psilopsid

The term "psilopsid" refers to plants belonging to the subdivision Psilopsida. These are primitive vascular plants characterized by a lack of true roots and leaves, though some may have partially differentiated leaves. Their stems exhibit a simple, forking (dichotomous) branching pattern, with the stem assuming the photosynthetic function. The vascular tissue is organized into a basic central cylinder. The order Psilotales, which includes whisk ferns, represents the living members of this group. These plants are typically small and herbaceous, found primarily in subtropical regions.1234