The study of Botany

11. The Study of Botany

A.Definition

Botany is the study of plants, their form and structure, their functions and behavior,their diseases, modes of reproduction and evolution, and their uses to mankind.

The term "botany" itself probably came from the Greek words botanikos (botanical) and botane (plant or herb).

(1) Importance of Plants:

a. Photosynthesis-sustains life on earth.

b. Plants fundamental source of food.

c. Plants provide fuel, shelter, and paper products.

d. Biotechnology

(2) The study of Botany or plant biology encompasses:

1.Origin

2.Diversity

3. Structure and internal processes of plants as well as their relationships with other organisms and with the nonliving physical environment.

(3)Characteristics of Plants:

a. highly organized -atoms, molecules (levels of biological organization)

b.takes in and uses energy.

c. grows and develops.

d.reproduces.

e. transmits information from one generation to another (DNA)

f. plant population undergoes genetic changes over time.

g. biological diversity

B. Historical Background

Plants have been used by man since pre-historic times for one purpose or another but there was no science of plants, no orderly or systematized knowledge about them.

The first study of plants by primitive man was undoubtedly a practical one,centered upon their economic importance, chiefly concerned with the medicinal values of plants. The Ebers papyrus (1500 BC) contains a list of several Egyptian drug plants and their uses. In 2500 BC, Chinese in the Orient cultivated orange,rice, and ephedra, a source of important nasal medication, the ephedrine.

Plant science, like other sciences,traces the first definite expression of its

principles and problems to the Greeks.

Aristotle (384-322 BC) - studied the nature of plants but wrote of them chiefly from the philosophical standpoint of their philosophical aspects. It is his disciple Theophrastus of Eresus (371-287 BC),whom botanists generally regard as the “Father of Plant Science". Among his many writings are The Inquiry into Plants and The History of Plants”. The latter is of interest to botanists,for in it,all the plants then known were classified and named for the first time.Many of these names are still in use today. Another Greek student was Dioscorides,who,early in the Christien era wrote a valuable book on medicinal plants, the Materia Medica.

Rome, too, had her share in the development of plant science through the contribution of:

1.Gato-who wrote the first agricultural book; “De Rustica”in Latin.

2. Pliny the Elder(AD 23-79)-who,early in the first century AD described almost a thousand species of plants, most of which were valued for their medicinal uses. His "Natural History”, a compendium of facts and fancies about living things, was for a long time the storehouse of botanical information throughout Europe, and which until 1469 existed in manuscript form. The Middle Ages,which lasted until the beginning of the 16th century,was a period of inactivity in European science. However, about the beginning of the 16th century, a group ofpioneering botanists in the Rhine Valley took up a renewed interest in plant studies chiefly for their curative qualities. This ushered in a new era im pramt studies, the Period of Herbs which lasted for abom 200 years (1500-1700).

Albertus Magnus - a typical philosopher and writer of the Renaissance. He wrote Botany during his time and was called the “Aristotle of the Middle Ages”.

The pioneers who wrote and published the herb books or herbals are known as the Herbalist.

Among the outstanding herbalists were:

1. Otto Brunfels (1464-1534)-wrote the book, Herbarium Vivae Eicones.

2. Helronymous Bock(1498-1554)-who emphasized the importance of descriptions of plants in their natural living conditions; also distinguished the effects and names of herbs.

3. Leonard Fuchs (1501-1566)-wrote the book,The History of Herbs.

4.Andrea Caesalpino (1519-1603)-who recognized the importance of the seed and fruit in plant classification; he was also known As the First Plant Taxonomist.

5.Gaspard Bauhin (1550-1624)-who adapted the binomial system of nomenclature.

6.Matthias de L'Obel (1528-1616)-who recognized the distinction between monocots and dicots based on leaf structure.

The Herbalists are generally regarded as the Founders of Modern Botany. That they were still rather primitive in scientific ideas shown by the fact that some of them maintained the Doctrine of Signatures which states that the Creator has placed a definite sign in each kind of plant which indicates its fulness.

Example:

a. Pomegranate seed - shaped like teeth so believed to dure toothache.

b. Plants with heart-shaped leaves can be used to cure heart ailments.

c.Plants with 3-lobed leaves can be used for liver trouble.

