Dr. Keir Wefferling (Biology, Fewless Herbarium Curator) has coauthored an article that was recently published in The Bryologist, titled “The surprising appearance of Riccia cavernosa (Ricciaceae) in North American pavement cracks.“
The article highlights that, in recent years, bryologists have noticed a liverwort, the cavernous crystalwort (Riccia cavernosa), appearing in sidewalk cracks/seams and at the edges of parking lots in Vermont, Wisconsin, New Jersey, and Florida (and likely are to be found growing in other urban areas globally). This is a striking observation because the species is known historically as a rare and ephemeral liverwort found in mud flats at the edges of rivers, swamps, and agricultural fields. In the current study, the researchers used molecular data to explore the possibility that this is a newly invasive species; the data confirmed the species identity as Riccia cavernosa, suggesting that the species has expanded into a novel niche (salty, heavily trafficked, subject to periodic drought and flooding) in recent years.
You can read the article here: https://www.researchgate.net/publication/393798903_The_surprising_appearance_of_Riccia_cavernosa_Ricciaceae_in_North_American_pavement_cracks