Herbarium News
AUGUST
2010
Herbarium answers call to counter ‘stowaway’ weeds Every day, plants in gardens across Tasmania make a bid for freedom. Some do it the hard way, by casting their seeds to the wind or squeezing through fences; others get a helping hand from an obliging host, be it a bird or beast, or – as often as not – a human being. Irresponsible contractors and landowners are often the culprits, and green waste – cuttings, soil, debris and the like – is usually the medium in which these ‘stowaways’ lurk. It’s nothing new to Matthew Baker of the Tasmanian Herbarium. ‘Most people do the right thing and take their garden waste to the tip,’ he said. ‘Some, though, take the easy way out and dump their rubbish at the first secluded spot they find.’ ‘Usually they’ve had a few garden plants along for the ride, and it’s these stowaways that take root and turn into weeds.’ As the Herbarium’s Weed Taxonomist, Matthew is responsible for identifying and cataloguing the state’s troublesome plants. He receives dozens of reports and collections of new weeds every year – many of ornamental plants that have made their escape in garden waste. This month, three stowaway weeds have been brought to his attention: two in Tasmania, and a third on the verge of sneaking into the state. The first two plants – identified by Matthew as Yucca aloifolia and Helleborus foetidus – were found growing in native bushland near the East Tamar Highway. Both had arisen from dumped garden waste.
A native of Mexico, Yucca aloifolia is a popular garden plant both here and elsewhere. Its distinctive leaves radiate from the stem, and are thin and pointed – hence its common name, Spanish Bayonet. Like Yucca, Helleborus foetidus is popular with gardeners, although more for its green bell-shaped flowers than its unprepossessing common name (Stinking Hellebore). It too is exotic, having originated in Europe. ‘Yucca is thought to be growing wild in some places on the mainland, but this is the first we know of it – or of Helleborus – doing so in Tasmania,’ Matthew said. ‘Because both species spread mainly by suckers from their roots, the plants were unlikely to spread far; that said, they were a blight on the native bushland in this one place.’ Whereas these two plants came from domestic flower beds, the third – and more sinister – stowaway was the inhabitant of a commercial garden. Early this year, the exotic fungus, Uredo rangelii (Myrtle Rust), was discovered for the first time in Australia, at a nursery in New South Wales. Uredo is known to deform, stunt and even kill plants in the family, Myrtaceae – our much-loved eucalypts, tea trees and bottlebrushes among them. As a stowaway on these plants, it is also capable of spreading to other parts of the country. In response to the outbreak, the Tasmanian Government put restrictions on imports of plants, cut flowers, seed, fruit, pollen, foliage and tissue culture from all Myrtaceae species.
Tasmanian Museum and Ar t Galler y Depar tment of Economic Development, Tour ism and the Ar ts
Matthew Baker inspects a specimen of Helleborus foetidus
In doing so, it published a full list of the prohibited plants – no easy task. ‘There are many hundreds of species in this one family,’ Matthew explained. ‘And, like any plant group, the family is being revised as our knowledge grows, so it can be hard for the non-specialist to know what’s what.’ Which is why the Herbarium lent a helping hand. ‘It’s our job to know – and often to determine – the current name of every Tasmanian plant, and to publish the Census, which is a list of these names,’ said Matthew. ‘It was easy enough for us, then, to provide the information that was needed.’ As yet, there have been no reports of Uredo in Tasmania – this stowaway, at least, has been nipped in the bud. ‘It’s no surprise that we’re called upon to help deal with a problem like this,’ Matthew added. ‘After all, knowledge is power.’