ZZZZZZZZZZZZSSSSSSDDDDchew!! Excuse me; Toby’s photo of the pollinating pine in that last post just makes my nose tickle.
His points about pollinating trees make sense to me; wind-pollinated trees are different in nature from insect-pollinated trees, and have quite different effects on those allergic to fine particulates.
I have to say that Mr. Ogren’s original Op-Ed piece stood out as much for its hypo-allergenic focus as for its assertions about what trees do get planted in cities. To set the record straight, a number of the plants he mentioned (both favorably and unfavorably) — box elder, mulberry, silver maple, willow, cottonwood, and even red maple — are considered either outright weed trees or are simply weak-wooded and would never pass muster for planting in dense urban areas. More often than not, most of these trees volunteer in the city, and are able to thrive because they are wind-pollinated, produce a lot of seed, and are able to grow quickly and under conditions that would stymie less tenacious trees.
Landscape architects and arborists working in cities tend to avoid these plants for street tree plantings; in fact, I would think of using some of them — if any — only on larger sites where space was not an issue, where I wanted fast and effective growth, and where there was no chance that they would invade other areas. Municipal lists of acceptable street trees are actually, quite limited, as the piece points out, and mainly include slower-growing or more structurally sound trees than some of these worst culprits — the criteria for street tree selection in a city have to take into account those trees that have relatively reliable structure and habit, can deal with difficult soil, exposure, and moisture conditions, and that don’t create walking hazards with heavy fruit set.
What struck me most, after reading Mr. Ogren’s piece, was the realization of how much vegetative biomass there is in cities, despite our best efforts to pave wherever possible. The ocean of pollen we swim in every spring and summer comes from volunteer as well as planted trees, shrubs, grasses, and forbs, and reducing the pollen count in any area feels a little bit like setting aside a piece of the ocean to make a freshwater pond…
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