Trees

Types of Trees

source: wikipedia.com

Trees are the source of many of the world’s best known fleshy fruits. Apples, pears, plums, cherries and citrus are all grown commercially in temperate climates and a wide range of edible fruits are found in the tropics. Other commercially important fruit include dates, figs and olives. Palm oil is obtained from the fruits of the oil palm (Elaeis guineensis).

The fruits of the cocoa tree (Theobroma cacao) are used to make cocoa and chocolate and the berries of coffee trees, Coffea arabica and Coffea canephora, are processed to extract the coffee beans. In many rural areas of the world, fruit is gathered from forest trees for consumption. Many trees bear edible nuts which can loosely be described as being large, oily kernels found inside a hard shell. These include coconuts (Cocos nucifera), Brazil nuts (Bertholletia excelsa), pecans (Carya illinoinensis), hazel nuts (Corylus), almonds (Prunus dulcis), walnuts (Juglans regia), pistachios (Pistacia vera) and many others. They are high in nutritive value and contain high-quality protein, vitamins and minerals as well as dietary fibre.

Walnuts are particularly beneficial to health and contain a higher level of antioxidants than do other nuts. A variety of nut oils are extracted by pressing for culinary use; some such as walnut, pistachio and hazelnut oils are prized for their distinctive flavours, but they tend to spoil quickly.

Many trees have flowers rich in nectar which are attractive to bees. The production of forest honey is an important industry in rural areas of the developing world where it is undertaken by small-scale beekeepers using traditional methods.The flowers of the elder (Sambucus) are used to make elderflower cordial and petals of the plum (Prunus spp.) can be candied.

The leaves of trees are widely gathered as fodder for livestock and some can be eaten by humans but they tend to be high in tannins which makes them bitter. Leaves of the curry tree (Murraya koenigii) are eaten, those of kaffir lime Citrus × hystrix (e.g., Thai food) Ailanthus (e.g., in Korean dishes such as bugak) and those of the European bay tree (Laurus nobilis) and the California bay tree (Umbellularia californica) are used for flavouring food. Camellia sinensis, the source of tea, is a small tree but seldom reaches its full height, being heavily pruned to make picking the leaves easier.

Sugar maple (Acer saccharum) being tapped for the production of maple syrup

In temperate climates there is a sudden movement of sap at the end of the winter as trees prepare to burst into growth. In North America, the sap of the sugar maple (Acer saccharum) is most often used in the production of a sweet liquid, maple syrup. About 90% of the sap is water, the remaining 10% being a mixture of various sugars and certain minerals.

The sap is harvested by drilling holes in the trunks of the trees and collecting the liquid that flows out of the inserted spigots. It is piped to a sugarhouse where it is heated to concentrate it and improve its flavour. One litre of maple syrup is obtained from every forty litres of sap and has a sugar content of exactly 66%.

Similarly in northern Europe the spring rise in the sap of the silver birch (Betula pendula) is tapped and collected, either to be drunk fresh or fermented into an alcoholic drink. In Alaska, the sap of the sweet birch (Betula lenta) is made into a syrup with a sugar content of 67%. Sweet birch sap is more dilute than maple sap; a hundred litres are required to make one litre of birch syrup.

Various parts of trees are used as spices. These include cinnamon, made from the bark of the cinnamon tree (Cinnamomum zeylanicum) and allspice, the dried small fruits of the pimento tree (Pimenta dioica). Nutmeg is a seed found in the fleshy fruit of the nutmeg tree (Myristica fragrans) and cloves are the unopened flower buds of the clove tree (Syzygium aromaticum). Sassafras oil is an important flavouring obtained from distilling bark from the roots of the white sassafras tree (Sassafras albidum).