Khaki Weed

Khaki Weed (Alternanthera Pungens)

Photo Kim and Forest Starr

Khaki Weed (Alternanthera pungens) is an invasive ground-creeping plant, native of South America, with oval leaves and numerous sharp burrs on each  mature plant. The plant goes by 'creeping chafweed' in some parts of the U.S. and by another Latin alias 'Telanthera pungens.'

Because of its sharp, stinging burrs and exceptional invasive nature, khaki weed poses a serious threat to the environment and culture in Hawaii.

The plant is exceptionally invasive because of (at least) two anatomic features.
1) Its ability to grow laterally along the ground, even beneath the height of mowed lawn level. Consequently casual mowing does not interrupt the seed setting process, as mowing does with many other common weeds.
2) A mature plant may produce hundreds of burr-covered seeds. Rate of fertility of seeds appears to be very high. Seed-burrs attach to footwear, tires, clothing, etc....and are transported far distances that way. It is likely that the many marathons, hosted on Oahu, contribute significantly to the spread of the weed. Seeds are also spread by lawn-maintenance equipment, wind, and birds that eat the seeds.


Khaki Weed Tap Root--photo Andrew Lawrence

Khaki weed is usually supported by a single woody tap root. Though sometimes the prostate stems that extend from the central tap root, also launch tap roots themselves. The plant may remain dormant for periods, though the tap root is perennial and very hardy. Khaki weed is said to flower June through October...at least in temperate climates.* In Hawaii's more tropical climate, it 'blooms' year round.

Khaki weed is registered as a 'Declared Plant' of high priority by the State Government of South Australia (SA) and is considered a very serious weed threat in that State..  According to David Deer, of the Animal and Plant Control Commission, in SA, Khaki weed is a "very difficult weed to control as it establishes on dry areas that have little competition, extensive root structure, and resilience to chemicals makes control difficult."

For more information, see the (Pdf) "Declared Plant Policy" for Khaki weed, published by the Government of South Australia. You may also see Effect on Animals and Medicinal & chemical properties.
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* This AU reference says Dec. through May, but that's the Southern hemisphere.