(i) Microspores (n) are formed at the end of microsporogenesis.
(ii) Microspore develops into pollen.
(iii) The pollen protoplast consists of dense cytoplasm with a centrally located nucleus.
(iv) The wall is differentiated into an outer exine and an inner layer is intine.
(v) Exine is thick and is made up of cellulose sporopollenin and pollenkitt.
(vi) The intine is thin, uniform and is made up of pectin, hemicellulose, cellulose and callose together with proteins.
(vii) Exine has thin areas are small and round it is called as germ pore. It is associated with the germination of pollen. 
(viii) Germ pore does not contain sporopollenin.
(ix) The surface of the exine is either smooth or sculptured in various patterns (rod like, grooved, warty, punctuate etc.,) which is used in the plant identification and classification.
(x) Pollen may be globose, ellipsoid, fusiform, lobed, angular or crescent-shaped.
(xi) The size of the pollen varies from 10 micrometers in Myosotis to 200 micrometers in members of the family. Eg: Cucurbitaceae and Nyctaginaceae.
(xii) Sporopollenin consists of pollen cytoplasm and tapetum derived from carotenoids.
(xiii) It is resistant to physical and biological decomposition.
(xiv) It helps to withstand high temperature, Strong and alkali and enzymatic actions.
(xv) Hence it preserves the pollen for long periods in fossil deposits and it also protects pollen during its journey from anther to Stigma.

Microsporogenesis:
The stages involved in the formation of haploid microspores (n) from diploid microspore mother cell (2n) through meiosis is called Microsporogenesis.

(i) Primary sporogenous cells directly undergo few mitotic division to form sporogenous tissue.
(ii) Some cells function as microspore mother cells (2n) produce Plants. 
(iii) Each microspore (n) divides by meiosis to form  4 microspores or tetrads (n, n, n, n).
(iv) Microspores remain free in the anther locule and found as pollens (n). 
(v) Bounded microspores is called pollinium. Eg: Calotropis.
(vi) Pollinia are attached to a clamp or clip live sticky structure called corpuscular. 
(vii) The filamentous or thread like part arising from each pollinium is called retinaculum.
(viii) The whole structure looks like inverted letter 'Y'  and is called translator.
T.S. of Mature anther: 
(i) Each anther is bilobed (dithecous) each has 2 microsporangia. So a typical anther is tetrasporangiate.
Anther wall:
(i) It consists of four layers (a) Epidermis, (b) Endothecium, (c) Middle layers and (d) Tapetum
(a) Epidermis:
(i) It is single layered.
(ii) It aids in protection.
(iii) Cells undergo repeated anticlinal divisions to cope up with the rapidly enlarging the internal tissues.
(b) Endothecium:
(i) It is found below the epidermis.
(ii) It is a single layer of rapidly elongated cells.
(iii) The inner tangential and few radical walls made up of a cellulose develop bands. Such cells are hygroscopic.
(iv) In the anthers of aquatic plants, saprophytes, cleistogamous flowers and extreme parasites endothecial differentiation is absent.
(v) The cells along the junction of the two sporangia of an anther tube lack these thickenings. This region is called stomium.
(vi) The stomium along with the hygroscopic nature of endothecium helps in the dehiscence of anther at maturity.
(c) Middle layers:
(i) Two to three layers of cells next to endothecium constitute middle layers.
(ii) They are generally ephirneral.
(iii) They disintegrate or get crushed during maturity.
(d) Tapetum:
(i) It is the innermost layers of another wall.
(ii) It attains the maximum development at the tetrad stage of microsporogenesis.
(iii) Tapetum is a dual in origin as it develops from the peripheral wall layer and a partly develops from the connective tissue of the anther liping the anther locule.
(iv) It serves as nutritive tissue layer for microsporogenesis.
(v) Cells are uninucleated or polyploid.
(vi)  It also contributes to the wall materials sporopollenin, pollenkitt, tryphine and number of proteins that control incompatibility reactions.
(vii) Tapetum also controls the fertility or sterility of the microspores or pollengrains.

Advantages of modern methods:
(i) In a short duration, the plants with desired characteristics can be multiplied rapidly.
(ii) Plants produced are structurally and genetically identical.
(iii) Tissue culture can be carried out in any season to produce plants.
(iv) Tissue culture can propagate some plants which do not produce viable seeds
v) Rare and endangered plants can be propagated.
(vi) Disease free plants can be produced by meristem culture.
(vii) Cells can be genetically modified and transformed using tissue culture.
Disadvantages of modern methods:
(i) It is labour intensive and needs skilled workers.
(ii) Sterile conditions must be maintained which adds to the cost.
(iii) Since the clones are genetically identical, the entire crop is susceptible to new diseases or changes in environmental conditions will wipe out the species.
(iv) Sometimes callus undergoes genetical changes which are undesirable for commercial use.

