This edition of Forest and Shade Trees of Iowa has all-new color photos that are amazingly detailed, almost three-dimensional. Tell us how you accomplished this.
Don: Digital imagery has revolutionized the production of biological images. More than 10,000 photos were saved for this project. This number doesn’t include many, many more that were immediately discarded as “not in the running” for the final selections. These are numbers that would be prohibitive for film photography. A further advantage of digital photography is the depth-of-field that is easily obtainable without cumbersome equipment or a photographic studio. Macrolens capability and a dedicated flash that senses the correct amount of light are all that is required for stunning close-ups. Digital images are also more adaptable to cleaning and alteration of backgrounds to display the subjects more clearly.
This having been said, it is also important to know the subject and the most important characteristics to emphasize. For example, to identify red maple vs. silver maple at flowering time, it is important to show the tiny red petals that are present in red maple but absent in silver maple flowers. To display these differences, the flowers are best photographed from a particular angle at just the right stage of development.
About 10 years ago, the late Anna Gardner and I discovered the utility of flatbed scans for botanical images. Anna prepared full sets of these for the nearly 200 species of trees the students in our dendrology class were required to know. We were amazed at the popularity and effectiveness of these images. The clarity and lifelike three-dimensionality were amazing, and the close-up scans of buds and leaf scars allowed students to see these useful characteristics as never before. This became the inspiration for the species plates in Forest and Shade Trees of Iowa.
Accumulating the images for the book was a three-year project. The first 80 percent was easy; the remainder was more challenging than I ever anticipated. Finding a perfect leaf is relatively easy, but try finding a branch with no leaves ravaged by insects, wind, diseases, or other trauma. Most fun were the fruits, because of their menagerie of colors and textures and the fact that most remain in good condition over a fairly long period of time. Twigs, buds, and leaf scars proved more challenging than one might think. To be useful for winter identification, they must appear in the book as they do in winter, thus necessitating collection after all the leaves have fallen naturally, i.e., in winter.
The most challenging were flowers—they have to be found and photographed during the short time of their appearance. Tree flowers, more often than not, are pretty inconspicuous. I was already familiar with the flowers of most species, but for a few, I came to realize that I had never seen flowers and had no clue as to when the trees bloomed. The sycamore, Platanus occidentalis, for example, necessitated periodic visits to trees that I knew had produced fruits the previous season. After a few weeks, when I finally found sycamore flowers, I was delighted at the beauty of the tiny balls studded with forked red stigmas. A special challenge was the hedge apple, Maclura pomifera. Not only did I not know when it bloomed or what the flowers would look like, I also didn’t know where to find mature trees that I could be sure would flower. I finally found appropriately large trees in Red Rock State Park but had to continue to visit them until very late spring in order to photograph mature flowers. I now know that this species is among the latest of all Iowa trees to bloom.
How did you decide which species to include?
Peter: Actually, this was the most difficult task we faced in preparing the first edition. We decided early on to include all Iowa’s native trees, but there was no complete list of those, so I had to prepare one. Some of those are rare and obscure, so we had to figure out how to cover them in the book; we didn’t think mountain maple deserved the same treatment as sugar maple, for example. Selecting the introduced species proved to be an even greater challenge. They range from species you see on almost every corner, to species you might find once or twice in an entire town, to species you almost never see. I knew that whatever we decided to include, someone would say, “Why isn’t so-and-so in the book?”
The decision was easier in the third edition. We covered everything from the first two editions plus some additional introduced species. Still, I am sure there will be readers who question why we included or excluded a particular species or didn’t give more coverage to their favorite trees.
Don: There is not much of a secret here. We wanted to include all the species that readers are likely to see in Iowa, both native and introduced. Experienced readers will see that we didn’t quite accomplish this due to the large number of introduced trees in arboretum and similar plantings. A few native species also are not included because of the difficulty of their identification to species. We included some species that might more properly be called shrubs, but can be confused with young trees, and some that are especially important in landscaping.
We have not included full descriptions of a number of species that are found just over the border in adjacent states to Iowa’s north and south, but many of these are included in the discussions of similar Iowa trees. With these few exceptions, Forest and Shade Trees of Iowa should be usable in adjacent parts of all neighboring states.
What’s different about the organization of this edition compared to the first two editions?
Peter: Users of the first two editions will be surprised at how different this edition is. The format of those editions was a bit rigid, with only one page for each species, regardless of the tree’s importance. That limited how much we could write about the natural history, culture, and uses of the trees, and for some species we wanted to write more.
We solved this problem in the third edition by separating the descriptive information from the text. The photographs and descriptions come first, and only the most common species are covered in that part. In the following part, we discuss those species plus many others, with the amount of text varying from species to species depending on their ecological and economic importance in Iowa.
In the first two editions, species were arranged in an esoteric taxonomic sequence that was once followed in most botany books but is now outdated and rarely used. In the third edition, the descriptive information is organized by similarities in foliage. The text is arranged alphabetically by botanic name.
Don: The basic information about trees and the keys haven’t changed much from the earlier editions, and I would be embarrassed if they did. The organization has changed a lot. Peter has completely rewritten the text in a user-friendly style, and we have reorganized the parts to make identification faster and easier. A major change is the full-color images of the trees and their parts. These are crisp images of real plants made possible by digital photography and by the use of computer scanning. Through the latter it is possible to “flatten” branches into entirely “in-focus” images while still retaining a three-dimensional appearance. Flowers are now included for nearly all species. Although flowers are not necessary for most tree identifications, they provide fuller insight into the species’ biology, and, although often tiny, they can be surprisingly beautiful. Finally, the University of Iowa Press has done a wonderful job of combining everything into a very attractive, user-friendly format.
Peter van der Linden and Donald Farrar, Forest and Shade Trees of Iowa
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