There's dandruff in the forest, scattered on every surface. It's the disintegrated remains of female birch flowers, which are cone-like catkins, and consists of the scales of the "cones" intermixed with the seeds, which are known as winged nutlets.
Paper birch, Betula papyrifera.
Paper birch is the dominant native deciduous tree in Richmond, and is associated with peat-bog remnants. It thrives, weed-like, in modified bogs and disturbed areas where more nutrient-rich soil has been added to the original peat. Because its seeds are windblown, it is a fast colonizer, producing almost instant forests.
Added to the native birch are exotic, often weeping, forms planted throughout this suburban landscape. It's likely that hybrid trees are common.
The catkins, which open in spring before the trees leaf out, are monoecious, each being either male or female. By mid-November, most of the catkins remaining on the trees are female, slowly disintegrating and broadcasting seeds. If you roll one between your fingers it easily crumbles apart. In the slightest breeze the seeds disperse.