Modern botanical study began in the later part of the 17th century. Plant science,however, made its most rapid advances only during the 19th and early 20h centuries. Up to the middle of the 17th century, most of the botanical works were on classification.

1.John Ray (1628-1705) - laid the foundation of modemn plant taxonomy,when he conceived that a natural system should neither bring together dissimilar species nor separate those that are closely allied.

2.Carolus von Linnaeus (1707-1778)-who is regarded as the Father of Plant Taxonomy, proposed a sexual system of plant classification which was not based on natural relationships, it was, however, a tremendous advance over what had been done before.

3. A.L. de Jussieu (1748-1836)and A.P.de Candolle-formulated a system of plant classification which was largely phylogenetic.

4. Zacharias Jansen-perfected the magnifying lens in 1590. Plant taxonomy then was given emphasis.

5. Robert Hooke (1635-1703) -using these lenses accidentally found that plant tissues are made of units which he termed “cells”. This was the beginning of cytology, a new field of study then.

6.Marcello Malpighi (1678-1694) and Nehemiah Grew (1641-1712)-started investigations on the internal structure of plants thus paving the way for our modern knowledge of plant taxonomy.

7.Camerarius (1665-1721)-who demonstrated by experiments the sexuality in flowers, he proved that the pollen grain is necessary for fertilization and the formation of seeds.

The invention of the compound microscope and its continued improvement made possible a more accurate knowledge of plant structures.

8. Mattias Jakob Schleiden (1804-18881)-a German botanist who formulated in 839,together with a zoologist named Theodore Schwann (1810-1881),the Cell Theory which states that the cell is the basic structural unit of plants and animals.

9.Charles Darwin(1809-1882)-published in 1859 The Origin of Species recognized that the plants of today have developed from simpler ancestors.His theory of evolution stimulated interest in phylogeny of the plant kingdom; and led to extensive studies of the laws of inheritance and variation and the cause and methods of evolution.

10. Gregor Mendel (1822-1884)-an Austrian monk,proposed in 1866 the Laws of Inheritance. For his contribution to the science of heredity, he is generally regarded as the Father of Genetics.

A better understanding of the changes occurring in matter and energy came with the development of physical sciences and made possible that phase of modern botany dealing with the activities of plant physiology. It underlies the other fields of botany since it concerns all vital activities.

11.J.B.von Helmont(1577-1644)-after experiments with a potted willow plant, arrived at the conclusion that the increase in mass of the plant was derived from the water and not from the soil, thus laying the foundation of plant physiology.

12.Stephen Hales (1677-1761)-a contemporary of von Helmont who made critical experiment upon the manufacture of food by plants and upon the transportation of materials within the plant body. These contributions made him,one of the first great figures in the field of plant physiology.

C. The Scope of Botany

Botany is divided into Pure and Applied botany.

Pure botany concerns itself with the study of plants without regard to their utility to man. This is divided into General and Specialized botany.

I. General Botany is further divided into:

1. Plant Taxonomy or Systematic Botany - the study of plant identification,classification, and nomenclature.

Major part of systematics that include four components:

1.Description - assignment of features or attributes to a taxon.The features are called characters. Two or more forms of a character

(character state)

e.g.petal color-yellow or red

leaf shape -lanceolate, ovate

2. Identification-associating an unknowm taxon with a known taxon.

Dichotomous key-pair of contrasting statements. Each statement is a lead.

3.Nomenclature-naming of taxa according to standardized system.

4.Classification-arrangement of entities into some type of order -utilizes categories for ranks (hierarchical)

Taxon -a group of organisms typically treated at a given rank,e.g. Magnoliophyta is a taxon placed at the rank of Phylum.

Major Taxonomic ranks:

Scientific name: Cocos nucifera or Cocos nucifera

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2.Plant Morphology-the study of plant structure and form; gross morphology deals with the form, arrangement, and relationships of the external organs of plants.

3.Plant Physiology-the study of the activities and functions within plants.

4.Plant Genetics-the study of inheritance and breeding.

5.Plant Evolution-the study of the development of present-day forms from ancestral types in the past or the unfolding of more complex plants from the simplest ones.

6.Plant Ecology-the study of the distribution of plants and their environment.

7.Phytogeography-the study of the distribution of plants in relation to spaces or the study of plants on the surface of the earth.

8.Paleobotany-the study of plants in relation to time through the study of fossils.

