SOUTHLAND NATURALISTS’ SOCIETY

Southland Times, Issue 17620, 7 April 1914, Page 2

SOUTHLAND NATURALISTS’ SOCIETY

THE WEATHER AND PLANT LIFE, On Friday evening Mr L. Lennie gave a most interesting address on the effect of tlie weather on the growth and character of plant life. The lecturer prefaced his remarks by stating that what he had to say would be of a practical nature, and that lie laid no claim to treat the subject from the scientific point of view. Science, however, had been defined us organised common sense, and if this definition be accepted then the lecturer’s remarks were of an eminently scientific nature. Plants, said Mr Lennie, throughout their life, had many tilings to contend with. They had natural enemies’; they had foes of their own household—plant struggled witli plant. Then, there was the soil and the situation, both prominent considerations for failure or success. But the chief tiling in the struggle, tho dominant feature in plant environment, was the weather, in fact, lie thought it was not saying too much to affirm that the weather gave to each locality its special vegetable life. Those species which were best, adapted to endure an excess of wind, or frost, or drought, survived in the regions where such conditions prevailed, while those which were less adafiled could not gain a footing. For the purpose of considering its effects on plant life the weather might he divided into frost, wind, moisture and snow. Frost was popularly looked upon as the great enemy of the vegetable world, but It hail to he remembered that there was much on the credit side of the ledger. By the contraction and expansion of frost and thaw the soil was broken up and rendered more suitable for the plants’ t needs, and it was probable that a fair amount of frost bad the effect of keeping away many injurious insect pests. In Southland ten or twelve degrees of frost was about the average, and to fall much below this would perhaps result in as much harm as a similar rise above the mean. A great many plants had adopted the method of disappearing below the earth when the frost season set in, and nature’s hint in tills direction was largely followed by gardeners. For instance, dahlia crowns were safe enough under four inches of soil but if left witli less than ’two they were almost sure to be frost-bitten. The wind also was an imporant factor in plant environment. To adapt themselves to this many plants had adopted a creeping habit of growth: they lay down to it, thus escaping much of the gale’s force. Many delicate plants suffered severely from the wind, but. to balance this there was the fact that, blights, both animal and vegeablo. were less likely to do harm where the wind had reasonable access. Moisture played an active pan in the production of plant variety. This was noticeable in the rarefied atmosphere of mountain regions, where many devices had been brought about by which the plant checked the evaporation of moisture through its leaf surfaces, for if more water left the plant than entered it withering and death would ensue. In some cases the leaves had become very small, in others their surfaces were covered with a sort of wool or felt. In both instances the end to he attained was the conserving of moisture within the plant. Excess of moisture again resulted in the production of soft tissues which would not stand the frost. In New Zealand snow might perhaps he almost disregarded in the economy of plants, but in oilier countries it had resulted in a snow-re-sisting type. This consisted of a strong central trunk with drooping branches and narrow foliage. -On a tree of this kind the snow easily slipped from the flexuous houghs, thus reducing the risk of breakage from its weight to a minimum.

At the conclusion of Mr Bennie's address an animated discussion took place, many facts being elicited in support of the lecturer's statements. Mr Crosby Smith drew on his store of botanical knowledge for a number of comments, and concluded by suggesting ttiat the context of the matter, viz.. "The effect of plant life on the weather." might he worth considering at some future dale.