Blackberry (Rubus allegheniensis)
Thorny canes of blackberry can make the edge of the woods nearly impenetrable, but they reward us with these pretty (though often a bit sloppy) white flowers, and then of course with sweet blackberries. This stand grew at the edge of an old German Lutheran cemetery in Beechview.
Gray describes the genus and the species:
RUBUS [Tourn.] L. BRAMBLE
Calyx 5 (3-7)-parted, without bractlets. Petals 5, deciduous. Stamens numerous. Achenes usually many, collected on a spongy or succulent receptacle, becoming small drupes; styles nearly terminal. Perennial herbs, or somewhat shrubby plants, with white (rarely reddish) flowers, and usually edible fruit. (The Roman name, kindred with ruber, red.)