1. The Evolution of Land Plants
1: Colonization of Land
2: Evolution of Seed Plants

2. Colonization of Land Overview:
Plants appeared on land about 475 mya, as the descendants of green algae = charophytes
The phylogeny of the Plant Kingdom reflects increasing adaptation to terrestrial habitats
The colonization of land by plants changed the biosphere and created adaptive zones that paved the way for other organisms

3. Adaptations to Life on Land
Plant characteristics
Embryophytes - new mode of reproduction that solves two problems
Alternation of generations - review

4. Plant Characteristics
multicellular, eukaryotic, photosynthetic autotrophs
cell walls of cellulose
surplus carbohydrates stored as a starch
chloroplasts contain chlorophyll a and b
stomata
secondary products: cuticle; lignin; sporopollenin

5. Diversity of Modern Plants
Highlights of plant phylogeny
Classification of plants

6. Origin of Plants Evolution from charophytes
Delayed meiosis and the evolution of alternation of generations

7. Nonvascular Plants Evolution of embryophytes
Gametophyte-dominant life cycle
Mosses (Bryophyta)

8. 3 major challenges to life on land
water conservation:
thick waxy coating on plant surface = cuticle
internal system of tubes and vessels = vascular tissue
reproduction: spore production and alternation of generations
gametophyte: haploid form; produces gametes
sporophyte: diploid form; produces spores
absorption of nutrients and minerals: symbiotic relationship w/ fungi called mycorrhizae

9. Nonvascular Plants characteristics
transport materials by osmosis and diffusion
have flagellated sperm
anchored by root-like structures = rhizoids
due to first two, these plants need lots of water
gametophyte is the dominant form
Mosses = most common and well-known nonvascular plants
pioneer plants - grow in inhospitable places

10. Evolution of Vascular Plants
have tissues which are able to transport water and nutrients over great distances which allows for greater size and complexity
vascular seedless plants: club mosses, horsetails and ferns
these plants have the sporophyte as the dominant form: spores develop on the underside of fronds
gametophyte forms sex cells; dependent on water for fertilization

11. Seed Plants
vascular plants with seeds: very successful, water is not needed for sustained growth
seed = specialized structure that develops from the fertilized egg. Provides 2 advantages:
enables embryos to survive in dry/harsh climates
provide protection to embryo - physical protection
cotyledon = leaflike structures found on a plant embryo which store food and help absorb nutrients from the seed

12. Two Types of Seed Plants: gymnosperms . . .
gymnosperms = “naked seeds”; plants with naked ovules. Most have seeds in the form of cones.
Pine, spruce, fir, and gingko
2 types of cones: seed and pollen cones
pollen cone = produce male gametophytes - pollen grains
seed cone = female gametophyte containing egg cells - ovule
Pollination and Germination

13. . . . and angiosperms
angiosperms = “flowering plants”; ensure gamete exchange during reproduction. Produce embryos contained within seeds that are usually inside a fruit