Ah-choo! That sound, combined with watery, itchy eyes and a drippy, irritated nose, heralds the arrival of spring for millions of people. Their allergy usually results from an atmosphere laden with pollen. The BMJ (formerly British Medical Journal) estimates that... 

NOT all plants in Arizona’s Saguaro National Monument are stingy with their water. In the coniferous forests of the majestic Rincon Mountains, the great bulk of the water is merely passing through, in at the roots and out through the leaves. But that is the remote... 

Then there are the succulent cacti that survive the deserts long dry spells by storing up water on the rare rainy days. Some use underground containers, while others hoard it in thick stems. For these green stems to absorb carbon dioxide and perform photosynthesis,...