Why do pine trees have needles?
Pines are coniferous species of tree meaning they have leaves with conical structure, sometimes fine enough to be called needles. They are widely visible in the northern hemisphere. They are also classified as evergreens; they retain their leaves throughout the four seasons. Unlike their deciduous counter parts their coping mechanism in the face of cold winters is not in shedding of leaves but rather an evolution in the shape and morphology of their extensions. Pine trees are a classic example of evergreens and conifers; they have soft needle-like leaves which are crucial to the plants survival during the dry winters. Ever wonder why they make excellent Christmas trees? It is primarily due to this astonishing quality to retain their leaves that lends to their traditional and distinguished place among all who embrace in the spirit of this festivity.
The reason behind the reduction to this needle state is to combat water loss. Water loss is minimized by the reduced surface area of the needles as compared to flat faced deciduous leaves. While broad leaves may suffer frost damage (if they haven’t been shed by then). Besides the reduction in evaporation levels especially in the winter due to their shape, the skin of the leaves is also of significance. The skin is generally thicker, providing a coating of waterproof wax that inhibits further water losses. The shape of the leaf is a balancing act between capturing light , taking in carbon dioxide and survival in extreme weather. Trees higher up the canopy generally have reduced surface area and have complex structures like those of pine trees. The needles provide a distinct advantage over that of deciduous trees, while essentially deciduous trees go into ‘hibernation’ after the shedding of their leaves; evergreens have leaves that continue to gather energy for the tree regardless of the time of the year.
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