Enigma inside Aglaophyton
spores
Spores
of the early land plants of the Devonian
Rhynie chert are
found in their sporangia or scattered throughout. Aglaophyton spores
are often seen in large
numbers but germinating ones are very rare. Nevertheless they had been
found and pictured in several stages of germination [1].
Those
pictures do not provide any indication of structures inside
the spores. The present pictures show a distinct structure in one spore and less distinct ones in a few others. It
looks like a small patch of tissue consisting of tiny unequal polyhedral
cells and a
few not yet finished cell walls protruding at edges. Apparently, Aglaophyton spores
of such aspect had not been described before.
It is thinkable that an advanced stage of
the phenomenon could provide the aspect of
Dictyotriletes spores
[1,2]. This would raise the question of the compatibility with
Retusotriletes spores
[1], which are usually associated with Aglaophyton.
Independent of possible affiliations there is the relevant problem of
whether the structure seen inside
the spore is an hitherto unnoticed early stage of germination or
something else.
A
search for more spores with inner structure among the Rhynie chert
samples stored in collections might help to answer the remaining
questions.
Figs.1,2: Aglaophyton sporangium, detail
with palisade wall and variously affected spores, a few ones with
distinct structure inside. Spore size up to 70µm. Width of the pictures
1.4mm.
Sample: Rh2_8 (1.36kg), Part 1, obtained from Shanks
in 2000.
H.-J.
Weiss 2020
[1] www.abdn.ac.uk/rhynie/spores.htm
[2] C. Rubinstein, J.H.G. Melob, Ph. Steemans: Lochkovian
(earliest Devonian) miospores ... Rev. Palaeobot. Palyn. 133 (Jan
2005), 91-113.
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