Part I parts of a tree Unit 1 The functional parts of a tree

1.1 Active vocabulary:

bark	кора
bud	почка
branch	ветвь, сук, ответвление
crown	крона
cambium	камбий
cell	клетка
heartwood	сердцевина, ядро
inner bark	луб, лыко
limb	сучок, ветвь
leaf (pl leaves)	лист (мн. листья)
root	корень
sap	сок
sapwood	заболонь древесины
stem	ствол, стебель, стебелёк
stem cutting	стеблевой черенок
strength	прочность
tissue	ткань
trunk	ствол

1.2 Read and translate the text 1 using the active vocabulary and a dictionary. Text 1 Tree structure

Trees are the largest plants on earth. They are complex organisms that harness energy from the sun to reduce the impact of global warming and help maintain balanced ecosystems.

One large, healthy tree can:

• lift up to 4000 liters of water from the ground and release it into the air

• absorb as many as 7000 dust particles per liter of air

• absorb 75 per cent of the CO2 produced by the average car

• provide a day’s oxygen for up to four people.

A

Figure 1.1 Parts of a tree

tree has three major parts: crown, trunk and roots (figure 1.1).

The crown of a tree contains of leaves/needles, branches, limbs, twigs, buds, flowers and fruit. Leaves and needles are food factories in the tree’s crown. Food-making, or photo­synthesis, begins when the sun’s warmth and light is trapped by green chlorophyll in the leaves. This energy is used to combine carbon dioxide from the atmosphere with water drawn from the roots to create sugar and starch. The inner bark then carries this food to all living parts of the tree. In turn, oxygen and water are released into the atmosphere as by-products of photosynthesis. The process of photosynthesis occurs in the chlorophyll-containing tissues in the leaves. Every spring the tree grows taller as a new set of branches develops at its top, and wider as buds develop along the older branches, twigs and tips. Soft tissue inside the buds is protected from damage by a tough covering of moisture-saving bud scales. Trees produce flowers or cones that hold fertilized seeds. In late summer or fall, the seeds come loose and are scattered by wind, water and wildlife. Within each seed is the soft tissue that is the basis a new tree. Seeds have a tough coating that protects them during dispersal to their new home. The flowers and fruit are particularly important in propagating or reproducing a species and in development of hybrid species. Trees may also be reproduced through vegetative propagation, the growth which develops from root or stem cuttings, or tissue culture. Branches and twigs support the leaves, holding them up to receive the sun’s light and warmth. They also produce buds that form new twigs, leaves and flowers.

The trunk is the main stem of the tree. It supports the crown of branches, leaves/needles and transports food and water throughout the tree. The tough outer bark protects the tree from heat, cold, moisture loss and injury. The soft inner bark carries food from the leaves and needles to all living parts of the tree. Beneath the inner bark is a thin layer called the cambium that each year develops new cells (the building blocks of life) of inner bark on its outer wall and new sapwood cells on its inner wall. The sapwood carries water from the roots up to the leaves/needles. As the tree grows, old inner layers of sapwood die and become heartwood, a rigid fiber that gives the tree its strength.

The roots act as an anchor, holding the tree firmly in place. They grow and spread out underground from the root tips, forming a huge network that draws nutrients to the tree and protects the soil from erosion. Small root hairs grow out from the roots to absorb water and elements in solution from the soil. This soil solution (sap) is conducted in vessels or tracheids through the larger roots, up through the sapwood of the trunk and branches, and out to the leaves. Here the sap is converted, or assists in the conversion, into available plant food. Larger roots support the tree and store manufactured plant food.

1.3 Translate the following word-combinations into Russian: soil solution, elements in solution, vegetative propagation, tissue, a huge network, sugar and starch, root or stem cuttings, dust particles.

1.4 Read the text 1 again and say if the statements are false or true. Correct the false ones.

1. A root system anchors the tree in the ground.

2. The inside bark on the trunk protects the outer bark of the tree from mechanical injury.

3. The total surface area of root system is quite small.

4. The inner bark carries food to all living parts of the tree.

5. Trees may be reproduced only through vegetative propagation.

1.5 Match the verbs of column A and the nouns of column B (use the text 1).

A	B
absorb protect produce store divide support	tree food soil water trunk cells

1.6 Form plural of these nouns:

branch, series, leaf, growth, cone, ray, pith, inner bark, tissue, stump, area, species, bud, oak, wood.

1.7 Use the verbs in the brackets in the Present Simple Passive Tense.

A tree (to anchor) in the ground using a network of roots, which spread and grow thicker in proportion to the growth of the tree above the ground. In a mature tree, most of the cells of the trunk, roots, and branches (to die) or inactive. All growth of new tissue takes place at only a few points on the tree, by the division of specialized cells. These actively growing areas (to locate) at the tips of branches and roots and in a thin layer just inside the bark. Lastly, trees have reproductive structures; either flower or cone. Most trees can (to identify) by the leaf alone.