Gardening in Arabia: Ornamental Trees of Qatar and Arabian Gulf (Arabic)

Perennials

Perennials

Cordia sebestena

Orange cordia flowers

This plant group has a life cycle of more than two years, and includes plants such as trees, shrubs, climbers and woody-based perennials, as well as long-lived herbaceous species. While some perennials live only a few years, others have life spans of 100 years or more.

There are two types of perennials:

Evergreen perennials: In some species, perennials retain their foliage all year round. Examples of evergreen perennials include palm trees, palm-like trees, and conifers.

Deciduous perennials: This type of perennial loses its leaves during the dry season, or in the winter. An example of a deciduous perennial is the Erythrina caffra tree.

Callistemon viminalis

Weeping bottlebrush tree flower

Plant physiology

Internal workings of plants and trees

God says in the Holy Quran: Surat Ibrahim, Verse 24:

Have you not considered how Allah presents an example, [making] a good word like a good tree, whose root is firmly fixed and its branches [high] in the sky?

To provide an environment where plants and trees can grow and thrive, it is necessary to understand the life processes of the plant. Trees absorb and transport food and water in the outer layers of their branches, trunk, and roots. If these layers become damaged or are removed, the tree will die. Transportation in these layers moves in both directions, upward and downward. Water, minerals, and fertilizer are absorbed from the roots through the process of transpiration, which takes place in the leaves. The leaves also make food, through photosynthesis, which is then transported downwards in the phloem. This same process removes carbon dioxide from the air and transforms it into oxygen, which is then released back into the environment.

Cassia javanica

Pink shower tree flowers

Trees

Boswellia sacra

Frankincense flowers

Surat Al-Naml, Verse 60:

[More precisely], is He [not best] who created the heavens and the earth and sent down for you rain from the sky, causing to grow thereby gardens of joyful beauty which you could not [otherwise] have grown the trees thereof? Is there a deity with Allah? [No], but they are a people who ascribe equals [to Him].

Members of the tree group are some of the largest, tallest, and most long-lived of plant species. Trees are woody perennial plants, and can be either deciduous or evergreen. They show great variety in shape and height depending on the species, ranging from dwarf cultivars that are only 1m in height to towering trees that grow to over 90m tall. On average, trees are classified as being usually over 6m in height, and tending to develop a distinct crown. They usually have a single woody stem, called a trunk, although some trees can have two or three stems. When a tree is cut, rings can be seen in the cross-section of the trunk. These rings tell us about the life of the tree; lighter rings describe seasons when the tree grew quicker, and darker rings show slower growth, perhaps during summer or autumn seasons. The older a tree, the more rings can be seen. Some trees live for thousands of years.

Importance of trees: From the beginning of time, trees have provided people with food, in the form of fruits and nuts, which can supply all the nutrients needed for life and growth. Planting trees also provides an important source of food and shelter for birds and other wildlife. This is mentioned in the Holy Quran:

Surat As-Sajdah, Verse 27:

Have they not seen that We drive the water [in clouds] to barren land and bring forth thereby crops from which their livestock eat and [they] themselves? Then do they not see?

Trees are a source of wood and paper. This is mentioned in the Holy Quran:

Surat Luqman, Verse 27:

And if whatever trees upon the earth were pens and the sea [was ink], replenished thereafter by seven [more] seas, the words of Allah would not be exhausted. Indeed, Allah is Exalted in Might and Wise.

Trees are a source of charcoal and other illuminants such as oil. This is mentioned in the Holy Quran:

Surat Ya-Seen, Chapter 36, Verse 80:

[It is] He who made for you from the green tree, fire, and then from it you ignite.

Trees provide people with industrial materials such as fiber, cork, gum, wax, and oil, as well as medicines, including aspirin, quinine, and cocaine.

Trees are important to our quality of life, whether they are planted in private gardens or in public areas. They are planted for many different reasons—for their appearance (shape, kind of leaves, color, smell), for food production, and most importantly in the Middle East, to provide shade.

Most bees build hives in trees. Bees eat pollen from the flowers of the tree they inhabit, as well as neighboring trees, giving people honey, with all its health and curative properties. This is mentioned in the Holy Quran:

Surat An-Nahl, Chapter 16, Verse 68:

And your Lord inspired to the bee, “Take for yourself among the mountains, houses, and among the trees and [in] that which they construct.”

Trees can be used to create boundaries in the garden, and also to hide unattractive features such as to block out the view of a busy road.

Planting trees in public areas such as parks, or in private spaces such as home gardens, is like installing a natural air conditioning and heating system. In the summer the leaves of deciduous trees absorb sunlight and give shade, reducing the ambient temperature of the area. In cooler weather, when the tree branches are bare, sunlight is let through, warming the area.

Trees, when properly placed, can be used to control wind-flow patterns, and can absorb and reduce the force of wind on surrounding areas. For example, conifers such as cypress trees, when planted in rows along a given space, are natural windbreaks, and also act as a living privacy fence.

Trees can increase road safety. Many traffic accidents are caused by driver’s exceeding the speed limit. Speeding is more of a problem on empty roads, where drivers increase their speed unknowingly because their eyes have no point of reference. When trees are planted along roadsides and in meridians, they provide the illusion that cars are travelling faster than their actual speed, thus causing drivers to slow down. In the Gulf region, palm trees are often planted for this purpose.

Trees, through their root systems, fix the soil they are planted in and prevent desert sands from encroaching on cities. They can also help to conserve water, and their roots prevent soil from being washed away by heavy rains.

No matter what the reason for planting trees, in doing so we have the power to positively change the local climate.

