Take a look at Tod Stuessy's book, Plant Taxonomy (1990, Columbia University Press; ISBN 0-231-06784-4). He has an excellent chapter titled "Subspecies, Variety and Form." Dick Richard J. Jensen | E-MAIL: rjensen at saintmarys.edu Dept. of Biology | TELEPHONE: 219-284-4674 Saint Mary's College | FAX: 219-284-4716 Notre Dame, IN 46556 |