Polycyclic solenostele–a new synapomorphy for Pteris sect. Litobrochia

Abstract. The vascular architecture of the stem–the stele–is one of the most well studied topics in pteridology, and has fascinated botanists for more than 200 years. Stelar architecture has attracted much attention, in part, due to its diversity in the fern lineage as well as its use as a stable taxonomic character for circumscribing species, genera, families, or larger informal clades. One aspect of stelar morphology that has garnered specific attention is polystely: the development of multiple concentric cylinders of vasculature. This feature has evolved in lineages throughout the fern phylogeny, including in the genus Pteris L. (Pteridaceae). Here, I describe a polycyclic solenostele as a new synapomorphy for Pteris sect. Litobrochia. The identification of this character as a synapomorphy furthers our understanding of the morphological evolution and circumscription of Pteris as well as aides in species identification within this speciose genus.