Prickly lettuce-Lactuca serriola

Prickly lettuce-Lactuca serriola, a photo by pdecell on Flickr.

Not one of my favorite plants. Very invasive in the garden and unpleasant to handle without gloves. Plus the flowers are small and pale yellow, seemingly an after thought. But even the most noxious weed has some redeeming features...OK maybe not musk thistle-but seen in the right light even this plant does. Also it turns out-if WIkipedea can be trusted that this plant is the closest relative of cultivated lettuce.

Magnolia

Here is a pink Magnolia from campus. One thing I didn't realize is that it is possible to isolate DNA from Magnolia fossils going back to the Miocene (17-20 million years ago)  and use it to help understand the phylogeny of these trees.  See Kim et al (2003)  http://www.amjbot.org/content/91/4/615.full doi: 10.3732/ajb.91.4.615 Am. J. Bot. April 2004 vol. 91 no. 4 615-620

Reverse superposition

Reverse superposition, a photo by pdecell on Flickr.

Via Flickr:
The principle of superposition is the common sense notion that in geological strata the oldest rocks are generally the lowest strata. Of course the way trees grow from the cambium out, in the bark the oldest layers are on the top.