Date of this Version
The Prairie Naturalist 49:19–22; 2017
Portions of the United States are becoming increasingly dominated by annual species, with cheatgrass (Bromus tectorum L.) and medusahead (Taeniatherum caput-medusae [L.] Nevski) as the most common and well-known invaders (Bansal et al. 2014). Other invasive annual species also are present and increasing in abundance, including ventenata (Ventenata dubia [Leers] Coss.), an invasive annual grass that has been expanding within the Pacific Northwest, Great Basin, and Great Plains regions of the United States. Ventenata was first reported in North America in 1952 in Washington (Old and Callihan 1987) and has since spread to 7 western states in the USA (CA, OR, ID, WY, WA, UT, MT) as well as portions of western Canada (US Department of Agriculture 2016). It is only listed as noxious in the state of Washington (National Weed Control Board 2016). Because it is a relatively new invader to these states, only basic life-history traits of this species are documented (Wallace et al. 2015). Ventenata is believed to originate from the Mediterranean portion of Europe and northern Africa (Scheinost et al. 2008). As a winter annual, this species mostly germinates in the fall when temperatures range from 8 to 28° C (Northam and Callihan 1986a, Wallace et al. 2015) with optimal germination on the higher end of temperatures, and a small portion of seed emerging in the spring (Wallace et al. 2015). Ventenata grows with slim, erect culms from 10 to 46 cm in height and typically produces about 15 to 35 seeds per plant (Scheinost et al. 2008).