ANATOMY AND DISTRIBUTION OF FOLIAR IDIOBLASTS IN SCRIPHULARIA AND VERBASCUM (SCROPHULARIACEAE)

Internal secretory structures have rarely been reported from Scrophula riaceae, and foliar idioblasts only once before, in 1887. Presented he re are the first unambiguous descriptions of subepidermal foliar idiob lasts in the family, from Scrophularia and Verbascum, genera regarded as closely allied on other grounds. Leaf samples from 183 mostly herba rium specimens (128 species, with 55 replicates) were cleared and stai ned, which revealed idioblasts in 62 (69.7%) of 89 Scrophularia specie s and 13 (33.3%) of 39 Verbascum species. We then chose 14 representat ive species to examine by resin sectioning and scanning electron micro scopy. Idioblasts occurred both adaxially and abaxially. Most were con spicuous, in some species penetrating to vasculature level. Idioblasts had a thin primary wall and were empty at maturity. Verbascum and Scr ophularia species with and without idioblasts were scattered among the subgeneric taxa without taxonomic clustering: likewise, both types oc curred in approximately proportionate numbers throughout the geographi c range, except that 14 of 15 North American Scrophularia species had idioblasts. Petals of two species had abundant idioblasts. The 1887 re port illustrated a huge idioblast in S. deserti and we also found the largest in either genus in this species. We also noted trichome and st omata types and report that paraveinal mesophyll and foliar endodermis with casparian strip were both absent.