树木上所有的枝条和花都是由芽发育来的。芽是枝条和花的原始体。其中分化形成花的芽称为花芽。大多数生长在温带的树木,秋天形成的花芽需要越冬。翌年春季,幼弱的花芽生长膨大,萌发开花。为什么幼小的花芽能安全地越过寒冬呢?通过实验观察,发现了花芽越冬的秘密。原来,花芽内部含水量有着微妙的变化。当气温下降时,花芽迅速排出内部的水分,使其汁液高度浓缩,细胞内的水化程度降低,冰点下降。所以,即使在严寒的冬季,花芽内的汁液也不容易结冰。这样,花芽有效地防止了细胞膜因内容物结冰、膨胀引起的裂伤。一般在-30℃的情况下,许多树木花芽都能安然无恙。大多数树种的花芽外面都有芽鳞包被,芽鳞上具有绒毛或蜡质层,一方面有防寒作用,另一方面 All the branches and flowers in the trees are developed from buds. Buds are the original of shoots and flowers. The buds that differentiate to form flowers are called flower buds. Most grow in temperate trees, the flower buds formed in autumn need to wintering. The following spring, weak flower buds grow and bloom, germinate and bloom. Why young flower buds can safely cross the winter? Through experimental observation, found the secret of winter flower buds. The original, flower bud moisture content has subtle changes. When the temperature drops, the flower bud quickly exudes internal moisture, making it highly concentrated juice, reducing the degree of intracellular hydration, freezing point down. So, even in the frosty winter, the juice inside the flower buds does not freeze easily. In this way, flower buds effectively prevent lacerations caused by the freezing and swelling of the cell membrane. Generally at -30 ℃, many trees flower buds can be safe and sound. Most of the species of flower buds outside the bud scale package, bud scale with hair or waxy layer, on the one hand have a cold effect, on the other hand