The gymnospermous tree Cordaites
Click at the pictures to see more details. .
Sometimes leaves of Cordaites are abundant in Upper-Carboniferous
(Pennsylvanian) layers. In most cases you will find fragments and with good
fortune you can collect a leave top or a leaf base.
The leaves of Cordaites principalis possess fine, parallel veins
and between those veins there are from 2 to 5 'false' ribs which lack
In the South of France leaves of a different shape also occur: e.g.
leaves with rounded upper part at Montceau-les-Mines and small, narrow leaves
Inflorences of Cordaites are not rare. Sometimes they occur in
great numbers. They are spike-shaped. The axis of the cone, which can be
sized up to 30 cm, bears two rows of small shoots in the axils of modified
leaves, called bracts. A shoot has either female or male flowers: so the
inflorence is unisexual. Commonly both types of inflorences are called
Cordaianthus. In most cases it not possible to determine wether the
cone is female or male.
The pollen is of the grain type Florinites and has a diameter of about 50 µm. A pollen tube has never been found so probably the fertilisation occurred by free-swimming spermatozoa.
The seeds attributed to Cordaites are all heartshaped and flattened.
There are three genera:
In the lowlands Cordaites generally was a tree with a trunk of
10 m, sometimes even 20 or 30 m. In peat-forming swamps Cordaites
was mangrovelike or a shrub. There are studies showing that Cordaites
could form mangrove-woods in brackish or salt water environments.
Fossil wood of Cordaites is called Cordaixylon if the entire section of the trunk, with bark and pith, is present. Besides that, Dadoxylon (see the picture) possibly originates from Cordaites. It can however hardly be distinguished from conifer wood.
The wood of a root of Cordaites lacks the central cavity and is called Amyelon.
In spite of the shortness of the 'flowering time' of the cordaits, they have played an important role and they have left many fossils behind. The group disappeared in the Upper Permian.