Story by HEATHER DEWAR
Photos by FERN SHEN
I took myself on a three-hour tree tour of Baltimore Tuesday morning, armed with a couple of field guides, and this is what I learned:
– Spring-blooming trees are in every neighborhood, even the ones I think of as solid concrete.
– The city is really a patchwork of microclimates, with huge differences from block to block and from one side of the street to the other.
– It’s hard to drive and look into the treetops at the same time. Sorry, if you were stuck behind me, but I was gawking at some wild sights.

Loitering for a good cause
At times, this gawking, u-turning and dawdling was taking place in areas where such behavior can give people the wrong impression. Red light district, blue light district, schoolhouse, drug corner – it’s all the same to a flowering plum. Or a flowering plum-watcher.

Flowering plants’ bloom cycles are cued by a combination of lengthening days and warming temperatures, both of which have arrived right on schedule. The city is awash in pink and white petals. Our common ornamental street trees, Japanese cherries and Bradford pears, are in the midst (actually, already on the downslope) of their brief bloom. They line curbsides from Canton to Pigtown. They shade green lawns in Roland Park and the swale alongside the McCulloh Homes. They’re blooming in places they never were planted – like a highway embankment off I-895 and a dusty truck yard in Highlandtown.

Showy out-of-towners supplanting natives. More gentrification!
Ornamental cherries and pears were popular city trees for many years because they grew fast, withstood pollution, and were generally barren – no messy fruit to clutter up the sidewalk. But they’re short-lived and brittle, and tend to shatter in storms. A few do have seeds. Because they flower early, these seeds get a head start. Our native trees evolved to match our climate and flower a bit later, after the danger of frost is past. The imports’ seeds have spread to disturbed lands, and the trees are now growing wild all over the place.

They’re pretty, but their fruit is inedible to most wild creatures. One of the trees they’re crowding out is the native dogwood, a major food source for migrating songbirds in autumn. According to the U.S. Fish and Wildlife Service’s handbook of Chesapeake Bay native plants, as many as 43 kinds of birds feed on dogwoods. So when Bradford pears take over a Baltimore woodland, migratory bird populations throughout the Northeast suffer for it.

Beautiful and tough
The dogwoods are hanging on, though, and they’ll be flowering soon. You’ll see a few of them on the edge of the woods at Cylburn Arboretum and along Herring Run, Stony Run and the Jones Falls. Their white or pink blossoms seem to float against a background of leafless trees. (The parts we consider flowers are actually modified leaves, called bracts – there’s a cluster of tiny yellow flowers in the center of the bract.)

A few native trees have already bloomed. Most maples, oaks and other common trees are wind-pollinated. They flower early, before any leaves are out to block the flow of pollen. Because they don’t have to grab the attention of bees or birds for pollination, the flowers tend to be tiny and green, and most of us don’t notice them.
Most of the city’s trees are still bare-branched, but in some areas, they seem right on the verge of leafing out. One warm day might be all it takes – blink and you’ll miss it. They’re greening up fast in parts of Canton and Highlandtown, around Hollins Market, and along Lombard Street downtown.

Baltimore’s many micro-climates
These are urban “heat islands” – places where sunlight reflects off abundant concrete and tall buildings provide shelter from the winds. Spring will come a little later in the suburbs, and in neighborhoods with less concrete, like Guilford. It should come later still in low-lying spots like the sunken sculpture garden at the Baltimore Museum of Art and the cool ravines carved by the city’s streams.

Our region is officially all in the same climate zone, but really it’s a complex landscape of microclimates, created by many factors: the ratio of concrete to open space, proximity to the water, exposure to the wind, and elevation.

It hardly felt like spring at all in the little strip of parkland next to the police dock in Canton yesterday. A cold wind came whipping across the harbor, and except for one brave, foolish cherry, all the trees were bare.

But just two blocks inland, on Foster Street, it was another season entirely. Four red maples were in exuberant bloom, their branches covered with soft red pinwheel-shaped flowers. Soon the boomerang-shaped seeds will break loose and go whirling away on a blustery spring wind.

I’m betting that the Inner Harbor will be one of the last neighborhoods to leaf out and break into bloom. But I’m done with three-hour tours for now. It’s hard on my neck and my carbon footprint.

Tell us what you see
Brewsters, I’m hoping we’ll keep each other up to date on which trees are the next ones to bloom and which neighborhoods go green the fastest. I’ll file updates every now and then, along with a story or two about the city’s plants, animals and open spaces. I’m counting on you to chime in early and often.