City Trees is a premier publication focused on urban + community forestry. In each issue, you’ll learn how to best manage the trees in your community and more!
Issue link: https://read.dmtmag.com/i/1136305
The Tree Book: Superior Selections for Landscapes, Streetscapes, and Gardens. Michael A. Dirr and Keith S. Warren. 2019. Timber Press, 900 pages. I am a lifelong fan of Dr. Dirr and Mr. Warren, leg- endary plantsmen with 66 patented and trademarked plants between them, whose 30-year collaboration culminated in the publication of The Tree Book. The layout resembles Dirr's Encyclopedia of Trees and Shrubs (2011), with an introductory section followed by an alphabetical listing of taxa by sci- entific name. The Tree Book focuses on trees and palms—"trees" defined by the authors as woody plants greater than 15 feet (4.6 m) in height—adapted to temperate regions in the northern hemisphere. In the first 33 pages, Dirr and Warren address a variety of topics: their reasons for writing the book; insights regarding the breeding, selection, and evaluation of trees; a discussion of eco- system services provided by urban trees; and explanations of cultivars, patents, trademarks, and provenance. The attractive photographs in this section complement the text nicely. The section, "Origins of New Shade and Ornamental Trees: The Roles of Serendipity and Breeding" fascinated and enlightened me. The section on "Provenance" offers the reader parallel arguments: one that extols the importance of locally sourced seed-propagated shade and ornamental trees to improve biodiversity and urban resilience, and the other that supports the use of clones because of their availability, predictability, and reliability. The A-Z index comprises more than 2,400 species and cultivars. For each taxon, the opening para- graph summarizes noteworthy characteristics that include mature height and spread, form, growth rate, texture, and ornamental features. It's fol- lowed by a series of criteria reminiscent of Dirr's magnum opus, Manual of Woody Landscape Plants, 6th ed: foliage, flowers/seeds/fruits/cones, adapt- ability (origin and habitat), and landscape use. In The Tree Book, the authors add two criteria not listed in the Manual: street tree use and availability in the trade. While their discussion of streetscape adaptability lacks the detail and depth of other print and digital resources, it brings attention to the crucible-like conditions of the urban environment. Street tree selection often relies on a Darwinian survival-of-the-fittest approach—the arboricultural equivalent of The Hunger Games—that results in a pared-down list of a few overused but resilient taxa. Their "In the trade" comments address the commer- cial availability of the taxa, which ranges from "rare" to "omnipresent." Species that are uncommon and rare, such as Henry Wilson tree (Sinowilsonia henryi), received the "BIO" designation: botanical garden interest only. Additionally, some entries include information about how the taxa are sold (as seeds or clones) and propagated, provenance, and opinions and anecdotes from the ultimate nursery insiders. An outstanding feature of The Tree Book are the photos: closeups and wide shots of foliage, flowers, and forms that range from so-so to BOOK REVIEW: Dirr and Warren's The Tree Book By Bob Polomski, Clemson Extension Specialist, Horticulture/Adjunct Assistant Professor, Dept. of Plant & Environmental Sciences, Clemson University 20 CityTREES