Twigs, Buds and Leaf Scars, Leaves

Twigs offer an excellent means of identifying trees and shrubs

throughout the year, except for a short time during the spring when the

buds formed the previous season are opening and those for the current season

have not yet appeared.

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The most conspicuous features of twigs are their buds, leaf scars, stipule

scars, and pith, although their color, taste, odor, and the presence or absence

of cork, spur shoots, spines thorns, glaucous bloom, or pubescence

are also valuable characters for purposes of identification.

Buds are young, undeveloped shoots. If they are leaf-buds only they

finally grow out to produce either single leaves or branch stems bearing

other leaves. On the other hand, if they are flower-buds, they finally produce

the flower or flowers and then their growth ceases. Axillary buds

produce branch shoots, or single leaves or flowers.

When a leaf falls from a twig, there remains at the point of attachment

a leaf scar. Leaf scars vary in size and shape with different species and

hence are usually diagnostic. On the surface of each leaf scar are found

one or more minute dots or patches, which show where the now ruptured

strands of vascular tissue passed from the twig into the leaf. The size,

number, and arrangement of these so-called vascular bundle scars are often

helpful in identification.

Leaves are diverse in size and form. Thus we have the comparatively

small and simple leaf of the privet, and, in contradistinction to this, the leaf

of the banana plant, which, though roughly similar in shape, is from one to

three yards long.

A typical leaf is composed of a leaf-stalk or petiole which usually

widens at its base where it joins the stem at the node. The main flattened

expansion of the leaf is called the leaf-blade or lamina. In some cases, the

leaf-blade is borne directly on to the stem, that is, there is no leaf-stalk, in

which case the leaf is said to be sessile. Where there is a leaf-stalk, it may

be thick or thin, long or short.

On the leaf-blade thicker lines are visible. These are the veins, and are

the channels for conducting water with its dissolved substances into the

leaf and for transporting manufactured food substances away from the leaf.

The main veins give off branch veins, thus presenting a complete network

of veins. The whole arrangement of veins in a leaf is called venation. In

some leaves there is one main vein, which branches. The branches give off

secondary branches, and so on, thus producing a reticulate or net venation.

This is seen in such leaves as elm, oak and all broad-leaved trees.

In many leaves, despite diversity of shape, the whole-leaf-blade is a

single structure, as is the case in the elm, oak, maple and pine. Such leaves

are simple. In other cases, each leaf is composed of several leaflets arranged

in a definite order, for example, horse-chestnut, ash and acacia.

Such leaves are compound.

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Roots

By virtue of their genetic origin, root systems of trees tend to exhibit

three morphological types: taproot, heartroot, and plate or flatroot (see

Fig. 1). A taproot consists of a nearly vertical main root and many laterals

terminated in feeding roots; the feeding roots carry either root hairs or fungusmodified

short roots, called mycorrhizae. A taproot system is particularly

common to pine and oak species. Its full development is reached in

permeable, adequately moist, but well-aerated soils. A heart-root lacks the

main root but consists of several primary and secondary laterals, extending

into a network of fibrous feeding roots. This root system pattern is produced

by maple, beech, and fir. It attains its full development also in permeable,

well-aerated soils. A plate or flatroot is composed of anchoring

horizontals and numerous fringe roots. It is exhibited by spruce, hemlock,

and other trees of saprophytic tendencies, especially when they grow in

poorly drained soils.

1 2 3

Fig. 1. Major types of root systems of forest trees:

1 — taproot; 2 — heartroot; 3 — plate-shaped or flafroot

Flowers

Petal. Flowers may be considered to be modified branches whose

leaves have undergone such change that they have become, or support, the

reproductive organs of the plant. Flowers of woody plants are ordinarily in

blossom for so short a time that, during the greater part of the year, they

are of little value for practical purposes of identification. However, since

all natural classifications of seed plants are based upon flower structure

(see Fig. 2), it is essential to have a basic knowledge of tree flowers.

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Fig. 2. Flower Structure:

1 — peduncle; 2 — receptacle; 3 — sepals; 4 — petals; 5 — stamens; 6 — pistil

Flower parts. A flower having a calyx (sepals), a corolla (petals), stamens,

and one or more pistils is said to be complete. A perfect flower includes

actively functioning organs of both sexes, but the accessory parts

(calyx and corolla) may or may not be present. It follows, therefore, that a

perfect flower may be either complete or incomplete. A flower lacking either

functioning stamens or functioning pistils is imperfect. Imperfect

flowers are also known as unisexual flowers, while perfect flowers are

called either bisexual or hermaphroditic. An imperfect flower in which the

only functioning sex organs present are stamens is called a staminate

flower, while that in which the pistil is the only active organ is said to be

pistillate. A species in which these separate staminate and pistillate flowers

are both borne on the same individual, although frequently on different

branches, is termed monoecious; in contrast, when the staminate flowers

occur on one tree and the pistillate appear on another it is said to be dioecious.