Advantages of conventional methods:
(i) The plants produced are structurally and genetically uniform.
(ii) In some plants little sized or no seeds do not produce new plants, In such cases, plants can be produced in a short period by this method.
(iii) Some plants can be propagated more economically by vegetative propagation.
Eg: Solanum tuberosum
(iv) Two different plants with desirable characters live as disease resistant and high yield can be grafted and grown as a new plant with the same desirable character.
Disadvantages of conventional methods:
(i) Use of virus infected plants as parents produces viral infected new plants.
(ii) Vegetative structures used for propagation are bulky and so they are difficult to handle, and store.

Flower - adopted for bee pollination protandrous
Corolla - bilabiate with two stamen
Mechanism of pollination - lever mechanism
Adaptations:
(i) Anther - Upper fertile lobe Lower sterile lobe
(ii) Separated by a long connective that helps the anthers to swing freely
(iii) pollination bee visit the flower
(iv) Sits on the lower lobe (acts like platform)
(v) Push its head into the corolla
(vi) Body strikes against the sterile end the connective.
(vii) Fertile part descend, strike at the back of the bee and pollen get deposited on it
(viii) Bee visit another flower
(ix) Pollen gets robbed against its stigma pollination gets completed.

(i) Plant - monoecious, unisexual
(ii) Male infloreseance - (tassel) borne terminally
(iii) Pollen - large, heavy cannot be canied by light breeze Femaie inflorescence - (cob)
(iv) Borne laterally at lower level has long stigma (about 25 cm in length ) Project beyond the leaves.
(v) Mild wind shakes the male inflorescence to release pollen which falls vertically below and caught by the stigma.

Flowers
(i) Large, tubulat cup or urn shaped.
Colour
(i) Brightly coloured - red, scarlet, pink, orange, blue, yellow
Secretions
(i) Produce nectar in large quantities, scentless.
Texture
(i) The formal parts are tough and leathery to withstand the powerful impact of the visitors. - The bird.

Inflorescence:
(i) Produced in pendulous catkin or spike inflorescence axis well elongated to bring flowers well above the leaves.
Flowers
(i) Small, colourless, scentless, produce no nectar. perianth absent or reduced.
Stamen
(i) Numerous, filaments long, exerted, versatile.
Pollen grains
(i) Minute, light, dry produced in enormous quantities. Anthers burst violently to release pollen grain (eg) Urtica.
Stigma
(i) Large protruding sometimes branched and feathery-adapted to catch pollen grains.
(ii) Flowers are produced before new leaves appear, so pollen can be carried out without the hindrance of leaves.

(i) The outer wall layer of pollen grain, the exine made of sporopollenin which is a most resistant organic material.
(ii) The wall material sporopollenin is contributed by both pollen cytoplasm and tapetum.
(iii) It is derived from carotenoids resistant to physical and biological decomposition.
(iv) It helps the pollen grain, to withstand high temperature, resistant to strong acid and alkali and enzyme action.
(v) Preserve the pollen for long periods in fossil deposits. Protects pollen during its journey from another to stigma.

(i) Structure of a Cicer seed as an example for Dicot seed The mature seeds are attached to the fruit wall by a stalk called funiculus.
(ii) The funiculus disappears leaving a scar called hilum. Below the hilum a small pore called micropyle is present.
(iii) It facilitates entry of oxygen and water into the seeds during germination.
(iv) Each seed has a thick outer covering called seed coat.
(v) The seed coat is developed from integuments of the ovule.
(vi) The outer coat is called testa and is hard whereas the inner coat is thin, membranous and is called tegmen.
(vii) In Pea plant the tegmen and testa are fused. Two cotyledons laterally attached to the embryonic axis are present.
(viii) It stores the food materials in pea whereas in other seeds like castor the endosperm contains reserve food and the cotyledons are thin.
(xi) The portion of embryonal axis projecting beyond the cotyledons is called radicle or embryonic root.
(x) The other end of the axis called embryonic shoot is the plumule.
(xi) Embryonal axis above the level of cotyledon is called epicotyl whereas the cylindrical region between the level of cotyledon is called hypocotyl.
(xii) The epicotyl terminates in plumule whereas the hypocotyl ends in radicle.

Anemophilous plants have the following characteristic features:
(i) The flowers are produced in pendulous, catkin-like or spike inflorescence.
(ii) The axis of inflorescence elongates so that the flowers are brought well above the leaves.
(iii) The perianth is absent or highly reduced.
(iv) The flowers are small, inconspicuous, colourless, not scented, do not secrete nectar.
(v) The stamens are numerous, filaments are long, exerted and versatile.
(vi) Anthers produce enormous quantities of pollen grains compared to a number of ovules available for pollination. They are minute, light and dry so that they can be carried to long distances by wind.
(vii) In some plants, anthers burst violently and release the pollen into the air. Example: Urtica.
(viii) Stigmas are comparatively large, protruding, sometimes branched and feathery, adapted to catch the pollen grains. Generally, a single ovule is present.
(ix) The plant produces flowers before the new leaves appear, so the pollen can be carried without hindrance of leaves.

