Invasives Blog

In January and February 2016 the following datasheets were published on CABI’s Invasive Species Compendium (ISC). You can explore the open-access ISC here: www.cabi.org/isc.

1. Agropyron cristatum

A. cristatum is a resilient and long-lived perennial grass with stems that are 20-70 cm long and with finely-branched deep roots that extend to a depth of 1 m. It is able to grow in a wide range of habitats making it a very effective invader. Its native range is the Russian and Siberian steppes but it is now present in the North American prairies where it was planted in the 20th century to reseed abandoned cropland. It has since invaded vast areas of rangeland across the upper USA and southern Canada where it outcompetes native vegetation, altering soil chemical properties as a result.

2. Andropogon glomeratus

A. glomeratus is another invasive perennial grass, but is taller than A. cristatum, with stems that can be 1.5 m in height. It is a popular ornamental because of its bushy/tufted appearance and is consequently found outside of its native range of southeastern USA, Mexico and parts of Central Mexico and the Caribbean. Introduced to Hawaii, USA, where it is considered a noxious weed, it is outcompeting the small, native and endemic shrub Vaccinium reticulatum. A. glomeratus can also change fire regimes as it is highly flammable. This can promote invasion by other non-native species.

3. Atriplex semibaccata

A. semibaccata is a perennial shrub which can grow up to 80 cm tall and is drought and salt-tolerant. It is a valued fodder crop but it can form dense and fire retardant groundcover that displaces native species. In Hawaii, USA, it is impacting on a number of endangered plants such as Panicum niihauense, along with other invasive species. In California, USA, it is competing with Verbesina dissita which is endangered and restricted to the Laguna Beach area of Orange County.

4. Phleum pratense

P. pratense is a (yet another!) invasive perennial grass which can grow up to 1.5 m tall and spreads vigorously. It is an important forage grass, native to Europe and Asia, which can alter native plant communities by forming monocultures (vegetation consisting of the same species). Its seed is considered a contaminant of grass and other seed lots in the eastern US states of Delaware, Maryland, New Hampshire, New Jersey, Pennsylvania, Virginia and West Virginia, thus reducing seed lot quality and price. P. pratense is also a host to diseases, such as ergot (Claviceps purpurea), that are serious pathogens of cereal crops.

5. Rubus parviflorus

R. parviflorus is a deciduous, perennial raspberry species which produces edible fruits and can act as a soil stabiliser. Its fruits are eaten by the indigenous peoples of North America who also use parts of the plant to treat a wide variety of ailments such as stomach ache and diarrhoea. It is native to North America and Canada, however it has been recorded as invasive in British Columbia, Canada, due to the fact it can outcompete seedlings of economically important conifer species. It has also been recorded as invasive in parts of Europe.

1. Agropyron cristatum by Franz Xaver (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
2. Andropogon glomeratus by Homer Edward Price (Bushy-Bluestem  Uploaded by Amada44) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
3. Atriplex semibaccata by scott.zona (Flickr: Atriplex semibaccata) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
4. Phleum pratense by I, Hugo.arg [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or CC BY-SA 2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/2.5-2.0-1.0)], via Wikimedia Commons
5. Rubus parviflorus by Walter Siegmund (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons