Morphological phenotypes of the angustifolia (an) mutant of arabidopsis. A) Gross morphology of leaves of the wild type and an mutant. Note the narrow shape of the an leaf. Bar, 5 mm. B) Trichomes on the leaf. Wild-type trichomes are three-branched in most cases (left), whereas an trichomes are two-branched. The longitudinal direction of the panel corresponds to the leaf-length direction. C) Cross-section of leaves of the wild type (left) and an mutant (right). Note the narrow, longer shape (in the leaf-thickness direction) of the an leaf cells. Bar, 100 μm. D) Arrangement of cortical microtubules (MTs) in leaf epidermal cells. The longitudinal direction of the panel corresponds to the leaf-length direction. Compared with wild-type MTs, the an MTs are arranged more simply and parallel to the leaf-width direction. Modified from Kim et al.⁶