Friday, July 1, 2011

Gardening in July

Friday, July 1

I kept to my course, gazing at everything along the way, from the recently opened pink and rose hollyhocks in front of our neighbor's peeling white shed, to the yellow Hyperion day lilies just beginning to open behind the currant bushes, to all the summery colors and shapes on display in Kate's perennial border, now at the climax of its third bloom phase. The tall fuchsia spikes of the lythrum, the sky blue of the stirrup-flowered delphiniums, the navy blue of the salvia spikes, the violet blue of the veronica spikes, the orange and pink and white of the tiger lilies, the yellow of the yarrow, the white of the small-petaled feverfew. So many colors and shapes so carefully arrayed from back to front, from one end to the other, I was momentarily transfixed by the spectacle.

Carl H. Klaus, My Vegetable Love: A Journal of the Growing Season

Wednesday, June 29, 2011

Plant of the Week

Purple prairie clover
Petalostemum purpureum (Vent.) Rybd.
scientific name, 2008: Dalea purpurea Vent.
other common names: thimbleweed, red tassel flower

White prairie clover
Petalostemum candidum (Willd.) Michx.
scientific name, 2008: Dalea candida Michx. ex Willd.
other common names: thimbleweed, white tassel flower
Petalostemum: from the Greek, meaning “petal and stamen,” referring to the way the petals and stamens are joined
Purpureum: meaning “purple”
Candidum: meaning “shining white”
Legume family: Fabaceae (Leguminosae)
Photo: Dalea purpurea

Photograph by Thomas Rosburg, Wildflowers of the Tallgrass Prairie: The Upper Midwest, Second Edition

Monday, June 27, 2011

Interview with Peter van der Linden and Donald Farrar Part 2

When did you begin writing the first edition of this classic book? How did you divide the labor?
Peter: I wrote the text as a graduate student at Iowa State in the late 1970s. The academic year was organized into quarters then, and I alternated between teaching and research. I taught botany labs in the fall and spring quarters, working on the book during the evenings. In the summer and winter I worked on the book full time. I tried to write one species account every day. That included the research necessary to complete the descriptions and text.

Don: A few decades ago, Peter, as a beginning graduate student, came into my office at Iowa State as a rare commodity—a student who knew exactly what he wanted to do for his MS thesis. It would be a book on the trees of Iowa, the best ever written, and that is what he did! Peter was in charge of all of it, including obtaining funding and working with ISU Press. I just read the manuscript and made suggestions. For the second edition, while Peter was employed at the Morton Arboretum, I added a little more on forest ecology, including a number of text photos of Iowa tree communities. Upon Peter’s return to Iowa, as director of the Iowa Lakeside Laboratory, the University of Iowa Press extended the opportunity for us to work together again. For the third edition, Peter concentrated on the text revision and I on the new color images.

Keys can be daunting, but you have managed to create keys that are as user-friendly as possible. How did you do this?
Peter: You are right, keys are a challenge. By the time you become expert enough to prepare one, you can recognize small differences between species that are not obvious to everyone else. So you include those obscure characters in the key, and people who use it say “huh?” What helped me most, I think, was that I was teaching young people who had no previous experience in plant identification, and I could see the trees as they see them.

Don: During the course of the book’s development, we built on knowledge gained through teaching dendrology. Later I could tell my dendrology students that the book’s keys were the best keys ever written…because they had written them. There was a lot of truth in this because their repeated testing of the early versions of the keys revealed many characteristics that didn’t work, as well as some that worked better. The terms and monikers they came up with for new characteristics were often humorous, but invariably they were based on real characteristics that we were able to incorporate into the keys. It’s easy to construct a key that works in your mind, but one that works for others is another matter. Without question, it is the multiple testing by thousands of students over the years that is a primary reason why these keys are superior.

Do you have favorite trees or families of trees?
Peter: I have always been partial to oaks, but no particular species stands out. They’re all great trees.

If I had to pick an individual species of tree, I would probably choose the eastern white pine. The Lake Superior Highlands are my favorite place in all the world, and the white pines are a characteristic part of the forest there. I love how they stand so tall above everything else, and how the wind sounds in their foliage.

Another favorite is the three-flower maple, a beautiful small tree from eastern Asia that is hard to find but very nice for landscaping. I have planted one at every house where we have lived.

Then there are the tulip tree, katsura, and ginkgo…so many wonderful trees. How do you choose one?

Don: My favorite tree is the white oak, because of a very special white oak. In the mid 1880s, my great grandfather purchased the land in southeastern Missouri where I grew up. My grandfather cleared a site in the virgin forest to build my family’s home. As a little boy, I explored the giant stumps left under the house. My grandfather also left a few trees for shade—two huge black oaks in the front yard that survived into the 1940s and a white oak in the back yard that looms especially large (as it was) in my memories. That old white oak sheltered us from generations of summer suns and was the site for picnics, watermelon feasts, and the making of home-made ice cream. It was the site for work projects and innumerable games. Its trunk supported our basketball hoop and served as backboard! I recall, in the fall, the thumps on the roof of its large acorns—just the right size for little hands to gather and throw. Though hollow at the time of my earliest recollection, the old white oak of my childhood still stands, more majestic than ever, its giant spreading limbs still sheltering the home it has always been part of.

How did you become interested in trees in the first place? And what other species interest you?
Peter: My dad was a journalist but very interested in trees. One day we were driving down the highway on a family vacation, and Dad pointed to a tree about a hundred yards away, and said, “Look at that beautiful elm.” I thought he was joking…how could you identify a tree from so far away, moving so fast? It intrigued me and I started looking at trees more closely. I must have had a genetic predisposition to liking trees; something just clicked.

Don: Growing up on an Ozark farm in the 1940s, I had no choice but to be interested in trees. Electricity had not yet come to that part of the country, and propane or natural gas was also not available. We heated our house and cooked by wood-burning stoves. Through one of my early chores of splitting kindling wood for the cook stove, I quickly learned to identify which kinds split most easily and to select these from the wood pile by their bark. Later, as I helped my father select trees from our woods for felling and preparing for various uses, I learned which were best for firewood, fence posts, and telephone poles and which could be sold for stave bolts or used for construction lumber. Our telephone system was a local co-op for which all members had to supply poles. I learned to cut, debark, and cure telephone poles, choosing the species that would last the longest.

My dad was an excellent woodsman. I remember how surprised I was at his knowledge when in college, working on an oak identification project, I found a species new to me, chinkapin oak, Quercus muehlenbergii. I couldn’t wait to tell my dad about it. His reply—“yep, there’s one of them down there in the thicket.”

Coming to Iowa State, I did not expect to be teaching dendrology for 36 years. But, as often happened at that time, the new hire was expected to teach all the courses taught by the professor he replaced, even though he may not have been informed about what those were going to be. Looking back, inheriting dendrology this way was a most fortunate accident. I loved teaching tree identification and forest biology to the future caretakers of our forests. It is a special pleasure now to see so many of those students currently employed in influential positions in Iowa and around the country.

Where should we go to see a variety of trees, something more interesting than the lindens and maples that line the streets in our community?
Peter: Arboretums are the best places, really, because the trees are accessible and usually labeled. A new chapter in the third edition describes several of those, plus a few state parks and other places people can go. Some readers may question why our list isn’t more complete, but it isn’t meant to be exhaustive, just a few places Don and I recommend. We included a broad geographical representation so people in all parts of the state can see a variety of trees without traveling far.

Peter van der Linden and Donald Farrar, Forest and Shade Trees of Iowa