- Twigg, H. J. R.
- Twigg, Laurie E
- Twigg, Laurie E.
- Twiggs, Robert
- Twight, Edmund H.
- Twilley, Clinton E.
- Twilley, Otis S.,
- Twilley, Robert Reece, 1952-
- Twilprawat, Panupon
- Twin Brook Greenhouses, Inc.,
- Twin City Experimental Gardens.
- Twin Elms.
- Twin Falls Nursery.
- Twin Larches Nursery.
- Twin Maple Gladiola Gardens.
- Twin Trees Gardens.
- Twining, Alfred, 1853-1922
- Twining, Elizabeth, 1805-1889
- Twin-Larches Nursery.
- Twinn, C. R. (Cecil Raymond)
- Twiss, Wilfred Charles 1868-
- Twisselmann, Ernest C
- Twistflower, Bracted
- Twitchell, A. H.
- Twitchell, M. W. (Mayville William), 1868-1927
- Twitty Nursery.
- Twitty, R. S.
- Twogood & Cutter (Riverside, Calif.)
- Twombley, Asa D.
- Twombly, Clarence E.
- Twomey, Arthur C. (Arthur Cornelius), 1908-1996
- Twomey, J. M
- Twort, Frederick William, 1877-1950
- Twycross, Lindy
- Twyman, E S
- Twyman, Richard M.
- Tyabji, Hashim
- Tyagi, Brij Kishore
- Tyagi, Kaomud
- Tyagi, L. K.
- Tyas, Robert, 1811-1879
- Tyberghein, Edmond J.
- Tybor, C.
- Tydeman, William E., 1942-
- Tye, Alan
- Tye, Hilary
- Tye, Simon P.,
- Tyl, Jindřich
- Tyler Duida Expedition Of The American Museum Of Natural History 1928-1929
- Tyler Duida Expedition of the American Museum of Natural History (1928-1929)
- Tyler, Albert, 1906-
- Tyler, Carl C.
- Tyler, D. D.
- Tyler, Diane M.
- Tyler, Dorothy.
- Tyler, F. J.
- Tyler, Frederick Jared.
- Tyler, H. W. 1863-1938
- Tyler, Hamilton
- Tyler, Harry R.
- Tyler, Heather
- Tyler, Jack D
- Tyler, James C., 1935-
- Tyler, Jocelyn, 1900-
- Tyler, John G
- Tyler, John M. (John Mason), 1851-1929
- Tyler, Jonathan
- Tyler, Lieut.
- Tyler, M. G.
- Tyler, Martha G.
- Tyler, Michael J.
- Tyler, Paul A.
- Tyler, Peter
- Tyler, Peter A
- Tyler, Peter J
- Tyler, R. E.
- Tyler, S
- Tyler, Seth.
- Tyler, Stephanie J.
- Tyler, T L
- Tyler, Winsor M
- Tylor, Alfred, 1824-1884
- Tylor, Edward B. (Edward Burnett), 1832-1917
- Tymms, A. O. V.
- Tymstra, C. (Cordy)
- Tymstra, Y. Robert
- Tyndale, Walter,
- Tyndall, A. C.
- Tyndall, John, 1820-1893
- Tyner, C. Lee
- Tyneside Naturalists' Field Club.
- Typas, Milton
- Typographia Academica (Coimbra)
- Typographia Regia.
- Tyrberg, Tommy
- Tyre, Jeffrey E
- Tyrl, Ronald J.
- Tyrner, Pavel
- Tyroff, H. I.,
- Tyroff, Martin, 1704-
- Tyron, Alice F
- Tyrrell, Christopher D
- Tyrrell, Francis X.
- Tyrrell, J. W. (James Williams), 1863-1945
- Tyrrell, Joseph Burr, 1858-1957
- Tyser, Robin W
- Tyshing, Chris; Gibson
- Tyson, B T
- Tyson, Edward, 1650-1708
- Tyson, J. David
- Tyson, James, 1841-1919
- Tyson, Philip T., 1799-1877
- Tyson, William H.
- Tyson, William, 1851-1920
- Tyson-Donely, Toni
- Tysovsʹkyĭ, Oleksander, 1886-1968
- Tysowsky, M
- Tyszecka, Katarzyna
- Tyszkiewicz, Edwige.
- Tytex Rose Nurseries.
- Tytler, H. C.
- Tytler, Patrick Fraser, 1791-1849
- Tytler, Robert C
- Tytler, Robert Christopher
- Tytler, William Fraser
- Tyts, Veronica
- Tyus, Harold M.
- Tyutenkov, Oleg Y.
- Tyzack, Susan M.
- Tyzzer, E. E.
- Tyzzer, Ernest Edward
- Tzafesta, Eftychia
- Tzai, D T
- Tzanopoulos, Joseph
- Tzeek-Tuz, Juani
- Tzeng, Hsy-Yu
- Tzeng, You-Wei
- Tzompantzi, David Bravo
- Tzonev, Rossen
- Tzoras, Elias