Solid, usable information on a huge selection of plants (3,600 species) that grow well (or Armitage will tell you otherwise) in North America between hardiness zones 3 to 8. Armitage shows his long-standing expertise in this field by including insightful details about the many cultivars of perennials which with he is intimately familiar.
Handy keys throughout this encyclopaedic reference (fondly called “The Big Perennial Book”) help differentiate one perennial from another similar one. The keys reflect this books’ value as a reference text as it has many more written words than color pictures.
Armitage includes a concise description of each plant type but can’t help add a little extra valuable information, as shown by white Boltonia, "Although the species produces showy flowers, it is too large, floppy, and weedy for my liking and should not be grown in the 'formal' garden. However, one of the finest garden plants is a selection of this 'weed'…. 'Snowbank' is a cultivar of which I am most fond." It is these candid comments that make this book such a treasure.