Laboratory VI - Sphenopsids and Ferns -- Lineages of Mysterious Origin]
Objective: In this lab we will become familiar with the biology, morphology and diversity of both the sphenopsids (horsetails) and the ferns. Morphologically speaking, these two groups may seem like a strange combination. However, most phylogenetic studies suggest that they are sister groups (sometimes even an unresolved node!). Because the divergence of these two groups was extremely ancient and there are few synapomorphies that clearly define the clades, the ferns and sphenopsids provide a great deal of grist for the evolutionary theory mill. After reviewing ancient sphenopsids and ferns, compare evolutionary history of especially the horsetails with the lycopsids from last week. What was each group doing in the Paleozoic? What are they like today? How have they changed in morphology and ecology?


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