365 Urban Species. #317: Swamp White Oak. #318: Bur Oak.

[urbpan]

Photos by urbpan. Location: the Riverway, Boston
Urban species #317: Swamp white oak Quercus bicolor


Location: Lawrence Schoolyard, Brookline.
Urban species #318: Bur oak Quercus macrocarpa

I know of at least two monumental swamp white oaks in the city. One looms next to Sever Hall on Harvard Yard in Cambridge. The other is pictured here, a broad and spreading mature tree at the end of the Riverway, across from Landmark center. This tree is probably about mid way through its 300 year life span. Swamp white oaks are fairly tolerant of urban stresses, provided that their roots have room to spread and aren't under the compressed soil of the street. The trees are native to eastern North America, found in low-lying areas near water. They occasionally hybridize with bur oaks.

The bur oak is a "species of special concern" in Massachusetts. It probably was never very common here, being a plant of the central North American plain states. There are a number of bur oaks in Boston and Brookline in schoolyards and city parks, and it may be more numerous as a planted tree than as a wild tree. Bur oak is distinguished by its huge shaggy acorn, which isn't produced until the tree is nearly 40 years old. It's one of the best acorns to eat, less bitter than the red oaks' tannin-laden fruit. The bur oak's leaf is distinctive as well, with large rounded lobes and a deep sinus between lobes near the leaf stem and lobes at the leaf end.



The autumn leaf of the swamp white oak.


The swamp white oak at night.

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[urbpan.livejournal.com]

Slush is the dominant organism in the Boston ecosytem from December to March.