A New Anatomical Examination of Onoclea sensibilis. Most surprisingly, the anatomy of organs of the fern Onoclea sensibilis has been sparsely described over the centuries.  Studied since 2016 from an often wet setting along a driveway, roots typically have a diarch or monarch stele with an endodermis of Casparian bands which are not revealed by all staining and microscopic methods; cortex cells are thin-walled, and the epidermis usually has root hairs in old roots.  Rhizomes are typically dictyostelic and each of the six meristeles is surrounded by a distinct endodermis with Casparian bands; pith and most cortex cells are thin-walled, but hypodermis usually has sclerenchymatous cells and epidermis has a thick cuticle.  Meristeles have bundles of xylem with phloem primarily located in two zones internal and external to the xylem.  Near their connection to rhizomes, the upright megaphylls have at their bases two meristeles with primary xylem and phloem, and each meristele is surrounded by a distinct endodermis.  The meristeles unite in the petiole to form a truncated V-shaped stele with phloem patches spaced around the xylem, surrounded by one endodermis, that then dichotomize just prior to entering blades with each meristele then vein surrounded by endodermis.  Petioles usually have a prominent, multi-layered sclerenchymatous hypodermis.