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Agastache scrophulariifolia (Willd.) Kuntze
Purple Giant-hyssop
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G4
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: 8
Habitat Summary for element in Georgia: Forested floodplains; river terraces
Perennial herb up to 6 feet (2 meters) tall, often forming clumps, with erect, purple-tinged, 4-sided stems that have hairs only on the angles. Leaves up to 5 inches (13 cm) long with leaf stalk up to 2 inches (5 cm) long, opposite, oval or heart-shaped, with rounded base, pointed tip, and toothed edges; underside of the leaf is hairy mainly on the veins; leaves have a strong anise-like odor when crushed. Flower spikes up to 6 inches long (15 cm), erect at tips of stems, tightly packed with flowers and small, pinkish bracts. Flowers lavender, purple, pink, or whitish, with two lips, the lower lip slightly ragged; stamens extend directly beyond the lips; calyx is white, pink, or purplish, with 5 narrowly pointed lobes that are more or less the same size.
Germander or Wood-sage (Teucrium canadense) is a smaller plant with pink or lavender flowers, often in a leafy spike, but its flowers have a very small upper lip and a much larger lower lip, with upward arching stamens; its stems are hairy throughout.
Yellow Giant Hyssop (Agastache nepetoides, Special Concern) occurs in moist, limestone- or mafic-based soils in wooded floodplains of small streams in northwest Georgia. For more information, see: https://www.georgiabiodiversity.org/portal/profile?group=plants&es_id=15707
Rich woodland borders, cracks in limestone outcrops, sunny gaps in forested floodplains over limestone.
Purple Giant Hyssop flowers in late summer and fall, and the fruiting stems persist through the winter. Leaf rosettes emerge as early as March. It is pollinated by a variety of insects, including bees, flies, and butterflies, and possibly hummingbirds. Some members of this genus are used for flavoring and perfumes; it is not known if Purple Giant Hyssop has the potential for similar uses.
Surveys are best conducted during peak flowering (August–early October) and fruiting (September–October).
Georgia, north to New Hampshire and west to Nebraska. Agastache scrophulariifolia is rare throughout much of this range.
Logging and other clearing in hardwood forests and bottomlands. Invasion by exotic pest plants.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Residential & commercial development | Climate change & severe weather | None |
| Specific Threat | None | None | None |
Agastache scrophulariifolia is ranked S1 by the Georgia Department of Natural Resources, indicating that the species is critically imperiled in Georgia. Eight populations in five counties are known although only 3 have been seen since 2000; half occur on the Chattahoochee National Forest, the others on private land.
Avoid logging and other clearing in floodplains and rich hardwood forests. Eradicate exotic pest plants. Georgia’s plants are the southernmost populations of this species. 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.
Ayers, G. S. and M. P. Widrlechner. 1994. The genus Agastache as bee forage: an historical perspective. American Bee Journal 134: 341-348. https://lib.dr.iastate.edu/ncrpis_pubs/66/
Chafin, L.G. 2007. Field guide to the rare plants of Georgia. State Botanical Garden of Georgia and University of Georgia Press, Athens.
Corrigan, E.E. 2002. Agastache scrophulariifolia (Willd.) Kuntze – purple giant hyssop, conservation and research plan for New England. New England Wild Flower Society, Framingham, Massachusetts. https://tinyurl.com/y837wsc6
Dole, C.H. 2002. Butterfly buffet – late-flowering plants that lure pollinators to the fall garden. Brooklyn Botanic Garden Plants & Gardens News 17(3).
GADNR. 2020. Element occurrence records for Agastache scrophulariifolia. Georgia Department of Natural Resources, Wildlife Resources Division, Social Circle, Georgia.
Gleason, H.A. and A. Cronquist. 1991. Manual of vascular plants of north-eastern United States and adjacent Canada, 2nd edition. New York Botanical Garden, New York.
Lint, H. and C. Epling. 1945. A revision of Agastache. American Midland Naturalist 33: 207-230. https://www.jstor.org/stable/2421328?seq=1#metadata_info_tab_contents
Radford, A.E., H.E. Ahles, and C.R. Bell. 1968. Manual of the vascular flora of the Carolinas. University of North Carolina Press, Chapel Hill.
NatureServe. 2020. Agastache scrophulariifolia species account. NatureServe Explorer. Arlington, Virginia. https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.136311/Agastache_scrophulariifolia
Vogelmann, J. E. and G. J. Gastony. 1987. Electrophoretic enzyme analysis of North American and Eastern Asian populations of Agastache sect. Agastache (Labiatae). American Journal Botany 74: 385-393. https://bsapubs.onlinelibrary.wiley.com/doi/abs/10.1002/j.1537-2197.1987.tb08620.x
Weakley, A.S. 2015. Flora of the Southern and Mid-Atlantic States. University of North Carolina Herbarium, Chapel Hill. http://www.herbarium.unc.edu/flora.htm
Linda G. Chafin
L. Chafin, Sept. 2007: original account.
K. Owers, Jan. 2010: updated status and ranks, added pictures.
Z. Abouhamdan, April 2016: updated link.
L. Chafin, Jan. 2020: updated original account.
