Pacific Island Ecosystems at Risk (PIER)
RISK ASSESSMENT RESULTS: High risk, score: 24
|
Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i. Information on Risk Assessments Original risk assessment |
| Cortaderia selloana (Common name- pampas grass, silwegras) Synonyms: Arundo selloana, Cortaderia argentea, Gynerium argenteum | Answer | Score | |
| 1.01 | Is the species highly domesticated? | n | 0 |
| 1.02 | Has the species become naturalized where grown? | y | |
| 1.03 | Does the species have weedy races? | n | |
| 2.01 | Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical” | 2 | |
| 2.02 | Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2 | 2 | |
| 2.03 | Broad climate suitability (environmental versatility) | y | 1 |
| 2.04 | Native or naturalized in regions with tropical or subtropical climates | y | 1 |
| 2.05 | Does the species have a history of repeated introductions outside its natural range? y=-2 | y | |
| 3.01 | Naturalized beyond native range y = 1*multiplier (see Append 2) , n= question 2.05 | y | 2 |
| 3.02 | Garden/amenity/disturbance weed y = 1*multiplier (see Append 2) | ||
| 3.03 | Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2) | y | 4 |
| 3.04 | Environmental weed y = 2*multiplier (see Append 2) | y | 4 |
| 3.05 | Congeneric weed y = 1*multiplier (see Append 2) | y | 2 |
| 4.01 | Produces spines, thorns or burrs | y | 1 |
| 4.02 | Allelopathic | n | 0 |
| 4.03 | Parasitic | n | 0 |
| 4.04 | Unpalatable to grazing animals | n | -1 |
| 4.05 | Toxic to animals | n | 0 |
| 4.06 | Host for recognized pests and pathogens | n | 0 |
| 4.07 | Causes allergies or is otherwise toxic to humans | n | 0 |
| 4.08 | Creates a fire hazard in natural ecosystems | y | 1 |
| 4.09 | Is a shade tolerant plant at some stage of its life cycle | y | 1 |
| 4.1 | Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island) | y | 1 |
| 4.11 | Climbing or smothering growth habit | n | 0 |
| 4.12 | Forms dense thickets | y | 1 |
| 5.01 | Aquatic | n | 0 |
| 5.02 | Grass | y | 1 |
| 5.03 | Nitrogen fixing woody plant | n | 0 |
| 5.04 | Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers) | n | 0 |
| 6.01 | Evidence of substantial reproductive failure in native habitat | n | 0 |
| 6.02 | Produces viable seed. | y | 1 |
| 6.03 | Hybridizes naturally | ||
| 6.04 | Self-compatible or apomictic | n | -1 |
| 6.05 | Requires specialist pollinators | n | 0 |
| 6.06 | Reproduction by vegetative fragmentation | y | 1 |
| 6.07 | Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1 | 1 | 1 |
| 7.01 | Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas) | y | 1 |
| 7.02 | Propagules dispersed intentionally by people | y | 1 |
| 7.03 | Propagules likely to disperse as a produce contaminant | y | 1 |
| 7.04 | Propagules adapted to wind dispersal | y | 1 |
| 7.05 | Propagules water dispersed | n | -1 |
| 7.06 | Propagules bird dispersed | n | -1 |
| 7.07 | Propagules dispersed by other animals (externally) | Y | 1 |
| 7.08 | Propagules survive passage through the gut | n | -1 |
| 8.01 | Prolific seed production (>1000/m2) | y | 1 |
| 8.02 | Evidence that a persistent propagule bank is formed (>1 yr) | ||
| 8.03 | Well controlled by herbicides | y | -1 |
| 8.04 | Tolerates, or benefits from, mutilation, cultivation, or fire | y | 1 |
| 8.05 | Effective natural enemies present locally (e.g. introduced biocontrol agents) | ||
| Total score: | 24 |
Supporting data:
| Notes | Reference | |
| 1.01 | No evidence | |
| 1.02 | "naturalized in British Isles, s. Europe, s. Africa, Australia, New Zealand, w. United States, & Canary Islands." | http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl |
| 1.03 | "Many varieties of pampas grass are available for use in the landscape. There are dwarf varieties (C. selloana 'Pumila') that are perfect for smaller spaces. Others have pastel colored flowers, while others provide an assortment of leaf variegations ('Silver Stripe', 'Gold Band') ." [No evidence that the varieties have characteristics that make them more weedy]. | http://www.floridata.com/ref/c/cort_sel.cfm |
| 2.01 | Native: SOUTHERN AMERICA- Brazil: Brazil, Southern South America: Argentina; Chile; Paraguay; Uruguay." | http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl |
| 2.02 | "naturalized in British Isles, s. Europe, s. Africa, Australia, New Zealand, w. United States, & Canary Islands." | http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl |
| 2.03 |
(1) "An amazing feature about Pampas Grass is that it can live in almost any
habitat. This amazing grass can grow in hard, rocky areas, flooded areas,
dry and damp ground plus its normal habitat. The leaves die during frosts in
northern climates, but grow back in the spring. The habitat it flourishes in
is a damp, warm environment like that of the South American Pampas."
