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Lewisias -- A Plant Gem and a Book Gem

© Diana Pederson

Lewisias, written by B. LeRoy Davidson and published by Timber Press in 2000, is a book that opens a gardener's eyes to the wonders of a plant from our own American West. Named for Merriwether Lewis of the famous Lewis and Clark expeditions, this plant has been known only since the late 1700s and early 1800s. Known as bitterroot to the Indians of the region, its roots were a valued dried food in times of scarcity.

B. LeRoy Davidson writes about the circumstances surrounding the discovery of this plant species in a manner that makes one wish we had been on the journey with Lewis and Clark. A Voyage of Discovery (Chapter 1) details the history surrounding the final classification of this plant as a Lewisia. It is fascinating to see how plants are moved into other genuses by botanists and plant explorers I particularly liked the conclusion to this first chapter:

The story of Lewisia classification is still unfinished. There are problems to be sorted out concerning natural hybrids; and despite almost two centuries of exploration, the vastness of the American West may still hold Lewisias yet unseen by botanists. New taxa continue to turn up stirring renewed interest in the genus among both scientists and gardeners. One thing is certain: this group of plants is now held in the highest regard wherever discriminating plantspeople are found. [p. 20]

Davidson, then carefully explores and explains the geology of the regions where Lewisia species grow. While explaining the geology, he explains terms such as "sky desert" and "snowbeds" which are unfamiliar to most gardeners. As you read through this account, it is easy to picture the scene being described. Of course, the colored photographs help also. As part of explaining how Lewisias have increased their range over the years, a good discussion of Lewisia seed dispersal is included.

The Family and the Plant, chapter 3, was fascinating to me. I had no idea that these plants were related to Portulacas (purslane family), to which one of my favorite garden plants, the moss rose, or Portulaca grandiflorabelongs. These are the succulent leaved plants with the brightly colored flowers which grow so well in hot, dry conditions. Here you will find an excellent discussion of what makes a Lewisia a Lewisia instead of some other plant species. The explanation is written in a way that both taxonomists and ordinary gardeners can understand.

The bulk of the book is found in chapter 4. Here you will find detailed discussion, including keys to Lewisia classification. Davidson justifies his classification scheme by talking about the works of others and explaining the choices he made. He divides the various species into sections, describes each plant and where it grows, and then provides a simplified key to make it easier for a gardener to distinguish between the species. Both the professional taxonomist and the amateur gardener will find suitable information for their purposes in studying plants.