The Variable Chirality of Plant Twining Stems

Twining stems are an important form of plant stems. Twining stems can exhibit two different chiralities: right-handed and left-handed, with right-handed twining stems being much more common than left-handed ones. The determination of chirality in twining stems has always been a fascinating topic. Many people believe that the direction of twining stems in a given species is fixed, but this is not the case. Some species have twining stems that exhibit both chirality types, i.e. the chirality is variable. Moreover, such species or genera are not rare and can be commonly encountered in everyday life. Here, we report the presence of variable-chirality twining stems (VCTS) in several species or genera within the Asteraceae, Campanulaceae, Rubiaceae, Lamiaceae, Polygonaceae, Santalaceae, and Ranunculaceae families, including common plants such as Mikania micrantha and Pleuropterus multiflorus. VCTS is an objectively existing phenomenon, but often overlooked. Understanding and accepting this concept will greatly assist future research in this field.