In some instances both perfect and unisexual flowers occur on the

same tree. Species exhibiting this condition are termed polygamous.

When both calyx and corolla are wanting*, a flower is said to be naked.

If only the corolla is omitted however, the flower is apetalous. When

the corolla is composed of separate petals, the flower is classified as a

polypetalous type; but when the petals are partially or wholly fused with

one another it is said to be sympetalous.

Fruit

A fruit may be defined as the seed-bearing organ of a plant. Since the

fruits of conifers are quite different in structure from those of the angiosperms

(broad-leaved trees), each group is considered separately.

Coniferous fruits may be either dry or fleshy. In the majority of cases

they ripen during the first season, although in several genera, two and occasionally

three years are necessary for their maturation.

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The principal unit of the cone is the cone scale. The scales are attached

to a central woody axis and may be spirally inserted. They may be

either thin or thick, flexible or rigid, broader than long (some species of

fir), narrow-oblong (some pines), or peltate (shield-shaped) in some "cedars"

and cypresses.

The exposed portion of the cone scale in a mature unopened cone is

known as the apophysis. In some species the apophysis is smooth, in others

it is wrinkled; also it may be grooved or ridged.

Seeds are borne at the base of the cone scales.

Angiospermous fruit is generally described as a ripened ovary, although

in some fruits various accessory parts such as the receptacle, involucre,

calyx and style are also included. These fruits may be classified in

a number of ways. If their origin is traceable to a single pistil, they are

known as simple fruits, but when two or more pistils on the same receptacle

are involved in their formation, they are said to be compound. Both

types of fruits may be either dry or fleshy.

Note:

* are wanting — отсутствуют.

Topical Vocabulary

twig — веточка, прут;

cruise — таксация (леса) || таксировать, проводить таксацию;

tally — подсчитывать, пересчитывать;

poplar — тополь;

lenticel — чечевичка (поры в коре ветвей);

bud — почка; зачаток;

leaf scar — листовой рубец;

stipule — прилистник;

pith — сердцевина;

spine thorn — колючка, шип;

glaucous — тусклый; покрытый налетом;

pubescence — опушение, опушенность;

leaf-bud — листовая почка;

axillary bud — пазушная почка;

ruptured strand — оторванная, разорванная жила;

vascular tissue — сосудистая ткань; сосудистая сеть, сплетение;

vascular bundle — сосудистый пучок;

privet — бирючина;

leaf-stalk — стебель листа;

petiole — черешок листа;

node — узел; нарост; мутовка;

leaf-blade (lamina) — пластина листа;

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sessile — сидячий; бесчерешковый;

network of veins — сеть жилок;

venation — жилкование; венозная сеть;

reticulate — сетчатка; сетчатый, ретикулярный;

horse-chestnut — конский каштан;

ash — ясень;

acacia — акация;

taproot — главный стержневой корень;

heartroot — сердцевидный корень;

plateroot / flatroot — пластинчатый, плоский корень;

feeding root — питающий корень;

mycorrhizae — микориза;

fibrous root — мочковатый корень;

fringe root — бахромчатый корень;

saprophytes — сапрофиты (микроорганизмы, питающиеся органическими

веществами отмерших организмов);

blossom — цвет, цветение;

calyx — чашечка (цветка);

sepal — чашелистник;

corolla — венчик цветка;

petal — лепесток;

pistil — пестик;

uni(bi-)sexual flower — однополый (двуполый) цветок;

hermaphroditic — гермафродитный, бисексуальный, двуполый;

s taminate flower — тычиночный цветок;

pistillate flower — женский цветок;

monoecious — обоеполый;

dioecious — двудомный;

apetalous — безлепестный;

polypetalous — многолепестный, раздельнолепестный;

sympetalous — спайнолепестный;

angiosperms — покрытосеменные растения;

maturation — созревание; достижение полного развития;

cone scale — чешуйка шишки;

cypress — кипарис;

apophysis — апофиза (видимая часть семенной чешуйки сомкнутой шишки);

ripened ovary — созревшая завязь;

receptacle — цветоложе;

involucre — обертка соцветия.

