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Non-Native Plant Species of Alaska Splitlip hempnettle (Galeopsis bifida Boenn.) Brittlestem hempnettle (Galeopsis tetrahit L.) Family: Lamiaceae Galeopsis bifida Synonyms: Galeopsis tetrahit var. bifida (Boenn.) Lej. & Court. Other common name: none G. tetrahit Synonyms: none Other common name: none Description Splitlip and brittlestem hempnettle are annual plants with erect, simple or branched stem from ½ to 3 feet tall. Leaves, 1 to 5 inches long, are short-stalked, opposite, ovate-lanceolate to lanceolate, and sparsely pubescent on both sides. The stem is usually swollen below leaf nodes. The flowers are terminal or borne in axillary clusters. They range in color from purple and pink to white, are ½ to ¾ inch long and bilaterally symmetrical with a split lower lip. Seeds are egg-shaped, mottled grayish brown (Hultén 1968). Splitlip hempnettle. Flowering stem. This taxon is distinguished from other Alaskan Lamiaceae by having a calyx of five nearly equal lobes, well developed bracteal leaves in flower axes, and rounded lobes of the lower corolla lip. Ecological Impact Impact on community composition, structure, and interactions: Hempnettle has been observed established in disturbed areas, creating a dense midforb layer and reducing the cover of graminoids and low forbs. Impact on ecosystem process: Hempnettle consumes soil moisture and limiting nutrients. It is likely to delay establishment of native species in disturbed sites. Biology and Invasive Potential Reproductive potential: Each plant is capable of producing up to 2,800 seeds (Royer and Dickinson 1999). The seeds can remain dormant in soil for several years. This species does not reproduce vegetatively. Role of disturbance in establishment: Both speices of hempnettle generally occur in disturbed sites. Potential for long-distance dispersal: The seeds are large and do not have any apparent adaptations for long-distance dispersal. Potential to be spread by human activity: Hempnettles appear to spread as a contaminant of hay or other agricultural products. Germination requirements: Germination occurs at ½ to 1½ inches depth. Growth requirements: Unknown. Listing: The species complex Galeopsis bifida and Galeopsis tetrahit is declared noxious in Alberta, Manitoba, and Quebec. It is a prohibited noxious weed seeds in Alaska (Alaska Administrative Code 1987, Rice 2006). Distribution and abundance Splitlip and brittlestem hempnettles are plants of disturbed sites, roadsides, gardens, and agricultural lands. Native and current distribution: Native to Europe and Asia, it is now found throughout Canada and northeastern quarter of the United States. It is introduced into New Zealand and Canary Islands (Hultén 1968, USDA 2002). Galeopsis bifida has been reported from all three of Alaska’s primary ecogeographical regions (University of Alaska Museum 2003). G. tetrahit is known from South-Coastal and Interior Boreal ecogeographic regions of Alaska (Weeds of Alaska Database. 2005). South Coastal Interior- Boreal Arctic-Alpine South Coastal Collection Site Interior- Boreal Arctic-Alpine Collection Site Distribution of brittlestem hempnettle in Alaska. Management Both species are difficult to control once it establishes. Therefore maintaining weed-free areas is of primary importance. Once established, dense cover crops planted early may inhibit hemp-nettle. Herbicides are also effective (Manitoba Agriculture, Food, and Rural Initiatives 2001). Distribution of splitlip hempnettle in Alaska. References: Alaska Administrative Code. Title 11, Chapter 34. 1987. Alaska Department of Natural Resources. Division of Agriculture. Hultén, E. 1968. Flora of Alaska and Neighboring Territories. Stanford University Press, Stanford, CA. 1008 p. Manitoba Agriculture, Food, and Rural Initiatives. 2001. On-Line Document. http://www.gov.mb.ca/agriculture/crops/wee ds/fab08s00.html Rice, P.M. 2006. INVADERS Database System (http://invader.dbs.umt.edu). Division of Biological Sciences, University of Montana, Missoula, MT 59812-4824. Royer, F. and R. Dickinson. 1999. Weeds of the Northern U.S. and Canada. The University of Alberta press. P. 248-249. University of Alaska Museum. University of Alaska Fairbanks. 2003. http://hispida.museum.uaf.edu:8080/home.cf m USDA (United States Department of Agriculture), NRCS (Natural Resource Conservation Service). 2002. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 708744490 USA. Weeds of Alaska Database. 2005. Database of exotic vegetation collected in Alaska. University of Alaska, Alaska Natural Heritage Program – US Forest Service – National Park Service Database. Available: http://akweeds.uaa.alaska.edu/ Alaska Natural Heritage Program Environment and Natural Resources Institute University of Alaska Anchorage 707 A Street, Anchorage, Alaska 99501 Phone (907) 257-2780 Fax (907) 257-2789 Last Updated November 29, 2006