(2) Hardiness: USDA Zone 7a: to -17.7° C (0° F) USDA Zone 7b: to -14.9° C (5° F) USDA Zone 8a: to -12.2° C (10° F) USDA Zone 8b: to -9.4° C (15° F) USDA Zone 9a: to -6.6° C (20° F) USDA Zone 9b: to -3.8° C (25° F) USDA Zone 10a: to -1.1°C (30° F) USDA Zone 10b: to 1.7° C (35° F) |
(1) http://www.blueplanetbiomes.org/pampas_grass.htm (2) http://davesgarden.com/guides/pf/go/1291/ |
| 2.04 | Native: SOUTHERN AMERICA- Brazil: Brazil, Southern South America: Argentina; Chile; Paraguay; Uruguay." | http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl |
| 2.05 | "naturalized in British Isles, s. Europe, s. Africa, Australia, New Zealand, w. United States, & Canary Islands." | http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl |
| 3.01 | "naturalized in British Isles, s. Europe, s. Africa, Australia, New Zealand, w. United States, & Canary Islands." | http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl |
| 3.02 | "It can be found in a variety of habitats from subtropical regions to disturbed areas along roads, and trails. It forms dense stands that can exlude other plants, and its sharp leaves can cut skin and limit recreational use." | http://www.issg.org/database/species/ecology.asp?si=373&fr=1&sts=sss |
| 3.03 | " Although the more aggressive Cortaderia jubata is often called pampas grass, true pampas grass (C. selloana) can also be weedy in California. In other areas of the world, particularly New Zealand and Australia, C. selloana is an important weed problem in forestry operations and conservation areas (Gadgil et al. 1984, Harradine 1991) . In forests it competes with seedling trees and can slow their establishment and growth." | http://ucce.ucdavis.edu/datastore/detailreport.cfm?usernumber=35&surveynumber=182 |
| 3.04 |
(1) "This plant is considered invasive by the authoritative sources noted
below. This plant may be known by one or more common names in different
places, and some are listed above. Click on an acronym to view each invasive
plant list, or click here for a composite list of Invasive Plants of the
U.S. CalEPPC California Exotic Pest Plant Council. 1999. Exotic Plant Pest List(http://www.cal-ipc.org/1999_cal-ipc_list/, October 19, 1999) . California Exotic Pest Plant Council. California. HEAR USDI, Geological Survey. 1999. Information Index for Selected Alien Plants in Hawaii(http://www.hear.org, October 20, 1999) . Hawaiian Ecosystems at Risk Project, Biological Resources Division, Haleakala Field Station. Makawao, Hawaii." (2) "In conservation areas pampas grass competes with native vegetation, reduces the aesthetic and recreational value of these areas, and also increases the fire potential." (3) "A problem species in Australia and New Zealand. On New Zealand noxious weed list and banned from sale in that country." (4) "General impacts - C. selloana can form dense stands that exclude other plants. Its sharp leaves cut skin and can limit recreational use of areas, and it can form dense colonies that can become or increase fire hazards (May et al., UNDATED) . Once seedlings become established, it is a substantial threat to the ecological quality of preserves, particularly in coastal and grassland sites due to competition with native plants. Its rapid growth and accumulation of above ground and below ground biomass allow it to acquire light, moisture, and nutrients that would be used by other plants. It can be damaging even at low densities because of the amount of cover it can occupy (Starr et al. 2003) ." (5) "In South Africa, C. jubata and C. selloana are considered category 1 restricted plants according to the Conservation of Agricultural Resources Act, 1983 (Stellenbosch 2003) . Category 1 plants may not occur on any land or inland water surface other than in biological control reserves. Land users are required to control any of these category 1 plants that occur on any land or inland water surface (Stellenbosch 2003) ." |
