Climate Matching Map
| Attachment | Size |
|---|---|
| climatematch-aegopodium_podagraria-washington-20260331.pdf (1.22 MB) | 1.22 MB |
1. Question 1
Yes
1
High
Aegopodium podagraria is native to Europe and northern Asia. Lind (2011) reported that A. podagraria had naturalized statewide in Wisconsin. It is recognized as a naturalized and invasive species in Alaska (Nawrocki et al. 2011), Minnesota (Garske 2000, cited in Schimpf et al. 2014), Pennsylvania (Commonwealth of Pennsylvania no date), Vermont (The Nature Conservancy 2010, Vermont Invasives no date), and the Province of Ontario and elsewhere in Canada (Kendall 2021).
Lind, S. 2011. “Aegopodium Podagraria L. Invasive Species Assessment”. Madison, WI: Wisconsin Department of Natural Resources. https://dnr.wisconsin.gov/sites/default/files/topic/Invasives/LR_Aegopo….
Nawrocki, T, H.I Klein, L.A Flagstad, and M.L Carlson. 2011. “Alaska Non-Native Plant Invasiveness Ranking Form: Aegopodium Podagraria L. Bishop’s Goutweed”. Anchorage, AK: Alaska Natural Heritage Program. https://accs.uaa.alaska.edu/wp-content/uploads/Aegopodium_podagraria_RA….
Kendall, C. 2021. “Goutweed (Aegopodium Podagraria): Best Management Practices in Ontario”. Peterborough, Ontario, Canada: Ontario Invasive Plant Council. https://www.ontarioinvasiveplants.ca/wp-content/uploads/2022/05/OIPC_BM….
Pennsylvania, Commonwealth of. 1000. “DCNR Invasive Species List”. https://elibrary.dcnr.pa.gov/GetDocument?docId=2700788&DocName=dcnr_200… .
Invasives, Vermont. 1000. “Goutweed or Bishop’s Weed”. https://www.vtinvasives.org/invasive/goutweed-or-bishops-weed.
Conservancy, The Nature. 2010. “Goutweed”. https://vtinvasives.org/sites/default/files/fact-sheets/goutweed2010.pdf.
2. Question 2
Yes
2
Very High
The Cal-IPC Climate Match Map indicates Aegopodium podagraria occur in areas climatically similar to the Pacific Northwest in eastern North America from the maritime provinces of Canada south down the Appalachian Mountains to Georgia in the U.S. Within this area, the species is reported to be invasive in natural areas in Pennsylvania and Vermont (Commonwealth of Pennsylvania no date, The Nature Conservancy 2010, Vermont Invasives no date). The Consortium of Pacific Northwest Herbaria (2025) lists numerous records from western Washington, Oregon, and Vancouver, British Columbia indicating persistent, naturalized occurrences.
Invasives, Vermont. 1000. “Goutweed or Bishop’s Weed”. Burlington, VT: University of Vermont Extension. https://www.vtinvasives.org/invasive/goutweed-or-bishops-weed.
Conservancy, The Nature. 2010. “Goutweed”. https://vtinvasives.org/sites/default/files/fact-sheets/goutweed2010.pdf.
Pennsylvania, Commonwealth of. 1000. “DCNR Invasive Species List”. https://elibrary.dcnr.pa.gov/GetDocument?docId=2700788&DocName=dcnr_200… .
Herbaria, Consortium of Pacific Northwest. 2025. “Aegopodium Podagraria L”. https://www.pnwherbaria.org/data/results.php?ExcludeCultivated=Y&Search….
3. Question 3
Yes
2
High
Rationale: Aegopodium podagraria is an aggressive invader in the Province of Ontario, Canada, where it reportedly forms dense, persistent patches of that outcompete and exclude native species (Kendall 2021). In a southern boreal forest site in Minnesota, Garske (2000, cited in Schimpf et al. 2014) reported that A. podagraria formed a continuous ground cover with greatly reduced vascular plant richness and diversity, and reduced the density of native shade tolerant conifer seedlings and saplings by more than 80%.
