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How Plants Colonized the Land 
and Evolution of Seed Plants 
Selected Topics in Biology 
Ariane B. Sogo-an 
MST Biology
Objectives 
At the end of the lesson, the MST Biology 
students are expected to conduct the following 
with at least 80% l...
Biodiversity and Evolution 
• There are more than 290,000 recorded species 
of plants known today to be inhibiting the 
pl...
Biodiversity and Evolution 
• There are even terrestrial plants that 
seemingly shares characteristics from aquatic 
plant...
Biodiversity and Evolution 
• The great diversity of life is 
the PRODUCT of evolution. 
It represents the many 
different...
An Overview of Land Plant Evolution
• For more than the first 3 
billion years of Earth’s 
history, the terrestrial 
surface was lifeless and 
plants first in...
• The movement onto land carried many 
benefits: including unfiltered sun, more 
plentiful CO2, nutrient-rich soil, and fe...
Aquatic to Terrestrial plants 
• Three (3) major obstacles. 
– Water retention (not drying 
out), 
– Structural support (a...
Shared Traits of Algae and Plants 
• Like brown, red, and some green algae, plants 
are multicellular, eukaryotic, photosy...
Charophytes 
• Many species of Charophyte algae live in 
shallow water around the edges of lakes and 
ponds. How do they w...
EVIDENCES THAT SUPPORT THE PHYLOGENETIC 
CONNECTION BETWEEN LAND PLANTS AND GREEN ALGAE 
• Homologous chloroplasts 
• pres...
EVIDENCES THAT SUPPORT THE PHYLOGENETIC 
CONNECTION BETWEEN LAND PLANTS AND GREEN ALGAE 
• Homologous peroxisomes 
– Both ...
EVIDENCES THAT SUPPORT THE PHYLOGENETIC 
CONNECTION BETWEEN LAND PLANTS AND GREEN ALGAE 
• Molecular systematics 
– In add...
Terrestrial Plant Adaptation 
• Alternation of generations and multicellular, 
dependent embryos 
• Spores produced in spo...
Evolution of Roots, Stem and Leaves
Physiological modifications of plants 
to survive above sea level: 
• root system. 
• shoot system 
• Stems grew and branc...
Further adaptations of plants 
• Cuticle 
• Mycorrhizae – important to plants without 
roots. Nitrogen fixing agent. 
• Se...
From Haploid to Diploid Dominance 
• In Algae, a haploid (n) phase in the form of 
gametophytes (gamete producing bodies),...
Evolution of Pollen and Seeds 
• Like some seedless species, seed bearing 
plants produce not one but two (2) types of 
sp...
Pollen Grain 
• The evolution of pollen 
grains contributed to 
the successful radiation 
of seed bearing plants 
into hig...
Seeds 
• It was no coincidence that 
during the Permian time 
when the climate was 
extreme, seed plants rose 
dominant.
Plant Diversity 
• Bryophytes 
• The Bryophytes lineage consists of about 
18,600 species called mosses, liverworts and 
h...
Examples of Bryophytes 
Liverworts 
(Phylum Hephaeophyta) 
Hornworts 
(Phylum Anthoceraphyta)
Mosses 
Phylum Bryophyta
Physical Characteristics of Bryophytes 
• All known Bryophytes are less 
than twenty (20) centimeters 
(eight inches tall)...
Evolution of Bryophytes 
• Presence of Cuticle 
• Cellular Jacket 
• Large gametophytes
Mode of Reproduction of Bryophytes
SEEDLESS VASCULAR PLANTS 
• Descendants of seedless plants lineage still 
exist today such as whisk ferns, lycophytes, 
ho...
How does Vascular plants differ from Bryophytes? 
• Sporophytes does not remain attached to 
gametophyte 
• It has true va...
Characteristics of Seedless Vascular 
plants 
• Most seedless vascular plants live in wet, 
humid places, and their gameto...
Life Cycle of Vascular Seedless plants
Examples of Seedless Vascular Plants 
Whisk Ferns 
(Psilophyta) 
Lycophytes 
(Lycophyta)
Examples of Seedless Vascular Plants 
Horsetail 
(Sphenophyta) 
Ferns 
(Pterophyta)
RISE OF THE SEED-BEARING PLANTS 
• In terms of diversity, numbers and 
distribution, they would become the most 
successfu...