(1) http://plants.usda.gov/java/profile?symbol=COSE4 (2) http://ucce.ucdavis.edu/datastore/detailreport.cfm?usernumber=35&surveynumber=182 (3) http://www.hear.org/pier/species/cortaderia_selloana.htm (4) http://scholar.google.com/scholar?hl=en&q=%22Cortaderia+selloana%22&spell=1 (5) http://www.hear.org/starr/hiplants/reports/html/cortaderia_spp.htm |
| 3.05 | Cortaderia jubata - (1) "In Hawai‘i naturalized in dry to wet zones, from 2000 ft to 7,000 ft. Forms dense monotypic stands in mesic to humid areas with the potential to replace or compete with native species." "A problem species in New Zealand (declared noxious weed) . On Hawai‘i noxious weed list." (2) "It is an aggressive colonizer that competes with native vegetation. It can displace native coastal dune, shrub, and estuarine vegetation, and it slows early forest re-growth on logged lands. ... Andean Pampas/Jubata grass is a threat to the integrity of coastal dune, shrub and estuarine ecosystems." (3) "Jubatagrass is one of the most invasive nonnative species along sensitive natural coastal sites of California." (4) It is on the 'State Noxious weed list' of 46 states in the U.S. | (1) http://www.hear.org/pier/species/cortaderia_jubata.htm (2) http://www.nps.gov/archive/redw/pampas.htm (3) Drewitz, Jennifer J.; DiTomaso, Joseph M. Seed biology of jubatagrass (Cortaderia jubata) Weed Science 52 (4) : 525-530 July 2004 (4) http://plants.usda.gov/java/profile?symbol=COJU2 |
| 4.01 | (1) "Danger: Plant has spines or sharp edges; use extreme caution when handling." (2) " It forms dense stands that can exlude other plants, and its sharp leaves can cut skin and limit recreational use." | (1) http://davesgarden.com/pf/go/1291/ (2) http://www.issg.org/database/species/ecology.asp?si=373&fr=1&sts=sss |
| 4.02 | Not allelopathic | http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=COSE4 |
| 4.03 | No evidence | |
| 4.04 | Low browse and graze palatibility. | http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=COSE4 |
| 4.05 | Toxicity - none. | http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=COSE4 |
| 4.06 | This speceis lists 23 fungi species to be associated with C.selloana. [No evidence of economic pests being associated with C. selloana]. | https://nt.ars-grin.gov/fungaldatabases/index.cfm |
| 4.07 | Toxicity - none. | http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=COSE4 |
| 4.08 | "Pampas grass creates a fire hazard with excessive build-up of dry leaves, leaf bases, and flowering stalks. In addition, heavy infestations can block access to plantations and pose a significant fire hazard." | http://ucce.ucdavis.edu/datastore/detailreport.cfm?usernumber=35&surveynumber=182 |
| 4.09 | (1) "Light: Give pampas grass full sun. Will also grow in light shade." (2) "It cannot grow in the shade." | (1) http://www.floridata.com/ref/c/cort_sel.cfm (2) http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Cortaderia+selloana |
| 4.1 | "Pampas is capable of becoming established on a wide variety of soil types. Deep soil with good drainage gives best growth results." | http://www.issg.org/database/species/ecology.asp?si=373&fr=1&sts=sss |
| 4.11 | No evidence | |
| 4.12 | " It forms dense stands that can exlude other plants, and its sharp leaves can cut skin and limit recreational use." | http://www.issg.org/database/species/ecology.asp?si=373&fr=1&sts=sss |
| 5.01 | ||
| 5.02 | Large clump forming pernnial grass. | Staples, W George and Derral H Herbst. 2005. A Tropical Garden Flora. Bishop Museum Press. Honolulu. Hawaii. Page 744. |
| 5.03 | Nitorgen fixation - none. | http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=COSE4 |
| 5.04 | ||
| 6.01 | "In its native range, in South America C. selloana grows in relatively damp soils and along river margins. C. selloana is found along streams and in the low wet areas of Argentina and southern Brazil." | http://www.invasivespecies.net/database/species/ecology.asp?si=373&fr=1&sts= |