II. Specialized Botany deals with groups of plants.

1.Phycology-study of algae

2.Mycology-study of fungi

3. Pteridology-study of ferns

4.Agrostology-study of grasses

Applied Botany or economic botany deals with the study of plants with the aim of using the knowledge in the interest of man.

1.Agronomy-science of crop production or farm management

2.Horticulture-art of growing flowers

3. Forestry- deals with forest management

4.Orchidology-science of growing orchids

D.Reasons for Studying Botany

There are several arguments for devoting a part of one's life to the study of plants. In the first place, we owe our very existence to plants. Green plants are the only mechanisms with the ability to construct from simple and elementary substance types of chemical compounds essential for the existence of all human life. Everyone recognizes the economic importance of the common field crops,rice, com,or vegetables and fruits, and hum'ber. The fohowing is a hist of some interesting facts regarding the importance of plants.

III. The World of Plants

A. Kind of Plants

Plants differ in sizes,form, color,life history, distribution, mode of adjustment to environment, and usefulness.

The different kinds of plants may be grouped according to:

1.)Size

a. Bacteria- 1/2 micron length and 1/5 micron wide

b. Seaweeds-several hundred feet long

c. California Redwoods (Sequoias) - some of which attain heights of over 350feet diameters of 30 feet, and weights of 2100 tons, (lumber from one tree can supply 235, 5-room houses covering 3-sauare city (blocks). Thus, the Redwood are the tallest known land plants.

2.) Body Forms

The forms of plant vary even more than to their sizes. They may exist as:

a. unicellular - the simplest form

b. multicellular - may be colonial, filamentous or chain like: thalloid or with no differentiation into roots, stems and leaves; or a seed plant body with true roots,stems and leaves.

3.) Seed-bearing or non-Seed-bearing Forms (flowerless or flowering plants)Plants also differ among themselves in the mode of reproduction.

a. Cryptogams- those which are non-seed-bearing or flowerless plants (e.g.algae,fungi,bryophytes,mosses,and ferns)

b. Phanerogams those which are seed-bearing or flower-bearing plants.

They are in turn composed of two distinct groups.

(1)Gymnosperms or the naked-seeded plants (pines, cycads)

(2) Angiosperms or those whose seeds are enclosed in ovaries. They are composed of dicot and monocot plants.

Differences between Dicot and Monocot Plants

4.)Texture and Habit

Each species has its own characteristic habit of growth, texture and other peculiarities which enable us to distinguish it readily from other kinds of plants.

a. Tree- tall woody plants having a single main stem which develops for some distance from the ground.

b. Shrub-woody plants but without a single mai stem,branching freely. from the ground. It is comparatively shorter than a tree.

c. Herb-those which are soft stemmed or non-woody plants.

5.)Position of Growth

According to the position or direction of growth, plants may be described as:

a. erect or upright

b. prostrate or creeping along the surface of the ground.

c. climbing-e.g.vines

6.) Longevity

Another physiological difference in plants is found in their longevity. In some bacteria, the lifetime of an organism may last for only 20 to 30 minutes after which time it forms two new organisms. At the other extreme of age are certain coniferous trees which attain ages of over 3,200 years.(e.g. Sequioas)

Many of our plants may be grouped as follows:

a. Annuals -live for only a single growing season,usually less than a year,e.g.corn,sugar cane.

b. Biennials - live through two seasons, more than a year but not more than 2years,e.g.eggplants,squash.

c. Perennials - continue to grow for many years,e.g.buri palm.

7.)Habitat

One of the most striking physiological differences among plants is their varying distribution in diverse habitats.

a. terrestrial plants - those living on land or soil.

b. epiphytes-those that live in air perched on other plants or objects.

c. aquatic plants -those living in water (marine or fresh water)

8.)Water Requirements

a. Hydrophytic plants -those which require an abundance of water;water-loving plants.

b. Mesophytic plants-those which thrive under moderate conditions.

c. Xerophytic plants-those that thrive best under dry conditions (desert)

d. Xerophytic plants-those that thrive best under dry conditions (desert)

e. Xerophytic plants -those that thrive best under dry conditions (desert)

f. Halophytic plants -those that thrive best under salty conditions.

