Resistant Flowers The botanists have made some attempts, not wholly
without success, to discover why some flowers resist frost successfully and some do not. Kerner, who was very much interested in local opinion on the Drei Eismanner, alleges that the cup of the snowdrop, where the source of fertility lies, is habitually two degrees warmer than the surrounding air. The flower has a sort of central-heating system. The leaves are a great defence against frost, and there is always a week or two of accentuated danger for the plums, on which the flower just precedes the leaf. Yet we have a bumper crop of plums every five or six years, while apples, which blossom later and after the leaf is out, give a bumper crop about once in twenty years. The blackthorn, which is the most naked of flowers and one of the earliest, is a very free and regular cropper. Strawberries are in fact served by their succession of flowers. You go to your strawberry bed and find each open flower quite black at the centre : the frost has wholly killed them. Yet when you inspect the bed a week later the plants are quite as well furnished as is good for them with undamaged flowers. It is established that the frosts are nearly always more destructive in the valleys than on the hills. The cold flows down the hillside and lies in a sort of stagnant pool in the valley. The blackening of leaves (especially of potatoes) is due principally to the suddenness of the succeeding warmth, and they may on occasion be saved by watering with a hose as soon as the sun touches them ; but blossom can hardly be so treated. I shall never forget the demonstration of the effect of such watering in the grounds of Reading University, where the horticulturist had watered some rows and not others. Every watered row was unhurt, and every neglected row severely blackened. Early leaves are often more delicate than early flowers. How very sensitive is the rose leaf, for example, even in the wild species, and how immune the stitchwort flower !
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