Thanks mdvaden. I hadn't seen that web site before, but I do have several editions of "Trees to Know in Oregon".
Current editions have color photographs. The old editions from the 50s and 60s are pamphlet style, full of the most wonderful woodcuts and charming mnemonics. I will pick them up whenever I can find a copy, they are a treasure.
The author of recent editions and this web site is Ed Jensen. I had the pleasure of taking his dendrology course in 1999, and I recently ran in to him in the grocery store in Corvallis. He is a wonderful teacher.