Anatomical study of an aquatic mustard: Subularia aquatica (Brassicaceae)

Subularia aquatica is a small annual aquatic plant in the family Brassicaceae with unique leaf morphology. Its anatomical features were studied using light microscopy. We show that the leaves of S. aquatica are bifacial dorsiventral phyllodes, having adaxial–abaxial polarity, rather than the alternative unifacial type. This morphology is also manifested in the collaterally arranged vascular bundles, which are clearly bifacial. The roots exhibit typical anatomical features of an aquatic plant, including prominent aerenchyma. Although unique within the Brassicaceae, S. aquatica displays many of the same morphological characteristics as other Isoetid life-forms.