This was the heading in the 1938 copy of the Catalogue of Hardy Perennials, Alpines and Rock Plants which the McDiarmid & Squires family had at "Riverview" in Robson B.C. This Nursery, established in 1922, continued until1962. When we purchased the property in 1984, the Cotoneaster Horizontalis was growing six feet tall in many places.
There was confusion in naming this shrub correctly for the above Plant Combination, as Rock Cotoneaster is meant to be two to three feet tall, whereas it is shown closer to six feet here.