Another tangle of tubes in chert
The nematophytes, from palaeobotany monographs also known as Enigmatic
Organisms, are not often seen in the Rhynie chert. Judging from the few
samples hitherto found, they come in tangles of tubes which can be more
or less aligned, or even strictly aligned as with Pachytheca.
There are several species, among them apparently unnamed ones.
Some of them seem to consist of smooth-walled tubes only, as those
presented in Rhynie
Chert News 13,
consist of a combination of tubes with smooth walls and tubes
with a pattern of
spirals or annular rings on the walls .
Fig.1: Nematophyte tube fragment, diameter 26Ám, with
spirals or annular rings on the wall, spacing
mostly 5-6Ám. (Part of the tube is hidden in the depth.) Width of
the image 0.8mm.
behind the different types of tubes and their possible mutual relation
remains obscure. With Nematoplexus ,
the tubes are thought to somehow originate within "branch
but the present sample does not provide evidence for this although a
branch knots surrounded by smooth-walled screw-like
tubes are seen only 3cm away. The tubes with patterned walls are found
scattered fragments only, similar as in Fig.1, with one quite
unexpected exception seen in Fig.2, where the large tubes seem to be
embedded, together with a tangle of
poorly visible tiny
filaments, in a separate lump which had probably
been organic gel before silicification.
As noticed by P.
, the fossil in Fig.2 strongly resembles Nematothallus pseudo-vasculosa
known from compressions . The size data are roughly compatible,
the dimly seen tiny filaments in Fig.2 which seem to correspond with
between 1.5 and 3Ám in diameter" seen on the lectotype of that
Similar as with the tube fragments scattered sparsely
throughout the chert, the tubes in the gel lump do not show branching
nor other remarkable features, perhaps except for one peculiarity
poorly seen above left: A big tube suddenly reduces its diameter to
less than half.
What looks like a series of orderly turns of a screw in
Fig.1 is often interrupted by disorder due to merging or branching
turns, as repeatedly seen in Fig.2.
assemblage of nematophyte tubes as a
separate patch, probably of silicified organic gel, with tube diameters
around an average of 20Ám,
wide variety of spacings between
the image 1.9mm, same scale as above.
Drawing conclusions from
only one sample may not be justified here but asking questions may
be appropriate: Why do patterned tubes often
grow not far from or
even emerge from branch-knots
among smooth-walled tubes like
those of Nematoplexus
? Why are the conspicuous tubes in Fig.2
not seen emerging from branch-knots ?
Why does this veritable 3D-version of Nematothallus pseudo-vasculosa,
too, prefer a place where Nematoplexus
Finally it may be mentioned that this sample of mere 0.28kg
found in 2003 has offered several remarkable items: Nematoplexus
with tubes larger and smaller than hitherto known, Castracollis
eye (? 2015) and unidentified moults, an unknown archetypal charophyte
(2016), and possibly the first 3D-version of Nematothallus pseudo-vasculosa
Annotation 2018: The tube wall patterns, more clearly seen in Rhynie
Chert News 122, resemble the tracheid wall patterns of land plants. This has led to the following conclusion: "The study of the nematophytes will become more central to
the issue of the rise of the earliest land plants because they
clearly have developed a diverse and somewhat complex tubular
anatomy, which in many ways appears to be analogous to vascular
H.-J. Weiss 2017
(modified: June 2017) 2018
On the fragmentary remains of an organism referable to the
from the Rhynie chert, Nematoplexus
Trans. Roy. Soc. Edinburgh
65(1961-62), 79-87, 2
error on Plate I Fig.1: not x19 but x1.5)
private communication (2017).
Clarification of the genus Nematothallus
J. Paleont. 67(1993), 1090-1094.
 W.H. Lang:
On the plant-remains from the Downtonian ... .
Phil. Trans. Roy. Soc. London B 227(1937),