Nelson Leader : January 29th 2015
GARDENING Good intentions from settlers backfires the things they did was to try and make the place a bit more like home so they imported many plants and animals which were familiar to them back in dear old England, Ireland and Scotland. Unfortunately, some of these organisms, freed from the checks and boundaries of their original homelands, have become out of control here, wreaking havoc with both our native flora and fauna. The early settlers acted out W of blissful ignorance and with the best of intentions, as then the study of the mechanisms which make an organism a regulated part of its natural environment was then completely unknown. The study of ecology was still a long way off. When shifted to a new country, a plant or animal is often freed of its natural predators which have been left behind, and the climate may be far more suitable in its new home. When these conditions prevail there is potential for that organism to become a serious pest. Many plants such as bar- berry, hawthorn, gorse and broom were brought to New Zealand for stock food and hedging. By STEPHEN MCCARTHY hen European settlers arrived in New Zealand one of Decorative plants were also introduced for the settlers’ house gardens. These included lupins, roses, clematis, buddleia and many more. Also many others were inadvertently introduced, mixed in with imported grass seed. In those days grass seed was threshed from ordinary meadow hay, complete with all the weeds it contained. Serious pasture pests such as docks, thistles, ragwort and many others were introduced this way. All of these have found life much easier here and have developed into serious pests. Strict border controls have now been introduced to try and ensure we don’t inadvertently introduce even more unwelcome visitors. Old man’s beard, Clematis vitalba, was first officially recorded in New Zealand in 1940 but was probably here much earlier. In England it was used as an understock on which to graft the large-flowered clematis garden varieties and this may be how it was introduced. In England I have seen it growing in the wild and it is a much smaller vine and was possibly introduced for use in cottage gardens to make the settlers feel more at home. Early New Zealand must have seemed a pretty wild place compared with what they were used to – many parts of Britain have been developed for many hundreds of years and virtually all of the southern areas are almost park-like in their vastly modified form. Unfortunately, the climatic conditions in many parts of New Zealand and the total absence of natural predators meant Clematis vitalba was completely free to run amok, which is exactly what happened. Rather than being a small vine it grows here to 30 metres or so with stems often the girth of a man’s forearm. Because of this rampant growth here, old man’s beard will completely smother native trees, covering them so completely as to shut out the light necessary for their growth thus killing them. The small, cream-coloured, typical clematis flowers are abundantly produced in midsummer. It is often not noticed until it produces its fluffy, white seeds in the thousands, which are spread far and wide by the wind. Here in the Motueka Valley, in the early winter, it sometimes looks like a snow flurry, so thick are the seeds in the air. It has certainly spread a lot in the 40 years we have been in Nelson, from sea-level to some 500m and some islands. It can be controlled by persistent cutting and poisoning the stumps, plus Pest plant: Flowers of the smothering vine, old man’s beard. hand weeding the often plentiful seedlings. In our garden, weeding out the seedlings is an annual event. It is surprising just how fast seedlings reach flower and seed production. There has been a lot of work done on research and the introduction of C vitalba’s natural predators from its home range, such as stem borers and leaf miners. These will not eradicate the plant but hopefully weaken it so it is not quite so vigorous. THE NELSON LEADER, JANUARY 29, 2015 33 Promotional pricing expires 28 february 2015, or until stocks are sold and can't be used in conjunction with any other offers. Only available at participating stores. s Nelson Bays Flooring Xtra 72 Oxford Street Richmond Phone 03 544 6000 6497087AC Motueka Flooring Xtra 23 Old Wharf Road Motueka Phone 0800 528 753 s.
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