This volume includes an introductory chapter on the phylogeny and classification of Lamiales with emphasis on Scrophulariaceae in the broad sense plus treatments prepared by 53 authors covering 952 species in 95 genera classified in nine families.
Among the families treated in this volume, the largest are Plantaginaceae (460 species), Orobanchaceae (292), Phrymaceae (139), Scrophulariaceae (45), and Linderniaceae (10).
Additionally, three families included in the volume – Paulowniaceae (1), Pedaliaceae (2), and Mazaceae (2) – are known only by introduced species. Descriptions for all of the families, genera, and species (plus infraspecies, if recognized) are provided plus occurrence maps for species and infraspecies are included with more than 25% of the species illustrated. Keys are included to aid in the identification of genera in families and species plus infraspecies within the genera. Volume 17 is the twenty-first volume to be published in the planned 30-volume Flora of North America North of Mexico series.