began to prepare manuscripts for publication. He exchanged letters with Zaccheus Collins and William Darlington on Cyperus, Scirpus, and Rhynchospora, members of the family Cyperaceae that he was preparing a treatment of. He wrote to Darlington that "It will not do to hurry - there has been too much hurrying among our botanists." But his plans were not to be fulfilled. The U.S. government was preparing an expedition, to be led by Major Stephen Long, to explore the upper reaches of the Missouri River. William Darlington and John Eatton Le Conte recommended Baldwin as the botanist for this mission and urged him to go. Missouri William Baldwin dropped his work on the grasses Panicum and Paspalum to accept the appointment as botanist on Major Long's expedition. In March 1819, he traveled to Pittsburgh to join other members of the expedition. There were delays in Pittsburgh, and departure did not occur until May 5. Baldwin believed that travel would sustain his health, but might have had premonitions of his fate. Soon after he started down the Ohio River, He wrote to Darlington: In another letter to Darlington, he described the condition of the boat. A stop was made in Cincinnati for a whole week, partly for repairs, and partly because of the alarming condition of Dr. Baldwin. The expedition reached Franklin, Missouri, a small town across the river from Boonville in mid-July where Baldwin resigned from the expedition to convalesce in the home of John J. Lowry. The following October, William Darlington received a letter from John J. Lowry, which began as follows: William Baldwin was among the first of about 100 members of Major Long's expedition to die of disease and deprivation. When word of this reached the U.S. Congress, they immediately declared the expedition a failure and terminated its funding. Thus ended the ill-fated venture which claimed the life of one of America's greatest botanists. Baldwin was 40 years and 5 months of age at the time of his death. He was buried on the banks of the Missouri River. At the end of his biographical sketch of Baldwin, Darlington, in 1843, wrote: In January 1844, Lowry wrote to Darlington to tell him that the grave of his friend had been washed away by the floodwaters of the Missouri. Papers Many of Baldwin's personal papers have been preserved. Some of these are in the Mertz Library at the New