invasive weed
pictures taken in early may (left) and mid-june (right).
the invasive norway maple is almost identical to the native sugar maple, but can be distinguished by its milky white sap - which i tried to take a picture of on the right, but it didn't work super well. it was introduced to north america in the 1700s for ornamental reasons and has been a problem ever since. it grows in bad soil and urban environments, unlike the sugar maple, so it's often used in cities for shade and decoration.
unlike the sugar maple, its sap is not especially good for maple syrup, and its leaves have a smaller and less attractive range of colors in the fall. the norway maple spreads like a weed, producing a large number of seeds with a high germination rate which sprout little mini-maples all over yards and in the cracks of pavement. it's also not eaten as much as sugar maples, giving it a leg up there. it forms dense clusters with too much shade for native plants to tolerate, allowing it to invade forests with relative ease.
its seeds travel in winged fruits called samaras, which are slightly sticky on the inside if you split them open. when i was a kid, we'd open them and stick them on our noses! this seemed very fun at the time, though i couldn't tell you exactly why.
wikipedia says that stradivarius violins may be made of norway maple wood! neat.