Garske, S.C. 2000. “Ecological Effects of Goutweed (Aegopodium Podagraria L.) on a Southern Boreal Forest Site”. Duluth, MN: University of Minnesota.
Kendall, C. 2021. “Goutweed (Aegopodium Podagraria): Best Management Practices in Ontario”. Peterborough, Ontario, Canada: Ontario Invasive Plant Council. https://www.ontarioinvasiveplants.ca/wp-content/uploads/2022/05/OIPC_BM….
Schimpf, D.J, S.C Garske, and R.R Regal. 2014. “Persistent Effects of Herbaceous Species on the Infectious Lethality of Soil for Conifer Seedlings”. Duluth, MN: University of Minnesota. https://conservancy.umn.edu/items/2c286b82-d60d-4869-8195-47c99d486d3d.
4. Question 4
Yes
3
High
The species is reported to be invasive in natural areas in the northeastern U.S. – for example Vermont (The Nature Conservancy 2010, Vermont Invasives no date) and Pennsylvania (Commonwealth of Pennsylvania no date) -- where the Cal-IPC Climate Map indicates a climate similar to the Pacific Northwest.
Pennsylvania, Commonwealth of. 1000. “DCNR Invasive Species List”. https://elibrary.dcnr.pa.gov/GetDocument?docId=2700788&DocName=dcnr_200… .
Invasives, Vermont. 1000. “Goutweed or Bishop’s Weed”. Burlington, VT: University of Vermont Extension. https://www.vtinvasives.org/invasive/goutweed-or-bishops-weed.
Conservancy, The Nature. 2010. “Goutweed”. https://vtinvasives.org/sites/default/files/fact-sheets/goutweed2010.pdf.
Council, California Invasive Plant. 2026. “Climate Match Map for Aegopodium Podagraria - Washington”. https://weedmap.cal-ipc.org/climatematch/?areaType=states&areaList%5B%5….
5. Question 5
No
0
High
No other Aegopodium species are known to occur in North America (USDA PLANTS 2025). The Global Compendium of Weeds (Randall 2017) lists only one other Aegopodium, A. alpestre, native to temperate Asia; the GBIF/Cal-IPC Climate Match Map indicates only a few scattered occurrences of A. alpestre outside of this range.
Database, U.S. Department of Agriculture Plants. 2025. “Aegopodium L”. https://plants.usda.gov/plant-profile/AEGOP/subordinate-taxa.
Randall, R. P. 2017. “A Global Compendium of Weeds. Third Edition”. https://www.researchgate.net/publication/313645439_A_Global_Compendium_….
Council, California Invasive Plant. 2026. “Climate Match Map for Aegopodium Podagraria - Washington”. https://weedmap.cal-ipc.org/climatematch/?areaType=states&areaList%5B%5….
6. Question 6
No
0
Medium
The GBIF/ Cal-IPC Climate Match Map indicates exhibits considerable distribution of Aegopodium podagraria in areas with a climate similar to the Pacific Northwest; however, > 50% of the species’ global distribution appears to lie outside matching areas.
Council, California Invasive Plant. 2026. “Climate Match Map for Aegopodium Podagraria - Washington”. https://weedmap.cal-ipc.org/climatematch/?areaType=states&areaList%5B%5….
7. Question 7
Yes
1
High
In a southern boreal forest site in Minnesota, Garske (2000, cited in Schimpf et al. 2014) reported that Aegopodium podagraria formed a continuous ground cover with greatly reduced vascular plant richness and diversity, and reduced the density of native shade tolerant conifer seedlings and saplings by more than 80%. A U.S. Forest Service fact sheet (2006) states that deer avoid grazing on A. podagraria, suggesting another mechanism by which the species may gain an advantage on potential competitors.
Garske, S.C. 2000. “Ecological Effects of Goutweed (Aegopodium Podagraria L.) on a Southern Boreal Forest Site”. Duluth, MN: University of Minnesota.
Schimpf, D.J, S.C Garske, and R.R Regal. 2014. “Persistent Effects of Herbaceous Species on the Infectious Lethality of Soil for Conifer Seedlings”. Duluth, MN: University of Minnesota. https://conservancy.umn.edu/items/2c286b82-d60d-4869-8195-47c99d486d3d.
