Phylum Anthophyta Angiosperms - PowerPoint PPT Presentation

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Phylum Anthophyta Angiosperms

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    3. Phylum Anthophyta (Angiosperms) Constitutes ~300,000 species (Gymno. 720 spp) Most recently evolved & most diverse group Divided into many groups: Basal Angiosperms Magnoliids (~8500) Eudicotyledones (dicot) Monocotyledones (monocot) Most living vascular plants are angiosperms Angiosperms are characterized by a unique organ system called the flower It seems like each of the mono and the eudicots is a monophyletic groupMost living vascular plants are angiosperms Angiosperms are characterized by a unique organ system called the flower It seems like each of the mono and the eudicots is a monophyletic group

    4. Phylogeny of Angiosperms Each branch of the tree can be called a clade or lineage. Amborella is considered an intermediate between Gymnosperms and Angiosperms. It consists of one species in New Caledonia. This is a shrub with small flowers and lacks vessels (has only tracheids). The early (basal) angiosperms have alternate and simple leaves, flowers with multiple whorls of tepals ( a common term for sepals and petals when they look alike), stamens are undifferentiated into filaments and anthers), and many separate carpels. Also carpels are not completely closed. Amborella and Nymphaeales lack vessels, Austroballeyales has simple vessel. Carpel is a modified leaf that protects ths developing seed. It includes the stigma, style and an ovary. Each branch of the tree can be called a clade or lineage. Amborella is considered an intermediate between Gymnosperms and Angiosperms. It consists of one species in New Caledonia. This is a shrub with small flowers and lacks vessels (has only tracheids). The early (basal) angiosperms have alternate and simple leaves, flowers with multiple whorls of tepals ( a common term for sepals and petals when they look alike), stamens are undifferentiated into filaments and anthers), and many separate carpels. Also carpels are not completely closed. Amborella and Nymphaeales lack vessels, Austroballeyales has simple vessel. Carpel is a modified leaf that protects ths developing seed. It includes the stigma, style and an ovary.

    5. Fusion of Carpel

    6. Characteristics of Angiosperms Double fertilization: egg + sperm produce zygote (2n) egg + 2nd sperm produce endosperm (3n) Mostly closed carpels: enclose ovule Reduced gametophytes (pollen grain, embryo sac) Sieve tubes and companion cells (phloem) Vessels (xylem) Stamens with 2 pairs of pollen sacs Chemical evolution!

    7. Refinements in vascular tissue, especially xylem, probably played a role in the enormous success of angiosperms in diverse terrestrial habitats. Like gymnosperms, angiosperms have long, tapered tracheids that function for support and water transport. Angiosperms also have fiber cells, specialized for support, and vessel elements (in most angiosperms) that develop into xylem vessels for efficient water transport.

    8. The plant is dioecious. Female flowers with 5-6 carpels (a). Male flowers 10-25 stamens (b). Amborella (Basal angiosperms) Notice the female flowers have 0-several stamenoids (sterile stamens). This is a genus of one species native to New Caledonia (an Island E of Australia)Notice the female flowers have 0-several stamenoids (sterile stamens). This is a genus of one species native to New Caledonia (an Island E of Australia)

    9. Follicle is a dehiscent fruit from a single carpel.Follicle is a dehiscent fruit from a single carpel.

    11. Differences Between Monocot & Eudicot MONOCOT Embryo with single cotyledon Pollen with a single furrow or pore* Flower parts in multiples of three Major leaf veins parallel Stem vascular bundles scattered Have fibrous roots Secondary growth absent EUDICOT Embryo with two cotyledons Pollen with three furrows or pores Flower parts in multiples of four or five Major leaf veins reticulate Stem vascular bundles in a ring Have taproots Secondary growth often present Fibrous roots: many small roots of same size originate from the base of monocot stem because their primary root is short-lived. Taproot: the main embryonic root giving rise to smaller later roots as in dicot Adventitious root: roots from places other than root Magnoliids have pollen like MonocotFibrous roots: many small roots of same size originate from the base of monocot stem because their primary root is short-lived. Taproot: the main embryonic root giving rise to smaller later roots as in dicot Adventitious root: roots from places other than root Magnoliids have pollen like Monocot

    12. Pollen of Horse chestnut Eudicot like these have pollen with 3 aperturesEudicot like these have pollen with 3 apertures

    13. Flower: the main feature of angiosperms

    14. The Flower Perianth: Sepals & petals collectively Androecium: stamens collectively Gynoecium: pistils collectively

    15. Types of Flowers Complete flower: has all 4 floral parts Incomplete flowers: missing a floral part(s) Perfect Flower: bisexual Imperfect flower: unisexual flowers Staminate flowers: have only the stamens Pistillate (carpellate) flowers: have only pistils Monoecious plants: separate staminate and pistillate flowers on the same plant Dioecious plants: either staminate or pistillate flowers Monoecious: (grasses) Dioecious (willows) Monoecious: (grasses) Dioecious (willows)

