Recently, I have been conducting site visits for some of the rare, threatened, and endangered (RTE) plant species that occur within the C&O Canal NHP, in order to gain a better understanding of their habitats, populations, and threats within the park. All of this information is critical for deciding the best way to conserve populations and species.


Baptisia australis (foreground) grows in rocky prairies formed by river scour within the gorge. Photo credit: Vida Svahnstrom

In my last blog post, I mentioned that the Potomac Gorge is one of the hotspots for RTE plants in the park. When I’m botanizing in the gorge, I no longer feel like I’m in Maryland. Riverside rock outcrops contain some of the same plant species as Midwestern prairies, as well as other rare plants which can withstand the extreme heat and lack of soil. Periodic flood events prevent most woody species from establishing, allowing these rocky prairies to persist. Baptisia australis (Blue Wild Indigo) is one example of a state imperilled (S2) plant species found in this habitat. In Maryland, this species only occurs in a few scattered populations along the Potomac.


Solidago racemosa is a rare habitat specialist, only growing in rock crevices and cracks along certain rivers. Photo credit: Vida Svahnstrom

If you look carefully in the cracks and crevices of exposed rock outcrops and cliffs in late summer, you might see a spike of yellow flowers belonging to Solidago racemosa, a globally vulnerable (G3) and state critically imperilled (S1) species of Goldenrod. The exposed outcrops of the Potomac gorge is the only place in Maryland where this plant grows.


Hibiscus laevis grows on depositional bars and shorelines along the Potomac. Photo credit: Vida Svahnstrom



You can spot the beautiful and state vulnerable (S3) Hibiscus laevis (Halberd-leaf Rosemallow) flowering along the shores of the Potomac and even in the canal itself this time of year as well. The flowers only last for one day!




View of the Potomac Gorge from one of the extremely biodiverse river scoured islands. Photo credit: Vida Svahnstrom

These are only a small selection of the amazing diversity of rare plants found within the gorge. The stunning geography of this part of the Potomac River as well as its proximity to Washington D.C. attracts a high volume of visitors every year. If you visit this special place, please make sure you stick to the trails and boardwalks. Many of these plants are extremely sensitive to trampling!