Who knows why I didn't photograph the largest Monterey cypress in Oregon this weekend - also one of the largest in the country. Here's a page about it (not it specifically, but its kind ) - just one of the first pages I glanced at..
eNature: FieldGuides: Species Detail
They seem to do marvelously over here, and the form is among the more interesting to look at.
As far as arboretums in general, I read an article about forests in the paper yesterday that had some interesting stuff about fires and plants. I'm going to condense the "highlights" to a few paragraphs on my forestry blog later today...
Forest and Forestry related page
I'm going to add extra comments with dates from now on.
Anyhow, a quick comment: the forest soil man, said that certain trees and shrubs help to fix nitrogen and are beneficial for other trees. I'm beginning to think that maybe a good thing for arboretums is to plant shrubs under imported trees, that are found under those trees. As long as they don't become invasive.