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ECOL 182 (Spring) Intoductory Biology - Lecture 2 - comment and summary

Well, I'm not sure why I became uninterested in the Pteridophytes today at the end of the lecture and faded so abruptly. I'll make the excuse that I was excited to get to tell you all about the more derived Tracheophytes that produce seeds - they are very cool.

Within the Tracheophytes, the Rhyniophtes are exciting because there are the first groups that you would really identify as being 'plants' - those with distinguishable leaves, stems and root-like structures. The Lycophyta are exciting because they dominated the Earth for a significant amount of time - altering the landscape significantly and leaving marks on the land that are still here to this day. Much of the interesting adaptations to living on land are incorperated in the early Tracheophytes, and the Pteridophytes are the group where signficant development of complexity occurs.

You should take home the message that radiation within the Pteridophytes was significant. They expanded to many different environments throughout the world and specialized in many different settings. It is in the Pteridophytes that the sporophyte generation really began to dominate the life-cycle.

Again, the goal of the lecture today was to take a look at the diversity of plant form on the planet and to understand the shared derived traits of the major groups of 'lower' plants (up to the non-seed producing Tracheophytes). A very good exercise would be to take Figures 29.1, 29.4, and 29.10, line them up, looking at the different ways to chop up the different plant groups - looking at the features that separate them.

I would also focus on the different patterns of sporophyte and gametophyte life-cycle patterns across the groups (not to mention the differences among groups that can be classificed as homosporous versus heterosporous).