EXERCISES

Exercise 4. Make the words negative. In case you are not sure check

the forms in the texts. Model: perfect — im perfect.

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woody; fortunately; complete; opened; petalous; developed; accessible; variably;

regard; like (adj.).

Exercise 5. In scientific texts prefixes of Greek origin are often used.

Some of them can be found in the texts under study, e. g. mono- (греч.

‘один, единый, единственный’), di- (греч. ‘два, дважды, двойной’),

poly- (греч. ‘много, многое’).

Compare: uni - (лат. ‘один’) и bi- (лат. ‘два, двойной’), multi -

(лат. ‘много’).

A) You can easily guess their meaning and translate the examples

suggested: unisexual; monoecious; dioecious; polygamo-monoecious; polygamo-

dioecious; polygamous; polypetalous;

B) Translate the following words with prefixes. Consult the dictionary

if necessary:

- polyatomic; polychromatic; polyglot; polysemantic; polyvalent; polygamy;

- digamy; digraph; dimorphic; diode; diptych; diatomic;

- monoculture; monorail; monogamy; monologue; monotone; monoxide.

Exercise 6. Insert the right word from the list below.

axillary buds; binomial system; boundary; dendrology; generic names; herbaceous;

in blossom; leaf scar; morphological types; polypetalous; selection;

Timber cruiser.

1. Linnaeus developed the … of nomenclature, which is now used.

2. The average … relies almost wholly upon bark in tallying species.

3. … tends to focus on economically useful woody plants, their identification

and horticultural or silvicultural properties.

4. … always appear first and are invariably capitalized.

5. The root systems of trees tend to exhibit three …: taproot, heartroot,

and plate or flatroot.

6. There is no sharp … between plant taxonomy and dendrology.

7. Flowers of woody plants are ordinarily … for so short a time and

they are of little value for practical purposes of identification.

8. When the corolla is composed of separate petals, the flower is classified

as a … type.

9. … produce branch shoots, or single leaves or flowers.

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10. Theophrastus differentiated between woody and … forms but

failed to indicate any botanical relationships.

11. The chief characteristics of trees usually influence the … of

their common names.

12. When a leaf falls from a twig, there remains at the point of attahment

a ….

Exercise 7. Supply synonyms for the words taken from the texts.

bare; bushes; commemorate; dominating; form; in blossom; leaves; ripening;

Sleeping; stem.

1. Douglas-fir is the common name applied to coniferous trees of the

genus Pseudotsuga in the family Pinaceae, which honours David Douglas,

the Scottish botanist who first introduced the tree into cultivation in 1826.

2. Larches are among the dominant plants in the immense boreal forests

of Russia and Canada.

3. Others are shrubs less than 10 metres tall with a number of small

trunks originating at ground level.

4. Though individually flowers may be small, the effect of an entire

tree in flower can be striking in several species.

5. Most species require stratification in order to germinate, and some

seeds can remain dormant in the soil for several years before germinating.

6. Junipers vary in size and shape from tall trees, 20—40 m tall, to

low spreading shrubs with long trailing branches.

7. The seed maturation time varies between species from 6—

18 months after pollination.

8. The needles turn yellow and fall in the late autumn, leaving the

trees leafless through the winter.

9. Because of its beautifully shaped crown and dense lustrous foliage,

the silver fir is commonly used ornamentally.

10. All firs are trees, reaching heights of 10—80 m tall and trunk

diameters of 0.5—4 m when mature.

Exercise 8. Insert who, which, or that into the complex sentences with

attributive clauses. Translate the sentences into Russian.

1. Because of the great confusion on common names, it became necessary

to find some universal system, … could be used throughout the world.

2. Such a system has been developed through the use of Latin names,

many of … were first applied when this language was employed by scien 68

tists. 3. Thus in the scientific name Quercus imbricaria Michaux Quericus

is the generic or group name, imbricaria is the specific or species name,

and Michaux is the person … named and described the tree. 4. It should be

indicated that the factors, … influence the original choice of common

names apply as well to scientific names. 5. The first extensive classification

of plants was that of Caesalpino (1519—1603), an Italian physician,

who arranged and classified a large number according to the nature and

structure of their fruits and seeds. 6. Linnaeus gave every plant species a

name … remained the same no matter what other species were placed in

the genus, and thus separated taxonomy from nomenclature. 7. It was soon

found that the structure of the flower was a suitable basis upon which to

classify all seed-bearing plants. 8. The most productive of the early naturalists

was Alexander von Humboldt, … collected 60,000 plant specimens

on a five year voyage to South and Central America from 1799 to 1804. 9.

