Plants from the deep past

Tuesday, June 2, 2015

The Devonian period, beginning 416 million years ago, is when plants began to colonize the land. Scientists speculate that they probably spread vegetatively. But by the late Devonian (395 million years ago), roots, leaves and spores were plentiful, and seed plants appeared by the end of the Devonian.

A window into the evolution of plants is now spread across table tops in the herbarium. These fossils were collected by Dr. David Lee, now emeritus biology professor of FIU, and Brett Jestrow, keeper of our herbarium. Paleobotany, if turns out from listening to the people who oohed and ahhhed over them, is a secret interest we all share, whether we pick up sea creatures stuck in oolitic limestone and coral reefs or find them on vacation and bring them home to rest on our book shelves.

 Some of the fossils Dr. Lee had identified by expert Patricia Gensel at the University of North Carolina. They include ancestors of Psilotum nudum from the earl Devonian; arborescent lycopsids called Lepidendrons, with cambium produced inside an otherwise hollow stem and purselike sporangia on the smallest branches; Genselia, a plant from the Carboniferous.

Look for a story about them by Ken Stezer in the fall issue of our magazine. Meanwhile, here's a peek at some.

Sawdonia acanthotheca, early Devonian, gave rise to lycopsids

Leaf scars of Lepidodendron, tree-like lycopsid, from the Carboniferous; coal is black, sparkling.

Sporangia shaped like little purses developed on this Sawdonia branch tip in the middle Devonian