In riparian areas of canyons throughout the Southwest, the bigtooth maple (Acer grandidentatum) is a common sight. In fall their leaves turn a beautiful red-orange color. You’re probably familiar with the samara, which is the winged fruit of the maple. This is a double samara, because each half contains one seed. Notice the intricate pattern…

Tucson today is cold, windy, and wet – but it’s not quite winter yet. Animals are still out: we saw this rattlesnake sunning itself on a rock just two days ago. Looks like it had some success hunting, too!

In the Sonoran desert, the indications of autumn can be subtle. Grasses set seed, summer annuals die back, and ephemeral pools dry up. Fall is a season of brown. But there are exceptions, including this desert cotton (Gossypium thurberi). Its leaves turn a scarlet, almost purple shade of red. Soon the pods will open, but…

Another hot day in Tucson, bringing back memories of cold mountain-tops. Above is Treasury Mountain (13462′ elevation) at the edge of the Raggeds Wilderness in Colorado. When I took this photograph at the end of July there was still deep snow on most of the high ridges. An inhospitable place for life to take hold,…