veining

1890, Ambrose Bierce, “An Occurrence at Owl Creek Bridge”, in Tales of Soldiers and Civilians, New York: Lovell, Corvell & Co., 1891, p. 32, He looked at the forest on the bank of the stream, saw the individual trees, the leaves and the veining of each leaf—saw the very insects upon them, the locusts, the brilliant-bodied flies, the gray spiders stretching their webs from twig to twig.