Florida’s rarest sedge: Carex paeninsulae


Fig. 1: This former Gulf Coast Forest was logged and mowed. The lawn area is now a mix of St. Augustine grass and low-growing native herbs

Our globally imperiled Peninsula Sedge

Carex paeninsulae

by Linda Curtis

What happens when a dense Gulf coast forest is logged and then mowed as a public park? Almost all the understory plants are destroyed except for the few that are very short and can live between lawn grasses (Fig. 1).

This may be true for Peninsula Sedge that grows as low tufts of grass-like leaves. It survives mowing by sending out underground stems known as rhizomes. Farther away, the rhizomes send up leafy shoots in rows or in clusters nestled aside tree trunks (Fig 2). Small and inconspicous, this globally imperiled plant was discovered by Robert Naczi in 1991 and later given its official scientific name Carex paeninsulae, named for the Florida peninsula.


Carex peninsula grows alongside a tree trunk. Just a tuft of narrow leaves, it is quite grassy in appearance, but has triangular culms rather than the round culms found in grasses.

Peninsula Sedge was given species status when first described in Novon: A Journal for Botanical Nomenclature Vol. 12, Issue 4. Seven New Species and One New Combination in Carex (Cyperaceae) from North America (Naczi, Bryson, Cochrane (2002).

Previously unknown in botany manuals before 2002, C. paeninsulae is now included in the 3rd edition of Guide to the Vascular Plants of Florida (Wunderlin and Hansen 2011). Illustrations can be seen in Flora of North America, Vol. 23 (2002).

Overall, this short grassy plant survives some mowing, but then remains vegetative only without seed heads. Deer also nip the leafy shoots in early spring which also removes the seed heads. As the leaves mature and become tougher and scabrous, the plant becomes too harsh on deer tongues, so they avoid eating them.

Peninsula Sedge was given a globally imperiled rank of G2, which means found in six to twenty locations on the planet (Fig 3).  A G1 species is found in one to five locations as determined by NatureServe, a status system. (www.natureserve.org).


Fig. 3: The globally imperiled peninsula sedge has been found in fewer than 20 locations in these Florida counties. Source http://www.florida.plantatlas.usf.edu/Plant.aspx?id=4167


While the other six species described in Novon were in various states  including North and South Carolina, Georgia and Alabama, Peninsula Sedge grew only in Florida, thus was endemic to the state. Peninsula Sedge was one of three sedges discussed in the Oligocarpa complex of Carex that were characterized by purple-red shoot bases and two-ranked or disticious perigynia. That differs from other Carex species whose perigynia are arranged in threes to sixes on the rachis of their seed heads (Figs. 4, 5).


Fig. 4: Culms of Carex paenibsulae have reddish bases near the roots.


Fig. 5: Carex peninsula has 4–6 perigynia, each sac-like with a single seed-like achene inside. The sacs are opposite each other and two-ranked or distichous. Most Carex are 3–6 ranked on their spike’s rachis.





The Florida Atlas gives the distribution map with presence in 16 counties. The specimens collected from those counties were pressed, labeled, and sent to a Florida herbarium. C. paeninsulea was collected in 2008 in Citrus County at the Crystal River Churchhouse Hammock Trail, a hydric Gulf forest along Highway 19. My specimen was labeled as C. godfreyi and sent to Curator Dr. Bruce Hansen of University of Florida-Tampa (Herbarium (USF) who later annotated the specimen as C. paeninsulae. All Carex species were collected with previously sought research permits, approved by the Florida Department of Environmental Protection and so noted on the herbarium sheets labels.

Peninsula Sedge was discovered again in 2014 at the Crystal River Archaeological Preserve State Park, near Temple Mound.  In 2015 the small shoots were sprouting seed heads with stamens in bloom in February, indicating an early spring compared to the previous years bloom in March 2014 (Figs. 6, 7). Keith Morin, Crystal River State Park biologist, restricted mowing in that area and several new shoots had seed heads the following year. The plant competition was mostly lawn grasses and Viola sp. at the tree trunk bases of Quercus virginiana, Virginia live oak, and Carya glabra, pignut hickory.

Known threats to state endangered and globally imperiled plants in pedestrian areas are mowing, trampling and trail expansions. Another danger to rare plants is poaching by collectors. Curators of herbaria often black out the global coordinates or location data on plant specimen labels. The rare specimens can be seen on a herbarium’s webpage, but the location is not readable on labels by many, but not all, herbaria.


Fig. 6: The staminate terminal spike bears the stamens with pollen that will disperse onto the stigmas of the lower pistillate spikes.


Fig. 6: Keith Morin and Linda Curtis find G2 peninsula sedge.


The most threatened plants are the orchids, and although Peninsula Sedge would not be sought for its exquisite color and form, some collectors simply like to collect rare items, and many trade in them.

Small plants like Peninsula Sedge have beautiful miniature designs that are seen under a microscope, but digital enlargements of microphotographs reveal their beauty (Figs. 8, 9, 10).


Fig. 8 A specimen of the rare C peninsula from the Crystal River Archaeological State Park was sent to the herbarium at the University of South Florida, Tampa. The specimen was digitized for their website. Citation: Wunderlin, R.P., and B.F. Hansen. 2008. Atlas of Florida Vascular plants. (http://florida.plantatias.usf.edu)


Fig. 9: The perigynia have impressed nerves that appear grooved. Most Carex Have raised nerves. The tiny bumps on the leaves are diagnostic in some species, but only seen under 40x magnification. The leaf is papillose, not smooth.


Fig. 10: This achene was revealed when the sac was opened. Only a few millimeters long, it seems like a seed, but technically is a dry fruit. Sometimes the achene shape and design is used in speeches identification.


Ball, P. W. and Reznicek A. A., eds. 2002. Cyperaceae. Flora of North America, Vol. 23: 254-573. New York: Oxford University Press.

Naczi, R. H. Bryson, C. T., Cochrane, T. S. 2002. Seven New Species and One New Combination in Carex (Cyperaceae) from North America. Novon: 12, No. 4, p526

Wunderlin, R. P. and B.F. Hansen, 2003. Guide to the Vascular Plants in Florida, 3rd. ed., University Press of Florida, Gainesville.

Linda Curtis is author of botany books and journal articles.

www.curtistothethird.com. Previous articles in Palmetto about Florida Carex may also be viewed on the website.

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