expansion of tiny rootlets (as is
> the
> case for all soil penetrating roots), and the bud and rootlets seem
> eminently suitable for penetrating forest floor (or floating mat)
> debris.
> The stigmaria I have seen in association with coals and in isolated
> sandstones show no evidence of having grown where they are found (there
> is
> no evidence of alteration of the surrounding sand, as would be the case
> were it in situ, the roots and rootlets can be found to terminate
> abruptly,
> and I have found lots of Stigmarian roots without attached rootlets at
> all.)

But the rootlets likely fall off the main stigmaria root. They do NOT
originate from an internal pericycle and force their way through the
outer layers of the root as is the case in most angiosperm roots. This
works better for a plant rooted in peat than in hard sediment. Not sure
it says anything about transport since the lack of rootlets may have
abscised while the plant was growing.

>Even when the roots are found intact suspended in sand, the
> rootlets
> often appear tangled and displaced. I am convinced that the stigmarian
> roots I have seen are transported with the sand.
> Art

I have not seen enough of them myself to comment from personal
observation but there are LOTS of good field observation of rooted
horizons of rootlets in the underclay and I have seen some. That would
tend to indicate perhaps that lycopods were once rooted in those
clastics. On the other hand there are also many underclays that show no
evidence of rooting, which might be used to support transport or some
other reason for lack of penetration of the roots.

I don't usually follow this group (too noisy), so if you want to insure
my reading your response cc it to me too. Actually I did a little study
on noise on this group, ASA list and paleonet (low noise) and hope to
share it with you folks soon. 

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