Groups and Periods in Periodic Table

GROUPS AND PERIODS

(a) Groups:
"Elements with similar properties are placed in vertical columns called groups."
        There are eight groups, which are usually numbered by Roman numerals I to VIII. Each group is divided into two sub groups, designed as A and B sub-groups. The sub-groups, containing the typical or normal elements or representative elements, are labeled as A sub-groups whereas B sub-groups contain less typical elements, called transition elements and are arranged in the centre of the Periodic Table.


(b) Periods:
"The horizontal rows of the periodic table are called periods."

Period 1: 
        The period 1 contains only two elements, hydrogen and helium.

Period 2 and 3:
        The Period 2 and 3 contain eight elements each are called short periods. All the elements in these periods are typical elements and belong to A sub-groups. In these periods, every eight element resembles in properties with the first element. As lithium and beryllium in the 2nd period resemble in most of their properties with sodium and magnesium of the 3rd period respectively. Similarly boron and aluminium both show oxidation state, of +3 fluorine in 2nd period has close resemblances with chlorine of 3rd period.

Period 4 and 5:
        The period 4 and 5 are called long periods. Each long period consists of eighteen elements. Out of these, eight are typical elements belonging to A sub-groups similar to second and third periods. Whereas the other ten elements, placed in the centre of the Table belong to B sub-groups and are known as Transition Elements. In these periods the repetition of properties among the elements occur after 18 elements. As after 19K (having atomic number 19), the next element with similar properties is 37Rb.

Period 6:
        The period 6 is also a long period, which contains thirty-two elements. In this periodic there are eight typical elements, ten transition elements and a new set of fourteen elements called Lanthanides as they start after 57La. Lanthanides have remarkably similar properties and are usually shown separately at the bottom of the Periodic Table.

Period 7:
       The period 7 is incomplete so far. It contains only two normal elements 87Fr and 88Ra, seven transition elements and fourteen inner transition elements. The inner transition elements of this period are called Actinides as they follow 89Ac. The actinides are also shown at the bottom of the Periodic Table under the Lanthanides. Due to their scarcity, the inner transition elements are also called rare earth elements.
        Trans-uranic elements (elements after uranium) they are prepared in the laboratories.
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Artificial, Natural & Phylogenetic System Of Classification



History Of Different System Of Classification

Various attempt made to classify the plants fall in one of the following in three categories.
·        Artificial system of classification
·        Natural system of classification
·        Phylogenetic system of classification

Artificial system of classification: the earliest system of classification were artificial system and the system of this nature remained dominant from 300 BC upto 1830 AD. Since vary little information was available about plants these system were based on one or few character. The artificial system proposed by early herbalist were based on habit, trees, shrub, herbs and Linnaeus sexual system on floral character.

Theophrastus: (370-287 BC) A Greek naturalist who is called is father of botany. He was the student of great philosopher Plato and Aristotle. He classified the plants into four group on the basis of their habit that is herbs under shrub and trees. He gave name and description to some 500 plants in his book (Historia Plantarum). The oldest botanical work in existence because a wide use his name received general recognition and some of them still appeared as generic name in modern classification for instance. 

E.g Aspharagos (Greek)   Asparagus (Latin).

He pointed out fundamental difference between monocotyledon and dicotyledon and also recognized difference types of insertion of floral appendages, Thus so lying out foundation for the study of floral morphology.

Angera Caisapina (1519-1603) He was first plant taxonomist and Italian botanist director of botanical and professor of botany in Bologna university. He went to Rome in 1592 as a personal physician of Pop.

Gasspard Bauhin (1560-1624) He was Swedish botanist (1st generic name and 2nd species name this idea gave by them).

John ray (1627-1705) English botanist he was head of padiest.

