Switch to text mode
Republic of the Marshall Islands Biodiversity Clearing House Mechanism
RMI Office of Environmental Planning and Policy Coordination (OEPPC)

banner of the RMI biodiversity CHM website
rounded cornerrounded corner RMI flag
RMI State Emblem
pixel element pixel element
rounded corner rounded corner
pixel element
Invasions of plants

The term "invasive species" has recently come into popular use in preference to "weed." A weed usually means a plant that is unwanted in an agricultural area or a garden. However, an "invasive species" much more accurately describes the problems associated with a plant that has been brought in from other places and tends to aggressively invade areas, competing with native species, taking over habitats, even destroying ecosystems.

A clear example of this which recently came to the fore is that of cobbler's pegs, shepherd's needles or beggar's ticks (Bidens pilosa) on Majuro. When in blossom, this plant has rather attractive, although small, daisy-like white and yellow flowers. The young leaf-tips can even be used as a vegetable, and in some parts of the world, it serves as a poor substitute for spinach after it is boiled for a while. But when those pretty flowers mature, they form little dark-brown pompons of narrow seeds with tiny hooks on the end which readily attach to clothing, shoes, animals fur or just about anything they can get a hold of. This provides an easy means of spreading this species from one place to another... to another... and another.

So it is that from its native Central America, B. pilosa has expanded its range to much of the world, including the Marshall Islands. It does exceptionally well in freshly cleared areas as it likes lots of sunshine and doesn't require much water or even a lot of nutrients in the soil.

It's bad enough to have such a pestiferous species "sneak" into an area as B. pilosa tends to do, but the trouble is further aggravated once such invasive species are established. Then, after people are used to having them around, conditions can change, and these unwanted species can really take over.

B. pilosa has been in the Marshalls since at least the early 1980's when it was reported to have been already introduced into Enewetak. However, when a survey of Pacific Islands' weeds was published in 1997, it listed this species as a major weed on some Pacific Islands, yet not even as a minor weed in the Marshalls. Then Typhoon Paka hit and there was an extended drought. Around Majuro Atoll, other plants suffered during this time, but B. pilosa went to town - and out of town. Everywhere, from Rita to Laura, and all along the road between, even on the more isolated northern islets, in almost every field or clearing, there could be found very healthy looking B. pilosa. Even hardy native plants, such as the beach sunflower or "markubwebwe" (Wollanstonia biflora) was overrun by this aggressive import.

Once an invasive species like this becomes so well established on an atoll, it is virtually impossible to get rid of. The thin limestone soil makes the use of herbicides risky since these poisons can easily seep down into the valuable water lens. Often, though, the most that can be hoped for is to prevent further spreading. If people are aware of the potential problems associated with invasive species, they may be able to help prevent the spread of seeds into new areas. This is easier said than done with "hitchhiking" style seeds, like those of B. pilosa, which seem to jump out and snag onto clothing and then are indiscriminately tossed about afterwards.

back to top

menu itemAdvanced search
menu itemHome
menu itemNews
expandible menu itemOverview of local biodiversity
expandible menu itemNational implementation
expandible menu itemNational Initiatives
expandible menu itemPublications
expanded menu itemThreats to Biodiversity
menu itemIntroduction
menu itemInvasive species
menu itemCase 1: snails...
you are hereCase 2: invasions of plants
menu itemCase 3: ants - environmental disasters
menu itemChanges in population and lifestyle
menu itemCase: albatrosses and man
menu itemNuclear testing and the biota
menu itemCase: radiation and the biota
menu itemClimate change
expandible menu itemRMI natural resources database
expandible menu itemMisc. datasets and maps
expandible menu itemPartners and links
menu itemContacts
menu itemFeedback
menu itemCopyright
menu itemAccessibility
menu itemDisclaimer
menu itemPrivacy

What's new

rss feed RSS

03 Nov 2008
New publications available check it!

Read more show more

28 Oct 2008
List of legislative documents has been updated check it!

Read more show more

29 Jul 2008
New feature - RSS feed check it!

Read more show more

31 Mar 2008
Featuring new section - videostreams check it!

Read more show more

rss feed RSS

pixel element
rounded cornerrounded corner
pixel elementpixel element
bulletHOME bullet NEWSbullet OVERVIEW OF LOCAL BIODIVERSITY bullet NATIONAL IMPLEMENTATION bullet NATIONAL INITIATIVES bullet PUBLICATIONS bullet THREATS TO BIODIVERSITY:[ Introduction ::: Invasive species ::: Case 1: snails... ::: you are hereCase 2: invasions of plants ::: Case 3: ants - environmental disasters ::: Changes in population and lifestyle ::: Case: albatrosses and man ::: Nuclear testing and the biota ::: Case: radiation and the biota ::: Climate change ] bullet RMI NATURAL RESOURCES DATABASE bullet MISC. DATASETS AND MAPSbullet PARTNERS AND LINKS bullet CONTACTS bullet FEEDBACK bullet COPYRIGHT bullet ACCESSIBILITY bullet DISCLAIMER bullet PRIVACY bullet
pixel element
GEF logo and link
pixel element
©RMI Office of Environmental Planning and Policy Coordination (OEPPC)      Last update: 2 October 2008 
pixel element
Documents.rdf.xml | Multimedia.rdf.xml
pixel element
Design & programming by ekoinf.net