The plant is actually inedible if ingested raw because of needle-shaped raphides in the plant cells — severe gastrointestinal distress can occur. The initial affect on the mouth is an immediate painful irritation, burning and swelling of the lips, tongue and other mouth parts with a subsequent feeling of local anaesthesia. It is also toxic to handle, care needs to be taken with removal. Wear gloves and avoid coming into contact with plant parts. Leaves are usually very large, arrowhead shaped, dark green and velvety.
Infested creekbank. Photo: Robert Whyte
The taro in Brisbane is mostly the common purple-black stemmed cultivar known as Colocasia esculenta ‘Fontanesii’ or a variant thereof.
Photo: Mark Crocker
Xanthosoma violaceum. Photo: Sheldon Navie
Sterile tip of flower structure
Photo: Sheldon Navie
Usually some material will be left and new plants will continue to emerge, which have to be treated gradually. Others will appear after having drifted downstream, and yet others will come up from seed.
The plants can also be removed by hand, using a mattock to help lift the root mass which can be carried and heaped well above the flood line, and cooked out under black plastic. Removal this way can take with it a lot of the stinky, decaying mass the plants seem to produce and thrive in. It can also dislodge and harm frogs, fish and invertebrates, which should be protected from harm. Mechanical removal will leave some broken plant parts which will resprout.
Wild taro will commonly form monocultures which can be sprayed if care is taken not to let the spray drift into the water. Even though the leaves are quite moisture repellent, do not use surfactant as this is known to harm frogs.
This plant has resprouted from an old tuber. Photo: Robert Whyte