Carolus  Linnaeus (1707- 1878) He was consider father of botany, 24 classes of classification gave be them, books written by them (species plantarum and generic plantarum)

Natural system of classification: The 2nd half of the 18th century was a period when great number of living plants, seed plants and collection of prepared specimen was coming to European botanical institution from all over the world. A large proportion of these were of species new to science each was to began a name to be describe and place in classification. Preparation of flora  the realization that there were great nature affinities / linking  between plants then the so called sexual system of Linnaeus would indicated.
This realization was not derived from theory and philosophy or logic but was made by means of increase knowledge and understanding of the organography / morphology of the plants. Microscopy was invented in these period, function of plants also noted and help of microscopy new system were called natural system. And they were so in the sense that they reflected means understanding of nature at their time. The plants were placed together existed a correlation of character in common.

Natural System Of Classification


Augustin Pyramus de Candolle system of classification

Ø Vascular plants with vascular bundles and cotyledons.

Exogene: dicotyledons, vascular bundles are arrange in a ring

Endogene: monocotyledon vascular bundle are scattered on the ground tissue .

Ø Celulares plants without vascular bundles.

Foliaceae: leafy sexual plant include mosses and liverworts.

Aphillar: leafless, algae, fungi and lichen

 

Bentham and Hooker Natural system of classification

George Bentham 1800-1884,josep-dalton hooker 1817-1911 two british botanists were associated with royal botanical garden kew at london. They jointly produce  a book genera plantarum 1862- 1883 completed this book.




Classification of Bentham and hooker

1.       Polypetalea: 82families include these are group of dicotyledon

2.       Gamopetalae: 45 families include

3.       Monochlamydeae: 36 families lower plants include.

4.       Gymnosperm: 3 families include

5.       Monocotyledon: 4 families include.


Phylogenetic system of classification

The outlook of taxonomy was changed with the publication of origin of species through natural selection by Darwin in 1859 ,24 November. Every copy of 1st edition was sold on the first day of 24 November 1859 which revolutioned biological thinking. The system of this period are based on the course of evolutionary descent and try to reflect the genetic and phylogenetic relationship. The most widely known system of this period are those of Engler  and Prantl both was German scientist.

John Hutchinso: 1884 -1930 belong to England royal botanical garden .
Two modern systems Arman Takhthan Jaan 1911-1997 authur cronquest 1919-1992 his system of classification was published in fully documented form Coloumbia university USA.

Engler and prantel the two german botanist publish a twenty volume work.
Die naturalichen pflanzan families 1887-1899 published this book where in classified the plants of the world from algae to angiosperm according to their system of classification.

This system has gone undersome changes in syllabis der pflanzen families one volume book which were published in several edition.
The 12th edition appeared  in 1964.
Angler and prantle system of classification is as important as that of benthum and hooker.

The system of classification published in following heading.
1.     Metachlamydeae
2.     Archechlaymdeae
3.     Apetalae

Metachlamydaea fused carpel includes gamopetlous form where aa archeclamydeae into polypetlous form.
The polypetlos form were included in chloropetale and Apetale [without petals].
Each subclass is divided into orders and ordes are composed of group related families.


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Taxonomy & Its Realtionship


Taxonomy

“May be defined as study of principle rule and procedure of classification”

Or

 “The study and description of variation of an organism

Explanation: The investigation of causes and consequences of variation and manipulation of data obtained to produce system of classification such a definition is wider then sometime given and coincide with the meaning of systematic. In fact the two term are used now a day synonymously, it should however be realised some author prefer to differentiate between them.

In which case systematic has more or less broad definition & taxonomy is restricted to study of classification.

According to sole bridge systematic more or less broad definition & its cover all relationship existing between the organism.

Systematic is concern with comparison study of organism and all relationship existing among them.

1.     Relationship of descent: also called phylogenetics relationship indicate the degree to which to individual plants are related to one another.

2.     Relationship of similarities of phenetic relationship: [morphological] indicate the degree to which to individual plant look alike not only in their external morphology but in all other aspect such as anatomy, physiology & cytology.

3.     Geographical relationship [spatial]: indicate how closely two  plants are related on the basis of geographical relationship .e.g. population of one species is found in Japan & other population in temperate America.

4.     Tropical and nutritional relationship: indicate independence that is the extent to which to individual plants depend upon each other. For example, when one is parasites on other or when both utilize the same mineral in the soil.

Although systematic deals all of these relationships phylogenetics & phenatic relationships emphasize.

