Flora of the Black Hills of South DakotaPer Axel Rydberg · First published 1896 · Latest edition 2018Open the Tome
Flora of the prairies and plains of central North AmericaRydberg, Per Axel · First published 1932Open the Tome
Flora of the Rocky Mountains and adjacent plainsRydberg, Per Axel · First published 1917Open the Tome
Flora of the Rocky Mountains and adjacent plains, Colorado, Utah, Wyoming, Idaho, Montana, Saskatchewan, Alberta, and neighboring parts of Nebraska, South Dakota, North Dakota, and British ColumbiaRydberg, Per Axel · First published 1922Open the Tome
Flora of the Rocky Mountains and adjacent plains, Colorado, Utah, Wyoming, Idaho, Montana, Saskatchewan, Alberta, and neighboring parts of Nebraska, South Dakota, and British ColumbiaRydberg, Per Axel · First published 1917Open the Tome
Scandinavians who have contributed to the knowledge of the flora of North AmericaRydberg, Per Axel · First published 1907Open the Tome
The American species of Limnorchis and Piperia, north of MexicoRydberg, Per Axel · First published 1901Open the Tome
Catalogue of the flora of Montana and the Yellowstone National ParkRydberg, Per Axel · First published 1900Open the Tome
The North American species of Physalis and related generaRydberg, Per Axel · First published 1896Open the Tome