9.1 Form of Shoot

The method of branching in plants is characteristic of the species.

a. excurrent plants - those having a single main trunk, tending towards a cone-shaped crown,e.g. pine tree.

b. deliquescent plants - those which are greatly branching, forming an almost

hemispherical crown,e.g.acacia.

10.)Shedding of leaves

The shedding of leaves is one of the most interesting physiological activities which occur in plants.

a. Deciduous plants - leaves fall off the branches which bear them at the end of their growing season.

b. Evergreen plants-leaves persist for several seasons, often for four years or longer,e.g.gymnosperms

B. Activities of Plants

Each individual plant carries on different processes necessary for its existence.These activities are two-fold: vegetative and reproductive activities.

1.)Vegetative activities-those which have to do with the growth and preservation of the individual. Organs performing these activities are termed vegetative organs (roots, stem,leaves).

Important vegetative activities are:

a.) absorption of water and nutrients from the soil

b.) translocation of substances within the plant

c.〕photosynthesis or food manufacture in the green cells or plants using carbon dioxide and water as raw materials with the aid of sunlight

d.) digestion and conversion of insoluble food to soluble form

e.) assimilation or the transformation of non-living substance into living protoplasm

f) respiration or the oxidation of food to release energy, involving exchange of gases

g.)transpiration or loss of water in the form of water vapor from the leaves and other aerial parts of the plant.

2.) Reproductive activities-those which have to do with the continuation and propagation of the species. Reproductive organs are flowers,fruits,and seeds.

C. Distribution of Plants

The entire land surface of the earth is covered with a mass of vegetation except in areas where it is too cold or too dry. Plants inhabit the ocean floor to a depth of 425 feet and highest mountains up to 20,130 feet above sea level. Such vegetation is so varied in any one region and so different in different regions that it has long excited the interest of botanists and layman alike.

The diversity of plant populations is due to two main causes:

1.Differences in environmental factors in the regiom where plamts grow.

2.Differences in the evolutionary history of the plant populations.

D.Classification and Nomenclature of Plants

The necessity for classification arises from the fact that there are so many kinds of plants. A system of some sort is needed to effectively handle this tremendous number of kinds.

1.Methods of Classification

Several systems of plant classification have been proposed and adopted since the time of Theophrastus,each representing a distinct advance over the preceding.

a. System of classification based on habit and uses - adopted by classical botanists and was in general use even up to the 17th century.

b.Artificial system of classification - introduced by Linnaeus, was one in which there are no recognition of any actual relationship between different kinds but based only upon superficial characteristics as number of floral parts, etc.

c. Natural system of classification - supplanted the artificial system later. This was based on natural relationships, that is, upon the true affinities of similar plants which are grouped together. In general, the simpler forms of plants are placed first. And the more complex ones follow. This was an attempt to classify plants as they occurred in nature.It doesn't recognize ancestry.

d.Phylogenetic system of classification -the latest and the most widely accepted system of classification at present. This is based on genetical relationships between plants. It is based on ancestry or grouped descent.

E. Plant Groups or Categories

In plant taxonomy, just as in methods of classifying all sorts of things, a series of groups within group has been recognized and its parts named. Subgroups are sometimes employed. The most important of these plant groups arethe following arranged in order of their size with corresponding examples of names.

Examples:

Kingdom Plantalia

Phylum Magnoliophyta (flowering plants)

Class Liliopsida(Monocots)

Order Cyperales (grass and sedges)

Family Poaceae(Graminae)

Genus Zea

Species Z.mays(corn)

Kingdom Plantalia

Phylum Magnoliophyta

Class Magnoliopsida (Dicots)

Order Rosales

Family Rosaceae

Genus Lathamus

Species odoratus (rose)

F. Naming of Plants

a. Common Names

Very familiar plants have, through the ages acquired common names.Attractive and interesting as these common names,are, they have,however, no very wide usage or value in scientific publications.

The chief objections to the use of common names are the following:

(1)there are often many different common names for the same plant in different localities.

(2)the same name may refer to several kinds of plants

b. Scientific Names

Scientific names have been given to plants to establish uniformity and universality, i.e. a single valid name is used all over the scientific world.

To achieve this, aim all scientific names, as well as the technical names for the various plant groups are in Latin.

The regulations used in the construction of scientific names are formulated by the International Botanical Congress which first met in Paris in 1867. rules adopted by this congress is observed and generally followed by botanists.

