This taxonomic monograph of the Phacelia crenulatae group for North America recognizes 35 species and 7 varieties. A brief discussion of the history, general morphology, phylogeny, and cytology is given. All entities are separated by a comprehensive key followed by a list of types, synonyms, descriptions and general habitat. Distribution maps and illustrations are included. One variety is described as new. The body of this work is based on herbarium specimens and extensive field observations and collections made throughout much of North America.
Atwood, N Duane
"A revision of the Phacelia Crenulatae group (Hydrophyllaceae) for North America,"
Great Basin Naturalist: Vol. 35:
2, Article 1.
Available at: https://scholarsarchive.byu.edu/gbn/vol35/iss2/1