Lecture 17.ppt

‫بسم اللـه الرحمن الرحيم‬ In the Name of Allah the compassionate, the Merciful Dr. Abdel Moneim Arhegoniatae Dr.Abdel Moneim Ibrahim Order: Coniferales  ‫تقسيم معراة البذور ‪Classification of‬‬ ‫‪Gymnosperms‬‬ ‫ تضم معراة البذور ثالث طوائف ه...

‫بسم اللـه الرحمن الرحيم‬ In the Name of Allah the compassionate, the Merciful Dr. Abdel Moneim Arhegoniatae Dr.Abdel Moneim Ibrahim Order: Coniferales  ‫تقسيم معراة البذور ‪Classification of‬‬ ‫‪Gymnosperms‬‬ ‫ تضم معراة البذور ثالث طوائف هى‪:‬‬ ‫‪ ‬طائفة سيكادوبسيدا‪Class:..................................‬‬ ‫‪Cycadopsida‬‬ ‫– ويتبعها رتبة السيكادالت ‪Order: Cycadales.........................‬‬ ‫ ويزرع منها فى مصر نبات السايكس ‪Cycas...........‬‬ ‫‪ ‬طائفة كونيفروبسيدا‪Class:................................‬‬ ‫‪Coniferopsida‬‬ ‫– ويتبعها رتبتين األولى رتبة المخروطيات‪a) Order: Coniferales...‬‬ ‫ ويزرع منها فى مصر نبات الصنوبر ‪Pinus...........‬‬ ‫‪b) Order: Taxales.................................‬‬ ‫– رتبة التاكسيالت‬ ‫ ويزرع فى مصر نبات السرو ‪Cupressus...........‬‬ ‫و نبات التوية ‪.………… Thuja.....‬‬ ‫‪ ‬طائفة جنتوبسيدا‪Class:........................................‬‬ ‫‪Gnetopsida‬‬ ‫‪Ephedra‬‬ ‫ ويوجد منها فى مصر نبات اإلفيدرا‬ Order: Conifer ales  Pinus (Description) Pines are evergreen, coniferous resinous trees (or rarely shrubs) growing 3–80 m tall, with the majority of species reaching 15–45m tall. The bark of most pines is thick and scaly, but some species have thin, flaking bark.  Pinus (Description) Pines have four types of leaf: 1-Seed leaves (cotyledons) on seedlings, borne in a whorl of 4–24. 2-Juvenile leaves, which follow immediately on seedlings and young plants, 2–6 cm long, single, green or often blue-green, and arranged spirally on the shoot. These are produced for six months to five years, rarely longer. 3-Scale leaves, similar to bud scales, small, brown and non-photosynthetic, and arranged spirally like the juvenile leaves. 4-Needles, the adult leaves, commonly 2–5, needles together which are green acicular and needlelike. They are borne only by the dwarf shoots. Foliage leaves & Scale Pinus  Pinus (Description) : Cones Pines are mostly monoecious, having the male and female cones on the same tree, though a few species are sub-dioecious with individuals predominantly, but not wholly, single-sex. The male cones are small, typically 1– 5 cm long, and only present for a short period (usually in spring, though autumn in a few pines), falling as soon as they have shed their pollen. The female cones take 1.5–3 years (depending on species) to mature after pollination, with actual fertilization delayed one year. At maturity the female cones are 3–60 cm long. Each cone has numerous spirally arranged scales, with two seeds on each fertile scale; the scales at the base and tip of the cone are small and sterile, without seeds.  Pinus (Description) :Seeds The seeds are mostly small and winged, and are anemophilous (wind-dispersed), but some are larger and have only a vestigial wing, and are bird-dispersed. At maturity, the cones usually open to release the seeds. In others, the seeds are stored in closed ("serotinous") cones for many years until an environmental cue triggers the cones to open, releasing the seeds. The most common form of serotiny is pyriscence, in which a resin binds the cones shut until melted by a forest fire.  Study of anatomy of young.root 1. The section is almost circular in outline. 2. The tissues are differentiated into epiblema cortex and vascular tissues. 3. Epiblema is outermost single layer. It gives out many thin and unicellular root hairs. 4. Cortex is multilayered and parenchymatous. 5. Endodermis separates outer cortex and central vascular cylinder. It is single layered and cells are radially thickened. 6. Pericycle follows endodermis. It is multilauered. 7. Vascular bundles are radial, exarch and diarch to hexarch. 8. Protoxylem is generally Y-shaped and a resin canal is present in between the arms of Y. 9. Pith is very small and lies between the groups of xylem. Anatomy of young root  Study of anatomy of the old. root 1. The section shows cork, cortex, primary and secondary vascular tissues and a small pith. 2. Cork forms the outermost several layers. (developed from pericycle and hence primary cortex is completely peeled off). 3. Stone cells occur in many groups scattered just below the zone of cork. 4. Secondary cortex follows cork. It is parenchymatous and a few layered deep. 5. Many resin canals are found in the secondary cortex. 