Noteworthy collections, California (Alternanthera philoxeroides)

Authors: WALDEN, GENEVIEVE - California Department Of Water Resources; SKURKA DARIN, GINA - California Department Of Water Resources; Grewell, Brenda; KRATVILLE, DAVID - California Department Of Food And Agriculture; MAULDIN, JARED - Department Of Fish And Wildlife; O'BRIAN, JON - California Department Of Parks And Recreation; O'REAR, TEEJAY - University Of California, Davis; OUGZIN, AICHA - Department Of Fish And Wildlife; VAN SUSTEREN, JANE - California Department Of Water Resources; WOODS, PATRICK - California Department Of Food And Agriculture

Submitted to: Madrono
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/4/2019
Publication Date: 6/5/2019
Citation: Walden, G., Skurka Darin, G., Grewell, B.J., Kratville, D., Mauldin, J., O'Brian, J., O'Rear, T., Ougzin, A., Van Susteren, J., Woods, P. 2019. Noteworthy collections, California (Alternanthera philoxeroides). Madrono. 66(1):4-7. https://doi.org/10.3120/0024-9637-66.1.4.
DOI: https://doi.org/10.3120/0024-9637-66.1.4

Interpretive Summary: Alternanthera philoxeroides (common name alligator weed; basionym Bucholzia philoxeroides Mart., synonyms Achyranthes philoxeroides [Mart.] Standley, Telanthera philoxeroides [Mart.] Moq.) is native to South America, invasive, and a noxious weed worldwide (EPPO 2016; Bartlett 2018). In North America, Alternanthera philoxeroides occurs in México (Mora-Olivo and Sánchez-del Pino 2014) and the United States (Clemants 2004; USGS 2019). In the USA, Alternanthera philoxeroides is reported from Alabama, Arkansas, California, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana, Maryland, Mississippi North Carolina, Oklahoma, Puerto Rico, South Carolina, Tennessee, Texas, and Virginia. Alternanthera philoxeroides is a perennial macrophyte, stoloniferous, mat-forming, vegetatively reproducing from rooting at nodes, and can spread rapidly by hydrochorous dispersal of plant fragments (Keffer 1982; CDFA Encycloweedia 2019). This article reports the first known records and specimen collections of in northern California, occurring as a naturalized noxious weed in the Sacramento-San Joaquin Delta, Suisun Marsh, and its tributaries. These are first specimens of Alternanthera philoxeroides established in wildlands for Contra Costa, Sacramento, San Joaquin, Solano, and Yolo counties. In total, these finds document a range expansion greater than predicted for California in a published risk assessment. Limits for Alternanthera philoxeroides in the Sacramento, American, and San Joaquin rivers of California are not yet known. Heightened awareness is needed for early detection in the Sacramento-San Joaquin Delta, Suisun Marsh, and its tributaries, and in irrigated and flood crops of the Great Central Valley. Re-evaluation of datasets and models for predicting invasion distributions for Alternanthera philoxeroides is needed, especially for pest risk assessments and introductions of biocontrol organisms into California.

Technical Abstract: Alternanthera philoxeroides (common name alligator weed; basionym Bucholzia philoxeroides Mart., synonyms Achyranthes philoxeroides [Mart.] Standley, Telanthera philoxeroides [Mart.] Moq.) is native to South America, invasive, and a noxious weed worldwide (EPPO 2016; Bartlett 2018). In North America, Alternanthera philoxeroides occurs in México (Mora-Olivo and Sánchez-del Pino 2014) and the United States (Clemants 2004; USGS 2019). In the USA, Alternanthera philoxeroides is reported from Alabama, Arkansas, California, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana, Maryland, Mississippi North Carolina, Oklahoma, Puerto Rico, South Carolina, Tennessee, Texas, and Virginia. Alternanthera philoxeroides is a perennial macrophyte, stoloniferous, mat-forming, vegetatively reproducing from rooting at nodes, and can spread rapidly by hydrochorous dispersal of plant fragments (Keffer 1982; CDFA Encycloweedia 2019). This article reports the first known records and specimen collections of in northern California, occurring as a naturalized noxious weed in the Sacramento-San Joaquin Delta, Suisun Marsh, and its tributaries. These are first specimens of Alternanthera philoxeroides established in wildlands for Contra Costa, Sacramento, San Joaquin, Solano, and Yolo counties. In total, these finds document a range expansion greater than predicted for California in a published risk assessment. Limits for Alternanthera philoxeroides in the Sacramento, American, and San Joaquin rivers of California are not yet known. Heightened awareness is needed for early detection in the Sacramento-San Joaquin Delta, Suisun Marsh, and its tributaries, and in irrigated and flood crops of the Great Central Valley. Re-evaluation of datasets and models for predicting invasion distributions for Alternanthera philoxeroides is needed, especially for pest risk assessments and introductions of biocontrol organisms into California.