Principles of Scientific Classification or Rules of Nomenclature

1.) Botanical names are independent of from zoological names.

2.) Scientific names must be Latinized T/F)

3.) Generic names should consist of a single word and should begin with a capital letter.

4.)Specific name is an adjective and should begin with a small etter.

5.)Author of the scientific name is the first person to publish the name with a valid description of the organism.

6.) A Family name has the ending -aceae, e.g. Asteraceae, while names of Orders end in ales, e.g.Asterales, names of Class ends in -opsida, eg Magnoliopsida; and names of Division/Phylum ends in-phyta,e.g. Magnoliophyta.

7.) No names are recognized prior to those included in the Systema Naturae,10th edition in 1758.

The present binomial system of nomenclature adopted in naming plants is so called because each species is given two names: the Genus and Species.

The first part of the binomial plant name is the generic name (genus) while the second part becomes the specific(species) name.

It is the practice to follow the binomial name with the name (or the abbreviation of the name) of the botanist who first gave the plant its scientific name to ascertain the original description of the plant or its exact identity in case of a duplication of names.

Example:Oryza sativa Linn.(rice)

Origin of Scientific names

Frequently, the generic name is the ancient Greek or Roman name for the plant, such as Pinus for pine. Usually,these names refer to some distinctive character of the plant. Thus,the coconut genus Cocos(from the Latin word, round) refers to the shape of the fruits.Often it honors some person,as Cummingia for Cumming.

The species name is usually descriptive of the plant andso the following names would signify:

(a)alba-white

(b) latifolia-broad leaf

(c) grandiflora-large flower

(d)trifolium-clover-like large flower

(e) aureus-golden

(f)vulgaris-common

(g) aphyllum-leafless

E. Division of Plants

1.Prokaryotes

not true nucleus

simple internal structure of cell

· non-membrane bound nucleus-

DNA not organized in true chromosomes

a) Bacteria

- simplest living organisms; unicellular, filamentous, heterotrophic, some are photosynthetic;others chemosynthetic; maybe flagellated; 3 billion years old.

b.) Cyanobacteria (blue-green algae)

- bluish-green in color, photosynthetic, unicellular,colonial, or filamentous,2million years old

2. Eukaryotes

have true nucleus

complex internal structures

· membrane-bound organelles

DNA organized into chromosomes

flagella may be present

a. Euglenophytes

unicellular;flagellated

with green chloroplasts

with contractile vacuoles

b.) Dinoflagellates

- unicellular,heavy wall of armorlike plates; two flagella; Photosynthetic,saprophytic, or phagocytic; mostly marine

c.)Diatoms

-unicellular or colonial: cell wall with silicates, motile; mostly photosynthetic a.)

d.)Brown algae

-brownish in color, multicellwlar, attached to rocks along seashores,photosynthetic

e.)Red algae

- bodies often reddish in color; occurring mostly as branched filaments; live and mainly attached to rocks or to larger algae along seashore; photosynthetic

f)Green algae

- bodies bright green in color, unicellular; colonial; filamentous; and tubular,photosynthetic,some are colorless and heterotrophic g.)

g)Fungi

- body usually composed of cobweblike threads (hyphae); some unicellular;heterotrophic

h) Bryophytes (liverworts and mosses)

-liverworts are usually small, delicate, creeping, or prostate plants with ribbonlike or leafy bodies. Mosses have usually short body, with an erect, leafy stem;have many adaptations for land life but lack water and food conducting tissues.

i) Vascular plants

- well adapted for land life with fostructures.er conducting tissues and supporting

tissues Clubmosses-trailing or creeping plants with small leaves;spores

produced in spore sacs clustered into clublike or conelike structures.

j)Horse tails

- plants with hollow, jointed stems; leaves small and inconspicuous; spores in conelike structures

k) Ferns

-leaves usually large, conspicuous but divided into distinct segments; spores are produced in tiny cases on underside of leaves.

1.) Seed plants

- trees, shrubs, or herbs producing seeds in either cones or fruit

m) Conifers (Gymnosperms)

- large trees, mostly with needle like leaves; many evergreens; produce seeds in cones

n) Flowering plants

- trees, shrubs, or herbs; usually with broad, net-veined leaves, produce flowers,and seeds enclosed in fruits.