Service, U.S. Forest. 2006. “Weed of the Week: Goutweed”. Weed of the Week. Newtown Square, PA: U.S. Forest Service, Forest Health Staff. https://www.invasive.org/weedcd/pdfs/wow/goutweed.pdf.
8. Question 8
No
0
High
Specific information regarding Aegopodium podagraria’s impact on fire regimes is limited (Waggy 2010). Goutweed’s herbaceous habit, low stature (i.e., probable low fuel loading) and typical mesic habitats (Kendall 2021, Waggy 2010) – habitats with historically low fire frequencies -- suggest it is unlikely the species promotes fire.
Waggy, Melissa A. 2010. “Aegopodium Podagraria. In: Fire Effects Information System”. US Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. https://www.fs.fed.us/database/feis/plants/forb/aegpod/all.html.
Kendall, C. 2021. “Goutweed (Aegopodium Podagraria): Best Management Practices in Ontario”. Peterborough, Ontario, Canada: Ontario Invasive Plant Council. https://www.ontarioinvasiveplants.ca/wp-content/uploads/2022/05/OIPC_BM….
9. Question 9
No
0
Medium
No information was discovered linking Aegopodium podagraria to significant health risks to humans, wildlife, or livestock. The species has been used in folk medicine for centuries. Debia et al. (2025) note the presence of compounds with some toxic properties in goutweed, but conclude that potential effects are minor or require improbably high rates of consumption. None of the published sources reviewed referred, either, to any impact to agricultural grazing systems, though one source (U.S. Forest Service. 2006) noted that deer avoid grazing on goutweed, suggesting another mechanism by which the species may gain an advantage on potential competitors.
Debia, K, M Dziecol, A Wroblewska, and K Janda-Milczarek. 2025. “Goutweed (Aegopodium Podagraria L.) - An Edible Weed With Health-Promoting Properties”. Molecules 30 (7): 23. https://pmc.ncbi.nlm.nih.gov/articles/PMC11990176/#sec6-molecules-30-01….
Service, U.S. Forest. 2006. “Weed of the Week: Goutweed”. Weed of the Week. Newtown Square, PA: U.S. Forest Service, Forest Health Staff. https://www.invasive.org/weedcd/pdfs/wow/goutweed.pdf.
10. Question 10
No
0
Very High
None of the literature reviewed for this evaluation suggested that Aegopodium podagraria was considered any impediment to the movement of humans, wildlife, or livestock. Although capable of forming dense patches (Kendall 2021, Garske 2000, cited in Schimpf et al. 2014), A. podagraria’s herbaceous growth form and relatively low stature (up to 1.0 foot tall; Missouri Botanical Garden no date) make it very unlikely that the species could have such an effect.
Garske, S.C. 2000. “Ecological Effects of Goutweed (Aegopodium Podagraria L.) on a Southern Boreal Forest Site”. Duluth, MN: University of Minnesota.
Kendall, C. 2021. “Goutweed (Aegopodium Podagraria): Best Management Practices in Ontario”. Peterborough, Ontario, Canada: Ontario Invasive Plant Council. https://www.ontarioinvasiveplants.ca/wp-content/uploads/2022/05/OIPC_BM….
Schimpf, D.J, S.C Garske, and R.R Regal. 2014. “Persistent Effects of Herbaceous Species on the Infectious Lethality of Soil for Conifer Seedlings”. Duluth, MN: University of Minnesota. https://conservancy.umn.edu/items/2c286b82-d60d-4869-8195-47c99d486d3d.
Garden, Missouri Botanical. 2026. “Aegopodium Podagraria ‘Variegatum.’”. https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails….
11. Question 11
Yes
1
Very High
Rationale: Aegopodium podagraria spreads primarily by long, branching rhizomes, allowing it to form dense patches that reduce or exclude native species (Kendall 2021, Garske 2000, cited in Schimpf et al. 2014).