In order to find the limit or extend plants are related one must compare them. Comparison is therefore the basic methodological approach of systematic.
[comparison  & distinction ]↔[species concept]


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International Code of Botanical Nomenclature



International Code of Botanical Nomenclature
The foundation of international code of botanical nomenclature are found in linnaeus (book name) philosophia botanica in 1751, where in he proposed certain principle of nomenclature and other significant work on plant nomenclature was Augustin de-candolle Theorie elementareae de ta botanique 1813 which give detail rule on plant nomenclature.

However the first organize effort to develop a precise and simple system of nomenclature to be used by botanist in all countries were made at the 1st  international botanical congress held in 1867 in paris. At this congress the laws of botanical nomenclature proposed by Alphone De-candolle. He was son of A.De-candolle  were adopted with some modification as a guide for nomenclature in plant kingdom. These rules are known as D.candolle rules or Paris code of 1867.

The subsequent internal botanical congress made significant contribution with regard to plant nomenclature, but it was only at Cambridge in 1930, that for the 1st time in botanical history a code of nomenclature came into being. That was international function as well as name.

The rule of nomenclature adopted at Cambridge congress were subjected to some changes and refinement from time to time. However in 12th botanical congress held in Russia in august 1975. The 15 botanical congress held at Tokyo 1993.

The code is divided into three parts.
(i)Principle (ii)Rules and (iii) Recommendation.

Principle form the basis for system of botanical nomenclature.

Rules six principle rules of code are as follow

1.     The botanical nomenclature is independent of zoological nomenclature.
2.     The application of name of taxonomy group is determined by means by nomenclature type.
3.     The nomenclature of taxonomy group is based upon priority of publication.
4.     Each taxonomic group bear only one correct name, the earliest that is in accordance with rules of except in specific cases.
5.     Scientific name of taxonomy group are treated as Latin regardless of their derivation.
6.     The rules of nomenclature are retroactive.

Recommendation are often practice application of the rules, their object to bring about uniformity and clearness, Specially in future nomenclature.
The code has three appendixes.

1)     Deals with name of hybrid.
2)     Nomina familiarum conservanda includes the names of families which are conserved.
3)     Nomina generica conservenda ET.Rejiscenda  
4)     list the name of genera against the priority of publication because of their long use.


Rules Of Nomenclature

Type method
1.     Holotype
2.     Lactotype
3.     Syntype
4.     Isotype
5.     Neotype
6.     Topotype

Type method/ Typification:
1.     Holotype: is a single type designated by the original author of a taxon is known as holotype.
2.    Isotype: are duplicates of the holotype often being sent to the herbaria. Isotype from single collection, that contain the holotype.
3.     Syntype: are two or more specimen designated by the original author when no holotype was designated.
4.    Lactotype: is one of the syntype subsequently chosen from the syntype to act in place of holotype.
5.     Neotype: is a specimen designated to act in place of a holotype. when no holotype and syntype exist. In some cases when all the material in which the description of new species was based is missing, then the neotype must be selected and selection once made must be followed by the subsequent botanist.
6.     Topotype: is a specimen collected from the same locality from where the holotype was collected previously.

Plural adjective and is formed by adding the suffix 'aceae' to the legitimate the name of genus; e.g Rosaceae from Rosa, Cucurbitaceae from Cucurbita etc.

Special exception is made for the following 8 families.
The names because of long usage are treated as validly published. For these families alternate name are primitive in the code.

·       Palmaceae             -                Arecaceae
·       Guttiferae              -                Clusiaceae
·       Compositae           -                Astraceae
·       Umbelliferae         -                Apiaceae
·       Leguminosae         -                Fabaceae
·       Graminae               -                Poaceae
·       Labiatae                 -                Lamiaceae
·       Cruciferae              -                Brassicaceae

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Ranunculaceae



Ranunculaceae

The family includes about 50 genera and 1500 species distributed in temperate and colder regions of the world.

Ranunculaceae is a large family containing a number of well known wild flowering plant and garden ornamentals, such as buttercup (Anemone) poisonous plant and also medicinal plant such as Aconitum napellus.

