These letters concern botanical matters, with special reference to descriptions and identification in Denke's herbarium.

There are observations from 1802 to 1810 made by Heckewelder at Gnadenhütten, Pennsylvania, which continue those he made for 1800 [published in "Philadelphia Medical and Physical Journal" 1,2 (1805): 134]. There are also observations from 1810 to 1814 made by George G. Miller at Beersheba, Ohio, and from September 1-7, 1800 made by Christian Frederick Denke at Fairfield, Upper Canada [the latter printed in "Philadelphia Medical and Physical Journal" 1,2 (1805): 142].