Planting trees: When planting trees around the home, there are some simple guidelines to follow. It is essential to leave a 3–4m gap between trees and any walls surrounding the property. Trees of similar type should be planted together, as they have the same water and fertilizer requirements. Trees should be planted 1–2m apart, depending on the type of tree, and saplings should be placed in holes at least 1m deep. Most tree saplings need to be supported in the first years to protect them from the wind. To support young trees, install 1–2m long stakes in the ground approximately 10–15cm away from the tree trunk. This distance is required to ensure that the tree’s root system is not damaged. Bind the stakes to the tree in at least three separate places, for equal lateral support.

Caring for trees:

Pruning: Pruning is an important procedure to protect the health of the tree; if neglected, the tree will grow in an unbalanced fashion. Pruning removes sick, dry, and dead branches, allowing the tree to direct its energy towards new, healthy growth. The best time to prune is in the autumn and at the beginning of summer.

Fertilizer: Fertilizer is the food plants need to thrive. All trees need essential elements such as nitrogen, phosphorus, potassium, magnesium, manganese, and boron to grow. The best, most well-rounded fertilizer for trees is NPK; this can be purchased from any plant nursery. To fertilize trees, inject fertilizer into the soil surrounding the tree, where the roots have spread. Make holes in the soil, 30–60cm deep, in a circle around the tree, with the radius of the circle a distance of 70–100cm from the trunk. Space each hole 30–60cm apart. Fertilize deciduous trees in spring when new growth can be seen, and evergreen trees twice a year, in autumn and spring.

Diseases and insects: Like any living thing, trees can be afflicted by illness or insects. These issues should be immediately addressed, with the help of a specialist if necessary.

Wounds: Trees can be wounded by people, animals, cars, and strong winds. Any injury to the trunk or branches of a tree should be treated immediately; if left unattended, infection can set in. To treat a wound, first clean the gash completely, removing all dead and damaged tissue. Next, cover the wound with a salve to protect it from bacterial and fungal infection. Finally, if the wound is very deep it must be filled with cement or a special plastic that the plant cannot absorb. This is done to prevent rot. Wounds of this type are best treated by experienced gardeners.

Tree reproduction: Like other types of plants, all trees have flowers, by which they reproduce. The egg of the tree is in the pistil of the flower, and it is fertilized by the pollen of the stamen. This produces the seed, which will grow into a new tree. Most trees have bisexual flowers, which means the same flower has both male and female structures. Some trees are monoecious, which means they produce separate male and female flowers, but both are on the same tree. Cypress (Cupressus) and fig (Ficus) are examples of monoecious trees. Less common are dioecious trees, plants which have only male flowers on one tree, and only female flowers on another. If trees are dioecious, male and female trees must be planted in proximity to one another to reproduce. Date palms (Phoenix dactylifera) are examples of dioecious plants. All trees require assistance with pollination; pollen is usually transferred by the wind, by insects (such as bees), or by birds or other animals.

Types of trees: Trees serve as a framework for gardens, a structure around which a personal oasis can be built. They come in a wide variety of colors, sizes, and shapes. Understanding the different types of trees available will help in planning a garden landscape.

Conifers: Coniferous trees often have a vaguely triangular shape; in these species the trunk of the tree grows faster than the side branches grow out, and the leaves produce a fuller shape on the lower branches. Also, the branches of the tree are generally shorter as they grow up the trunk. Coniferous trees do not require pruning, and are attractive when planted along the sides of a house. An example of a coniferous tree is the Italian cypress.

Flowering trees: Flowering trees are colorful additions to any garden. These trees are attractive as specimens, and are best placed under balconies or near terraces. Examples of flowering trees are the frangipani tree (Plumeria spp.) and the orchid tree (Bauhinia spp.).

Fragrant trees: Fragrant trees add another sensory dimension to gardens, as their delicate scent can often be smelled from a distance. Examples of fragrant trees are neem (Azadirachta indica), albizia (Albizia lebbeck), and tree jasmine (Millingtonia hortensis).

Fruit-bearing trees: In addition to their attractive foliage and fragrant blossoms, fruit-bearing trees provide an edible, healthy harvest. Examples of fruit-bearing trees include Assyrian plum (Cordia myxa) and fig (Ficus spp.).

Open-headed trees: The branches of open-headed trees grow in such a way as to give the tree an umbrella-like shape. An example of this is the royal poinciana (Delonix regia).

Round-headed trees: Round-headed trees get their name from the dome shape of their crowns. These stately trees have broad leaves, and can be planted as specimens in large gardens. An example of a round-headed tree is the neem tree (Azadirachta indica).

Weeping trees: Weeping trees are named for their drooping branches. This type of tree, when fully grown, usually has a large circumference, and takes up ample land space. Therefore, it is better to plant weeping trees individually, rather than in pairs or clusters. These dramatic plants are beautiful when placed near water, such as swimming pools or ponds. Examples of weeping trees are bottle brush (Callistemon spp.) and weeping myall (Acacia pendula).

Columnar trees: The leaves on this type of tree grow at an even rate on both the bottom and the top, giving the tree its columnar shape. This type of tree has tissue at the top that allows the plant to experience faster upward growth than lateral growth. Columnar trees do not require pruning; they naturally grow in a balanced, symmetrical shape. These trees are best planted in rows as a natural windbreak, or as a fence to delineate different sections of the garden. An example of a columnar tree is the horsetail tree (Casuarina spp.).

Delonix regia

Flame tree flowers

Acacia pendula

Weeping myall flowers

Acacia