‘The Day of the Triffids’ was a 1951 book and later cult film about post-apocalyptic plants which killed people and, whilst Agave americana ‘Marginata’ isn’t carnivorous or roaming, it does have toxic sap.
With its triffid-like arms reaching up to two metres high and four metres wide, this agave has sharp tips three to five centimetres long and serrated teeth.
Former local, Patka, was home for Christmas and cleared out some of the monster agave plants. He wore safety glasses but, because it was a hot day, his arms were bare.
“I cut the leaves with a saw so that I could get into the heart of the plant so I could remove it with a heavier tool, a mattock,” said Patka.
“I think there was more sap in the heart but it might have been because I was using more force that the sap travelled further.”
An hour and a half later, Patka noticed slight itchiness on his forearms, which progressed to a few welts on his arm where he appeared to have been splattered.
He tried washing it off with soap and water and continued working.
The next day, tiny blisters appeared, with general itchiness.
“Then over the course of the next few weeks, the blisters became more intense and the skin was really red and irritated,” said Patka.
“Maybe a week and a half after, it was mild to severe itchiness and I had to use calamine lotion because every time I scratched the skin it burst the blisters and would bleed.”
The rash, itchiness and blisters persisted for about two and a half weeks and, by the end of the third week, the blisters had gone but Patka still had dry, flaky skin.
Agave americana produces Chemical Irritant Contact Dermatitis. It has several toxic compounds and some have not yet been positively identified, according to the Cornell College of Agriculture and Life Sciences. Its sap contains microscopic needles of crystalline oxalate, which pierce the skin and irritate it, and there are also irritating oils.
It seems surprising that this poisonous plant is used to make the alcoholic spirit, mezcal.
Tequila is one type of mezcal but it is made from blue agave of the Agave Azul Tequilana Weber variety. In a 2001 study by M. L. Salinas and others, five sixths of workers who handled agave stems in tequila distilleries had experienced the characteristic irritation.
The leaves and core of Agave americana ‘Marginata’ are also used to make agave syrup.
Agave americana ‘Marginata’ can be known as Agave americana ‘Variegata,’ due to its colour variation of green centre and yellow stripes. Century plant is another name, although it only lives from 10 to 30 years. Its life culminates in a spectacular flower cluster up to eight metres tall.
The Queensland Department of Agriculture and Fisheries states that agave is native to northern and central Mexico, Arizona and Texas. It is an invasive species in Australia and mainly spreads into bushland from being dumped in garden waste.