Peltate glandular trichomes of Colquhounia seguinii harbor new defensive clerodane diterpenoids Anatomy and Histochemistry of the Leaf of Rehmannia glutinosa Libosch.ex Fisch (Scrophulariaceae) Morphology and Histochemistry of the Glandular Trichomes of Isodon rubescens (Hemsley) H. Hara [Lamiaceae]