How do they differ from Seedless 
Vascular Plants? 
• Besides microspores, seed-bearing plants 
also reproduce megaspores ...
• Compared with the seedless vascular plants, 
gymnosperms had water conserving traits, 
including thick cuticles and stom...
How do Pines Reproduce? 
• Pine tress produces pine cones. 
• The scales are parts of a mature female cone 
which bears ov...
• Unlike the seeds of 
flowering plant, which 
are enclosed in a 
reproductive chamber 
(an ovary), 
gymnosperm seeds 
gro...
Gymnosperm Diversity 
• Conifers
Gymnosperm Diversity 
• Cycads
Gymnosperm Diversity 
• Ginkgos
Angiosperms – The Flowering, Seed 
Bearing plant 
• Only the Angiosperm produce specialized 
reproductive structures calle...
Embryo Development of Angiosperms
Embryo Development in Angiosperm 
• The first mitotic division of the zygote splits the 
fertilized egg into a basal cell ...
Structure of the Mature Seed 
• The embryo and its food supply are 
enclosed by a hard, protective seed 
coat 
• Below the...
Derivation from seed to plant
• Seeds gives rise to mature plants when their 
dormancy is disrupted in the presence of 
water. Hypocotyl gives rise to s...
• There are two (2) classes of flowering plants 
called the dicots and monocots. 
• The monocots are grass and "grass-like...
Characteristics Monocot 
Dicot 
Number of 
cotyledons 
One Cotyledon Two Cotyledons 
Number of floral 
parts 
Floral parts...
END OF REPORT
How plants colonized the land and evolution
How plants colonized the land and evolution
How plants colonized the land and evolution
How plants colonized the land and evolution
How plants colonized the land and evolution
How plants colonized the land and evolution
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How plants colonized the land and evolution

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How plants colonized the land

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How plants colonized the land and evolution

  1. 1. How Plants Colonized the Land and Evolution of Seed Plants Selected Topics in Biology Ariane B. Sogo-an MST Biology
  2. 2. Objectives At the end of the lesson, the MST Biology students are expected to conduct the following with at least 80% level of accuracy: – Relate Evolution and Biodiversity of Plant Kingdom – Trace the evolutionary modification of plants throughout time. – Determine the different plant group per evolutionary modification and characteristics.
  3. 3. Biodiversity and Evolution • There are more than 290,000 recorded species of plants known today to be inhibiting the planet earth and most of them adapted mechanisms to be able for them to inhabit various corners of the world such as deserts, grassland and forest.
  4. 4. Biodiversity and Evolution • There are even terrestrial plants that seemingly shares characteristics from aquatic plants thus pushing the curiosity of mankind to try to explain the origin of plants and how it colonized the world since the beginning of time.
  5. 5. Biodiversity and Evolution • The great diversity of life is the PRODUCT of evolution. It represents the many different ways in which the common elements of life’s organization have combined to provide new and successful ways to survive and reproduce. • Modification for survival to certain environment • Ability to bear seeds
  6. 6. An Overview of Land Plant Evolution
  7. 7. • For more than the first 3 billion years of Earth’s history, the terrestrial surface was lifeless and plants first inhabited bodies of water.
  8. 8. • The movement onto land carried many benefits: including unfiltered sun, more plentiful CO2, nutrient-rich soil, and few herbivores or pathogens
  9. 9. Aquatic to Terrestrial plants • Three (3) major obstacles. – Water retention (not drying out), – Structural support (against gravity), and – Dependence on water for reproduction (getting gametes together).
  10. 10. Shared Traits of Algae and Plants • Like brown, red, and some green algae, plants are multicellular, eukaryotic, photosynthetic autotrophs. • Like green algae, plants have cellulose cell walls. • Like green algae, euglenids, and some dinoflagellates, plants have chlorophylls a and b.
  11. 11. Charophytes • Many species of Charophyte algae live in shallow water around the edges of lakes and ponds. How do they withstand that kind of situation? – Sporopollenin - a layer of a durable polymer that prevents exposed zygotes from drying out. – It was traced scientists that a similar chemical adaptation is found in the sporopollenin walls that encase plant spores.
