Fireweed

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Senecio madagascariensis [Asteraceae]
Origin: Africa

The lovely face that fireweed presents with its deep green leaves and bright yellow flowers belies the true nature of this aggressive, dangerous weed. Fireweed reached both the Big Island and Maui in shipments of grass seed used to re-vegetate highway shoulders, and has since spread like wildfire, taking over pastures in upcountry Maui and in Kohala on the Big Island.

Aggressive growth and an ability to out-compete even the notoriously tough kikuyu grass (another African import) is not the worst trait of fireweed. The plants produce poisonous alkaloids which can cause liver problems and eventual death in cattle and horses that consume them.

The state of Hawaii is currently conducting research to isolate an effective biocontrol agent from fireweed's native range.

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