How did Portland become the "City of Lindens," using so many linden trees for its street-landscaping choices? —Diane V.

To be brutally honest, Diane, I'm not sure anyone calls Portland the "City of Lindens" besides you. It's true lindens are fairly common in some of Portland's older residential neighborhoods, but if you're looking for a botanically based nickname for the City of Roses, you might get more traction with "City of Douglas Firs." (Or even, you know, "City of Roses.")

To be sure, the linden is not without its charms. Tall, stately and covered in summer with fragrant blossoms full of nectar that bees love, it's said to make exceptionally fine honey.

Unfortunately, aphids are also fond of the linden's nectar, excreting the unused portion in a fine mist of sticky droplets that are hell to wash off your car.

Still, this minor inconvenience isn't enough to get the linden kicked off the city's list of trees officially approved for planting on that right of way between the sidewalk and the street. But then again, what is?

Consider, for example, the ginkgo biloba, better known to those who have to walk by one regularly as the "dog vomit tree." (I personally think it smells more like the dog's crap, though, given the dietary preferences of dogs, I suppose there's no reason it couldn't be both.)

The ginkgo is a perennial favorite on lists of the top 10 worst-smelling plants, along with skunk cabbage and the stinking corpse lily. Nevertheless, if you want to torment the next 50 generations of passersby with its noxious odor—did I mention it lives for a thousand years?—that's A-OK with the city as long as it doesn't touch any power lines.

And what of the Callery pear? It's actually on the Bureau of Development Services' "Suggested Landscaping Plants" list, notwithstanding a bouquet that more demure sources describe as "rotting fish," but which you and I might call "teenage boy's sock hamper." Yeah, you know what I'm talking about.

I could go on—how the white oak never visits its kids, how the European larch still hasn't paid its arts tax—but what's the point? Clearly, if you want the city to overlook your flaws, be a tree.

…but don't overlook this opportunity! "That's Edutainment!" Dr. Know's TED-talk-on-acid-plus-sketch-comedy gala, happens Saturday, Sept. 7, at Alberta Rose Theatre! Visit