These trees are called by botanists Lepidodendrons, or scaly
trees; there are numbers of them in all coal-mines, and one trunk
has been found 49 feet long. Their branches were divided in a
curious forked manner and bore cones at the ends. The spores
which fell from these cones are found flattened in the coal, and
they may be seen scattered about in the coal-ball.
Week 23
Another famous tree which grew in the coal-forests was the one
whose roots we found in the floor or underclay of the coal. It
has been called Sigillaria, because it has marks like seals
(sigillum, a seal) all up the trunk, due to the scars left by the
leaves when they fell from the tree. You will see the
Sigillarias on the left-hand side of the coal-forest picture,
having those curious tufts of leaves springing out of them at the
top. Their stems make up a great deal of the coal, and the bark
of their trunks is often found in the clays above, squeezed flat
in lengths of 30, 60, or 70 feet.
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