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Carolus Linnaeus - late 18thC

Carolus Linnaeus - late 18thC. Species Plantarum 1753 Systems Naturae 1767 - (24) major categories of plants (Divisions) - (23) vascular ( Phanerogams ); - (1) non-vascular & vascular ( Cryptogams ). K: Plantae - Ordovician - Non-vascular - Silurian - Vascular.

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Carolus Linnaeus - late 18thC

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  1. Carolus Linnaeus - late 18thC Species Plantarum 1753 Systems Naturae 1767 - (24) major categories of plants (Divisions) - (23) vascular (Phanerogams); - (1) non-vascular & vascular (Cryptogams)

  2. K: Plantae - Ordovician - Non-vascular - Silurian - Vascular

  3. Continental Positions During Early Plant Evolution

  4. Vascular Plants - The Tracheophytes • 1. Have specialized cell type for conducting water - tracheids (early xylem tissue). Also has specialized cell type for conducting sugar - seive cells (phloem tissue). • 2. Lignin in xylem for rigid structural support. • 3. A branching, independent sporophyte.

  5. Vascular Plants - The Tracheophytes

  6. Vascular Plants - The Tracheophytes(300 mya) • Non-seed Tracheophytes - haploid & diploid generations totally independent • - spores most prominent resting state

  7. Rhyniophyta - the earliest Tracheophytes(extinct by Devonian Period 400 mya) • 1. Simple vascular system (xylem & • phloem) in stem. • 2. “Leaves” flattened scales - no • vascular tissue. • 3. No roots - but rhizomes. • 4. Dichotomous stem branching. • 5. Aerial branches and sporangia at • branch tips. • 6. Spores were in groups of four (?) • tetrads - indicate meiosis • plant body - a sporophyte (2n) • spores - (n) ---> gameophyte (n)--> • sexual reproduction--> sporophyte (2n) • (fossil)

  8. Lignier’s Hypothesis (1903)How Roots Evolved from Stems • ancestoral form --->

  9. Evolution of Leaves • Leaf - a flattened photosynthetic structure emerging from the stem and possessing true vascular tissue. • Probably evolved from sterile sporangia.

  10. Evolution of Leaves • Leaf - a flattened photosynthetic structure emerging from the stem and possessing true vascular tissue. • Complex leaves arose as photosynthetic tissue developed between complex branching patterns

  11. HomosporyThe Most Primitive Spore Process • one type of spore; one type of gametophyte

  12. HeterosporyThe Most Advanced Spore Process • two types of spores; two types of gametophytes • heterospory probably evloved several times

  13. K: Plantae Div: LycophytaG: Lycopodium “ground pines” • 1. Leaves small and sessile; no ligule • at base. • 2. Stems with aerial branches and • rhizomes; dichotomous branching. • 3. Branch roots originate deep within • main root. • 4. Mainly perennial. • 5. Low growing in temperate forest or • epiphyte in Tropical forest. • 6. Homosporous or Hetersporous

  14. K: Plantae Div: LycophytaG: Lycopodium “ground pines” • Plectostele - dissected xylem • with phloem branches in • between. • Xylem - all tracheids. • Phloem - all seive cells • Epidermis - contains stomata.

  15. K: Plantae Div: LycophytaG: Lycopodium “ground pines” • Plectostele - • Always a layer of parenchyma cells between xylem and phloem.

  16. K: Plantae Div: LycophytaG: Lycopodium “ground pines” • Plectostele - dissected xylem • with phloem branches in • between. • Xylem - all tracheids. • Phloem - all seive cells • mucilaginous canal • Epidermis - contains stomata. • ExarchStele -

  17. stomata

  18. K: Plantae Div: LycophytaG: Lycopodium “ground pines” • A. ExarchStele - • B. MesarchStele • C. EndarchStele

  19. K: Plantae Div: LycophytaG: Lycopodium “ground pines” • Sexual Reproduction: • sporophyte (2n) ---- meiosis ----> • ------> spores (n) --> gametophyte (n) --> antheridia (n) & archegonia (n) • antheridium ----> sperms (n) • -- fertilization --> zygote (2n) --> sporophyte (2n) • Archegonium ----> egg (n)

  20. K: Plantae Div: LycophytaG: Lycopodium “ground pines” • Sexual Reproduction: • sporophyte (2n) ---- meiosis ----> • ------> spores (n) --> gametophyte (n) --> antheridia (n) & archegonia (n) • (homospores) • antheridium ----> sperms (n) • -- fertilization --> zygote (2n) --> sporophyte (2n) • Archegonium ----> egg (n)

  21. K: Plantae Div: LycophytaG: Lycopodium “ground pines”

  22. K: Plantae Div: LycophytaG: Lycopodium “ground pines” • strobilus (2n) - • stem with short • internodes and fertile • appendages • sporophyll (2n) • sporangium (2n) • spores (n) • l

  23. K: Plantae Div: LycophytaG: Lycopodium “ground pines” • sporophyll & sporangium • adaxial view

  24. K: Plantae Div: LycophytaG: Lycopodium “ground pines”

  25. K: Plantae Div: LycophytaG: Lycopodium “ground pines” • gemmae or bulbils (2n) • (asexual reproduction) • axial sporophylls • g

