This is professional correspondence concerned primarily with botanical nomenclature. Some of the letters touch on personal matters, and there is also a series with the Texas Research Foundation relative to the disposition of Blake's herbarium. The most substantial correspondence is with Liberty Hyde Bailey, Nathaniel Lord Britton, and Waldo Lee McAtee.

Correspondence relates chiefly to "The Auk" and to investigations into the stomachs of birds carried on by the United States Biological Survey. Correspondents include: Francis V. Greene, Henry Wetherbee Henshaw, Edgar A. Mearns, Clinton H. Merriam, and Frank R. Rathbun. Also includes the Biological Society of Washington and the American Ornithologists' Union. The autograph collection was assembled principally from signatures on mailing instructions for "The Auk" and on envelopes addressed to McAtee and others.