  12. 12. EVIDENCES THAT SUPPORT THE PHYLOGENETIC CONNECTION BETWEEN LAND PLANTS AND GREEN ALGAE • Homologous chloroplasts • presence of chlorophyll b and beta-carotene and thylakoids stacked as grana. DNA comparison with terrestrial. • Homologous cellulose walls – cellulose comprises 20-26% of the cell wall.
  13. 13. EVIDENCES THAT SUPPORT THE PHYLOGENETIC CONNECTION BETWEEN LAND PLANTS AND GREEN ALGAE • Homologous peroxisomes – Both land plants and charophycean algae package enzymes that minimize the costs of photorespiration in peroxisomes. • Phagmoplasts – These plate-like structures occur during cell division only in land plants and charopyceans. • Flagellated sperm – Many plants have flagellated sperm, which match charophycean sperm closely in ultrastructure.
  14. 14. EVIDENCES THAT SUPPORT THE PHYLOGENETIC CONNECTION BETWEEN LAND PLANTS AND GREEN ALGAE • Molecular systematics – In addition to similarities derived from comparisons of chloroplast genes, analyses of several nuclear genes also provide evidence of a Charophycean ancestry of plants.
  15. 15. Terrestrial Plant Adaptation • Alternation of generations and multicellular, dependent embryos • Spores produced in sporangia • Multicellular gametangia • Apicalmeristem
  16. 16. Evolution of Roots, Stem and Leaves
  17. 17. Physiological modifications of plants to survive above sea level: • root system. • shoot system • Stems grew and branches extensively only after plants developed a biochemical capacity to synthesize and deposit lignin, an organic compound in cell wall. • xylem (distributes water) and phloem (distributes dissolved sugars and other photosynthetic products). • Cuticle • Stomata
  18. 18. Further adaptations of plants • Cuticle • Mycorrhizae – important to plants without roots. Nitrogen fixing agent. • Secondary compounds – ex. alkaloids, terpenes, and tannins
  19. 19. From Haploid to Diploid Dominance • In Algae, a haploid (n) phase in the form of gametophytes (gamete producing bodies), dominates their life cycles. • The dipoid (2n) phase is the zygote, which forms when gametes fuse at fertilization.
  20. 20. Evolution of Pollen and Seeds • Like some seedless species, seed bearing plants produce not one but two (2) types of spores. • This condition is called heterospory, an opposed to homospory (only one type). • pollen grains, which develop into a mature sperm bearing male gametophytes. – do not require free-standing water to reach the egg
  21. 21. Pollen Grain • The evolution of pollen grains contributed to the successful radiation of seed bearing plants into high and dry habitats
  22. 22. Seeds • It was no coincidence that during the Permian time when the climate was extreme, seed plants rose dominant.
  23. 23. Plant Diversity • Bryophytes • The Bryophytes lineage consists of about 18,600 species called mosses, liverworts and hornworts. • These nonvascular plants are mostly well adapted to grow in fully or seasonally moist habitats although there is also other rare types of mosses thriving in deserts and windswept plateaus of Antartica.
  24. 24. Examples of Bryophytes Liverworts (Phylum Hephaeophyta) Hornworts (Phylum Anthoceraphyta)
  25. 25. Mosses Phylum Bryophyta
  26. 26. Physical Characteristics of Bryophytes • All known Bryophytes are less than twenty (20) centimeters (eight inches tall). They have leaflike, stemlike and rootlike parts but these do not contain xylem and phloem. • Most have rhizoids, which are elongated cells or threadlike structures that attach gametophytes to the soil and serve as absorptive structures.
  27. 27. Evolution of Bryophytes • Presence of Cuticle • Cellular Jacket • Large gametophytes
  28. 28. Mode of Reproduction of Bryophytes
  29. 29. SEEDLESS VASCULAR PLANTS • Descendants of seedless plants lineage still exist today such as whisk ferns, lycophytes, horsetails and ferns.
