General references: These include some Plant Books that have significant coverage of penstemon or related genera.

These are listed for those who wish to increase their all-round knowledge of botany.

Allaby, Michael, "A Dictionary of Plant Sciences", Second Edition, Oxford: Oxford University Press, 1998. ISBN 0-19-280077-9 paper, 508 pp, few illus US$ 15.95 This is the most comprehensive dictionary of botany that is both inexpensive and readily available. It does suffer from a lack of illustrations and detail and patient cross-referencing may be required to make the best use of it. To allow for more than five-thousand terms to be included in a paperback, compromise is inevitable. Yet still this is an especially useful work for students and beginners and it will serve well to help anyone over the humps of terminology.

Capon, Brian, "Botany for Gardeners" Portland, Oregon: Timber Press, 1990. ISBN 0-88192-258-7 paper. 220 pp, 121 color photos, 53 b/w illus US$ 17.95 This work, states the author is plant science "from the plant's own view". Those who are new to the world of plants and gardening will find it especially comprehensive and useful. On the Internet the new list member can easily be overwhelmed with the many plant terms and phenomenon that are discussed in detail by enthusiasts. All general aspects of botany such as cell growth and structure; plant nutrition; plant adaptation; and plant reproduction are covered and illustrated. This is a popular, well-oiled, and well-used reference.

Harris, James G. and Melinda Woolf Harris, "Plant Identification Terminology: An Illustrated Glossary" Utah: Spring Lake Publishing, 1994. ISBN 0-9640221-5-X 199 pp. profuse illus. US$17.95 The book illustrates and describes the full range of descriptive terminology of plants beginning with the roots and ending with the fruits. The following quote from the back cover speaks to the dire need for a book such as this by all who wrestle with plant terminology: "Plant taxonomy employs an extensive and complex terminology. Professional botanists often need several years in the field to master this terminology, and it presents a daunting obstacle to the student of taxonomy. The meaning of most botanical terms, however is immediately apparent when an illustration is available. That is the purpose of this volume."

Hickey, Michael and Clive King, "Common Families of Flowering Plants" Cambridge: Cambridge University Press, 1997. ISBN 0-521-57609-1 paper. 209 pp, profuse line illus. US$ 22.95 Another excellent all-round reference that will enhance your knowledge, appreciation. The extensive introductory section on botany is a richly-illustrated gem. "...really enthusiastic gardeners and botanists, who would like to move their hobby from a casual to a more committed interest...For them this new book caters supremely well." (from the introduction by S.M. Walters)


Stearn, William T. "Botanical Latin (Fourth Edition)" North American Edition: Portland, Oregon: Timber Press, 1992. ISBN 0-88192-321-4. 560 pp, 42 line drawings, 6 3/4 X 9 3/4", hardcover $US 44.85 The most comprehensive available work on botanical Latin, it includes a "two-way" dictionary at the end. Unlike other works of its kind, this one covers geographic names and other Latinate names extensively. Also tremendously handy is a list of oft-used abbreviations.

Taylor, Ron, "Sagebrush Country: A Wildflower Sanctuary" ,Missoula, MT: Mountain Press Publishing Company, 1992. paper, 211 pp., profuse photos US$12.00 ISBN 0-87842-280-3-211 This is a wildflower guide that mentions a large number of penstemons. Sagebrush country is a botanically neglected area, but one that contains many of the most stunning penstemons, including some of the finest of the electric blue-flowering species. The comprehensive introduction discusses the floral zones within the sagebrush steppe and relates plants to general ecology, including wildlife and pollinators. Appendices include common names, plant lists for the floral zones of the sagebrush steppe, a key for identifying representative plant families (especially nice to have in a wildflower book!), diagrams of simple flower parts, and a glossary.