Asteroxylon mackiei

This is the reconstruction of the plant Asteroxylon mackiei made bij Kidston and Lang (1920).
The size of the plant could be up to 50 cms with a stem diameter up to 1 cm. It is the biggest plant in the Rhynie Chert.
The 'leaves' are scalelike like those of the clubmosses. The sporangia are attached laterally along the stem and for this reason the plant is considered to be a ancestor of the clubmosses.
The name Asteroxylon points to the star-shaped xylem.
The tracheids of this plant, reinforced with annular and spiral thickenings, are common. In most cases the cell structure of the softer parts is not present any more.
The cylindrical roots are also rather common.

Transverse section of the stem with stellate xylem.
At the top right a section through a leaf with xylem strand.
The black spots are xylem strands  leading to the leaflets.
Through the decaying stem grows a cylindrical rootlet.
Width of the photo 1.2 cm.

Asteroxylon mackiei

Star-shaped xylem

Tracheids with annular and spiral thickenings

Leaves