    16. Floral symmetry: Actinomorphic flower: floral parts are of similar shape & size (radially symmetrical) Zygomorphic: floral parts are different (bilaterally symmetrical) Inflorescence: A cluster of flowers with a definite arrangement Fertilization: the fusion of two gamete nuclei to produce a diploid zygote Pollination: transfer of pollen from the anther to the stigma Pollen transferred within the same flower is called self-pollination, and the species is an in-breeder Pollen transferred to a different flower is called cross-pollination and the species is out-breeder

    17. Example of Monocot Flower: Lilium sp.

    18. Dicot

    19. Dicot H. moscheutos is a Dicot, with five petals and five sepals. It grows naturally in cattail marshes along the shore of Lake Ontario and along the Hudson River between Albany and New York City. The showy pink petals are ten or more centimeters long. The style divides into five branches near its tip; each branch bears a capitate (hear-like) stigma It is a member of the Mallow Family (Malvaceae) As with all members of the Malvaceae, the numerous stamens are fused by their filaments to form a tube around the style.H. moscheutos is a Dicot, with five petals and five sepals. It grows naturally in cattail marshes along the shore of Lake Ontario and along the Hudson River between Albany and New York City. The showy pink petals are ten or more centimeters long. The style divides into five branches near its tip; each branch bears a capitate (hear-like) stigma It is a member of the Mallow Family (Malvaceae) As with all members of the Malvaceae, the numerous stamens are fused by their filaments to form a tube around the style.

    20. Hibiscus II A flower has been split open to show the ovary with ovules contained inside The flower remains open for only one day After the corolla, stamens, and style wither and fall away, the ovary develops into a capsule that splits open to release the seeds.A flower has been split open to show the ovary with ovules contained inside The flower remains open for only one day After the corolla, stamens, and style wither and fall away, the ovary develops into a capsule that splits open to release the seeds.

    21. Angiosperm Life Cycle

    22. Development of Pollen Microsporogenesis: the development of microspore mother cell (microsporocyte) into microspores This involves meiosis

    23. Liliy Flower

    24. Microsporocytes Microsporocyte is a single diploid cell (2n) that undergoes meiosis to produce 4 haploid cells (microspores or male spores) Tapetum is the non-reproductive tissues that provide nutrition to the developing spores Microsporocyte is a single diploid cell (2n) that undergoes meiosis to produce 4 haploid cells (microspores or male spores) Tapetum is the non-reproductive tissues that provide nutrition to the developing spores

    25. Microsporocyte undergo Meiosis The microspore mother (2n) cells undergoing meiosis. See cells in various stages of meiosis.The microspore mother (2n) cells undergoing meiosis. See cells in various stages of meiosis.

    26. Tetrads of Microspores At end of meiosis 4 haploid (1n) male spores are producedAt end of meiosis 4 haploid (1n) male spores are produced

    27. Development of Pollen Microgametogenesis: the development of microspores into male gametophyte (pollen grain) This involves mitosis

    28. Mature Male gametophyte

    30. Mature Pollen grain

    31. Development of Female Gametophyte Megasporogenesis: the megasporocyte (megaspore mother cell) develops into megaspores by meiosis

    32. Lilium Ovary Cross section of lilium ovaries.Cross section of lilium ovaries.

    33. Megasporocyte Before Meiosis The Megasporocyte or megaspore mother cell is a single diploid cell (2n) which undergoes meiosis to produce 4 haploid cells (megaspore or female spores). The Megasporocyte or megaspore mother cell is a single diploid cell (2n) which undergoes meiosis to produce 4 haploid cells (megaspore or female spores).

    34. Two-nucleate Stage (formed by meiosis)

    35. Four-nucleate Stage (formed by meiosis) The result of meiosis is 4 haploid cells. Only one of these cells survives. In the next slide you would see the surviving female sporeThe result of meiosis is 4 haploid cells. Only one of these cells survives. In the next slide you would see the surviving female spore

    36. Functional Megaspore This is the megaspore or the female spore (1n) which develops into the female gametophyte (by mitosis). See next sildes.This is the megaspore or the female spore (1n) which develops into the female gametophyte (by mitosis). See next sildes.

    37. Development of Female Gametophyte Megagametogenesis: the megaspore develops into mature female gametophyte (embryo sac) by mitosis Three mitotic divisions follow

    38. First mitotic Division: 2-nucleate embryo sac

    39. 2nd Mitotic Division: 4-Nucleate embryo sac

    41. 3rd Mitotic Division: 8-Nucleate embryo sac

    42. 8-Nucleate embryo sac

    43. Pollination & Fertilization

    44. Double Fertilization