6. Primary phloem occurs in two patches. The tissues are mostly crushed and obliterated.  Study of anatomy of the old. root 7. Secondary phloem that follows is a few layered deep ring. It consists of sieve tubes, sieve plates, phloem parenchyma and albuminous cells. 8. Secondary phloem and secondary xylem are separated by a cambium. 9. Secondary xylem is composed of tracheids arranged in regular rows. It is traversed by uniseriate medullary rays. 10. Pith is small and parenchymatous. Two groups of primary xylem are situated on opposite radii. 11. Each primary xylem group is Y shaped. The divided arm faces the outer side (away from the pith). 12. Resin canal. The characteristic of the pine root is the presence of large resin canal between the divided arm of Y, close to each primary protoxylem group. The old root  Study of anatomy of the young.long shoot 1. Outline is wavy due to the presence of scaly leaves. 2. The stem is differentiated into epidermis, cortex and stele. 3. Epidermis is the outermost single layer. It is thickly cuticularized. 4. Cortex is multilayered and lies below the epidermis. The outer few layers forming hypodermis are sclerenchymatous. Inner layers are thin walled and parenchymatous in which large number of resin canals and leaf traces are distributed irregularly. 5. Resin canal. The cavity of resin canal is bounded by a glandular, resin secreting epithelial layer. Outer to this layer are one or two layers of sclerotic cells. 6. In Pinus, resin canals are present in the cortex and secondary wood of both stem and root and on margins of the primary xylem in the root. Anatomy of the young long shoot T.S of Old stem  Study of anatomy of the young.long shoot 7. The stele is ectophloic siphonostele. 8. Endodermis is present but is undistinguishable and so also a few layered peri cycle located inner to it. 9. Vascular cylinder is composed of 5-8 vascular bundles, separated by medullary rays. Vascular bundles are arranged in a ring. 10. Each vascular bundle is conjoint, collateral endarch and open. 11. Xylem is composed of tracheids and xylem parenchyma only, vessels are absent. 12. The phloem is made up of sieve tubes, sieve plates and phloem parenchyma. Albuminous cells are also present. 13. Pith lies in the centre and is parenchymatous. It is connected with the cortex but narrow medullary rays separate the vascular bundles..Study of T.s. needle (leaf) 1. The outline of the section varies according to the species. (Triangular if spur is trifoliar, semicircular if spur is bifoliar) 2. The needle is differentiated into epidermis, mesophyll and stele. 3. Epidermis is single with tangentially elongated and thickly cuticularized cells. 4. Stomata are sunken. These are present on all the faces of epidermis. The needle is thus said to the amphistomatic..Study of T.s. needle (leaf) 5. Epidermis is followed by hypodermis. It is few layered thick at the corners and 1-2 layered in other parts. Sub-stomatal chambers occur in this region. Cells are sclerenchymatous and fibrous. 6. Mesophyll lies below the hypodermis. It is made up of polygonal parenchymatous cells, densely filled with the chloroplasts. Numerous plate-like or peg-like infoldings project into the cell lumen (cavity) from the wall of the mesophyll cells. 7. Resin canals generally occur in the sclerotic hypodermis but also occur in the mesophyll tissue. 8. Endodermis is conspicuous. Cells are barrel shaped and tangentially thickened. It is followed by a many layered, parenchymatous pericycle.  Study of T.s. needle.(leaf) 9. Generally two vascular bundles remain surrounded by this tissue. (In P. strobus there is only one vascular bundle). 10. The vascular bundles are separated from one another by a T-shaped thick walled transfusion tissue. 11. Each vascular bundle is conjoint, collateral and open. Protoxylem faces adaxial side. Phloem is located on the abaxial side. 12. Xylem and phloem groups are separated from one another by cambium at the base of the needle and by parenchymatous cells in the upper region. 13. Secondary growth is very little during which the medullary rays run between xylem and phloem. Internal structure of leaf  Study of L.s. of male cone 1. It shows a cone axis bearing microsporophylls 2. The cone axis is centrally located. 3. Microsporophylls are spirally arranged. These are scaly, triangular and expanded. 