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The Formosa Lily, a wolf in sheep’s clothing.

The Formosa Lily, a wolf in sheep’s clothing.
 by Peter Vaughan

This February we are seeing the mass flowering of a white Lily, Lilium formosanum, the Formosa or Taiwanese Lily. Once upon a time I considered the flowers attractive and it was a foreign plant I was prepared to accept and even appreciate.
However, time has shown this Lily to be very invasive, especially in cleared areas, so despite the attractive flowers, it is becoming a serious problem. The problems are:
1. Competition for nutrients. In a good season there is plenty of water and nutrients to go around, but in hard seasons, this Lily has a backup nutrient store in its bulbs, so it will grow more strongly and out compete native plants. It will eventually take over.
2. Our grasslands should be just that, grasslands. Birds of prey, the owls, kestrels, Tawny Frogmouths, and others, benefit from these grasslands where they will prey on the introduced house mice and rats (which will be eating the mass seeding of the Formosa Lily). However the lilies are up to two metres tall and dense, preventing these birds from effectively swooping in! So the rats and mice are safer!
So if we leave them, we get more rodents and less birds, and the birds are forced to hunt closer to homes, so they receive a higher dose of poisons. Our birds need natural grasslands.
I control the Formosa Lily with a small 3 litre hand sprayer with Roundup and Metsulfuron mix. I use pruning shears and cut and spray the flowering stems close to the ground. At this stage the stems are becoming hollow so they take more spray. This seems to be very effective and minimises the amount of herbicides applied. I also go around other times cutting and spraying every stem I can find and I often dig out the bulbs. This Lily can be controlled, and it has to be. It is on the cusp of out of control.
So while white flowers are attractive, we do not want to lose our birds and diversity. Save the lilies for our gardens. The landscape is for the natural world.
If you are walking and do not have the equipment, just pull the stems out of the ground, and ideally ensure they are completely out of the ground, as on occasions they will take root and keep growing. You will weaken the plant until someone can deliver the coup de grace. 

MMM … Issue 27, March 2022