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A tree map of Cambridge

Blossoms, pollen, shade? The city knows where to find them

For the past seven years, the City of Cambridge Department of Public Works has been sending interns out on a task that sounds tedious for an ordinary person but potentially magical for a budding arborist: find, identify, and map every tree on public land. Tens of thousands of trees and a bit of data cleanup later, the city now has an exhaustive database of all the trees in its care.

What does a city look like drawn in trees? The most common are maple, honeylocust, and oak, with a healthy scattering of ornamental fruit and berry trees. Plane trees spread their branches near the river. The North Point area has a cluster of magnolias, which developers planted to decorate a newly built neighborhood. Many streets are lined with white-blossomed Bradford callery pear, an ornamental tree so popular it’s “arguably on the verge of invasive status,” says the department’s Jack McGrath.

Every April and May, the city explodes into flower as cherry, serviceberry, pear, redbud, dogwood, and hawthorn trees bloom in sequence. In April, Cambridge first posted its data online as a “flowering tree map,” showing the hot spots where numerous trees are in bloom at once. The map doesn’t include every tree in the city: It skips the many in private yards and on university property. But what remains is an intriguing snapshot of how a bird, a bee, or an ambitious grain of pollen might experience the city. Sure, there are tree-rich parks and lush residential streets. But the Cambridge Cemetery appears as one of the liveliest spots, and the cherry-filled traffic median along Memorial Drive seems like a bucolic wonderland. Says Linda Ciesielski, who recently helped complete the census as an intern for the Cambridge arborist: “If only the cars weren’t there, it would a lovely place to picnic.”