By Sam Hoadley
I recently had the privilege of sitting down with Bill McAvoy to talk about sedges in the state of Delaware. In his role as Delaware’s state botanist, Bill has spent the past 32 years studying the First State’s native flora and habitats. Bill is an expert on the sedge plant family (Cyperaceae), which includes the genus Carex, and played an instrumental role in the planning and execution of the recently completed Carex trial at Mt. Cuba Center.
“I find sedges to be really fascinating plants,” says Bill, “they are the types of plants that I will seek out when doing field work.” Bill attributes his fondness for sedges partially due to their natural beauty, which he finds particularly striking in their often-overlooked details. Identifying sedge species can be challenging unless you know where to look. Close inspection of the seeds, or achenes, is often required, as they are frequently the most diagnostic feature of sedges. In those tiny seeds are shapes and structures that are both fascinating and beautiful.
Bill has tallied nearly 250 different taxa of sedges from ten different genera in the state. Carex is the largest of these genera, with 137 species found in Delaware. Forty-three percent of Delaware’s native sedges are considered rare or uncommon, including one species of Rhynchospora that is federally threatened. Several sedge species are near-endemic to the state, meaning that they occur nowhere else but in Delaware and a few surrounding states.
Many sedges grow in unique and interesting habitats that are high in plant diversity, and these habitats often host other rare plants. Delaware is located in the Delmarva Peninsula along with the eastern reaches of Maryland and Virginia. Bill describes the convergence of these three states as a place with high habitat and plant diversity. The area acts as a crossroads where species from both the northeastern and southeastern United States overlap; though the flora of the Delmarva Peninsula shares more in common with the plants of the south than those of the north. The rarity of some northern species in the area is a result of them having reached the southern limits of their geographic ranges; those same plants may be more common in other areas of their natural distributions.
Due to the rarity of some of these sedges in Delaware, Bill has actively worked to conserve several species, including one unnamed species of Rhynchospora, also known as beaksedge. This Rhynchospora species is exceptionally rare and is currently known to occur in just a few seasonally flooded wetlands in Delaware and Maryland. Bill was able to collect seeds from this imperiled sedge and delivered them to the greenhouse team at Mt. Cuba Center. Here, the team germinated the seeds and grew the plants until they were large enough to be transplanted back into suitable habitat in Delaware. Those reintroduced plants are now thriving and have resulted in a stable and growing population.
An additional example of Bill’s proactive sedge conservation involves another unnamed species, this one in the Carex genus. This Carex was described in the 1800s and was identified as an established species. It has since been determined to be a unique plant that only occurs in northern Delaware and in a few locations in eastern Maryland and southeastern Pennsylvania. One small population of this novel species was under extreme threat from encroaching invasive species, so Bill collected plant material to be propagated at Mt. Cuba. The established plants were then transplanted back into a suitable site, free from invasive species, resulting in a healthy new population of this rare Carex species in Delaware.
To conclude the interview I asked Bill, “Why should people care about and garden with Carex?” Bill responded by saying, “for the same reasons you would want to plant or promote the use of any native plant. They are part of the ecosystem and part of the chain of species diversity. They are often associated with other wildlife species including insects that require that plant to complete their life cycles and to survive. You are also able to preserve a part of Delaware’s nature heritage and native flora in your garden.”
For a further example of successful conservation in action involving sedges, see page 19 of the newly released Carex research report.