Field identification:
Herbs, leaf with sheath base, lamina often dissected, flowers bisexual stomata and carpels number spirally arrange, ovary superior, fruit achene and folical.

Distribution:
The family is cosmopolitan distribution throughout the world but is concentrated in temperate and cold region, of northern and southern hemisphere.

Diagnostic character:
Mostly herbs, sometime shrubs rarely trees, or climber or woody climber e.g clematis gratus are woody climber. The perennial herb species usually persist by mean of condensed root stock or rhizome.

Ranunculus ficaria have rhizome.

Leaf:
Mostly alternate, opposite and climates in ranunculus species, pamptly lobed or compound leaf stipule absent.

Inflorescence:
Solitary flowers or cymose, raceme, pennicles.

Flowers:
Bisexual, actinomorphic with spirally arrange stamen and carpels. Hypogynous (ovary superior below)

Calyx:
5 sometime 3 or many and free, polypetalous.

Corolla;
Petals 5 rarely 4 or many and free often with nectaries. Some time perianth is not differentiate in to sepals or petals.

Androecium:
Many stamens free spirally arranged looking and facing outward. Dehiscence of stamen longitudinally.

Gynoecium:
Simple many carpels unilocular with single or many ovules and placentation marginal.

Ovary:
superior, style 1 stigma 1

Fruit:
Achene, berry, follicle or capsule.

Seed:
With small embryo endosperm present.

Variation in the family.
The family shown variation in flowers.
Zygomorphic [Aconitum]
Ranunculus [actinomorphic]      
              
The family shows a wide variation in flowers structure and also wild variation  in pollination method. The ranunculaceae are generally protandrous. The stamens shedding their pollen before the ovary mature. This reverse case a protogynous the ovaries maturing before the stamen, also occur in this family.

Variation in this process favour cross pollination and out breeding. Different seed dispersal is by variety of agencies, Clematis pulsetella, have style  which lengthen after pollination in to long feathery structure adopted for wind dispersal. some species of Ranunculaceae e.g R. arvensis have hooked spines on the surface of for animals dispersal.

Helleborus sp. have some oil containing swelling on the seed testa, which attracts ants which then disperse the seed.

Phylogenetic relationships:
The Ranunculaceae are how generally regarded as   primitive family view put forward by A. Lawren de Jussia as long as 1773. It is widely regarded as most probably having evolved from ancestral magnoliaceae stack.

The family is related to Berberideacae, Minispermaceae. The ranunculaceae and berberideacae are phytochemical related in the position in alkaloid berberin. The order in ranunculus closely related to the order nymphiales.
On one side and to the mangonliales  and liliaceae on the other side.

Some phylogenetic is see relationship with primitive order Alismatcles [water plant] it is because of convergent evolution [both survive in same habitat]. A closed relationship between some family of order ranunculus berberidaceae order papviraline its widely accepted.

Phylogenetic find out by:
1.     By morphology
2.     Hybridization

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Euphorbiaceae


Euphorbiaceae
300 genera 7500 species distribution widely in tropical and subtropical region.
Field identification; Plants usually with milky latex, leaves alternate, flower unisexual, carpals three, ovary superior and ovule with caruncle fleshy outgrowth.

Description: Shrubs, herbs, trees with often milky colour latex.

Leaves: Alternate, rarely opposite simple or compound leaves, stipule present, sometime glandular rarely absent.

Inflorescences: Cup-shaped, cyathium.

Flower: Unisexual, monoecious, or dioecious species actinomorphic hypogynous.

Calyx: Perianth usually 5 representing sepals.

Corolla: Sometime absent rarely 5.

Androecium: 1 to 2 and many stamens, filament free sometime connate dehiscence longitudinally.

Gynoecium: Three carpel tricarpellary united [syncarpous]. Carpals rarely four to many, ovary superior, trilocular with 1 to 2 ovules, style 3

Fruit: Shizocarpic capsule [a simple dry fruit formed by a gynoecium segmented separating at fruit Sigma [ a dry schizocarpic  fruit with elastically opening segmented  as in castor oil. Rarely a berry pulpy fruit derived from a compound gynoecium with the seed enclosed within its fruit or drupes { fleshy one seeded  indehiscent fruit within the seed enclosed in the stony endocarp].

