See Ann Lovejoy,"Coping with Dry Shade'" Horticulture (September/October 1998). The only surprise to me was the inclusion in suggested plants= Hosta 'Krossa Regal'. I'd not include any hosta for truly dry shade. Also suggested is Milium effusum 'Aureum' . This one needs some sun. Almost one-half of the plants listed as suitable are hardy only to Z5. The other half are primarily suitable for zones 6 and higher. A well-done piece which does not try to cover the waterfront. Clyde Crockett z5