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Alnus maritima ssp. georgiensis, by Hugh and Carol Nourse. Image may be subject to copyright.
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Alnus maritima ssp. georgiensis Schrader & Graves

Georgia Alder

Federal Protection: No US federal protection

State Protection: Threatened

Global Rank: G3T1

State Rank: S1

Element Locations Tracked in Biotics: Yes

SWAP High Priority Species (SGCN): Yes

Element Occurrences (EOs) in Georgia: 1

Habitat Summary for element in Georgia: Open, spring-fed swamps


Shrub up to 33 feet (10 m) tall with a narrow crown and many, erect trunks with smooth bark. Twigs are green and hairy when young, smooth and reddish-gray when older. Leaves are 1.8 - 3.5 inches long, 0.8 - 2 inches wide (4.5 - 9 cm long, 2 - 5 cm wide), alternate, deciduous, with toothed edges, rounded or tapering bases, and 6 - 10 parallel veins on each side of the midvein; upper surface dark green and shiny; lower surface pale green with dark gland dots and yellowish hairs on the veins. Female flowers are held in small, oval catkins that mature in late summer to become solitary, woody fruiting cones that are 0.5 - 1 inch (1.2 - 2.8 cm) long and 0.5 - 0.9 inch (1.2 - 2.2 cm) wide; the fruiting cones persist on the plants for a year or more. Male flowers are tiny, held in drooping clusters of elongated catkins 0.8 - 2.4 inches (2 - 6 cm) long. Female flowers and male flowers  occur on the same plant.

Similar Species

Tag Alder (Alnus serrulata) leaves are dark green on the lower surface and have 8 - 14 parallel veins on each side of the midvein. Fruiting cones are smaller, 0.4 - 0.9 inch (1 - 2.2 cm) long and 0.2 - 0.5 inch (0.6 - 1.2 cm) wide, in clusters of 3 - 5 cones with very short or no stalks. Tag Alder flowers only in the spring.

Related Rare Species

None in Georgia.


Sunny areas in ponds, spring-runs, and spring-fed swamps in northwest Georgia.

Life History

Alnus maritima occurs in 3 widely disjunct populations, with each population considered a separate subspecies. The populations on the Delmarva Peninsula of Delaware and Maryland are named after the seaside location of the first observed plants – ssp. maritima. The plants in Oklahoma and Georgia are also named for their locations – ssp. oklahomensis and ssp. georgiensis, respectively. Georgia’s plants occur more than 700 miles from both the Oklahoma and Delmarva Peninsula populations. Botanists believe that Alnus maritima was once widely distributed across North America and that changing environmental conditions eliminated the species from all but its 3 currently known locations. Once isolated from each other, the populations diverged genetically to a degree that warrants recognizing each disjunct group of plants as separate subspecies. Oklahoma plants have longer, narrower leaves and cones and a rounder growth form than either the Georgia or the Delmarva plants. Georgia plants have narrower leaves than the Delmarva plants as well as smaller, rounder cones and a taller, narrower growth form.

Survey Recommendations

Plants flower and develop new cones in the late summer–fall. Leaves can be identified throughout the growing season and cones are present year-round.


Northwestern Georgia, southeastern Oklahoma, and the Delmarva Peninsula of Delaware and Maryland.


Disruption of natural hydrology in springs and spring runs. Shoreline clearing and development. Ditching, draining, and filling wetlands. Polluted runoff and siltation into ponds and springs from adjacent uplands. Lack of genetic diversity: mating system analyses have shown that Alnus maritima populations in Oklahoma and Georgia have high rates of outcrossing that produce genetically diverse live seeds (Jones and Gibson 2012) but that seed germination is rare and seedling establishment is apparently nonexistent at both of these locations. Populations apparently rely exclusively on asexual root sprouting for reproduction (Rice and Gibson 2009, Jones and Gibson 2012).

Georgia Conservation Status

Georgia Alder is ranked S1 by the Georgia Department of Natural Resources, indicating that the species is critically imperiled in Georgia. It is listed as Threatened by the State of Georgia. One large population of Georgia Alder is known, consisting of 300 - 3,000 clumps of stems. Although occurring on private land, the site is covered by a conservation easement with the corporate landowner, which is actively involved in the species' protection. The site is frequently monitored by federal, state, and private plant conservation scientists.

Conservation Management Recommendations

Avoid ditching, draining, and otherwise altering hydrology of ponds and spring-runs. Protect ponds and spring-runs from sedimentation and pollution. Protect pond and swamp shorelines from development. Monitor sites for exotic pest plant invasion.


Chafin, L.G. 2007. Field guide to the rare plants of Georgia. State Botanical Garden of Georgia and University of Georgia Press, Athens.

