Steve Taylor, who is in charge of the ACT government's battle against the seemingly invincible weed, said it was spreading faster than it could be controlled. He said the weed was disrupting the whole ecosystem by displacing native grasses - as these original grasses are pushed back, the insect population shrinks and that cuts the population of birds. It can grow more than a metre high so it can be a traffic hazard. African lovegrass can grow so high it impedes drivers' vision. Credit:ACT government The species came to Australia from southern Africa in the 19th century, perhaps by accident or deliberately as an import by misguided farmers who didn't understand that it had little use for either man or beast. It is of such low nutritional value that cattle that eat it may actually starve because they feel full with a feed that contains virtually no nutrition.

What experts do know is that it's spreading like wildfire. Mr Taylor said that apart from disrupting the ecosystem, it was a fire danger because it grew in summer, which meant there was dead, dry material in winter so the fire season was extended. His strategy is to protect nature reserves but he and his teams can't eradicate it everywhere; it's a fight against the tide. "It's out of control so we focus on containing," he said. They mow infested open spaces in the city where the plant had grown so high that it was a fire risk but the weed on other bits of wasteland had to be left. With nature reserves in the city, teams would spray herbicides from the edges of these areas of rare plants back to the road.

African lovegrass fire in winter. The weed extends the fire season. Credit:ACT government In the Black Mountain Nature Reserve, for example, there is a very rare native orchid from which the lovegrass has to be kept away. "In areas like that we have zero tolerance," said Mr Taylor. He urged people not to visit precious nature reserves in the ACT or the Namadgi National Park or the Tidbinbilla Nature Reserve near it without cleaning boots and tyres. Mud carries seeds. There is also a concern in more rural areas surrounding the ACT. According to Dr Arnold Dekker, president of Sutton Landcare, part of the problem is mowers spread the seeds. When verges were cut, he said, mowers should be cleaned or they would transport the African lovegrass to the next site. The ACT government said it was stepping up what it called its "ongoing battle" against the weed. A statement said it was "blowing down or washing down mowers as they move out of affected areas and before they move into clean areas".