1. Plant Evolution

2. Adaptations
Cuticle
alternation of generations
specialized tissues

3. Cuticle Waxy coating on surfaces resists drying out
stomata exist to allow necessary gas exchange

4. Alternation of generations
Plants live part of their life in a haploid stage and part in a diploid stage
haploid portion is called the gametophyte generation because it produces the reproductive cells
diploid portion called sporophyte generation because it produces spores

5. Alternation continued...
The gametophyte plant produces male and female sex organs (male and female gametangium)
eggs are fertilized by sperm to form a zygote
embryo development (seed) occurs within the female gametangium (see fig 23-1 on p 421, 23-5 on p 426 and 23-8 on p 430)

6. Specialized tissues
Other than bryophytes all other plants have vascular tissues
xylem - conducts water and minerals
phloem - conducts food

7. Bryophytes Only nonvascular plants (mosses, liverworts)
no ability to internally transport water and materials
require moist environment
live in colonies, has rhizoids to anchor it
important in soil formation
Rhizoids do not act like roots since they have no vascular tissues
Bryophytes are the only plant with a dominant gametophyte generation, that is the plant you see is in a haploid form!
The gametphyte is born at the top of the plant, there may be separate sexes that is male and femal plants or male and femal may be found on the same plant in other species.
The male sperm are carried to the female by flowing water.
The diploid zygote grows into a mutilcellur embryo and matures into a sprorphyte, a diploid plant. The sporophyte plant grows out of the top of the female gametophyte. The sporophyte remains attached and gets nutrition from the femal plant.. At maturity the sporophyte turns brown. It has a foot, a seta (stalk) and a capsule within which meiosis occurs to form the haploid spores.
At maturity the capsule opens the haploid spores are released and if they fall on sutiable ground grow into a gametophyte

8. Ferns Seedless, flowerless, vascular plants have xylem and phloem
has alternation of generation, the common familiar leafy plant is the sporophyte generation
has a rhizome and leaves

9. Ferns II
Spore production occurs on places on the fronds, sporangia are formed in which meiosis occurs to form spores.
Spores are often born in clusters called sori
spores are released and if they germinate will grow into the gametophytes
method of fertilization is primitive like bryophytes

10. Ferns
Whisk ferns - extinct, no roots, no leaves but did have vascular system above and below ground!
Horsetails - roots, rhizomes and vertical stems

11. Heterospory
Homospory - one type of spore produced by bryophytes and many ferns
Heterospory - some ferns have two types of spores produced microspores (male gametophytes) and macrospores (female gametophytes)
the development of heterospory leads two the two most successful kinds of plants

12. Gymnosperms Vascular, seed bearing, flowerless plants
means “naked seed”
largest division is conifers - woody cone bearing gymnosperms
leaves are called needles
most have male and female parts on same plant. Reproductive parts in cone.

13. Gymnosperm reproduction
Microspores and macrospores formed in separate cones
Male cones smaller than female, on lower branches
meiosis in male cone produces a male gametophyte, also called a pollen grain
carried by air current to female gametophyte

14. Angiosperms Flowering, vascular plants most successful plants
fertilization in flowering plants called double fertilization
2 sperm involved - 1 fertilizes the egg, the other fuses with 2 cells in female gametophyte to form endosperm

15. 2 classes of Angiosperms
Monocots - mostly herbaceous, long, narrow leaves,
parallel veination,
flower parts occur in threes,
single cotyledon (embryonic leaf),
endosperm present in seed
vascular bundles scattered

16. 2 classes of Angiosperms
Dicotyledons - herbaceous or woody,
leaves variable in shape,
netted veination,
flower parts occur in 4 and 5,
2 cotyledons,
endosperm usually absent in mature seed
vascular bundles arranged in a circle

17. Plant Evolution
Bryophytes - no roots, leaves or stems, no vascular system, simple reproduction relying on water, gametophyte (haploid) dominant generation
Ferns - first vascular system, rhizomes (horizontal stems), fronds, sporophyte (diploid) dominant generation

18. Plant Evolution
Gymnosperms - first leaves (needles), vascular system, stems and roots, naked seeds
Angiosperms - vascular system more organized, leaves, ability to shed leaves, seed provided with nutritive tissues, flowers, more sophisticated reproductive methods