Tree is a woody plant with a spreading crown, whose single trunk exceeds diameter of 15cm and attains a certain height. To exclude shrubs, minimum height a height of more than 4 meters and up to 7 metres may be called a small tree. All trees are capable of producing seeds under favourable environmental condition and grow vigorously for many years. A tree may show the height and shape of a shrub in a climatic condition different from the natural habitat and temperature, light, humidity and moisture and nutritional status of the soil are found to play important role on growth and flowering of plants. By manipulating the environment, delicate plants can be successfully grown if one knows the requirements of those plants. Trees are very fascinating because of their graceful appearance and the abundance of bloom. They are grown for their economic importance or aesthetic value or both. Fruit trees are planted for fruits and forest plantation for other economic products like timber, fuel, tannins, oils, gums, resins, waxes, spices, beverages, narcotics and drugs. The cultivation of trees for their aesthetic or recreational value is known as arboricultural. Here the individual tree is important in contrast to the wood as a crop as in forestry. They also exercise beneficial influences on climate and rainfall, regulate the water flow and prevent soil erosion. A large number of trees in our country are resplendent in riotous colours at the flowering time and are capable of transforming the landscape. The trees are the most permanent elements in landscape and a thorough knowledge of their ornamental properties, rate and mode of growth, their behaviour in different soil, situation and climate are essential. They should be planted carefully and thoughtfully for the benefit of height, shade colour and vertical emphasis.
We have got large number of indigenous and exotic flowering trees, which can be successfully utilized to beautify our cities, towns and villages. Along with the road plan, a plantation plan should be made and strictly adhered to. For the existing roads the dead and decaying trees should be replaced systematically according to a plan. Beautifully planted avenues with flowering trees are pretty with the colour and beauty. The trees should not be patchy due to lack of aesthetic sense of those maintaining the roads. The value of trees as both labour saving and attractive to the residents of any private garden has become increasingly evident. Many trees burst into bloom beautifully, while others afford a pleasing contrast with their decorative foliage. Although we have an abundance of flowering trees, selection of trees for private gardens which should create rhythm, accent, as well as balance in the garden and the dwelling place is rather difficult. One or two small flowering trees are often adequate selections and planting of trees should deserve just as much attention as is commonly given to the colour of the building, pool and paved path. The fruit trees should be planted to the back portion of the house where they are not visible from the entrance. A group of Plumeria or Cassia at the boundaries add charm and grace to the house. List of our indigenous ornamental trees will be very long and it includes many colourful flowering trees like Butea monosperma, Bauhinia purpurea, Cassia fistula, Lagerstroemia speciosa, Cochlospermum gossypium, Bombax malabaricum, Millingtonia hortensis, Dillenia indica and Saraca indica. Trees with ornamental foliage indigenous to India include Polyalthia longifolia, Putranjiva roxburghii, Melia azadirach, Mimusops elegi and Azadirachta indica.
The best time for planting trees is during the rainy season (June-September). In northern India planting can be done in January-February before the new growth starts and 1-2 years old saplings have better chance of survival and early flowering. Large pits (1 meter in depth and diameter) should be prepared 2-3 months before planting. The soil is mixed with adequate amount of organic manure and bone meal and allowed to settle by exposing to rains or watering the pits. The tree saplings should have straight stem and undisturbed main shoot. Before planting the ball of earth round the roots is cracked without damaging the roots and planted with root collar just below the ground level. During planting all dead and broken branches and roots are to be cut and removed. The soil around the plant should be firmly consolidated after planting, watered thoroughly and also staked. In the open and in public places tree seedlings are to be protected in gabions till they grow fairly large. Distance of planting trees usually varies from 5-14 metres depending on the size of the plant. For better growth of the plant, the pits should be weeded and hoed to keep the soil loose and free from weeds. Most of the tropical trees have short dormancy period and monsoon is the season for maximum growth. In order to maintain the shape of the tree it is often necessary to remove the old branches. Crossed branches in the centre of the crown should also be cut off. On the stem or large branches holes are made by insect, rats, squirrel and birds or cracking of wood. The exposed surface of the hole is thoroughly cleaned by removing dead, and rotten wood, coasted with coated or fungicides and filled with cement.
Bauhinia purpurea (Mountain ebony, Geranium tree)
A nearly evergreen tree attaining a height 10-12m growing sparingly throughout India. Flowers large about 6cm across, in various tones of rose, purple, in few flowered clusters at the ends of the branches. It is a very hardy tree, flowers profusely from October to March, when leaves fall off but not completely.
An evergreen tree of medium sizes growing up to a height of 10m and produces clusters of light mauve flowers. It is a quick growing tree in warm humid climate. The plant remains in bloom almost throughout the year but larger number of flowers develops from March to May.
Callistemon lanceolatus (Bottle Brush)
The plant is also known as "Bottle Brush" because the flower-bearing portions of the branches resemble bottle brushes in shape. Flowers in densely crowded cylindrical spikes 5 to 10cm long, with long scarlet stamens projecting stiffy outwards. The flowering may be observed more or less throughout the year, especially from February to November.
The trees have pendulous branches, often grown on roadside and in gardens.
Azadirachta indica (Indian liac, Margosa tree)
A medium sized almost evergreen tree usually maintaining a height between 10-15m. The tree is very popular in India because of its high medicinal properties. The dark evergreen foliage gives a very showy appearance and it is also grown as an ornamental tree.
Erythrina indica (Coral tree)
It is a tall deciduous tree reaching a height up to 18m; bark is smooth, yellowish or greenish grey. Flowers large, red 5 cm long, pea shaped in dense recemes 16-20cm long that appear in February-May. The tree is commonly planted in villages and along roadsides as shade trees and is used to make close hedges because it grows readily from massive cuttings and the prickles ward off intruders.
Delonix regia (Gulmohar, Flame tree, Peacock flower)
It is a large deciduous tree, native of Madagascar and reaching a height of 12-20 m with spreading branches, umbrella shaped crown and greyish bark. Flowers 5cm wide, scarlet in colour with a mild scent, borne on long stalks in short axillary recemes forming panicles on the new shoots; other portion or branches are bare of leaves. It is one of the most beautiful and common flowering trees grown in India and very suitable for parks, roadside and also large private gardens.
Ficus religiosa (Peepal)
A huge tree with greyish bark. Leaves smooth shining, broadly ovate, apex long and narrow, 10-18cm long. The tree is indigenous in Bengal and Burma and is cultivated all over India. Handsome dense foliage on the spreading branches gives a cool and pleasant shade under the tree.
Ficus bengalensis (Banyan)
A large evergreen tree, may attain a height of 30m, branches spreading, almost horizontal. The tree is indigenous near the foot of the Himalayas and Western India and is commonly planted all over the country.