Invasiveness Ranking System for Non-Native Plants of Alaska

Hesperis matronalis L.Ranking SummaryEcoregion known or expected to occur inSouth CoastalInterior BorealArctic AlpineYesYesNoPotential Max. ScoreEcological Impact 40 10Biological Characteristics and Dispersal 22 10Amplitude and Distribution 25 17Feasibility of Control 7 2Relative Maximum 41Climatic ComparisonCollected inAlaska regions?common names: sweet rocket, dames rocket,dame’s violet, mother-of-the-eveningCLIMEXsimilarity?South Coastal Yes –Interior Boreal Yes –Arctic Alpine No NoHesperis matronalis is cultivated and has naturalized in Juneau,Sitka, and Ketchikan (M. Shephard pers. com., Welsh 1974). It isgrowing in gardens in Anchorage and Homer (J. Riley pers. com.).It has also been recorded in Fort Wainwright Army Post (UAM2004).Ecological ImpactScoreImpact on Ecosystem Processes (0–10) 1Dames rocket may delay the establishment of native species onsites where it has formed stands (M. Shephard pers. com.)Impact on Natural Community Structure (0–10) 3Dames rocket causes a moderate increase in the density of themid-herbaceous layer, and in Ontario it has been recorded asdominating localized areas (CWS 2004).Impact on Natural Community Composition (0–10) 3Dames rocket likely competes with native species (WisconsinDNR 2003).Impact on Higher Trophic Levels (0–10) 3Dames rocket may alter pollinator behavior. Hawkmoths havebeen observed pollinating dames rocket in Alaska and may drawpollinators away from native species (M. Shephard pers. obs.). Itis an alternate host for number of viruses (Royer and Dickinson1999).Total for Ecological Impact 10/40Biological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 3Dames rocket reproduces entirely by seed. A single plant is capableof producing up to 20,000 seeds (Royer and Dickinson 1999).Long-distance dispersal (0–3) 2Dames rocket does not have particular adaptations to longdistancedispersal, but the large numbers of small seeds increasethe probability of a long-distance dispersal event.Spread by humans (0–3) 3Dames rocket is planted as an ornamental and quickly escapescultivation. This plant is often included as a part of “wildflower”seed mixes and is widely sold at nurseries (CWMA 2004,Wisconsin DNR 2003).Allelopathic (0–2) 0Dames rocket has no allelopathy potential (USDA 2002).Competitive Ability (0–3) 1Dames rocket likely competes with native species (WisconsinDNR 2003). It can outcompete grasses in open forest in Wisconsin(J. Riley pers. com.).B-46Thicket-forming/Smothering growth form (0–2) 0Dames rocket does not form dense thickets.Germination requirements (0–3)UIt is unknown if this species can germinate in establishedvegetation.Other invasive species in the genus (0–3) 0Other introduced species of Hesperis are not known in NorthAmerica (USDA 2002).Aquatic, wetland or riparian species (0–3) 1Dames rocket tends to invade riparian and wetland habitats as wellas moist and mesic woodlands (CWMA 2004). It also grows alongroadsides, fence lines, and in open areas (Wisconsin DNR 2003).Total for Biological Characteristics and Dispersal 10/22Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 4Dame’s rocket is widely planted as an ornamental. It is oftenincluded in “wildflower” seed mixes (Wisconsin DNR 2003).Known level of impact in natural areas (0–6) 3Dames rocket invades forests and prairies in Wisconsin competingwith native species (J. Riley pers. com., Wisconsin DNR 2003). Ittends to invade riparian and wetland habitat throughout Colorado(CWMA 2004).Role of anthropogenic and natural disturbance in2establishment (0–5)Dames rocket often establishes on anthropogenic disturbancesand can be maintained in previously disturbed forest remnants(M. Shephard pers. com.).Current global distribution (0–5) 3Dames rocket is native to Middle and Southern Europe andtemperate Asia. It is now introduced to the northern portion ofNorth America (USDA, ARS 2004).Extent of the species U.S. range and/or occurrence offormal state or provincial listing (0–5)Dames rocket is now found throughout Canada and the UnitedStates, except for the southern states (USDA 2002). The species isdeclared noxious in Colorado (Invaders Database System 2003,USDA 2002). It is considered a weed in Manitoba and Tennessee(Royer and Dickinson 1999).Total for Ecological Amplitude and Distribution 17/25Feasibility of ControlScoreSeed banks (0–3)USeeds of dames rocket can remain viable in the soil for severalyears (Wisconsin DNR 2003), but it is unknown if viability isretained 5 years or more.Vegetative regeneration (0–3) 0This plant has no ability to resprout (USDA 2002).Level of effort required (0–4) 2Pulling is required for several years to remove new plantsestablished from the seed bank. Seeds are likely to mature ifthe fruits have begun developing at the time the plant is pulled,putting plants in a bag or burning them will prevent further seeddispersal. Burning and herbicides treatment has been found to bean effective control method (Wisconsin DNR 2003).Total for Feasibility of Control 2/7Total score for 4 sections 39/94§5