  30. 30. How does Vascular plants differ from Bryophytes? • Sporophytes does not remain attached to gametophyte • It has true vascular tissues • Seedless Vascular plants is larger and have longer lived phase life cycle
  31. 31. Characteristics of Seedless Vascular plants • Most seedless vascular plants live in wet, humid places, and their gametophytes lack vascular tissues. Water droplets clinging to the plants are the only means by which flagellated sperm can reach the eggs.
  32. 32. Life Cycle of Vascular Seedless plants
  33. 33. Examples of Seedless Vascular Plants Whisk Ferns (Psilophyta) Lycophytes (Lycophyta)
  34. 34. Examples of Seedless Vascular Plants Horsetail (Sphenophyta) Ferns (Pterophyta)
  35. 35. RISE OF THE SEED-BEARING PLANTS • In terms of diversity, numbers and distribution, they would become the most successful groups of the plant kingdom. • Seed Ferns, Gymnospserm and much later the angiosperm were the dominant groups.
  36. 36. How do they differ from Seedless Vascular Plants? • Besides microspores, seed-bearing plants also reproduce megaspores – these develop within ovules the female reproductive structures which at maturity are seeds. • Each ovule consists of female gametophytes (with its egg cell), nutrient-rich tissue, and a jacket of cell layers which develops into seed coats. A zygote will form inside the ovule.
  37. 37. • Compared with the seedless vascular plants, gymnosperms had water conserving traits, including thick cuticles and stomata recessed below the surface of the leaf.
  38. 38. How do Pines Reproduce? • Pine tress produces pine cones. • The scales are parts of a mature female cone which bears ovules in which megaspores formed and developed into female gametophytes. • Pine trees also produce male cones, in which microspores forms and develop into pollen grains. • Pollination is completed when some land on ovules of female cones. • For pines, fertilization occurs months or a year after pollination.
  39. 39. • Unlike the seeds of flowering plant, which are enclosed in a reproductive chamber (an ovary), gymnosperm seeds grows, in an exposed location, on top of a spore-producing structure.
  40. 40. Gymnosperm Diversity • Conifers
  41. 41. Gymnosperm Diversity • Cycads
  42. 42. Gymnosperm Diversity • Ginkgos
  43. 43. Angiosperms – The Flowering, Seed Bearing plant • Only the Angiosperm produce specialized reproductive structures called Flowers. • Angeion, which means vessel, refers to the female reproductive parts at the center of the flower. The enlarged base of the “vessel” is the floral ovary, where ovules and seeds develop.
  44. 44. Embryo Development of Angiosperms
  45. 45. Embryo Development in Angiosperm • The first mitotic division of the zygote splits the fertilized egg into a basal cell and a terminal cell • The basal cell produces a multicellular suspensor, which anchors the embryo to the parent plant • The terminal cell gives rise to most of the embryo • The cotyledons form and the embryo elongates
  46. 46. Structure of the Mature Seed • The embryo and its food supply are enclosed by a hard, protective seed coat • Below the cotyledons the embryonic axis is called the hypocotyl and terminates in the radicle (embryonic root); above the cotyledons it is called the epicotyl • The plumule comprises the epicotyl, young leaves, and shoot apical meristem
  47. 47. Derivation from seed to plant
  48. 48. • Seeds gives rise to mature plants when their dormancy is disrupted in the presence of water. Hypocotyl gives rise to shoot system of the plant, Cotyledon diminishes once the plant is already able to have stable transport of nourishments.
  49. 49. • There are two (2) classes of flowering plants called the dicots and monocots. • The monocots are grass and "grass-like" angiosperms (flowering plants). Particularly, the embryos of monocots have only a single (mono-) first leaf (a.k.a., seed leaves or cotyledon), vascular bundles are arranged throughout the stem’s ground tissue and leaf venation projects in parallel unlike in Dicots which has netted venation and their vascular bundles are arranged in a ring.
  50. 50. Characteristics Monocot Dicot Number of cotyledons One Cotyledon Two Cotyledons Number of floral parts Floral parts in three Floral parts in four or five Leaf venation Parallel Netted Number of pores in their pollen grain Pollen grain has one pore or furrow Pollen grain has three pore or furrows Arrangement of the vascular bundles Vascular bundles are arranged throughout stem’s ground tissue Vascular bundles arranged in ring
  51. 51. END OF REPORT

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