Weeds Raised Carefully At Lincoln

Press, Volume CI, Issue 30007, 17 December 1962, Page 15

Weeds Raised Carefully At Lincoln

Weeds from all over New Zealand are being raised with every care by Mr A. J. Healy, deputy-director of the Botany Division of the Department of Scientific and Industrial Research at Lincoln. His object is to identify them, which usually means getting them to seed: and this may take four or five years. It was important that weeds should be identified as soon as possible after being noticed, Mr Healy explained. The identification usually gave a strong lead as to whether there was any potential danger from the plant, and was also a great help if measures to get rid of it seemed called for. Identification had become much more important since the new hormone weedicides were introduced. as a hormone that dealt effectively with one species might be relatively harmless to a near relative.

Mr Healy has many unusual weeds growing at Lincoln. A few are apparently still being brought into New Zealand with horticultural seeds, in spite of seed cleaning, he says. Others come with the packing round imported articles: others may arrive in travellers’ shoes or clothes. The means of arrival of any particular plant are often obscure. Although most of the plants he is growing look harmless enough, he quite naturally takes precautions to ensure they cannot escape. They are grown usually in glasshouses, which are effective prisons as well as nurseries. There is an occasional specimen with an outlaw look about it. however. Such a one is a large and flourishing dock with creeping stems, which looks like a gardener’s nightmare. This plant, picked up in Northland, is probably a native of South America. It has just set seed after five years’ growth during which it

has sprawled luxuriantly over several square yards of its surroundings. Another large weed, growing profusely in the fern house is a Chilean gunnera sent in from a Dannevirke swamp. where it is causing t rouble by forming thick - clumps. Mr Healy recently identified the species as one commonly planted in gardens close to the Avon in Christchurch. where it apparently does no harm. When the identification of a weed is particularly troublesome or important, Mr Healy sometimes grows seed from several known species and compares the results with the unknown. He is doing this with Watsonias. three species of which are bad weeds in the warmer parts of the North Island. The Watsonias are relatives of the gladioli, with a rather similar although smaller flower head.