Garske, S.C. 2000. “Ecological Effects of Goutweed (Aegopodium Podagraria L.) on a Southern Boreal Forest Site”. Duluth, MN: University of Minnesota.
Kendall, C. 2021. “Goutweed (Aegopodium Podagraria): Best Management Practices in Ontario”. Peterborough, Ontario, Canada: Ontario Invasive Plant Council. https://www.ontarioinvasiveplants.ca/wp-content/uploads/2022/05/OIPC_BM….
Schimpf, D.J, S.C Garske, and R.R Regal. 2014. “Persistent Effects of Herbaceous Species on the Infectious Lethality of Soil for Conifer Seedlings”. Duluth, MN: University of Minnesota. https://conservancy.umn.edu/items/2c286b82-d60d-4869-8195-47c99d486d3d.
12. Question 12
Yes
1
Medium
Rationale: The decay of older rhizomes leads to the separation of plants that were formerly vegetatively linked (Gatsuk et al. 1980). Kendall (2021) states that fragments of goutweed rhizome may be dispersed downstream along waterways. Presumably these are not uncommon phenomena, though how common they are is not quantified in any of the sources.
Kendall, C. 2021. “Goutweed (Aegopodium Podagraria): Best Management Practices in Ontario”. Peterborough, Ontario, Canada: Ontario Invasive Plant Council. https://www.ontarioinvasiveplants.ca/wp-content/uploads/2022/05/OIPC_BM….
Gatsuk, L, O Smirnova, and L Vorontzova. 1980. “Age States of Plants of Various Growth Forms: A Review”. Journal of Ecology 68 (2): 21.
13. Question 13
Yes
1
Medium
Vandelook et al. (2009) reported that more than 80% of Aegopodium podagraria seeds sampled (n = 120) had viable embryos. In the same study in Belgium, researchers recorded greater than 82% emergence after seeds had overwintered under natural conditions. In Hokkaido, Japan, Phartyal et al. (2009) planted seeds (n = 100) of A. podagraria in an open framehouse in August, 2007. After seeds overwintered under snow cover, cotyledon emergence began the first week of April, 2008, and by April 30th researchers had recorded greater than 97% emergence.
However, according to Roland and Smith (1969, cited in Waggy 2010) the variegated form of A. podagraria rarely produces seeds, and Gatsuk et al. (1980), stated that populations in shaded environments may seldom produce seeds at all, relying on vegetative growth as the primary reproductive strategy.
However, according to Roland and Smith (1969, cited in Waggy 2010) the variegated form of A. podagraria rarely produces seeds, and Gatsuk et al. (1980), stated that populations in shaded environments may seldom produce seeds at all, relying on vegetative growth as the primary reproductive strategy.
Gatsuk, L, O Smirnova, and L Vorontzova. 1980. “Age States of Plants of Various Growth Forms: A Review”. Journal of Ecology 68 (2): 21.
Phartyal, Shyam, Jerry Baskin, Carol Baskin, and Tetsuya Kondo. 2009. “Temperature Requirements Differ for the Two Stages of Seed Dormancy Break in Aegopodium Podagraria (Apiaceae), a Species With Deep Complex Morphophysiological Dormancy”. American Journal of Botany 96: 1086–1095.
Vandelook, Filip, Nele Bolle, and Jozef A. Van Assche. 2009. “Morphological and Physiological Dormancy in Seeds of Aegopodium Podagraria (Apiaceae) Broken Successively During Cold Stratification”. Seed Science Research 19: 115. doi:10.1017/S0960258509301075.
Waggy, Melissa A. 2010. “Aegopodium Podagraria. In: Fire Effects Information System”. US Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. https://www.fs.fed.us/database/feis/plants/forb/aegpod/all.html.
Roland, A.E, and E. C Smith. 1969. The Flora of Nova Scotia. Halifax, NS, Canada: Nova Scotia Museum.
14. Question 14
No
0
Medium
Information about seed production in Aegopodium podagraria is limited and somewhat contradictory. In a review, Gatsuk et al. (1980) state that plants flower and bear fruit only in sunlit places, though the species flowers and fruits profusely in these conditions. Seed viability is not mentioned. Kendall (2021) states that the number of seeds produced per plant is unknown but is assumed to be low. Roland and Smith (1969, cited in Waggy 2010) state that the variegated form rarely produces seeds.
