Amid last month's hoopla over the human genome sequence and what it says about humans, plant biologists announced two new efforts aimed at a firmer understanding of plant evolution--who is related to whom and how--a discipline better known as systematics. Constructing evolutionary family trees is harder than investigating personal genealogies--biologists don't have the equivalent of birth registrations or family bibles to consult. Fossils tell them what ancient plants use to look like, but placing them in context with living organisms is difficult at best. Even the systematics of existing plants can be contentious, as researchers disagree on lumping plants together or splitting them apart in search of the most natural taxonomy.
Scientists liken constructing phylogenetic trees to tracing all the branches and trunks of a real tree, like an oak, with only characteristics of its outermost twigs to go on. That's because present day organisms are the sole survivors--called "terminals" ...