| 6.02 | (1) "In nature it produces flowers two to three years after germination." (2) "The seed usually germinates in 2 - 3 weeks at 15°c. Keep the soil moist. The seed has a short viability[200]." | (1) http://ucce.ucdavis.edu/datastore/detailreport.cfm?usernumber=35&surveynumber=182 (2) http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Cortaderia+selloana |
| 6.03 | (1) "Abstract: Interspecific hybrids between New Zealand decaploid species of Cortaderia (sect. Bifida) are fertile and share a common gene(s) for control of male sterility, the determinant of their gynodioecious breeding system. The interspecific hybrid between the 2 sexually reproducing species of sect. Cortaderia is F1 fertile, but shows some slight degeneration in later generations especially through lethal albinism. They share a common gene(s) for male sterility control. Experimental intersectional hybrids are nonoploid and sterile. F1 C. araucana .times. C. toetoe consisted of a family of solely female plants with the androecial morphology of the female parent. Such hybrids share the 2 main characteristics of the several apomictic taxa in sect. Cortaderia; intersection hybridization is a possible pathway towards the evolution of solely female taxa. F1 C. toetoe .times. C. selloana segregated plants of both sex-forms. Different male sterility genes, or alleles, occur in the 2 sections and ratios of hermaphrodite to female plants are intersectionally discrete." (2) "Abstract: Species [8] 6 hybrids and 4 backcrosses of Cortaderia [C. araucana, C. jubata, C. rudiuscula, C. selloana, C. fulvida, C. richardii, C. splendens, C. toetoe C. araucana-X-C. selloana, C. richardii -X-C. fulvida, C. richardii-X-C. toetoe, C. richardii-X-C. splendens, C. splendens X-C. toetoe and C. araucana-X- C. toetoe] were investigated for cyanogenesis. Samples of 2 spp., 4 hybrids and 1 backcross were acyanogenic even if emulsin was added. All other samples contained a single cyanogenic glucoside which was identified with triglochinin. Results are discussed in a taxonomic context." [No evidence regarding natural hybrids]. |
(1) CONNOR H E CORTADERIA GRAMINEAE INTERSPECIFIC HYBRIDS AND THE BREEDING
SYSTEMS Heredity 51 (PART 1) : 395-404 1983 (2) TJON SIE FAT L CONTRIBUTION TO THE KNOWLEDGE OF CYANOGENESIS IN ANGIOSPERMS PART 11 CYANOGENESIS IN SOME GRASSES PART 4 THE GENUS CORTADERIA Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen Series C Biological and Medical Sciences 82 (2) : 165-170 1979 |
| 6.04 | (1) "The flowers are dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown if seed is required) and are pollinated by Wind. The plant not is self-fertile." (2) "Apomixis does not seem to occur in this species. Parts of an inflorescence covered by a cheesecloth bag at the time of ovule development failed to produce seeds." | http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Cortaderia+selloana |
| 6.05 | "The flowers are dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown if seed is required) and are pollinated by Wind. The plant not is self-fertile." | http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Cortaderia+selloana |
| 6.06 | "Pampas grass has escaped cultivation in many coastal areas in California, presumably by fragmentation of the parent plant or, to a limited extent, by seed. … Vegetative reproduction can occur when fragmented tillers receive adequate moisture and develop adventitious roots at the base of the shoot." | http://ucce.ucdavis.edu/datastore/detailreport.cfm?usernumber=35&surveynumber=182 |
| 6.07 | "C. selloana is a perennial tussock. Flowering begins in late summer - early autumn and are capable of flowering in the first season from seed." | http://www.issg.org/database/species/ecology.asp?si=373&fr=1&sts=sss |
| 7.01 | "Also the great quantity of fluffy seed has caused problems for kiwifruit growers since it clings to the fruit and causes it to be rejected for exprot." [Probably yes the fluffy seeds can stick]. | http://www.issg.org/database/species/ecology.asp?si=373&fr=1&sts=sss |