The functional megaspore is the first cell of the embryo sac or female gametophyte. The megaspore elongates along the micropylar-chalazal axis. The nucleus undergoes a mitotic division. Wall formation does not follow the nuclear division. A large central vacuole now appears between the two daughter nuclei. The vacuole expands and pushes the nuclei towards the opposite poles of the embryo sac. Both the nuclei divide twice mitotically, forming four nuclei at each pole. At this stage, all the eight nuclei are present in a common cytoplasm (free nuclear division). After the last nuclear division, the cell undergoes appreciable elongation, assuming a sac-like appearance. This is followed by the cellular organization of the embryo sac. Of the four nuclei at the micropylar end of the embryo sac, three organize into an egg apparatus, the fourth one is left free in the cytoplasm of the central cell as the upper polar nucleus. Three nuclei of the chalazal end form three antipodal cells whereas the fourth one functions as the lower polar nucleus. Depending on the plant the 2 polar nuclei may remain free or may fuse to form a secondary nucleus (central cell). The egg apparatus is made up of a central egg cell and two synergids, one on each side of the egg cell. Synergids secrete chemotropic substances that help to attract the pollen tube. The special cellular thickening called filiform apparatus of synergids to help in the absorption, conduction of nutrients from the nucellus to embryo sac. It also guides the pollen tube into the egg. Thus, a 7 celled with 8 nucleated embryo sac is formed.

There are 5 types of ovules.
1. Orthotropous: 
Micropyle is at the distal end and the micropyle, the funicle and the chalaza lie in one straight vertical line. 
2. Anatropous:
The body of the ovule becomes completely inverted so that the micropyle and funiculus come to lie very close to each other. 
E.g: Dicots, Monocots (Common)

3. Hemianatropous:
The body of the ovule is placed transversely and at right angles to the funicle.
E.g: Primulaceae.
4. Campylotropous:
(i) The body of the ovule at the micropylar end is curved and more or less bean shaped. The embryo sac is slightly curved.
(ii)  All the three, hilum, micropyle and chalaza are adjacent to one another, with the micropyle oriented towards the placenta.
E.g: Leguminosae.
5. a) Amphitropous:
The distance between hilum and chalaza is less. The curvature of the ovule leads to horse shoe shaped nucellus.
E.g: Alismataceae.
b) Circinotropous:
Funiculus is very long and surrounds the ovule.
E.g: Cactaceae

(i) The microspore is the first cell of the male gametophyte and is haploid.
(ii) The development of male gametophyte takes place while they are still in the microsporangium.
(iii) The nucleus of the microspore divides to form a vegetative and a generative nuclei.
(iv)  A wall is laid around the generative nucleus resulting in the formation of two unequal cells, a large irregular nucleus bearing with abundant food reserve called vegetative cell and a small generative cell.
(v) At this two celled stage, the pollens are liberated from the anther.
(vi) In some plants, the generative cell again undergoes a division to form two male gametes.
(vii) In these plants, the pollen is liberated at 3 celled stages.
(viii) In 60% of the angiosperms, pollen is liberated in 2 celled stages.
(ix) The growth of the male gametophyte occurs only if the pollen reaches the right stigma.
(x) The pollen on reaching the stigma of absorbs moisture and swells.
(xi) The intine grows as pollen tube through the germ pore.
(xii) In case the pollen is liberated at 2 celled stages the generative cell divides in the pollen into 2 male cells (sperms) after reaching the stigma.
(xiii) The stages in the development of male gametophyte occurs in gynoecium of the plant.

Anther wall: The mature anther wall consists of the following layers a. Epidermis
b. Endothecium
c. Middle layers
d. Tapetum.
a. Epidermis: It is single layered and protective in function. The cells undergo repeated anticlinal divisions to cope up with the rapidly enlarging internal tissues.
b. Endothecium: It is generally a single layer of radially elongated cells found below the epidermis. The inner tangential wall develops bands (sometimes radial walls also) of cellulose (sometimes also slightly lignified). The cells are hygroscopic. In the anthers of aquatic plants, saprophytes, cleistogamous flowers, and extreme parasites endothelial differentiation is absent. The cells along the junction of the two sporangia of an anther lobe lack these thickenings. This region is called stomium. This region along with the hygroscopic nature of endothecium helps in the dehiscence of anther at maturity.
c. Middle layers: Two to three layers of cells next to endothecium constitute middle layers. They are generally ephemeral. They disintegrate or get crushed during maturity.
d. Tapetum: It is the innermost layer of the anther wall and attains its maximum development at the tetrad stage of microsporogenesis. It is derived partly from the peripheral wall layer and partly from the connective tissue of the anther lining the anther locule. Thus, the tapetum is dual in origin. It nourishes the developing sporogenous tissue, microspore mother cells, and microspores. The cells of the tapetum may remain uninucleate or may contain more than one nucleus or the nucleus may become polyploid. It also contributes to the wall materials, sporopollenin, pollenkitt, tryphine, and a number of proteins that control incompatibility reaction. Tapetum also controls the fertility or sterility of the microspores or pollen grains.