Color/Appearance: Red Alder tends to be a light tan to reddish brown; color darkens and reddens with age. There is no visible distinction between heartwood .Red alder 's leaves also remind you of a birch 's, yet they are nearly twice as long, with a furry underside. In the fall, they drop to the ground still green. The wood of red alder, at 28 lbs. per cubic foot dry, weighs about one third less than red oak..