Consists of letters written to Walter Deane from 70 correspondents with surnames starting with T-W, mostly regarding botany, as well as personal matters. The letters are arranged alphabetically by sender. The collection also includes cards, postcards, picture postcards, etc. Correspondents are: Mary G. Tallant (including one letter to Edward Lothrop Rand from Susan C. Hosmer), Harrison Gray Otis Blake, Edward Sherman Hoar, K. Tamari; Edward Tatnall, Katherine A. Taylor, Roland Thaxter, Charles Henry Thompson, Henry David Thoreau, Felix Karl Albert Ernst Joachim von Thumen (Baron Thumen), George Thurber, Gustaf Augus Tiselius, Lottie Titcomb, Anna M. Coolidge, Edward Tatnall, Norman Taylor, Emily Hitchcock Terry, Kenneth S. Teslar, Jeanie I.W. Thacher, Roland Thaxter, Evelyn Forbes Thayer, Harriet L. Thayer, John Eliot Thayer, Nora Thayer, Ruth Thayer, Jocelyn Parker Thomas, John James Thornber, Albert Thorndike, Thomas Baldwin Ticknor, Tiffany and Company, Charles Wendell Townsend, William Trelease, Rodney Howard True, Ume Tsuda, Margaret M. Tuttle, Lora A. Underhill, Lucien Marcus Underwood, William Lyman Underwood, George Vasey, John R. Wakefield, George Lincoln Walton, Lester Frank Ward, Alice Ware (includes a poem by Edward Lear), Robert Allison Ware, Cornelia Blakemore Warner, Worcester Reed Warner, Benjamin Marston Watson, Arthur T. Wayne, Waynflete School, Charles Alfred Weatherby, Joseph K. Webster, T. Walter Weiseman, James Lloyd Wellington, Helen L. Wellington, Barrett Wendell, William Wendte, William Henry Weston, Jr., John Adams Wheeler, Leston Ansel Wheeler, Margaret L. Wheeler, Margaret F.G. Whitney, Charles L. Whittle, Karl McKay Wiegand, Charlotte Endicott Wilde, Edward Wilkinson, Arthur Williams, Emile Francis Williams, Grace D. Williams, Nellie T. Williams, Henry M. Williams, Robert Statham Williams, Robert W. Williams, Thomas Albert Williams, Robert Wheeler Willson; Annie Downing Willson, Wilson Ornithological Club (Lynd Jones),

Wings of the Wild, Clark Winter, Casey Wood, Cora Raymond (on behalf of C. Wood), Arthur B. Woodford, Samuel Washington Woodhouse, Norman Porter Woodward, Richard William Woodward, Alice White Wright, and Gerald W. Wright.