This site is for people who like plants -- growers, enthusiasts, aesthetes, novices and professionals, those who appreciate wild things and those who appreciate the cultivated. I garden in Chelsea, and I've been visiting people's yards for 20+ years in the course of my work. My goal is to make this blog a community project, so if you share my interests, please consider becoming a participant and contributing content -- Guerin. Info:

Sunday, January 30, 2011

1.5 billion poplar clones

And on the other side of the planet . . .

Jonathan Watts, in his spectacular 2010 book When a Billion Chinese Jump: How China Will Save Mankind -- or Destroy It,  introduces us to genetics professor Zhang Qiwen, known in her country as "Mother Poplar."  Watts posits that Zhang "was arguably responsible for changing a bigger chunk of the Chinese landscape than the emperors and engineers behind the Great Wall, the Three Gorges Dam, or the Sky Train railway to Tibet."

In 1980 Zhang began importing hybrid poplar seeds and saplings from Italy and North America. One plant, PH107, was a hybrid between our Eastern cottonwood (Populus deltoides) and the European Populus nigra, and it was found to grow up to 60% faster than a wild poplar. To Zhang it was love at first site: "Compare it to a baby: Imagine you have 10 children with you. We choose the best one, chop off its arms and legs, then cut the torso into ten pieces, and plant them in the ground."

Within just five years, 1.5 billion clones of this single specimen were planted along the roadsides, eventually covering a fifth of China's entire forest area.  Watts describes driving through the countryside for hours without feeling any sense of progress -- like "watching a minute-long clip on a daylong loop."

Watts concludes, "PH107 cultivation denied sex, destroyed beauty, and replaced local diversity with a superefficient standard. In that final narrow sense along, PH107 might be considered a good thing. But you could have too much of a good thing."

And to think of the fuss we made here about overplanting ash trees . . . 

Friday, January 21, 2011

Candidate for ugly tree contest

Yep, as far as trees go, this one is an abomination. I pass it almost every day when I drop off my kid at the Washington Street Education Center in Chelsea.  It's a glossy buckthorn, Rhamnus frangula, which means not only is it ugly, it's progeny are probably shooting up at an unholy rate in the woodlands nearby. God help us.

Big tree registry: little-leaf linden

Little-leaf linden (Tilia cordata), 2105 Devonshire: 43" diameter, 70' height, 69' crown spread. Total point: 196.

One doesn't usually think of this species as getting large, but there are massive specimens in the northeast US and in Europe. This specimen might have been planted soon after the house was built in 1924.

Thursday, January 20, 2011

First entry for the NEW Ann Arbor Big Tree Registry

The city used to maintain a registry of big trees --that is until the forestry office was moved away from West Washington Street. Nobody seems to have kept a record of the list. So I'm starting a new one. My first candidate is:

Kentucky coffeetree (Gymnocladus dioicus), 1205 Wright St: 105' height, 43" diameter, 63' average crown spread. Total:  246 points of 'big-tree-ness.'

And before you all get all hot and bothered, yes I intend to include the big chinkapin oak in Wurster Park seeing as it is the state champion. I just have to get over there and measure it.

If you want to join the fun, send in your candidates. You can even do the measurements yourself. Here's how: 

Wednesday, January 19, 2011

Finding pawpaws in Ann Arbor

This fall at the edge of some oak woods at a home near Geddes and Arlington, I found a pawpaw plant (Asimina trilolba). It was in the shade and arched over at about 5' -- definitely not big enough to be called a tree. The homeowner had lived there for 10 years and did not plant it and he wasn't even aware of it. So I'm fascinated by the question: where did it come from?
        You won't find pawpaws in many yards around here. I'm told there are some wild specimens growing in a hidden spot in Sugarbush Park. I've also seen numerous ones growing under sugar maples and bitternut hickories in the remnant rich beech-maple woodlands around Plymouth Township. And it's possible that pawpaw wasn't all that uncommon in Ann Arbor prior to settlement.
        The closest fruiting specimen I am aware of is north of a house on Vinewood, a bit more than 3/8 of a mile away. Could this be the parent? My guess is that Ann Arbor is rich with people who, like me, read garden books by the likes of Michael Dirr and Jack Elliot and who enjoy growing the unusual plant in the corner of the back yard. The more yards I visit, the more I discover. Wouldn't it great if pawpaws started to compete with buckthorn in some of our unmanaged woodlands?

Monday, January 3, 2011

February workshop to demystify plant propagation

There are probably few better opportunities on PLANET EARTH to learn about plant propagation than by attending the annual hands-on workshop at Arrowhead Alpines Nursery near Fowlerville in February. The workshop covers growing from seed, cuttings and grafting, and is hosted by the most experienced professionals in Michigan -- and that ain't no exaggeration.

If you are unfamiliar with Arrowhead Alpines, you should know that it is run by Bob and Brigitta Stewart, two people who are actually plant/human hybrids. OK, that is an exaggeration, but it's hard for me to suss out any other explanation as to how such a small group of individuals can successfully grow so many thousands of plant taxa. And it is said that Bob can identify most of them just by their emerging cotyledons.

If you plan to attend, you should consider becoming a member of the Great Lakes Chapter of the North American Rock Garden Society, the group that is sponsoring the workshop. Membership cost is $30, and being a member provides opportunities to tour gardens, attend presentations and mix with some truly outstanding plant experts. Workshop date is February 19. Check Arrowhead's website ( and that of GLC-NARGS ( for more information.

While on the subject, let me put in a plug for mail-order nurseries as a source for plant material. The selections available are limitless, and the quality rarely disappoints. Some of my favorite mail-order sources folded up in recent years (Seneca Hill Perennials and Asiatica are closed; Heronswood is barely a shadow of what is once was); but Arrowhead is still afloat, as is Plant Delights ( (the later with 26 selections of jacks-in-the-pulpit).

A Heads-Up for Viburnum Fans

photo by Paul Weston, Cornell University
Last summer I identified and collected a specimen of the Viburnum leaf beetle from some badly defoliated arrowwood viburnums near Arborland. One of the arborists at GreenStreet Tree Care, who used to work in the northeast U.S., tells me that this insect is a major pest there, making it impossible to grow healthy-looking viburnums in the landscape without the use of insecticides. I don't believe that many specimens of the insect have been found in Michigan. The identity of my find was confirmed by entomologists at Michigan State. Keep an eye on your viburnums. The insect won't kill plants outright but can make a mess of them by eating up the foliage.