Title: A field manual of the ferns & fern-allies of the United States & Canada
Subjects: Pteridophyta, Identification, Ferns, Forest ecology, Biological rhythms, Seasons, Ferns and fern allies, Ptéridophytes, Fougères, Varens, Farnpflanzen, Fougère, Ptéridophyte, Congresses, Ecology
Places: Canada, United States