Jun. 9, 2022

rock polypody, Polypodium virginianum

Rock polypody is well described by that name. It grows mostly on rock. But its not an obligate. A plant is an obligate if it grows exclusively in one habitat. Rock polypody sometimes grows on thin soil or on trees, so it is a near obligate. Mostly on rocks though, and that becomes one clue to identifying it. Those fuzzy spore structures are another. They're kind of fuzzy because they don't have covers. Some ferns have a cover for their sori called an indusium. Some, including rock polypody do not have indusia. Baraga Co MI, 7/13/14. Polypody family, Polypodiaceae.