Britton, from http://rptsweb.tamu.edu/Pugsley/Britton.htm
Botanist and Taxonomist Nathaniel Lord Britton was born on January 15, 1857 at New Dorp, Staten Island, New York. Britton founded (1891) and served as Director-in-Chief (1895-1929) of the New York Botanical Garden. Among his other botanical accomplishments were publications of such works as The Flora of Bermuda (1918), The Bahama Flora (1920, with Charles F. Millspaugh), The Cactaceae (1924, with Joseph Nelson Rose), and An Illustrated Flora of the Northern United States and Canada (1896-1898, financed by Judge Addison Brown). Britton also began Flora Borinquena (a flora of Puerto Rico), but was not able to finish this work before he passed away in 1934.
Sullivant, from http://www.ohiohistorycentral.org/entry.php?rec=362
Botanist, Bryologist, Surveyor, and Engineer William Starling Sullivant was born on January 15, 1803 in Franklinton, Ohio. Sullivant's major contribution in terms of vascular plants was A Catalogue of Plants, Native or Naturalized, in the Vicinity of Columbus, Ohio (1840). After this work, Sullivant turned his focus to mosses. Sullivant published Musci Alleghanienses (1845), Contributions to the Bryology and Hepaticology of North America (1846-1849), The Musci and Hepaticae of the United States East of the Mississippi River (1856), Musci Boreali Americani Exsiccati (1856, with Leo Lesquereux), Musci Cubensis (1860, based on collections by Charles Wright in Cuba), and Icones Muscorum (1864, 1874). The Saxifragaceous plant Sullivantia ohionis (now known as Sullivantia sullivantii) was first discovered by Sullivant in Ohio, and was named for him by Asa Gray and John Torrey; Asclepias sullivantii (Asclepiadaceae) was also named for Sullivant, who discovered it). Sullivant passed away in 1873, before he was able to finish working on bryophyte publications for Venezuela (based on collections by August Fendler) and the North Pacific (based on collections by Charles Wright).