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Dicerandra: A Very Special Genus
Article and photos by Roger L. Hammer
The genus Dicerandra was described in 1830 by English botanist George Bentham (1800–1884) for the 2 hornlike spurs on the anthers that characterize the genus. But what’s so special is that there are currently 10 members of this genus in Florida and 8 of them are known from Florida and nowhere else on Earth. Of those 8 Florida endemics, 6 are restricted to single counties each, and 1 other species is only known from 2 adjacent counties, with the final species being endemic to 8 Florida counties. One other Dicerandra species is spread across 11 northern Florida counties into southern Georgia while another species ranges across 5 counties in the Florida Panhandle into southern Alabama.
Two annual species found outside of Florida are Dicerandra radfordiana, a rare, endangered species endemic to Georgia with only 2 small populations known to exist, and Dicerandra odoratissima, endemic to eastern Georgia and South Carolina.
The genus is in the well-known mint family, Lamiaceae, and the leaves do, indeed, smell delightfully minty when crushed. They are small, shrubby plants of dry, sandy habitats such as scrub, sandhills, and coastal swales.
Lake Wales balm (Dicerandra christmanii) is a perennial species endemic to yellow sand scrub of Polk County and was named to honor Florida botanist Steven P. Christman, who was t he first to recognize it as an undescribed species, and was described as such in 1989. The flowers are white, speckled with red dots, and have yellow anthers. It is a federal- and state-listed endangered species.
Longspur balm (Dicerandra cornutissima) is a federal- and state-listed endangered species first described in 1981. It is a perennial species endemic to sandhills and white sand scrub in Marion and Sumter Counties. Most of the protected population is found along the Harris Carr Cross Florida Greenway between Interstate 75 and State Road 200 in Marion County but there are small, scattered populations on private lands, powerline corridors, and roadsides in Marion and Sumter Counties. The attractive flowers are pinkish-coral or rose-purple in color with darker dots and white anthers.
Florida balm (Dicerandra densiflora) is an annual that is endemic to sandhills and sandy woodlands of Hamilton, Columbia, Suwannee, Lafayette, Taylor, Dixie, Gilchrist, Levy, Duval, Putnam, and Volusia Counties, making it the most widespread endemic species in Florida. It was first described in 1848 and, as its species name implies, the flowers are in dense whorls around the stems. The flowers are pink with darker spots and the anthers are white.
Scrub balm (Dicerandra frutescens) is a federal- and state-listed endangered species that was first described in 1962, and is only known from yellow sand scrub and sandhills on the southern portion of the Lake Wales Ridge in Highlands County. The flowers of this perennial species are white with small, red dots and purple anthers. Much of its historic range in Highlands County has been eradicated by citrus groves and urban sprawl.
Smoky balm (Dicerandra fumella) is an annual and was described in 2010, making it the newest member of the genus. Its range extends across sandhills and pinelands in the western Panhandle, to include Washington, Holmes, Walton, Okaloosa, Santa Rosa, and Escambia Counties, with small populations extending into lower Alabama.
Lakela’s balm (Dicerandra immaculata var. immaculata) is a federal- and state-listed endangered perennial restricted to scrub habitat in Indian River and St. Lucie Counties and is characterized by uniformly pinkish-purple flowers with purple anthers. It was first described in 1963 from plants collected in Indian River County in 1962 by botanist Olga Lakela (1890–1980), who emigrated from Finland to the United States in 1906. Lakela received her doctorate in botany from the University of Minnesota in 1932, then later became the curator of the University of South Florida’s herbarium in 1960, where she remained until retiring in 1973. Many old timers (like me!) who have been involved in the flora of Florida for decades remember her as a coauthor of the monumental book, A Flora of Tropical Florida, published in 1971.
Savanna balm (Dicerandra immaculata var. savannarum) is a federal- and state-listed endangered perennial that was historically known from coastal dunes and interdunal swales of St. Lucie County until much of its habitat was ravaged by developers. In 1995, botanists Keith Bradley and George Gann found plants of savanna balm along a railway and on private property in St. Lucie County, so some of those plants were rescued and relocated to Bok Tower Gardens in Lake Wales where they were propagated for reintroduction projects. Cheryl Peterson of Bok Tower’s Rare Plant Conservation Program reports that through their reintroduction efforts there are now several thousand plants in 4 populations within Savannas Preserve State Park in St. Lucie County. It bears flowers similar to Lakela’s balm but with brownish anthers. Coastalplain balm (Dicerandra linearifolia var. robustior) is an annual found in sandhills from Jackson, Calhoun,
Liberty, and Franklin Counties west to Hamilton and Lafayette Counties, with outlying populations in Duval, Alachua, and Citrus Counties into southern Georgia. It has pink flowers adorned with dark pink dots and reddish-brown anthers. It was first described in 1987 by University of Florida botanist Robin Huck.
Blushing scrub balm (Dicerandra modesta) is a perennial species endemic to scrub habitat in Polk County and was first discovered by Nancy Bissett and Steve Riefler while searching for a rare Rhododendron. Botanist Kris DeLaney of Avon Park later found additional populations nearby. It was described as a new species for Florida in 2008 by University of Florida botanist Robin Huck but, surprisingly, is not yet listed by any agency as threatened or endangered. The white flowers bear red dots and the anthers are white to reddish-brown.
Titusville balm (Dicerandra thinicola) is a state-listed endangered species found exclusively in what is called Paola and Astatula fine sands that formed on marine ridges in Brevard County, where it was first discovered in 1987 and then described in 1993 by botanist Harvey Alfred Miller (1928–2020). There are only a few known populations in small preserves and on private lands. The flowers of this perennial are pink and white with dark pink lines and dots, and bearing white or purple anthers.
While habitat loss due to agriculture and development are the principal causes of plant extinctions, other factors that can contribute to the loss of our rare, endemic Dicerandra species in Florida are fire suppression, habitat mismanagement, invasive exotic pest plants, and sea level rise caused by global warming. The Florida Native Plant Society is actively monitoring populations of Dicerandra cornutissima and D. modesta, and is assisting land managers with habitat restoration efforts in Marion and Sumter Counties as well as restoring the area damaged by a pipeline and transmission line in Polk County. With rampant, unfettered development proceeding at a record pace throughout Florida, the protection and preservation of Florida’s critically imperiled endemic plants has taken on new urgency.
References
Hammer, Roger L. Complete Guide to Florida Wildflowers. 2018. Rowman & Littlefield FalconGuides, Helena, MT
Huck, Robin B. Dicerandra fumella (Lamiaceae), A New Species in the Florida Panhandle and Adjacent Alabama, with comments on the D. linearifolia complex. 2010. Rhodora, Vol. 112, No. 951, pp. 215–237.
University of South Florida Atlas of Florida Plants, Institute for Systematic Botany; https:// floridaplantatlas.usf.edu
Wunderlin, Richard P. and Bruce F. Hansen. Guide to the Vascular Plants of Florida. 2011. University Press of Florida, Gainesville, FL
About the Author
Roger L. Hammer is an award-winning professional naturalist, author, botanist and photographer. His most recent books are Paddling Everglades and Biscayne National Parks and Foraging Florida – Finding, Identifying, and Preparing Edible Wild Foods in Florida. Find him online at www.rogerlhammer.com.
