Produced
by the Population Genetics and Evolution class, Furman University |
The
Carboniferous: Lebachia |
Lebachia
is a genus of extinct cone-bearing plants from the order Voltziales. They
are believed to be the ancestor of all extant conifers except yews. The
cones were both pollen and seed bearing. The male is comparable to a modern
male conifer cone, but quite different from the male catkin of the chordaitales.
However, the pollen grains are enveloped in a large air sac, like those
of chordaites (Harris 1947). The female cone has spirally arranged leaves
with fertile shoots know as the “seed-scale-complex.” There
is a single megasporophyll, which expands into the base of a terminal
ovule. This ovule resembles that of chordaites (Harris 1947). They were
generally small trees with an orthotropic stem and plagiotropic (horizontal)
branches (Taylor 2009). The branches were arranged pinnately. The leaves
are short simple needles, arranged along the axis in spirals with pairs
at right angles to one another (as is seen in modern conifers) (Arens
1998). Page by Megan Aprill |
|
Lebachia piniformis. Photo from:
www.paleoportal.org |
|
Taylor C. 2009. Voltziales . www.palaeos.org . Accessed March 2, 2010. Arens NC. 1998. The Conifers. University of California Museum of Paleontology (UCMP).Accessed March 2, 2010 Harris TM. 1947. review: The Evolution of the Conifer Cone. New Phytol 46:174-177. |