Kendall, C. 2021. “Goutweed (Aegopodium Podagraria): Best Management Practices in Ontario”. Peterborough, Ontario, Canada: Ontario Invasive Plant Council. https://www.ontarioinvasiveplants.ca/wp-content/uploads/2022/05/OIPC_BM….
Gatsuk, L, O Smirnova, and L Vorontzova. 1980. “Age States of Plants of Various Growth Forms: A Review”. Journal of Ecology 68 (2): 21.
Roland, A.E, and E. C Smith. 1969. The Flora of Nova Scotia. Halifax, NS, Canada: Nova Scotia Museum.
Waggy, Melissa A. 2010. “Aegopodium Podagraria. In: Fire Effects Information System”. US Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. https://www.fs.fed.us/database/feis/plants/forb/aegpod/all.html.
15. Question 15
Yes
1
Very High
Seeds of Aegopodium podagraria require chilling at around 0 degrees C (to initiate embryo growth) plus a second period of low temperatures (5 degrees C and above) to stimulate optimal germination (Vandelook et al. 2009, Phartyal et al. 2009). These conditions appear to be satisfied in temperate climates; for example:
• In Belgium, Vandelook et al. (2009) buried wild-collected seeds (n = 150) at 1 cm depth in an outdoor garden in Belgium in August, 2005. Seedling emergence began in mid-February, 2006, and continued until late April, by which time researchers had recorded greater than 82% emergence.
• In Hokkaido, Japan, Phartyal et al. (2009) planted seeds (n = 100) of A. podagraria in an open framehouse in August, 2007. After seeds overwintered under snow cover, cotyledon emergence began the first week of April, 2008, and by April 30th researchers had recorded greater than 97% emergence.
• In Belgium, Vandelook et al. (2009) buried wild-collected seeds (n = 150) at 1 cm depth in an outdoor garden in Belgium in August, 2005. Seedling emergence began in mid-February, 2006, and continued until late April, by which time researchers had recorded greater than 82% emergence.
• In Hokkaido, Japan, Phartyal et al. (2009) planted seeds (n = 100) of A. podagraria in an open framehouse in August, 2007. After seeds overwintered under snow cover, cotyledon emergence began the first week of April, 2008, and by April 30th researchers had recorded greater than 97% emergence.
Vandelook, Filip, Nele Bolle, and Jozef A. Van Assche. 2009. “Morphological and Physiological Dormancy in Seeds of Aegopodium Podagraria (Apiaceae) Broken Successively During Cold Stratification”. Seed Science Research 19: 115. doi:10.1017/S0960258509301075.
Phartyal, Shyam S., Tetsuya Kondo, Jerry M. Baskin, and Carol C. Baskin. 2009. “Temperature Requirements Differ for the Two Stages of Seed Dormancy Break in Aegopodium Podagraria (Apiaceae), a Species With Deep Complex Morphophysiological Dormancy”. American Journal of Botany 96: 1086–1095. doi:10.3732/ajb.0800379.
16. Question 16
No
0
Medium
Quantitative information regarding seed production in goutweed is limited. A review by Gatsuk et al. (1980) places the age of first seed production in Aegopodium podagraria at five to six years.
Gatsuk, L, O Smirnova, and L Vorontzova. 1980. “Age States of Plants of Various Growth Forms: A Review”. Journal of Ecology 68 (2): 21.
17. Question 17
No
0
Medium
Debia et al. (2025) state that A. podagraria flowers in June and July in Poland. In the province of Ontario, Canada, goutweed flowers from June to August and seed ripening occurs from mid-July to September (Kendall 2021). In Illinois the flowering period lasts“about 1 month” (Hilty 2020).
Kendall, C. 2021. “Goutweed (Aegopodium Podagraria): Best Management Practices in Ontario”. Peterborough, Ontario, Canada: Ontario Invasive Plant Council. https://www.ontarioinvasiveplants.ca/wp-content/uploads/2022/05/OIPC_BM….
