Little joy in ‘old man’s beard’

Press, 21 January 1984, Page 15

Little joy in ‘old man’s beard’

By

DERRICK ROONEY

A single plant can cover 180 square metres, and a square metre of growth can produce 1000 seeds. But it is not a new wonder-crop; it is a pest which has noxious plants authorities increasingly concerned in several parts of New Zealand. The plant is Clematis vitalba, known as “old man’s beard” or “traveller’s joy.” It is gradually choking patches of native bush in areas throughout the central North Island. As yet it is not classified as a noxious plant, but that situation may change when a four-month distribution survey has been completed by the Noxious Plants Council and the Department of Lands and Survey.

Four areas considered most at risk from infestations of old man’s beard have been identified, according to a Wellington report. These are the Motu catchment; the Turakina, Whangaehu and Lower Wanganui valleys; parts of the Wairarapa Hill country from the Puketoi Range southward to the Martinborough district; and the Marlborough Sounds. A botany undergraduate, Heather Cameron, is helping to run the survey, with a botanist, Jenny Kieboom. They will talk with noxious plants officers and Lands and Survey Department rangers, to

build up a picture of the level of infestation in the danger areas. “We will look particularly at areas that are down river or down wind from seed sources,” Miss Cameron said. “We want to identify areas that are either heavily or lightly infested, or which are still completely free of the plant.

“It is impractical to eradicate the plant in heavily infested areas without killing the host trees, so in these places there will be a policy of containment.

“Isolated plants can be killed by cutting the vines and painting a 50:50 mixture of 2,4,5-T and diesel on the stump. The aim in areas of light or no infestation is to keep the plant out altogether.’ Old man’s beard can only grow if it has a support on which to climb, and for that reason it does not directly threaten pastoral farming. It can, however, threaten soil and water conservation and, in so doing, threaten lowland farming. The characteristic fluffy white seed heads and vines completely cover the trees in bad patches. Old man’s beard has been well established in New Zealand about 40 years. It comes from Europe, where “the cold winters tend to knock it back and it isn’t a problem,” Miss Cameron said.

Apart from natural spread, old man’s beard has been disseminated by gardeners, who were attracted by its ornamental qualities. Nurserymen have been discouraged from selling the plant.

Miss Cameron said old man’s beard had a phenomenal growth rate.

“It prefers any patches of bush where there is a bit of dampness but also plenty of light. This is usually provided by a break in the trees, caused by a windfall or cleared areas.

“It can produce shoots several metres long in a single growing season and it puts down roots as it spreads, so chopping the vine off at the base doesn’t always kill it. A five-year-old plant can produce more than .100 vines.’

Miss Cameron said the young vine had a very distinct ribbed stem with a purplish colouring around the nodes.

Apart from the characteristic “bearded” appearance of the fluffy seedheads, which occur from January to March, the plant has a small white flower with a faint almond scent. The compound leaflets are in clusters of three or five.

Miss Cameron said that anyone in the districts under survey who knew of an infestation of old man’s beard should inform the local noxious plants officer, or get in touch with her or'Miss Kieboom at the Advisory Services Division, Ministry of Agriculture and Fisheries, Wellington. “They will need to give fairly accurate details concerning the extent and location of the infestations,” she said. Clematis vitalba is native to Europe, and at one time was cultivated in gardens, until it was superseded by the introduction of more ornamental Asiatic and Himalayan species. According to a DSIR checklist of the buttercup family, to which clematis belongs, old man’s beard is one of four introduced species of clematis which have become naturalised in New Zealand. The others are Clematis montana and tangutica, both wellknown as garden plants, and the European Clematis flammula, which flowers in late summer.

Clematis vitalba is easily distinguished from native clematis species which may be found in

bushland. It is deciduous, and its young leaves have five leaflets, whereas the native bush clematis is evergreen, and has three leaflets.

Old man’s beard flowers in early summer, usually after the native clematis has finished flowering, and has small, creamy white flowers. These are succeeded in autumn or winter by masses of grey, silky seedheads, which gave the plant its popular name. The silky seedheads of old man’s beard are made up of numerous seeds to which fluffy “parachutes” are attached. They can drift considerable distances on wind currents, and it is believed to be in this way that the plant established itself in the wild in New Zealand, from plants cultivated in gardens. The first firm identification of its presence here as a wild plant was reported by the late Dr H. H. Allan in a DSIR bulletin in 1940.

The stems of old man’s beard are covered with pale, hairy bark which can be rubbed off. Where they lie on the ground, the stems quickly take root and send new shoots climbing towards the light. The young leaves are covered with fine hairs. Bush clematis has firm bark which cannot easily be rubbed off, and does not normally layer itself. Its leaves are hairless.