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Platanthera grandiflora (Bigelow) Lindl.
Large Purple Fringed Orchid
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G5
State Rank: S1
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): Yes
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: High Conservation Concern
Element Occurrences (EOs) in Georgia: 5
Habitat Summary for element in Georgia: Wet thickets; seepy open northern hardwood forests
Perennial herb with a smooth, green, erect stem 0.8 - 4 feet (27 - 120 cm) tall. The leaves are 5 - 9.5 inches (13 - 24 cm) long and 1 - 3.5 inches (2.5 - 9 cm) wide, 2 - 6 in number, and gradually decreasing in size to the flower spike, sheathing the stem, oblong to lance-shaped. The cylindrical flower cluster is held erect at the top of the stem and is densely packed with flowers. The flowers are lavender to pink-purple with a white patch at the base of the lip, about 1 inch (2 - 3 cm) long, not including the spur. The sepals are oval with pointed tips. The lateral petals are oval with rounded, slightly toothed tips. The lip petal is 3-lobed with a showy fringe more than ⅓ the length of the lip. The spur (a backward extension of the lip) is 0.6 -1.4 inch (1.5 - 3.5 cm) long. The opening into the spur at the center of the flower is round or oval. The lowest flowers in the cluster are still open when the upper flowers first open, so that the flower cluster is cylinder-shaped. The fruit is a slender capsule, 0.5 - 1 inch (1.2 - 2.5 cm) long, containing many tiny seeds.
Small Purple Fringed Orchid (Platanthera psycodes, Special Concern) is taller than Large Purple Fringed Orchid, but its flowers are smaller, less than 0.5 inch (0.5 - 1.5 cm) long, not including the spur, which is less than 0.8 inch (1.2 - 1.8 cm) long. The lip is fringed less than ⅓ of the length of the lip. The opening in the center of the flower is dumb-bell shaped rather than round or oval. Its flowers open from the bottom of the cluster to the top, with the lowest flowers open while the upper flowers are only in bud, so that the flower spike is cone-shaped. Small Purple Fringed Orchid occurs in streamside thickets, north-facing coves, and boulderfields in Union County. For more information, see: http://beta.floranorthamerica.org/Platanthera_psycodes Photos are at: https://www.flickr.com/search/?user_id=7449293%40N02&view_all=1&text=Platanthera%20psycodes
Purple Fringeless Orchid (Platanthera peramoena) occurs in moist meadows, sunny bogs in the backwaters of lakes, and in bottomland hardwood forests in Georgia's Blue Ridge. For more information, see: https://www.georgiabiodiversity.a2hosted.com/portal/profile?group=plants&es_id=20521
Ten species of Platanthera are rare in Georgia. For more information, see: https://www.georgiabiodiversity.org/portal/element_lists?group=plant).
Wet thickets and seepy areas along rocky streams.
Large Purple Fringed Orchid is pollinated by moths and butterflies, whose long tongues are adapted to probing the long, nectar-containing spur of fringed orchids. During the process of probing for nectar, sticky packets of pollen adhere to the front of the insects’ heads and are brushed off onto the stigmas of flowers that are subsequently visited. Flowers must be cross-pollinated for fruit to set. Each fruit contains thousands of dust-like seeds that are dispersed by wind and gravity. The seeds contain no stored food reserves (endosperm), and must land on a patch of soil containing a specific fungus that provides nutrients for germination and subsequent plant growth.
Surveys are best conducted during flowering (June–July).
Georgia, north to Newfoundland, and west to Ontario.
Logging and other mechanical clearing of habitat. Damming or ditching small streams. Plant poaching. Digging by feral hogs. Invasion by exotic pest plants. Plant poaching.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Agriculture & aquaculture | Residential & commercial development | Natural system modifications |
| Specific Threat | None | None | None |
Platanthera grandiflora is ranked S1 by the Georgia Department of Natural Resources, indicating that it is critically imperiled in Georgia. Four populations have been documented, all in the Chattahoochee National Forest.
Georgia’s plants are the southernmost populations of Platanthera grandiflora. Plants occurring at the periphery of a species’ range are thought to be of special conservation importance. Peripheral populations are usually smaller and less genetically diverse within the population, but genetically divergent from centrally located populations. These genetic differences may confer special survival traits that plants in other portions of the species’ range lack, such as the ability to survive changes in the climate or the arrival of a new pathogen. Peripheral populations may be in the process of evolving into a new species. They are especially deserving of conservation action.
Avoid logging, trail construction, and other mechanical disturbances near streams and wetlands. Avoid draining wetlands and damming small streams. Eradicate feral hogs. Remove exotic pest plants from habitats. Prosecute plant poachers.
Argue, C.L. 2012. The pollination biology of North American orchids: volume 1, North of Florida and Mexico, Part II: subfamily Orchidoideae (part one), Chapter 8, Platanthera. Springer Science+Business Media, LLC. https://link.springer.com/content/pdf/10.1007%2F978-1-4614-0592-4.pdf
Brown, P.M. and S.N. Folsom. 2004. Wild orchids of the southeastern United States, north of peninsular Florida. University Press of Florida, Gainesville.
Catling, P.M. and V.R. Catling 1991. A synopsis of breeding systems and pollination in North American orchids. Lindleyana 6: 187-210.
Chafin, L.G. 2007. Field guide to the rare plants of Georgia. State Botanical Garden of Georgia and University of Georgia Press, Athens.
Drake, J. 2013. Fringed orchids of the southeastern United States: a guide to the genus Platanthera. Breath o’ Spring, Inc. P.O. Box 2957, Suwanee, Georgia 30024.
Evans, J.R. 2006. Identification and comparison of the pollinators for the Purple-fringed Orchids Platanthera psycodes and P. grandiflora. University of Tennessee Honors Thesis. https://trace.tennessee.edu/utk_chanhonoproj/953
Luer, C.A. 1975. The native orchids of the United States and Canada, excluding Florida. New York Botanical Garden, New York.
McKeever, S. 2001. Some native orchids of the southeastern United States. Tipularia 16: 22-31.
NatureServe. 2019. Platanthera grandiflora comprehensive report. NatureServe Explorer. Arlington, Virginia. http://explorer.natureserve.org/servlet/NatureServe?searchName=Platanthera+grandiflora
Sheviak, C.J. 2003. Platanthera grandiflora species account. Flora of North America, Vol. 26. Oxford University Press, New York. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242101836
Stoutamire, W.P. 1974. Relationships of the purple-fringed orchids Platanthera psycodes and P. grandiflora. Brittonia 26: 42-58. https://link.springer.com/article/10.2307/2805919
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
Linda G. Chafin
L. Chafin, Jul. 2008: original account
K. Owers, Feb. 2010: added pictures
L. Chafin, Mar. 2020: updated original account
