The Persian ironwood tree glowed like an ember. Though leafless, it was in blossom and the winter sun caught the tiny red flowers growing on the lattice of interlacing branches. A little further on, we walked under a Caucasian alder tree, gigantic as a church steeple. In the middle of a British city, here in the botanical gardens we were surrounded by plant specimens from all over the planet. A Mongolian mulberry graced the January morning; swamp cypresses rose from the waters of the little lake, as though from their native Florida Everglades. The hothouses held palms and cacti.