Australian tree ferns: Plant possible invasive concern by Carolyn Lucas West Hawaii Today clucas@westhawaiitoday.com Wednesday, March 18, 2009 9:07 AM HST Though prized for its distinctive looks and rapid growth, the Australian tree fern is becoming an increasingly common and alarming fixture in Kona neighborhoods, according to a recent islandwide survey by the Big Island Invasive Species Committee's early detection crew. On the underside of its triangular fronds with lacy blades are millions of spores, which breezes -- as well as feral ungulates -- carry far and wide. This tree fern (Spahaeropteris or Cyathea cooperi) is already displacing native forests on Kauai, Maui and Oahu. Watersheds are also being choked. Such propagation is just beginning on the Big Island, said Page Else, spokeswoman for the Big Island Invasive Species Committee. "The tree fern crowds out our native hapuu, the mother of the forest. The soft fibers of the hapuu nurture young native seedlings of native plants like ohia and olapa," she said. "The Australian tree fern has a harder, scaled trunk which doesn't make a good home for seedlings. Consequently, the foreign plant can take over in our forests, changing the forest structure, lessening the number of native plants and decreasing the ability to capture water and provide good water quality in watersheds." It's no wonder that the Australian tree fern appears on a list of the most invasive plants in Hawaii, prepared by the Hawaii State Alien Species Coordinator and the Department of Land and Natural Resources' Division of Forestry and Wildlife. Officials urged people to not cultivate any of the listed species anywhere in Hawaii. The Big Island Invasive Species Committee recently issued an Australian tree fern alert, spreading awareness about the weed and hoping that residents will help prevent its spread. People should report tree ferns by calling the state pest hotline at 643-7378. Those who have purchased the popular ornamental but suffered buyer's remorse and now want to remove it can either snip the bud or cut down the tree fern and treat it with herbicide. "They should be aware that their tax dollars will be put to work combating the rapid growth of this plant in public watersheds as seeds spread out of their yard into other locations," Else said. Two years ago, the Kauai Watershed Alliance contracted the Nature Conservancy to coordinate a response to the invasive tree fern. Crews on foot are sent into valley uplands to remove plants at a cost of $365 per acre. Helicopters with herbicides spray in more remote, dangerous areas. The aerial spraying costs $560 per acre, Else said. James Leary, invasive weed specialist at University of Hawaii at Manoa College of Tropical College Agriculture and Human Resources, has been experimenting with an innovative way to apply herbicide selectively to Australian tree ferns by using paintball guns with a special pesticide formulation. While people may be fond of the tree ferns, a wide variety of noninvasive alternatives, including the native hapuu, can be used as ornamentals. Because each yard is different, residents can visit a nursery and talk to an expert to find the best fit. Many nurseries -- including 15 on the Big Island -- agreed not to sell the tree fern after learning its potentially detrimental impact. For more information, call the Big Island Invasive Species Committee at 933-3345.

I was just playing around. Here is a recipe I cook at home. Beef fillet steak with mountain pepper sauce. Grind in a mortar and pestle about 6 large dried mountain pepper leaves with half a teaspoon of sea salt. Crush 3 cloves of garlic and rub the garlic and a little olive oil into 4 premium fillet steaks. Sprinkle the mountain pepper leaf and salt mixture liberally over the steaks and rub in by hand. Cover the meat and allow to sit at room temperature for the flavours to infuse. Slice potato and sweet potato into rounds about 5 mm thick. Partially boil them in salted water making sure they are just still firm. Thinly slice an onion into whole rounds. Layer the potato, sweet potato and onion into an oiled baking dish. Pour half a cup of cream over the potatoes, season with pepper and a little freshly grated nutmeg. Pop into a hot oven (fan forced if available) until brown on top. Add a tablespoon of butter to a hot pan and fry the steaks for around 2 minutes each side, cook them to your liking but DO NOT OVER COOK. They should feel firm by still springy when pressed with a fork. Remove the steaks from the pan and allow to rest briefly whilst preparing the sauce. Add a good swig of red wine to the pan to deglaze, remove from the heat. In a mortar and pestle grind a teaspoon of mountain pepper berries and 4 or 5 dried bush tomatoes (Solanum centrale). Add this to the wine in the pan together with a tablespoon of honey, a knob of butter and a teaspoon of balsamic vinegar. Simmer briefly, transfer the steaks back into the oven to reheat (pour any juices into the sauce pan). Cut a triangular section of the potato bake and place in the centre of a PREHEATED plate. Slice the fillet steaks almost all the way through in strips creating a fan shape. Arrange on top of the potatoes (work fast or it'll go cold). Simmer the sauce to reheat and pour through a sieve over the meat and drizzle a little around the plate for effect. Serve immediately.

Luke, its a Tristaniopsis laurina (Myrtaceae). Strictly a riparian species. It is basically the Xanthostemon of the southern rainforest riparian niche. In the Wet Tropics we have Tristaniopsis exiliflora which is a close relative of T.laurina. Can be grown readily by seed and can be established away from water. You guys down there also have Tristaniopsis collina which grows at higher elevation and often is association with temperate rainforest (at least in the Tweed area). http://en.wikipedia.org/wiki/Tristaniopsis regards Kris

I grow everything from all over the world, together. I keep things from overwhelming their neighbors through pruning and careful placement of the larger ones. Eventually it will look like the jumbled mess that nature is up close. I am careful about leaf color and avoid anything that looks too civilized or has large over-hybridized flowers. So it is mostly natives of Mediterranean climates from around the world. I especially like things that spread by underground runners and self sow as long that they are not too vigorous. Most self-sowers can be kept under control by judicious deadheading and runner pulling. I avoid plants that have been labelled noxious weeds in our climate, even those that might not be a problem where I live. I have seen enough broom and pampas grass in the wild to want to perpetuate the problem.