1. Ch. 29 Plant Diversity I: The Colonization of Land

2. I.Plant evolution A. Four main groups of extant plants: 1.bryophytes (mosses) -Mosses -Liverworts -Hornworts

3. 2. pteridophytes (ferns) -Lycophytes -Ferns -Horsetail

4. 3. gymnosperms (pines and conifers) 4. angiosperms (flowering plants) DicotsMonocots

5. B.Plants are 1. multicellular 2. eukaryotic 3. photosynthetic 4. autotrophs C.How did they colonize the land? 1.Vascular tissue: tubes that transport water and food. a. However, most bryophytes do not have vascular tissue. (What makes them adapted to land is their reproductive adaptations.)

6. 2.The Seed (360 MYA): Plant embryo packaged along with food supply and a protective coat.

7. 3.The Flower: (130 MYA) a complex reproductive structure that holds both male and female parts. The flower holds the seeds in the ovaries.

8. D.Colonization on land overview: Algae  Bryophytes  Vascular Plants  Seed  Flowers E.Charophyceans: Green algae (closest plant ancestor) 1.Similarities between charophyceans and land plants: a. Produce cellulose in a similar way b. Peroxisomes c. Flagellated sperm

10. F.Characteristics that separated land plants from charophycean algae: 1.Apical meristem: region of cell division at the tips of roots and shoots.

11. 2.Multicelluar, Dependent Embryos (Embryophytes): Parental tissue provides developing embryo with nutrients Embryos

12. 3.Alternation of Generations: two multicellular body forms alternate, each form producing the other. Sporophyte: diploid multicellular organism Gametophyte: haploid multicellular organism

13. Antheridium: male Archegonium: female

14. Life Cycle of Fern:

15. 4.Walled Spores produced in Sporangia: a.Spores: haploid cells that grow into multicellular gametophyte by mitosis. -made from sporopollenin -made in the sporangia (singular = sporangium) -made from the “spore mother cells” 5.Multicellular Gametangia: gametophyte a. produce the haploid gametes b. Female: archegonia - egg c. Male: antheridia – sperm with flagella

17. G.Other adaptations to land: 1.Water conservation: a.Cuticle: waxy polymer protects the plant from microbial attack and acts as waterproofing, preventing excess water losss. b.Stomata: Open for exchange of CO 2 and oxygen; close to minimize water loss in hot, dry weather.

18. 2.Water transport: a.Roots, stems, and leaves have vascular tissues (tube system). -Xylem: tubes that carry water and minerals up from the roots. -Phloem: tubes that distribute sugars, amino acids, and other organic molecules throughout the plant.

19. 3.Secondary Compounds: alkaloids, terpenes, tannins, flavonoids. -toxic to defend against hervibores -flavonoids absorb UV radiation -human use: alkaloid quinine is used to help prevent malaria

20. II. The Origin of Land Plants A.Land plants evolved from green algae (probably charophycean) over 500 MYA. B.Evidence: 1.Homologous chloroplast (DNA analysis) 2.Homologous cellulose walls (cellulose- manufacturing rosettes) 3.Homologous peroxisomes (anti-photo- respiration enzymes in peroxisomes) 3.Phragmoplasts (cell wall forms only during cell division in charophyceans and land plants) 4.Homologous sperm 5.Molecular systematics (rRNA, and protein analysis)

21. C.Three versions of the plant kingdom: 1. Kingdom Plantae 2. Kingdom Streptophyta 3. Kingdom Viridiplantae

22. III. Bryophytes: A.Phylums: Mosses, Liverworts, and Hornworts B.Gametophyte is the dominant generation C.Flagellated sperm D.Most have no vascular tissue E.Short stature (no lignin)

23. IV.The Origin of Vascular Plants: Origin of the pteridophytes, gymnosperms, and angiosperms A.Vascular plants differ from bryophytes: 1. Vascular tissue 2. Dominant sporophyte generation 3. Independent sporophytes

24. V.Pteridophytes: Seedless vascular plants B.Pteridophytes provide clues to the evolution of roots and leaves A.Lycophyta: “club moss” (not a moss) Ferns 1.Lycophyta have small leaves with only one unbranched vein.

25. Lycophyta: club “moss” have small leaves known as “microphylls.”

26. Ferns have megaphylls which are larger leaves, made possible because of the higher branched vascular system.  Greater photosynthetic productivity