Plants > Phylogeny
Plant Phylogeny: Evolutionary History of Plants
Reading: Campbell, Ch. 28, 29 & 30.
Lab Manual, Ch. 3, 4, 5.
In Bio 6A, you'll do several labs on plant evolution. From a biologist's point of view, plant phylogeny isn't just about naming different kinds of plants. It's the story of the evolution of life on land. Green algae are anatomically simple, and they live only in water. Land plants have more complex bodies; their various complex features represent adaptations to life on land, and to interacting with the various other organisms (such as fungi, bacteria, and animals) with which they live. Our plant labs will be based on an evolutionary approach to plant structure and function.
Cladogram: Plants and their relatives
The plant kingdom
Most people are familiar with the plant kingdom -- or, as you may have learned in a bio class, "kingdom Plantae". However, your investigations of systematics so far in this class may have convinced you that taxa such as "kingdom" are not always easy to define. Some biologists group the green algae (Chlorophyta) together with the more familiar land plants in one large kingdom, called Viridiplanae ("green plants"). Others leave the green algae out, defining the kingdom Plantae as only those plants with more-complex anatomical structures.
However you name the kingdom, it's clear that the green algae and the land plants are closely related. As you go through the next few labs, you'll also learn the key features that define the plant groups, and you'll see why these features are so important.
Test yourself
Look at the various groups classified within the Viridiplantae on the cladogram above. Can you say what vascular plants can do that nonvascular plants can't do? In what ways is the reproduction of seed plants different from the reproduction of non-seed plants (it's more than just seeds!).
By the time you finish this quarter's plant labs, you should be able to draw this cladogram yourself. For each branching point, you should be able to identify the key characteristics that define each group, and explain how these characteristics relate to the organism's ability to live on dry land.
Don't worry if you don't know anything about this before you start. That's what these labs are for.
Links
The Green Tree of Life. Endlessly entertaining interactive cladograms. http://ucjeps.berkeley.edu/TreeofLife/
This page updated September 17, 2011