1. Kingdom Plantae
Arose from Green Algae approximately 1 billion years ago
Red and brown algae are not included
A single species of freshwater green algae gave rise to the entire Kingdom
Green algae subsequently split into two groups – the Chlorophytes which never made it to land, and the Charophytes, the sister group of all land plants
Freshwater alga evolved from saltwater alga; that single species is unknown, of course
Most closely related (sister group)

2. Kingdom Plantae is monophyletic

3. Kingdom Plantae Eukaryotic Multi-cellular
Cell walls are made of cellulose
Autotrophic

4. Kingdom Plantae Adaptations for living on land
Waxy cuticle – secreted onto surface; impermeable
Stomata – tiny mouth-shaped openings, which can be opened and closed
Gametangia – structures that produce (and house) gametes
Impermeable – limits gas exchange (disadvantage); stomata – can lose water vapor through (gas exchange occurs through stomata)
Waxy cuticle secreted by epidermal cells of leaves, make leaf hydrophobic, water beads off carrying with it contaminents and dust, etc

5. Plant Life Cycles
Reproduction is accomplished by an alteration of generations
A multi-cellular diploid phase alternates with a multi-cellular haploid phase
The gametophyte (“gamete plant”) is haploid; produces gametes by mitosis
The sporophyte (“spore plant”) is diploid; formed by two gametes; produces spores by meiosis, which germinate and develop into gametophytes!
Not meiosis like in humans; different from animals in that we don’t have a multicellular haploid phase
Remember mitosis results in a doubling of cells; meiosis results in four times the number of cells

6. Gametophyte – haploid, produces gametes by mitosis; gametes fertilize into a zygote which develops into a sporophyte, which undergoes meiosis to produce diploid spores, the spores settle and germinate into gametophytes

7. Plant Life Cycles
The diploid sporophyte is the dominant portion of the life cycle in most land plants (vascular plants: ferns, gymnosperms and angiosperms)
However, the haploid gametophyte is the dominant portion of the life cycle in Bryophytes (liverworts, hornworts and mosses)
Dominant = most conspicuous

8. Plant Life Cycles Bryophyte gametophyte
Vascular plant sporophyte (sori on the back of a fern)
Sori – spore –producing structures

9. Plant Life Cycles
In seed plants, the haploid gametophytes are male and female; the males occur as pollen and the females occur as seeds
The seed growing on the diploid sporophyte ‘parent’ contains a haploid female gametophyte bearing an egg cell, and is fertilized by a pollen grain which contains a miniature male gametophyte
diploid zygote diploid sporophyte
The offspring sporophyte and the parent gametophyte are then nourished by the ‘grandparent’ sporophyte while the seed is ripe enough to be released

10. Plant Life Cycles Pine cones contain seeds and pollen
The familiar pine cone is the female
The male (containing pollen) is not really a cone at all, but rather a cluster
Both cones will occur on one tree – male cones occur on top for wind to carry to female on lower branches

11. Chlorophytes
Green Algae
Aquatic
Unicellular and multi-cellular

12. Bryophytes The closest living descendents of the first land plants
Simple, but highly adapted
Lack roots
Mycorrhizal associations are found in many groups
Typically small (the conspicuous form are gametophytes!); <7cm in height
Non-vascular but have conducting cells for water and nutrients

13. Bryophytes
Liverworts and Hornworts

14. Bryophytes Mosses Multi-cellular rhizoids
Rhizoids function as roots; anchor to substrate and absorb water
Green parent plant is the gametophyte; sporophyte nutritionally dependent on gametophyte
But not nearly as much water as vascular plants

15. Tracheophytes The first vascular plants
Evolved lignified tissues for conducting water, nutrients and photosynthetic products through the plant
Xylem – draws water and nutrients up from roots to the upper sections of the plant
Phloem – conducts photosynthetic products and hormones throughout plant
“Xylem up, Phloem down!”
First plant appeared 420 mya; very small; Xylem and phloem first found in this group

16. You are Here

17. Tracheophytes

18. Tracheophytes (cont.)
Tracheophytes include 7 extant phyla

19. Lycophytes and Pterophytes
The Club Mosses (Lycophytes; not true mosses) and Ferns (Pterophytes)

21. Seed Plants Seeded plants
Embryo protected by an extra layer of sporophytic tissue; during development, this tissue hardens to produce the seed coat
Seed protects embryo from drought, allows for easier dispersal, and introduces a dormant stage, that allows the embryo to survive until environmental conditions are favorable for growth

23. Seed dispersal
nationalzoo.si.edu/AnimalsBackyardBiology/UrbanNatureWatch/Watches/PlantAdap...ersal.cfm

24. Gymnosperms
Plants with “naked seeds”

25. Gymnosperms Gametophyte stage is further reduced
Male gametophyte is inside pollen
Female gametophyte inside seed…

26. Reminder – conifers are gymnosperms
Pine cones contain seeds and pollen
The familiar pine cone is the female
The male (containing pollen) is not really a cone at all, but rather a cluster
Both cones will occur on one tree – male cones occur on top for wind to carry to female on lower branches

27. Angiosperms Flowering Plants
Include Monocots (one cotyledon) and Dicots (two cotyledon)

28. Angiosperms
Flowers – reproductive organs; considered to be modified stems with modified leaves
Consist of:
Stamen - produces pollen, bears pollen on anther
Carpel – includes the ovary (the swollen base), stigma (sticky, pollen grains adhere to), style (connects the stigma to the ovary)
(evolution a tinkerer)
Ovary later develops into a fruit

29. Can be perfect or imperfect (male and female together or male or female, respectively)

30. Angiosperms
Double fertilization – 2 sperm cells fertilize 2 cells in the ovary; 1 sperm fertilizes the egg forming the diploid zygote; the other fuses with 2 haploid polar nuclei resulting in a triploid cell, divides through mitosis and forms the endosperm – the nutriient-rich tissue inside the seed

31. Angiosperms
The flower is designed (evolved) to attract pollinators (or to aid in wind dispersal)
The flower uses color, scent, morphology and reward to attract pollinators
Color – advertises to pollinators
Scent – attracts pollinators
Morphology – can be specific, attracts pollinators (hummingbird bills, bee orchids)
Reward – nectar; sweet and nutritious
Flowers that self-fertilize tend to small, inconspicuous and unscented!
Bees have ‘favorite’ colors – attracts them to best necter; color differentiates flower from background foliage
Bees see in the UV range; so blues and violets, but no reds! Color of flower can be specific to pollinator!

33. Coevolution
Evolution of angiosperms led to increased diversity in animals; speciation (niche!)