The territory of southwestern Iowa in this report includes Harrison, Shelby, Audubon, Guthrie, Pottawatamie, Cass, Adair, Mills, Montgomery, Adams, Union, Fremont, Page, Taylor and Ringgold counties. Four of these border the Missouri state line and four are along the Missouri river. About half the region is prairie, unmodified by erosion or the deposition of loess in hills. The mosses were collected on the wooded banks of streams or in cultivated land. The collections were made mostly by Dr. Conard during 1930-1933. They are obviously incomplete. In some counties only one stop was made for collecting, in others the work was done more thoroughly