Debia, K, M Dziecol, A Wroblewska, and K Janda-Milczarek. 2025. “Goutweed (Aegopodium Podagraria L.) - An Edible Weed With Health-Promoting Properties”. Molecules 30 (7): 23. https://pmc.ncbi.nlm.nih.gov/articles/PMC11990176/#sec6-molecules-30-01….
Hilty, J. 2020. “ Goutweed; Aegopodium Podagraria”. https://www.illinoiswildflowers.info/weeds/plants/goutweed.html .
18. Question 18
No
0
High
Sources are unanimous that planting, vegetative garden escapes, improper yard waste disposal, and other human activities, are by far the principal means of spread for Aegopodium podagraria (e.g., Kendall 2021, Lind 2011, Garske and Schimpf 2006). A. podagraria fruits are smooth, lacking hairs or other surface structures that would facilitate dispersal by animals (Go Botany, no date).
Kendall, C. 2021. “Goutweed (Aegopodium Podagraria): Best Management Practices in Ontario”. Peterborough, Ontario, Canada: Ontario Invasive Plant Council. https://www.ontarioinvasiveplants.ca/wp-content/uploads/2022/05/OIPC_BM….
Lind, S. 2011. “Aegopodium Podagraria L. Invasive Species Assessment”. Madison, WI: Wisconsin Department of Natural Resources. https://dnr.wisconsin.gov/sites/default/files/topic/Invasives/LR_Aegopo….
Garske, Steve, and David Schimpf. 2009. “PCA Alien Plant Working Group - Goutweed (Aegopodium Podgraria)”. Plant Conservation Alliance. https://www.nps.gov/plants/alien/fact/aepo1.htm.
Botany, Go. 2026. “Aegopodium Podagraria — Bishop’s Goutweed”. https://gobotany.nativeplanttrust.org/species/aegopodium/podagraria/.
19. Question 19
Yes
1
Low
Kendall (2021) states that the seeds may be dispersed short distances by wind or water and that rhizome fragments can be carried downstream via waterways, but does not specify how far this dispersal may reach or how frequently this might happen. No other sources suggested long-distance transport of propagules by wind or water.
Kendall, C. 2021. “Goutweed (Aegopodium Podagraria): Best Management Practices in Ontario”. Peterborough, Ontario, Canada: Ontario Invasive Plant Council. https://www.ontarioinvasiveplants.ca/wp-content/uploads/2022/05/OIPC_BM….
20. Question 20
No
0
High
Aegopodium podagraria’s principal means of dispersal are human activities, but not the particular vectors highlighted in this question. A. podagraria spreads via intentional planting and escapes vegetatively from gardens and cultivated areas. Rhizome fragments can spread to new areas via dumping of yard waste or in contaminated soil (Kendall 2021 Lind 2011, Garske and Schimpf 2006).
Garske, Steve, and David Schimpf. 2009. “PCA Alien Plant Working Group - Goutweed (Aegopodium Podgraria)”. Plant Conservation Alliance. https://www.nps.gov/plants/alien/fact/aepo1.htm.
Kendall, C. 2021. “Goutweed (Aegopodium Podagraria): Best Management Practices in Ontario”. Peterborough, Ontario, Canada: Ontario Invasive Plant Council. https://www.ontarioinvasiveplants.ca/wp-content/uploads/2022/05/OIPC_BM….
Lind, S. 2011. “Aegopodium Podagraria L. Invasive Species Assessment”. Madison, WI: Wisconsin Department of Natural Resources. https://dnr.wisconsin.gov/sites/default/files/topic/Invasives/LR_Aegopo….
Evaluation Notes
The majority of sources in this evaluation refer to the base species, Aegopodium podagraria rather than var. variegatum. Following PRE instructions for evaluating cultivars, confidence levels for many of the evaluation answers were entered as Medium. A. podagraria var. variegatum is an interesting case in that reversion to the non-variegated form is fairly common, suggesting that these confidence levels may be understated.
Total PRE Score
14
20
75
