Аннотация:PSEUDO-BIFACIAL LEAVES IN SENECIO SERPENS
The linear, fleshy, outwardly bifacial leaves of Senecio serpens Rowl. cardinally differ anatomically, especially concerning the texture of the primary vascular tissue, from the bifacial leaves of the other species of Senecio and are also very similar to the unifacial terete leaves of related species of Senecio. As a result the leaves of S. serpens are interpreted as pseudo-bifacial, arising by the flattening in the horizontal plane of unifacial terete leaves in ancestral species. The edge of the linear leaf is secondary and not homologous to the morphological border between the adaxial and abaxial sides of the leaf. The pseudo-bifacial leaf is a rare example of transformation of unifacial leaves.