Taxonomic revision of genus Verbascum (Scrophulariaceae) in the Arabian Peninsula.

The species of the genus Verbascum L. in the Arabian Peninsula are revised. Seventeen species are recognized, a key to the species is provided, and all names are typified. Detailed morphological descriptions, distribution maps, habitat information, and field images are presented for each species. Verbascum sarawaticum A. Alzahrani is newly described, and Verbascum eremobium Murb. is newly confirmed for the flora of the Arabian Peninsula. Seven new synonyms are established in this study. Accordingly, Verbascum sheilae Hemaid is treated as a variety under V. deserticola (Murb.) Huber-Morath (as var. sheilae); Verbascum tabukum Hemaid is placed in synonymy with V. eremobium Murb.; Verbascum luntii Baker is placed in synonymy with V. longibracteatum Defl.; Verbascum hema-figranum Hemaid is placed in synonymy with V. medinecum Hemaid; Verbascum abyadicum Hemaid is placed in synonymy with V. shiqricum Hemaid; and both Verbascum chaudharyanum Hemaid and Verbascum asiricum Hemaid are treated as varieties under V. yemense Defl. (as var. yemense and var. asiricum, respectively). Furthermore, the previously segregated genus Rhabdotosperma Hartl is here reduced to synonymy under Verbascum L., and the species formerly known as Rhabdotosperma saudiarabicum A. Alzahrani is formally recombined as Verbascum saudiarabicum (A. Alzahrani) A. Alzahrani.