In Europe, classification often emphasizes indicator or diagnostic species

… separate one type from another. 10. Functional classifications, which

attempt to categorise all plant species into a very small number of groups,

are unlikely to be effective.

Exercise 9. Translate the complex sentences with adverbial (conditional)

clauses.

1. Buds are young, undeveloped shoots; if they are leaf-buds only they

finally grow out to produce either single leaves or branch stems bearing

other leaves. 2. On the other hand, if they are flower-buds, they finally

produce the flower or flowers and then their growth ceases. 3. If the terminal

bud is severed or injured so that it cannot itself develop, then some of

the dormant axillary buds develop. 4. If an individual plant is either female

or male the species is regarded as dioecious. 5. If perfect flowers, together

with unisexual flowers of both sexes, are present on a single individual, the

species is polygamo-monoecious. 6. But if the perfect flowers are accompanied

by one sex on some individuals and with the opposite sex on others

it is polygamo-dioecious. 7. If both calyx and corolla are wanting, a flower

is said to be naked. 8. If only the corolla is omitted however, the flower is

apetalous. 9. If the flower has no stem but forms in the axil of a leaf, it is

called sessile. 10. If the peduncle (стебель, ножка) ends with groups of

flowers, each stem that holds a flower is called a pedicel (цветоножка).

11. If the perianth (околоцветник) is bisected through the central axis

from any point, symmetrical halves are produced — the flower is called

regular or actinomorphic.

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Exercise 10. Transform the sentences with if to make up definitions.

Model: If both calyx and corolla are wanting, a flower is said to be naked. —

The naked flower is the one, which has neither calyx nor corolla.

1. If only the corolla is omitted, the flower is apetalous. 2. If the

flower has no stem but forms in the axil of a leaf, it is called sessile. 2. If

the peduncle ends with groups of flowers, each stem that holds a flower is

called a pedicel. 3. If an individual plant is either female or male the species

is regarded as dioecious. 4. If perfect flowers together with unisexual

flowers of both sexes are present on a single individual, the species is polygamo-

monoecious. 5. If the perfect flowers are accompanied by one sex

on some individuals and with the opposite sex on others it is polygamodioecious.

Exercise 11. Give definitions to the following biological terms:

bud; leaf-bud; flower-bud; axillary bud; leaf-stalk; leaf-scar; leaf-blade; sessile

leaf; venation; reticulate; compound leaf; taproot; heart-root; flatroot; flower.

Exercise 12. Translate the text about fires into English, sentence by

sentence. Then speak about the damage forest fires make and their and

comment on the suggested approach.

Лист — один из основных органов. Состоит из листовой пла-

стинки, черешка, влагалища и прилистников. Форма, размеры, окра-

ска, продолжительность жизни частей листа и их число положены в

основу классификации листьев. Листья делятся на простые и слож-

ные: у простого листа одна листовая пластинка; у сложного — две и

более.

По форме листовой пластинки листья бывают: продолговатые,

или узкоэллиптические, линейные, яйцевидные, округлые, ланцет-

ные, обратнояйцевидные, обратноланцетные, эллиптические, ромби-

ческие, лопатчатые. Эти названия даны по соответствию внешнего

контура листовой пластинки той или иной геометрической фигуре.

При более детальной конкретизации к упомянутым терминам добав-

ляют слова «узко», «широко», «вытянуто» (например, широкояйце-

видный, узколанцетный и т. д.).

Существенный морфологический признак листьев — характер

расположения жилок. Растения различаются по расположению и при-

креплению листьев к стеблю. По этому признаку различают растения

с черешковыми, с сидячими листьями и т. д. Расположение листьев

на побеге также бывает различным.

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Questions and tasks

1. Why do foresters resort to both dendrology and taxonomy in their work?

2. What information is considered important for the common name?

3. Where are the Latin names of plants used? Why?

4. What does the binominal system include?

5. Who were the first contributors to the plant classification? What did they do?

6. Why is the Origin of Species considered revolutionary?

7. Is the structure of the flower of any use for the plant classification?

8. Is it possible to differentiate between trees judging from the bark and stem?

Can you give examples to prove your point?

9. How do twigs help to differentiate between tree species?

10.Describe the structure of the leaf. What is diagnostic in the leaf, do you

think?

11.What parts make the flower? Can the flower help to identify the tree species?