Pine trees and their leaves

Kingdom: Plantae

Family: Pinaceae

Genus: Pinus

Pine trees are trees with evergreen leaves – they are green even in the middle of winter, adding a bit of colour to a forest that would otherwise appear bleak and dreary. They often grow to great heights. All species in the Pinaceae family have distinctive needle shaped leaves arranged in bundles, it is their most defining feature. The leaves have all the usual features of a leaf despite a different appearance – they have a waxy cuticle and stomata for gas exchange. Pine oil can be extracted through steam distillation of the needle-like foliage, and is popularly used in aromatherapy.

There are two types of pine leaf. Needles are arranged in bundles called fascicles, and there are 2 or 3 in diploxylon pines and 5 in haploxylon pines. Diploxylon (Pinus) and haploxylon (Strobus) are subgenuses within the genus Pinus. There is actually a third subgenus, containing only one species called Pinus krempfii, which has flat un-pinelike needles and is found in Vietnam. This is clearly an example of a diploxylon pine, also known as the hard pine.

Diploxylon pines are stiffer and have stomata on both the ventral and dorsal surfaces. The basal sheath lasts the lifetime, whereas it is shed or curves to form a rosette in haploxylon pines. In haploxylons, there is one fibrovascular bundle whereas in the diploxylons, as observed here, there are two fibrovascular bundles. This is the feature which sets them apart taxonomically. Fibrovascular bundles connect with the xylem and aid in transport of nutrients, sugar and water.

The trees symbolise longevity and wisdom, and legend says that its needles can protect people from illnesses and witchcraft. Some Native American tribes regard the pine tree as sacred. Different cultures from all around the world use the pine tree for different purposes and consider it valuable for different reasons. For example, in Korea it represents virtue, and is viewed as being honourable, strong and wise, and is revered. Traditional Korean people even pray to a sacred pine tree for good luck, prosperity and health. Pine branches are left on the doorsteps of homes who have just had a baby to congratulate the couple, and the branch may be tied to a rope made of straw with charcoal if the baby is a girl, to keep evil spirits away. The Korean pine tree is also regarded as a messenger that transports the souls of the dead to the afterlife. Many coffins are made of pinewood which helps facilitate transportation of the deceased's soul to Heaven.