If you visit Arizona you can hardly fail to miss the impressive saguaro cacti that march up the foothills of the mountains near Tucson. So it's not totally surprising to find that a bunch of Arizona mathematicians have turned their minds to the beautiful patterns in cacti. In particular, how do the striking patterns of ribs arise? Patrick Shipman and Alan Newell, at the University of Arizona in Tucson, have provided an important part of the answer. It all depends on elasticity. A Saguaro Cactus outside Cave Creek Arizona Since ancient times, people have noticed strange numerical patterns in plants. Marigolds have 13 petals, asters have 21, daisies have 34, 55, or 89, and sunflowers have 55, 89, or 144. These numbers have been familiar to mathematicians since 1202, when the Italian mathematician Leonardo of Pisa posed a problem about rabbits. His somewhat unrealistic rabbit population increased according to a fascinating sequence of numbers: 1 1 2 3 5 8 13 21 34 55 89 144 23...
The neo-Gothic Swallow's Nest castle perches 130 feet (40 meters) above the Black Sea near Yalta in southern Ukraine. Built by a German noble in 1912, the flamboyant seaside residence now houses an Italian restaurant.
ReplyDelete(Photo shot on assignment for, but not published in, "Ukraine," May 1987, National Geographic magazine)