SO ENDS this excursion into Morning Glories and tulips, to be concluded next weekend. Humans have the capacity to obsess on floral beauty and the technical capacity to breed exotic varieties, to the enormous appetite of the public. Flowers are potent symbols with many meanings in many cultures. In both the Morning Glory and the tulip, mankind has collaborated with viral elements to generate these objects of obsession, at great cost and labor. And coming full circle, we now have a good handle on the biology of these flowers.