4. It is attached to the cone axis by a stalk-like base. 5. The outer expanded part is sterile and is known as apophysis. 6. Microsporangia are present on the lower or abaxial surface. 7. Each micro sporangium has a wall that encloses a cavity. 8. The wall consists of epidermis. wall layers and tapetum. 9. The cavity shows numerous microspores in various stages of development. Male strobilus & Pollen grain  Study of morphology of the.female cone 1. Female cones are larger than the male cones. They are borne at the apices of the young elongated shoots, replacing the shoot of unlimited growth (long shoots). 2. Single shoot may bear one to four female cones which are reddish-green in colour and mature in three years. 3. In the fIrst year, cones are compact and sporophylls are closely arranged. 4. The second year cones are large in size and woody in nature but sporophylls are still compactly arranged. 5. In the third year, cone becomes loose. Sporophylls separate from one another due to elongation of the cone axis. 6. Each female cone consists of many sporophylls, arranged spirally around the cone axis. Female strobilus  Study L.s. of female.cone 1. Female cone is made of centrally located cone axis and spirally arranged sporophylls. 2. Each sporophyll consists of two kinds of paired scales : (i) bract scale or cone scale and (ii) ovuliferous scale or seminiferous scale. 3. Many small and thin bract scales are arranged spirally around the cone axis. They are directly borne on the cone axis. Each of these is present on the abaxial (lower) side of the Ovuliferous scale. 4. On the adaxial (upper) side of the bract scale, a thick, large, woody and triangular Ovuliferous scale is present..Study L.S. of female cone 5. The ovuliferous scales in the middle part of the cone are the largest and get gradually smaller towards its base and apex. 6. Ovuliferous scale and bract scale are fused for a little distance near the cone axis while free at a distance away from it. 7. Ovuliferous scale is shortly stalked and rest of the part is expanded. 8. At the base "of this expanded, triangular part, two naked and sessile ovules are present. These are situated on the adaxial, (upper) surface of the ovuliferous scale, at its base, with their rnicropyles directed towards cone axis. 9. The terminal part of the ovuliferous scale is broad and sterile and is known as apophysis..Study of L.S. of ovule 1. Ovule is elongated in shape 2. It is unitegmic and the integument is three layered. The outermost layer is thin. The middle layer is stony and prominent. The innermost layer is fleshy and well developed. 3. Nucellus is fused with inner layer of the integument, except at its tip where it forms an elongated and slender micropyle, directed towards the cone axis. 4. In the nucellar region lies a small cavity just opposite the micropyle. It IS known as pollen chamber. 5. Female gametophyte (endosperm) is differentiated from nucellus. About 2-5 archegonia are situated in this region at the micropylar end near the base of the archegonial chamber Pinus. L.S. of ovule.Study of seed 1. Fertilized ovules get transformed into seeds which are situated on the adaxial side of the ovuliferous scale at its base near the cone axis 2. Seeds are small, elongated and winged. The wing is a thin layer of tissue which splits off from the adaxial face of the ovuliferous scale. (Seed can be best studied by cutting longitudinal section of the seed of P. gerardiana; vern. chilgoza). 3. The seed is covered with red and brown testa..Study of seed 4. Inner fleshy layer of the integument still persists. It is membranous, thin and papery, termed as tegmen. 5. The nucellus is present as a thin layer and forms a nucellar cap at the micropylar end. 6. The larger part of the seed consists of oily endosperm. 7. The suspensor is long and becomes coiled. Embryo is differentiated into radicle, plumule and cotyledons (3-8 in number). 8. In between the radicle and plumule, is present a well developed hypocotyl..Pinus. L.S. of seed Key Haploid (n) Ovule Diploid (2n) Ovulate Megasporocyte (2n) cone Pollen Integument cone Microsporocytes Megasporangium (2n) Mature )2n( Pollen sporophyte grain )2n( Pollen grains (n) MEIOSIS MEIOSIS Microsporangia Microsporangium (2n) Surviving Seedling megaspore (n) Archegonium Female Seeds gametophyte Food reserves (n) Sperm nucleus (n) Egg nucleus (n) Seed coat (2n) Pollen Embryo tube )new sporophyte( )2n( FERTILIZATION Thank you for careful listening