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Home , Perianth, Whorl (botany)

BIOLOGY ASSIGNMENT CLASS IX UNIT II- FLOWERING Chap 3- The

Flower is the most attractive,brightly coloured and significant part of plant. It help in sexual reproduction and later forms and .

Characterstic of flower : The flower possesss the following characterstic – 1. Flower is the highly modified and specialized meant for Sexual Reproduction. 2.The nodes and internodes are highly condensed to form a flat thalamus or receptacles. 3. Thalamus is quiet short and usually borne at the end of the stalk called . 4.The flower arise from the like structure called . 5. The floral part of flower are borne on thalamus in the form of four whorls. 6. These four includes from outer side – Calyx ( ), Corolla( ) , Androecium ( ), ( carpel ).

Parts of a Flower : Floweris attached with the stem or its branch with the help of a stalk called Pedicel. If the flower is without pedicel it is called sessile . The pedicel arises from the axil of green leaf like structure called Bract.The other swollen end of the pedicel is Thalamus or torus . On the thalamus usually four whorl of Floral structure are present These four whorl from outside to inside are : i. Calyx iii. Androecium ii. Corolla iv. Gynoecium

I. CALYX It is the outermost and the lowermost whorl , green in colour which cover an unopened .The single unit of Calyx is called sepal .It may be fussed or free from each other. Additional floral whorl outside the Calyx is called Epicalyx. Function of Calyx : i. They protect inner whorl of flower during bud stage . ii. They can also synthesize food as they contain . iii. They may also attract insect or animals for .

II . COROLLA Corolla constitute the second whorl of flower. The single unit of corolla is called Petal. They are usually bright coloured with showy leaf like structure with beautiful colours in day blooming flower and strongly scented and whitish petal in night blooming . Function of Corolla : i. The primary function of corolla is to attract insects and animals for pollination. ii. The corolla protects the stamen and Pistil. iii. Some are scented and have a sugary . Some special structures on Corolla :The Corolla sometime bear some special outgrowth such as Spurs, Nectaries and Corona.

SPUR-It is the beak like tube shaped outgrowth of which contain nectar. Eg. Balsam, Larkspur etc. NECTARY : Special gland develops on or at the base of floral structure are known as Nectaries which contain nectar. CORONA : Sometime corolla splits and an additional whorl consisting of lobes ,scales or hair is formed .It adds to the beauty of Flower.

III. ANDROECIUM Androecium or also called as STAMEN forms the Male reproductive organ of Plant that produces male gamete.The stamen may be present in single or more whorls .Stamen may be regarded as highly modified leaf ( called Microsporophyll ). A typical stamen is differentiated into two parts – i. Filament ii. Anther A Filament is a long stalk which at its apex bears a fertile head called as Anther. The two anther lobes are attached at the back by a small connective. Each Anther consist of two lobes .Each lobe is differentiated into two chambers called sacs filled with Pollen grain .The wall of Pollen grain is made up of two layers – outer Exine , Inner Intine. Function of Androecium: i. The anther produce pollen grain that contain male gamete. ii. The attachment of filament with anther facilitate Pollination.

IV. GYNOECIUM Located at the center of the flower is the female reproductive organ called Gynoecium or Carpel .The free occurring units of the carpels in the flower are called Pistils. Each carpel is the flask shaped structure which is divided into three parts - i. ii. Style iii. . i.STIGMA : It is the tip of the carpel which is slightly swollen and sticky. It is meant for receiving Pollen grain and their . ii. STYLE : It is in the form of long tube that connects stigma from ovary. iii. OVARY : It is swollen basal part of the carpel. A ovary may be divided into single chamber or many chamber.Each chamber contain rounded egg like structure called as which develops into seeds on maturity. Each ovule encloses a large oval structure called as sac. Function of Gynoecium : i. The hollow cavity of ovary contain ovule . ii. Each ovule contain an Egg cell. iii. The stigma is structurally adapted to receive pollen grain.

Q. Define the following terms with example each :

1.Complete Flower: The flower is said to be complete if all the four whorl ie. Calyx , Corolla , Androecium and Gynoecium are present .e.g. Hibiscus , Petunia 2. Incomplete Flower: If the flower lacks one or more floral whorl ,it is said to be incomplete. E.g. Sunflower , Cassia , Salvia. a. Staminate : The flower is said to be male or staminate , if pistil or Gynoecium is absent or is non functional . The non functional Gynoecium is called Pistillodes. b. Pistillate : The flower in which pistil is present but androecium is either absent or non functional is called Pistillate . The non functional Androecium is called . c. Neuter : The flower is said to be neuter if both androecium and gynoecium is absent .eg.sunflower 3. Bisexual or Hermaphrodite : The flower having both the androecium and gynoecium are called as Bisexual or Hermaphrodite or Perfect flower. 4. Unisexual Flower : The flower having either the male reproductive organ or the female reproductive organ are called as Unisexual flowers . e.g.Gourd flower. 5. Monoecious : When both the male or female unisexual flower are present on the same plant ,,it is said to be monoecious. Eg. Gourd , maize ,cucumber 6.Diecious Plants : When the male and female flower are borne on different plants, they are called Diecious..eg. Papaya ,Palm , Mulberry. 7. Naked : The flower is said to be naked if both the and petals are lacking completely .It is also called as Achlamydeous .e.g. betel, 8. Actinomorphic : A cyclic flower which can be divided into two equal halves which are mirror image of each other ,by any vertical plane ,is said to be actinomorphic.eg. Petunia ,Mustard , Hibiscus 9. Zygomorphic: A flower ,that can be divided into two similar halves which are mirror image of each other by one plane is said to be Zygomorphic.e.g. Pea , Salvia 10. Placentation: The arrangement of placenta with in the ovary is called Placentation. 11. : The arrangement of flowers on the floral stem is called Inflorescence. The stalk that bears the flower is called or Rachis. 12. Syngenesious : When anthers of the stamen are united but filaments are free. Eg disc floret of flower. 13. : Undifferentiateds petals or sepals are called Tepals 14. Epigynous : Ovary occupies the lowest position on thalamus and all other whorls are present above ovary.Thalamus is fused with wall of ovary. 15. Gynandrous : When the are fused with the carpels either wholly or by their anther only .eg.Calotropis 16. Hypogynous : When the ovary is present at the highest position on the thalamus and all other whorls are present below the ovary. 17. Monoadelphous : It is the condition in which filaments of all the stamen fuse forming a tube like structure around gynoecium.

REVIEW QUESTION Q1 Differentiate between the following – i. Complete and Incomplete flower ii. Naked or Neuter Flower iii. Epigynous and Hypogynous flower iv. Unisexual and Bisexual flower

Q2. Define the following terms – Monoecious Placentation Monoadelphous Inflorescence Tapels

Q3. Why are the day blooming flower usually bright coloured where as the night blooming flowers are strongly scented ?

Q4. Give one example of the following – i. Flowers which contain all the four whorls. ii. Plant bearin both the male and female flowers . iii.Flower lacking both the stamens and carpels . iv. A flower in which stamen are absent . v. Stamens united with Gynoecium. vi. Filament of stamen fused with petals. Vii. Undifferentiated calyx and corolla. viii. When all the carpels are united . Q4. Discuss the structure of Gynoecium . Describe various parts of Gynoecium. Q5. Study the given diagram and answer the following questions : i. Name the parts marked . ii. Which part produces pollen grains ? iii. Which part produces pollen grain ? iv. Which part develops into fruit after fertization ?