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Monotropsis odorata Schwein. ex Ell.
Sweet Pinesap
Federal Protection: No US federal protection
State Protection: Threatened
Global Rank: G3
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: 14
Habitat Summary for element in Georgia: Upland forests
Perennial herb, lacking chlorophyll and parasitic on underground fungi associated with the roots of trees. Stems are 1 - 3 inches (3 - 8 cm) tall, fleshy, smooth, and hairless; they are red, purple, pink, or brown, and usually occur in clusters; stems are at first curved then become erect with age. Leaves are tan, papery, scale-like, triangular, less than 0.2 inch (4 - 8 mm) long. Flowers are very sweetly fragrant held in a nodding cluster at the top of the stem. Flowers are less than 0.2 inch (4 - 9 mm) long, bell-shaped with 5 white-tipped, purple petals that are united for almost half their length, and 5 tan, separate, papery sepals nearly as long as the petals. Fruit is a berry less than 0.2 inch (4 - 8 mm) wide, purplish, round, and nodding.
Pine-sap (Monotropa hypopithys) has yellow, pink, or red stems; its stems and flowers are hairy; the topmost flower has 5 petals and 5 sepals, the other flowers have 4 petals and 4 sepals; the petals of all flowers are completely separate from each other.
Indian-pipes (Monotropa uniflora) have white stems with a single white flower at the top.
None in Georgia.
Mixed pine-hardwood or chestnut oak-dominated forests with dry, acidic soil, often with mountain laurel, rhododendron, and blueberry.
Sweet Pinesap is a perennial herb. It sends up stems in the fall, reaching about ¾ of its full size; it then completes its growth and flowers the following spring. Getting that head start on growth is an advantage, allowing it to bloom earlier than other spring-flowering plants and to be among the first flowers to attract pollinators. The advance growth comes with a price, though, increasing the amount of time that the plants are available to hungry insects, birds, and rodents. However, the colorful stems and flowers of sweet pinesap are covered by tan, papery bracts that resemble the dead leaves that cover the ground around the plants in early spring. This camouflage largely protects Sweet Pinesap from plant-eating animals.
Sweet Pinesap flowers require cross-pollination in order to set fruit. Their pollen is relatively inaccessible to pollinators, held in tubular anthers with only one opening at the tip. Bumblebees extract the pollen by “buzzing” the anthers: they grasp the flower and rapidly move their indirect flight muscles (not their wings), causing the flower and anthers to vibrate and release their pollen. Some of this pollen is taken back to the bumblebee’s nest but some is carried to the next flowers the bumblebee visits. Sweet Pinesap seeds are dispersed by small animals.
Sweet Pinesap is a non-photosynthetic plant; it lacks chlorophyll and therefore the means to manufacture carbohydrates. It is an epiparasite, meaning that it grows on a fungal parasite (Hydnellum, a basidiomycete) which itself is attached to the roots of a green, photosynthesizing plant. The fungus extracts carbon from the photosynthetic plant, and Sweet Pinesap extracts carbohydrates from the fungus.
Surveys are best conducted during flowering (February–April) and fruiting (May–June). Plants are often hidden under leaf litter or fallen pine needles; the sweet, cinnamon-like fragrance of the flowers can be smelled from some distance and used to locate the hidden plants during flowering.
Georgia, Alabama, South Carolina, North Carolina, Tennessee, Virginia, West Virginia, Kentucky, Maryland, and Delaware.
Conversion of habitat to pine plantations and developments. Fire suppression. Foot traffic through populations.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Biological resource use | Human intrusions & disturbance | Natural system modifications |
| Specific Threat | None | None | None |
Monotropsis odorata is ranked S2 by the Georgia Department of Natural Resources, indicating that the species is imperiled in Georgia. It is listed as Threatened by the State of Georgia. Thirteen populations have been documented in Georgia since 1938, but only 4 populations have been seen since 2000, all on state park or National Forest land.
Protect sites from clearcutting and conversion to pine plantations and residential and commercial developments. Direct foot trails away from sites. Apply prescribed fire.
Bidartondo, M.I. and T.D. Burns. 2001. Extreme specificity in epiparasitic Monotropoideae (Ericaceae): widespread phylogenetic and geographical structure. Molecular Ecology 10: 2285-2295. https://onlinelibrary.wiley.com/doi/full/10.1046/j.1365-294X.2001.01358.x
Chafin, L.G. 2007. Field guide to the rare plants of Georgia. State Botanical Garden of Georgia and University of Georgia Press, Athens.
GADNR. 2020. Element occurrence records for Monotropsis odorata. Georgia Department of Natural Resources, Wildlife Resources Division, Social Circle, Georgia.
Horn, D., T. Cathcart, T.E. Hemmerly, and D. Duhl. 2005. Wildflowers of Tennessee, the Ohio Valley, and the southern Appalachians. Lone Pine Publishing, Auburn, Washington.
Klooster, M.R. and T.M. Culley. 2009. Comparative analysis of the reproductive ecology of Monotropa and Monotropsis: two myco-heterotrophic genera in the Monotropoideae (Ericaceae). American Journal of Botany. https://bsapubs.onlinelibrary.wiley.com/doi/abs/10.3732/ajb.0800319
Klooster, M.R., D.L. Clark, and T.M. Culley. 2009. Cryptic bracts facilitate herbivore avoidance in Monotropsis odorata (Ericaceae). The American Naturalist https://bsapubs.onlinelibrary.wiley.com/doi/full/10.3732/ajb.0900124
NatureServe. 2019. Monotropsis odorata comprehensive report. NatureServe Explorer. Arlington, Virginia. http://explorer.natureserve.org/servlet/NatureServe?searchName=Monotropsis+odorata
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.
Rose, J.P. and J.V. Freudenstein. 2014. Cryptic and overlooked: species delimitation in the mycoheterotrophic Monotropsis (Ericaceae: Monotropoideae). Systematic Botany 39(2): 578-593. https://www.ingentaconnect.com/content/aspt/sb/2014/00000039/00000002/art00021
Wallace, G.D. 1975. Studies of the Monotropoideae (Ericaceae): taxonomy and distribution. Wasmann Journal of Biology 33(1): 1-89. http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7710027914
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, June 2008: original account
K. Owers, Feb. 2010: added pictures
L. Chafin, March 2020: updated original account
