Monadenia bracteata first arrived in South Australia in 1988, spreading rapidly in South Australia in the 1990s, just as it did in Western Australia in the 1950s where it now covers hundreds of thousands of square kilometres. Monadenia is competing for moisture and nutrients with many small understorey plants such as lilies, as well as our precious local indigenous orchids.
Monadenia stemMonadenia is self-pollinated, unlike our threatened native orchids, most of which are dependent on specific tiny insect pollinators. Each plant produces produces tens of thousands of airborne seeds which blow about the hills.
The Friends of Scott Creek, with the assistance of a Save the Bush grant, dug up and destroyed more than 51500 Monadenia plants (tubers and all) in the 1993/94 season. Every single plant located was removed. Ninety five percent of these plants had not yet liberated any seeds. Careful documentation is ensuring that all populations are being mapped. We need observant helpers spread over the whole area to locate any further infestations. Please remove and destroy any plants found. If you cannot remove the plants yourself, contact Trees For Life.
The two main centres of distribution are the Eden Hills/Blackwood area and the Mylor/Scott Creek area. Smaller infestations have been found as far north as Mount Crawford Forest and Warren Conservation Park.
Monadenia grows as a single thick stem 20-30 cm high. Flowers (October - November) are tinged in green and yellow.
Removal needs to be carried out very carefully. The left photo shows a dead stem at about actual size. The seed head contains thousands of tiny seeds that fall out at the slightest touch, while the base of the plant has two tubers. To remove the plant, first gently bend the stem into a plastic bag, ensuring seeds only fall into the bag. Secondly, use a screw driver to lever up the two tubers. Store in plastic bags and dispose of in your weekly rubbish collection.
The right hand photo shows a new plant sprouting around the dead stem. The underside of the leaves at the base of the stem are streaked with red and purple.
Photographs: David Jones
Monadenia - A Trial.PDF PDF FileMonadenia - Time Efficient Weeding.PDF PDF File