| 7.02 | "Pampas Grass is used in many ways. A common use is as a hedge because of the razor sharp leaves and stiff stems. It is used mainly as a decoration. Pampas Grass makes a nice ornamental plant because of its large plume-like flowers." | http://www.blueplanetbiomes.org/pampas_grass.htm |
| 7.03 | (1) "Also the great quantity of fluffy seed has caused problems for kiwifruit growers since it clings to the fruit and causes it to be rejected for exprot." (2) "Dried plumes, dyed flamboyant colors and often sprinkled with glitter, can be purchased at better discount and souvenir stores throughout the country - especially in areas frequented by tourists." | (1) http://www.issg.org/database/species/ecology.asp?si=373&fr=1&sts=sss (2) http://www.floridata.com/ref/c/cort_sel.cfm |
| 7.04 | (1) "Propagation: Seed, wind-dispersed." (2) "Self-propelled (local) : C. selloana reproduces by seed and is wind dispersed. … C. selloana reproduces by seed. Seeds are primarily wind-dispersed and are capable of dispersal distances up to 20 miles (Starr et al. 2003) . C.selloana is gynodioecius but behaves dioeciously in nature (Knowles and Ecroyd, 1985) . Female seeds have long fine hairs on the lemma making it ideal for wind dispersal. Hermaphrodite seeds don't have these hairs (McGlone MSc thesis, 2003) ." | (1) http://www.hear.org/pier/species/cortaderia_selloana.htm (2) http://www.issg.org/database/species/ecology.asp?si=373&fr=1&sts=sss |
| 7.05 | No evidence | |
| 7.06 | No evidence | |
| 7.07 | "Also the great quantity of fluffy seed has caused problems for kiwifruit growers since it clings to the fruit and causes it to be rejected for exprot." [If seeds can stick to kiwi fruit then they could probably stick to the coat of animals]. | http://www.issg.org/database/species/ecology.asp?si=373&fr=1&sts=sss |
| 7.08 | No evidence | |
| 8.01 | (1) "Female plants are capable of producing up to 100 000 seeds per flowerhead (Ecroyd et al. 1984) ." (2) "Each plant can produce about a million wind-dispersed viable seeds (Connor and Edgar, 1974 and Lambrinos, 2002) ." | (1) http://www.issg.org/database/species/ecology.asp?si=373&fr=1&sts=sss (2) http://scholar.google.com/scholar?hl=en&q=%22Cortaderia+selloana%22&spell=1 |
| 8.02 | (1) "Little is known of the germination of Cortaderia selloana from seed." (2) "The seed usually germinates in 2 - 3 weeks at 15°c. Keep the soil moist. The seed has a short viability." | (1) http://ucce.ucdavis.edu/datastore/detailreport.cfm?usernumber=35&surveynumber=182 (2) http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Cortaderia+selloana |
| 8.03 | "Control of pampas grass can be achieved by spot treatment with a post-emergence application of glyphosate at about 2 percent solution or eight qts/100 gal. The addition of a non-ionic or silicone-based surfactant may enhance foliar penetration of the herbicide. For most effective control, plants should be sprayed to wet, but not to the point of herbicide runoff. In one study, over 90 percent control was obtained during the first season, but continued spot applications were necessary to prevent rapid reestablishment (Madison 1992) ." | http://ucce.ucdavis.edu/datastore/detailreport.cfm?usernumber=35&surveynumber=182 |
| 8.04 | (1) Burning does not provide long-term control, as plants resprout shortly thereafter. | (1) http://ucce.ucdavis.edu/datastore/detailreport.cfm?usernumber=35&surveynumber=182 |
| 8.05 | "Biological control: No information was found on biocontrol for Cortaderia. Sugar caneand ranching both cultivate grasses and would likely be hesitant to release a biologicalcontrol for Poaceae in Hawai'i. Unlike New Zealand, Hawai'i has no native Cortaderia." |
http://66.102.7.104/search?q=cache:INmMFaZ40e0J: www.hear.org/pier/pdf/pohreports/cortaderia_spp.pdf+%22Cortaderia+selloana %22+biocontrol&hl=en&gl=us&ct=clnk&cd=2 |
Need more info? Have questions? Comments? Information to contribute? Contact PIER!
[ Return to PIER homepage ] [Risk assessment page]
This page was created on 26 December 2006 by JS, and was last updated on 30 June 2017 by PT.