CYPERACEAE

CYPERACEAE View in CoL View at ENA

Discovery of disjunct populations of the Federally Threatened Golden Sedge ( Carex lutea ; sect. Ceratocystis) and first reported chromosome counts of the species, aided by social media and iNaturalist.

Primary authors:Derick B. Poindexter, Lilly Anderson Messec, J. Brandon Fuller, Bob Dellinger,Eric A.Ungberg, Alan S.Weakley

As historically recognized, Carex sect. Ceratocystis is a circumboreal clade consisting of ca. 7+ species, 5 of which can be found in North America ( Crins 2002), including Carex cryptolepis Mack. , C. flava L, C. hostiana DC. , C. lutea LeBlond , C. viridistellata Derieg, Reznicek & Bruederle , and C. viridula Michx. (broadly treated here but with multiple potential species and infraspecies included). Recent work by the Global Carex Group (2021) has expanded our interpretation of this group into a much larger and monophyletic “Ceratocystis- Spirostachyae Clade”—the Spirostachyae component with three species introduced in North America but confined in native distribution to the Old World ( Crins 2002).

Of the taxa of sect. Ceratocystis, only C. lutea occurs in the southeastern United States south of New Jersey, montane Virginia, Ohio, Indiana, and Illinois. This species was described in 1994, and until recently, it was only known from Onslow and Pender counties, NC ( LeBlond et al. 1994). On 23 January 2002, this species was officially classified as Federally Endangered, thereby granting it significant protection status, followed by a critical habitat designation in 2011 ( Suiter 2022). Phylogenetic assessments by Derieg et al. (2008) found C. lutea to be sister to a putative novel species endemic to calcareous wetlands of the upper Midwest (e.g., Indiana, Michigan, and Ohio), later described as Carex viridistellata ( Derieg et al. 2013) . Despite its rarity and protection, no cytological data exists for C. lutea .

On March 28, 2021, an unknown sedge morphologically conforming to C. lutea was discovered in FL by Lilly Anderson Messec (LAM) and Nicole Zampieri while conducting field surveys in the Apalachicola National Forest; it occurred in a diverse roadside ditch and later was found in cypress-dominated basin swamps extending out into the wet pine flatwood edges of those swamps ( Fig. 1). Puzzled by the sedge, LAM posted an image of it in the Florida Flora and Ecosystematics Facebook group with the query “Can anyone ID this Carex sp. ?,” leading to its identification to section within 30 minutes, and suggestions that it might be a disjunct population of Carex lutea within 35 minutes! Wanting to see the plants in live condition and “in habitat,” gather live material for DNA sampling and chromosome counts, and confirm the identification of this species with Federal Endangered status, a team of caricologists from the UNC Herbarium and Flora of the Southeast Project consisting of ASW, DBP, and EAU planned to make a visit to the Apalachicola National Forest population. On May 7, 2021, botanists and land managers from the Florida Native Plant Society, USDA Forest Service, Florida Natural Areas Inventory, UNC Herbarium, Southeastern Flora Project, Archbold Biological Station, and Florida Department of Agriculture and Consumer Services met on site; live materials

and voucher specimens were collected for genetic, morphological, and cytogenetic study, and management and inventory needs were discussed. Two later populations were discovered by Jenna Anis and Camille Eckelbin nearby, one on the Apalachicola National Forest and the other on the Lake Wimico Game Lands.

In a remarkable coincidence, a second unknown Carex lutea population was found by BD in April 2021 in Francis Marion National Forest. He photo-documented a population of a Carex unknown to him, adding it as an iNaturalist observation identified only to genus. On May 12, 2021, EAU was scanning iNaturalist observations of Carex not identified to species, and encountered BD’s observation, immediately recognizing it, as well, as a likely new state record for Carex lutea ( Fig. 2 View FIG ). BD, John Nelson, Bruce Sorrie, Richard Porcher, Samantha Tessel, Cecelia Dailey, and Jestin Clark conducted additional field work to confirm the identity. One small live collection was made by Samantha Tessel and deposited with DBP.

The coastal Carolina and Florida panhandle disjunction displayed by C. lutea is uncommon but not without precedent (see discussion). However, the ecological factors that drive this pattern are not well understood. Thus, further interrogation of these factors could significantly influence our ability to locate new populations and better protect the species from future decline.

With this in mind, we sought to accomplish three goals: 1) verify the identity of these populations with morphological assessment, 2) determine the chromosome number of the species, and 3) use Species Distribution Modeling (SDM) to accurately predict the new Florida population occurrences of C. lutea based solely on occurrence data from NC and to determine what environmental drivers are important to the species.

Collectively, this knowledge can then be used by conservationists and taxonomists to better understand the basic biology and biogeography of this globally rare (G2, Imperiled) species ( NatureServe Explorer 2024).