Seed:  Often with conspicuous fleshy outgrowth called caruncle. Embryo curved sometime straight endosperm abundant sometime absent.

Economic importance: The family includes a number of valuable plants such as source of brasiliensis rubber Hevea brasiliensis, cassava.

Ø Manihot esculenta [cassava] source of dietary fibre.
Ø The common ornamental plant such as Euphorbia pulcherrima, Euphorbia splendens, Acalypha hispida are ornamental plant.
Ø Jatropha panduraefolia source of biodiesel.
Ø The fruit of Phyllanthus emblica [ammla] very rich source of vitamin c and its oil used for best hair growth.
Ø Ricinus communis [castor oil] rich source of oil used for pharmaceutical and for industrial uses.

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Caryophyllaceae Family [pink family]


Caryophyllaceae Family [ pink family]

In this family include 80 genera and 2000 species.

Description: is a large family of mainly temperate herbaceous family about 80 genera and 2000 species. It include the popular carnation plants Dianthus caryophyllus and some well known wild plants such as Silene conidea, Stellaria media.

Distribution: the family is found in all temperate parts of the world and on mountains in tropical region. Several species of Stellaria and Cerastium have become almost cosmopolitan weeds. The centre of diversity and distribution is however Mediterranean region and adjoining parts of Europe and Asia.

Representation in the temperate and southern hemisphere is small in terms of genera and species. All the larger genera Silene danthus, Arenaria etc are found in northern hemisphere with the strong concentration in mediteranian region. Similar to Balochistan climate is mainly mediteranian region therefore many species of carophyllus is found.

Diagnostic feature: in spite of large size the caryophyllaceae is a relatively uniform and easily recognized family. The plants are usually herbaceous either annually and perennial or suffruticose shrub.

Leaves: the leaves are opposite are decussate simple leaves mostly linear to lanceolate. The leaves themselves are always simple and entire, no lobes in margin, stipule are absent. When present in the subfamily Paronychioides they are usually silicarous.

Inflorencence: the cymose construction although varies in detail. The most complex is dichasial panicles in which each of the two branches of the terminal flower have an inflorescences branches itself bearing  at terminal flower and two bracteoles which repeats the structure.

In the ultimate branches the dichasia pass into scorpiod suppression of individual flower can lead to raceme like monochasial and ultimately to a single flower and inflorescences.

Flower:
are regular, usually bisexual infrequently unisexual

Calyx:   
The calyx consist of four or typically five free sepals are of united sepals with a four or five lobed apices. The bracts are present at the of base of the calyx in some genera.

Corolla:
Consist four to five petals which are free from each other petals are absent in family of Paronychioides and some other species. The apices of the petals are notch and producing more or less bilobed or even fringed petals.

Stamens:
are typically as many as petals but may be reduced to as many as five or even four in Stellaria media.

Ovary:
The ovary is superior 2 to 5 united Carpals, three united carpel then tricarpellary ovary usually  it has single locule with free central placentation but in a few species a Sailene and Lychns it is septate at the base.

The style are free and as many as there are carpels. The ovules are usually numerous but may b reduce to one. Then the placentation is based.

Fruit:
The fruit is most frequently a capsule dehiscencing by means of teeth at the apices. These may be as many or twice as many as the number of carpels. More rarely single ovule genera. The fruit is then the achene. Capsule formed from compound ovary. Achene formed from one single ovule.

Seed:
Seed are usually numerous with the embryo curved around the food reserved materials which is usually perisperm   [is the tissue derived from diploid nucleus] rather than different from angiosperm derived from triploid nucleus of fertilized embryo in Silene and Lychns. The petals stamens and the ovary  separated from the calyx by a shortly extended internode.

The pollination is broad about by the help of insects, self pollination is prevented by dichogamy [the ripening of stamen and pistel of flower at different types so that self pollination is prevented] and protandary [stamen first mature the embroy]. The seeds are disperse by water in Stelleria aquatica and by wind is Stellaria media and by birds, human, animals in silene and Aspergula herpensis.


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