Species of Sigillaria

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.

Sigillaria elongata

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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