Furlow, J.J. 1997. Alnus maritima ssp. georgiensis species account. Flora of North America. Vol. 3, . Oxford University Press, New York. http://beta.floranorthamerica.org/Alnus_maritimahttp://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500036

GA DNR. 2014. Survey for Georgia Alder. Georgia Wild: News of Nongame and Natural Habitats. Georgia Department of Natural Resources, Social Circle, Georgia. http://content.govdelivery.com/accounts/GADNR/bulletins/decec7

GADNR. 2019. Element occurrence records for Alnus maritima ssp. georgiensis. Georgia Department of Natural Resources, Wildlife Resources Division. Social Circle, Georgia.

Gibson, J. P., S. A. Rice, and C. M. Stucke. 2008. Comparison of Population Genetic Diversity Between a Rare, Narrowly Distributed Species and a Common, Widespread Species of Alnus (Betulaceae). American Journal of Botany 95: 588-596. https://bsapubs.onlinelibrary.wiley.com/doi/full/10.3732/ajb.2007316

Jones, J. M. and J. P. Gibson. 2011. Population genetic diversity and structure within and among disjunct populations of Alnus maritima (Seaside Alder) using microsatellites. Conservation Genetics 12:1003-1013. https://link.springer.com/article/10.1007/s10592-011-0203-3

Jones, J. M. and J. P. Gibson. 2012. Mating System Analysis of Alnus maritima (Seaside Alder), a Rare Riparian Tree. Castanea 77:11-20. https://bioone.org/journals/Castanea/volume-77/issue-1/11-024/Mating-System-Analysis-of-Alnus-maritima-Seaside-Alder-a-Rare/10.2179/11-024.full

NatureServe. 2019. Alnus maritima ssp. georgiensis comprehensive report. NatureServe Explorer. Arlington, Virginia. http://explorer.natureserve.org/servlet/NatureServe?searchName=Alnus%20maritima%20ssp.%20georgiensis

Rice, S.A. and J.P. Gibson. 2009. Is seedling establishment very rare in the Oklahoma Seaside Alder, Alnus maritima ssp. oklahomensis? Oklahoma Native Plant Record 9:59-63. https://ojs.library.okstate.edu/osu/index.php/ONPR/article/view/128

Schrader, J.A. 2002. Biosystematics and phenology of Alnus maritima (Betulaceae). Retrospective Theses and Dissertations. 1028. https://lib.dr.iastate.edu/rtd/1028

Schrader, J.A. and W.R. Graves. 2000. Alnus maritima: a rare woody species from the New World. New Plantsman 7:74-82. https://lib.dr.iastate.edu/hort_pubs/14/

Schrader, J.A. and W.R. Graves. 2000. Seed germination and seedling growth of Alnus maritima from its three disjunct populations. Journal of American Society of Horticultural Science 125(1): 128-134. https://journals.ashs.org/jashs/view/journals/jashs/125/1/article-p128.xml

Schrader, J.A. and W.R. Graves. 2000. Timing of seed dispersal may limit the reproductive success of Alnus maritima. Castanea 65(1): 69-77. https://www.jstor.org/stable/4034032?seq=1#metadata_info_tab_contents

Schrader, J.A. and W.R. Graves. 2002. Infraspecific systematics of Alnus maritima from three widely disjunct populations. Castanea 67: 380-401. https://www.jstor.org/stable/4034133?seq=1#metadata_info_tab_contents

Stibolt, V.M. 1978. The ecology and systematics of Alnus maritima Muhl. ex Nutt. (Betulaceae). Thesis, University of Maryland, College Park.

Stibolt, V.M. 1981. The distribution of Alnus maritima Muhl. ex Nutt. (Betulaceae). Castanea 46: 195-200. https://www.jstor.org/stable/4033151?seq=1#metadata_info_tab_contents

Stibolt, V.M., C.R. Broome and J.L. Reveal. 1977. Alnus maritima Muhl. ex Nutt., not Alnus metoporina Furlow. Annals of the Missouri Botanical Garden 64: 373-374.

Weakley, A.S. 2015. Flora of the southern and mid-Atlantic States. University of North Carolina Herbarium, University of North Carolina, Chapel Hill. http://www.herbarium.unc.edu/flora.htm

Authors of Account

Linda G. Chafin

Date Compiled or Updated

L. Chafin, Sept. 2007: original account.

K. Owers, Jan. 2010: updated status and ranks, added pictures.

L. Chafin, June 2020: updated original account.

Alnus maritima ssp. georgiensis, female cones and male catkins in flower, by Alan Cressler. Image may be subject to copyright.
Alnus maritima ssp. georgiensis, illustration by Jean C. Putnam Hancock. Image may be subject to copyright.
Alnus maritima ssp. georgiensis, fruiting "cone," by Hugh and Carol Nourse. Image may be subject to copyright.
Alnus maritima ssp. georgiensis by Hugh and Carol Nourse. Image may be subject to copyright.
Alnus maritima ssp. georgiensis, by Alan Cressler. Image may be subject to copyright.