  26. K: Plantae Div: LycophytaG: Selaginella “spike mosses” • 1. Herbaceous: perennial. • 2. Ligulate* leaves; microphyllous; spirally or alternately arranged. • 3. Abundant branching. • 4. Some vessels* in xylem. • g

  27. K: Plantae Div: LycophytaG: Selaginella “spike mosses” • 1. Herbaceous: perennial. • 2. Ligulate*leaves; microphyllous; spirally or alternately arranged. • 3. Abundant branching. • 4. Some vessels* in xylem. • 5. Strobilus composed of sporophylls each bearing a single sporangium • on the adaxial surface. • 6. Heterosporous* reproduction. • g

  28. K: Plantae Div: LycophytaG: Selaginella “spike mosses” • 6. Heterosporous* reproduction. • Strobilus (2n) --> microsporophylls (2n) --> microsporangium (2n) --> • megasporophylls (2n) --> megasporangium (2n) --> • meiosis • microsporangium (2n) --> microsporocytes (2n) ---------------> microspores (n) • megasporangium (2n) --> (4) megasporocytes (2n) ----------> (4) megaspores (n) • g

  29. K: Plantae Div: LycophytaG: Selaginella “spike mosses” • meiosis • microsporangium (2n) --> microsporocytes (2n) ---------------> microspores (n) • megasporangium (2n) --> (4) megasporocytes (2n) ----------> (4) megaspores (n) • --> microspores (n) --> male gametophytes (n), antheridium --> sperms (n) • --> (4) megaspores (n) --> female gametophytes (n), archegonium --> egg (n) • dioecious • triradiate • walls --> • g

  30. K: Plantae Div: LycophytaG: Selaginella “spike mosses” • fertilization - -> zygote (2n) --> adult sporophyte (2n)

  31. K: Plantae Div: LycophytaG: Selaginella “spike mosses” • fertilization - -> zygote (2n) --> adult sporophyte (2n)

  32. K: Plantae Div: LycophytaG: Selaginella “spike mosses” • g

  33. K: Plantae Div: LycophytaG: Isoetes “quillworts” • Mainly aquatic or amphibious

  34. K: Plantae Div: LycophytaG: Isoetes “quillworts” • 1. Quill-like leaves spirally attached to a corm; microphyllus and ligulate. • Corm - thickened underground stem. Nodes very close together. • Lacunae --->

  35. K: Plantae Div: LycophytaG: Isoetes “quillworts” • 1. Quill-like leaves spirally attached to a corm; microphyllus and ligulate. • Corm - thickened underground stem. Nodes very close together. • 2. Each leaf has 4 lacunae; stomata in epidermis. • 3. Some seive cells lack nucleus *at maturity - plasmodesmata with adjacent • cells.

  36. K: Plantae Div: LycophytaG: Isoetes “quillworts” • 1. Quill-like leaves spirally attached to a corm; microphyllus and ligulate. • Corm - thickened underground stem. Nodes very close together. • 2. Each leaf has 4 lacunae; stomata in epidermis. • 3. Some seive cells lack nucleus at maturity - plasmodesmata with adjacent • cells. • 4. Stem and root protostelic:

  37. K: Plantae Div: LycophytaG: Isoetes “quillworts” • 1. Quill-like leaves spirally attached to a corm; microphyllus and ligulate. • Corm - thickened underground stem. Nodes very close together. • 2. Each leaf has 4 lacunae; stomata in epidermis. * • 3. Some seive cells lack nucleus at maturity - plasmodesmata with adjacent • cells. • 4. Stem and root protostelic. • 5. Xylem consists of large numbers of parenchyma cells with few tracheids. * • 6. Delicate roots grow from base of corm (rhizophores); stele bound by • well defined endodermis*; have root caps.

  38. K: Plantae Div: LycophytaG: Isoetes “quillworts” • 7. Heterosporous. • 8. Every leaf of Isoetes is potential a sporophyll; per season - • sterile leaves 1st; then megasporophylls; then microsporophylls. • --> 1 million microspores; 50 - -> 300 megaspores.

  39. K: Plantae Div: LycophytaG: Isoetes “quillworts” • Reproduction: • meiosis • microsporangium (2n) -----------> microspores (n) • megasporangium (2n) ----------> megaspores (n)

  40. K: Plantae Div: LycophytaG: Isoetes “quillworts” • Sporangium massive > 7mm. • Velum - covering over sporangium. • Trabecula - strands of sterile tissue extending from the sporangial wall. • Tapetum - innermost layer of the sporangial wall. Indistinguishable.

  41. K: Plantae Div: LycophytaG: Isoetes “quillworts” • meiosis (all spores set free) • microsporangium (2n) ---------> microspores (n) --> male gametophyte (n) • megasporangium (2n) --------> megaspores (n) --> female gametophyte (n) • male gametophyte (n) --> antheridium (4 sperms) multiflatelated • female gametophyte (n) --> archegonium (1 egg) • *further reduction of • gametophyte!* • colorless, saprophytic

  42. K: Plantae Div: LycophytaG: Isoetes “quillworts” • male gametophyte (n) --> antheridium (4 sperms) • female gametophyte (n) --> archegonium (1 egg) • *further reduction of • gametophyte!* • colorless, saprophytic • no suspensor • 1 embryo develops • from each gametophyte

  43. K: Plantae Div: LycophytaG: Isoetes “quillworts” • No suspensor; delayed development • of the stem.

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