Sigillaria species can
be distinguished by considering the form and the placing of the leaf scars.
It is an artificial classification. On one trunk more than one species can
occur. Transitional forms are found frequently.
On older (parts of) trunks the ribs are wider and the leaf scars
occupy a smaller part of the width of the ribs than on younger ones. On older
trunks the leaf scars at one rib are situated at a larger distance from each
other.
Identification table (Westfalian A and younger)
after Chaloner & Collinson:
An illustrated key to the commoner British Upper Carboniferous plant compression
fossils (1975).
Adapted after Josten: Die Steinkohlen-Floren Nordwestdeutschlands (1991)
Only twelve (common) north-west European species are included!
So be careful in using the
table.
Click the appropriate number.
| 1a. Leaf scars in vertical rows on clearly-defined ribs with straight or curved sides. | 1b. Leaf scars not situated on such clearly-defined ribs. |
| 2a. Leaf scars at least 1.25 times as high as broad. | 2b. Leaf scars about as high as broad, or shorter. |
 3a. Leaf scars oblong, pear-shaped, sometimes
with a small plumula (plume, fountain) on the top. The vertical distance
of the leaf scars is relatively large: two to three times the height of a
scar. Sigillaria rugosa |
 3b.
Leaf scars rounded rhombic. The vertical distance of the leaf scars is less
large: about the height of one scar.
|
| 4a. The leaf scars show rounded lateral angles or no lateral angles at all. | 4b. The leaf scars show clearly-defined lateral angles. |
| 5a. The vertical distance
of the leaf scars is very small. Often the leaf scars are almost in contact
with those above and below.
|
 5b.
The distance of the leaf scars is larger: at least half the height of
a scar and often larger. Leaf scars are much narrower than the ribs. They
have an oval outline. Sigillaria ovata |
6a.
The leaf scars are in contact with those above and below. No transverse line
above the leaf scar. There are longitudinal wrinkles in the furrow between
the ribs. Sigillaria cumulata |
 6b.
The vertical distance of the leaf scars is small: half the height of a scar
or less. Clearly-defined transverse line above the scar. No other wrinkles.
Sigillaria tesselata |
| 7a. Vertical distance of the leaf scars less than 5 mm. | 7b. Vertical distance of the leaf scars more than 5 mm. |
 8a. Vertical distance of the leaf scars mostly less
than half the height of a scar. Leaf scars hexagonal with rather acute lateral
angles.Sigillaria boblayi |
 8b.
Vertical distance of the leaf scars from very small to a maximum of one height
of a scar. Leaf scars more pear-shaped.Sigillaria mamillaris |
 9a. Plumulas (little plumes, fountains)
above the leaf scars.Sigillaria schlotheimiana |
9b. No plumulas of any significance. |
 10a. Clearly defined lines descending from the mid-points
of the sides. Moreover a smooth surface or a surface with a very fine marking.
Sigillaria principis |
 10b. No descending lines or very
small ones. Clearly defined transverse lines between the leaf scars.Sigillaria scutellata |
| 11a. No ribs present at all, though the leaf
scars are arranged in vertical rows. Sigillaria brardii (older stem) |
11b. Every leaf scar
on its own "leaf cushen", which is clearly separated from the surrounding
leaf cushens. |
 12a. Leaf cushens transversely lenticular
with acute lateral angles.Sigillaria brardii (young branch or stem) |
 12b.
Leaf cushens forming a honeycomb-like structure.Sigillaria elegans |
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