Chapter 29 Plant Diversity What are the characteristics of plants? Photosynthetic autotrophs Cellulose in cell walls Starch as storage polysaccharide PROBLEM – light, CO2 & air are above ground - water & minerals are below ground SOLUTION – evolution of specialized structures What adaptations do plants have for survival on land? Stomata – pores used for gas exchange Roots – absorb water & minerals from underground Apical meristems – tips of shoots & roots where growth occurs Cuticle – waxy covering to prevent water loss thru leaves Jacketed gametangia – gamete producing organ with protective jacket of cells to prevent dehydration Sporopollenin – polymer that formed around exposed zygotes & forms walls of plant spores preventing dehydration Lignin – structural polymer that provides strength for woody tissues of vascular plants Algae also

Alternation of generations: a generalized scheme Chapter 29 Plant Diversity What are the characteristics of plants? What adaptations do plants have for survival on land? Stomata – pores used for gas exchange Roots – absorb water & minerals from underground Apical meristems – tips of shoots & roots where growth occurs Cuticle – waxy covering to prevent water loss thru leaves Jacketed gametangia – gamete producing organ with protective jacket of cells to prevent dehydration Sporopollenin – polymer that formed around exposed zygotes & forms walls of plant spores preventing dehydration Lignin – structural polymer that provides strength for woody tissues Describe alternation of generations Alternates between sexual & asexual reproduction Gametophyte (n) make gametes by mitosis Sporophyte (2n) makes spores by meiosis Haploid multicellular organism (gametophyte) Mitosis Gametes Zygote Diploid multicellular organism (sporophyte) Alternation of generations: a generalized scheme MEIOSIS FERTILIZATION 2n n Spores

Chapter 29 Plant Diversity What are the characteristics of plants? What adaptations do plants have for survival on land? Describe alternation of generations What is the evidence that plants evolved from charophytes (green algae)? rose-shaped complexes for making cellulose Proteins in the plasma membrane that make cellulose microfibrils Linear arrays found in non-charophytes Similar %age of cellulose found in plants & charophytes 30 nm

Chapter 29 Plant Diversity What are the characteristics of plants? What adaptations do plants have for survival on land? Describe alternation of generations What is the evidence that plants evolved from charophytes (green algae)? Similarities?? rose-shaped complexes for making cellulose Proteins in the plasma membrane that make cellulose microfibrils Linear arrays found in non-charophytes Similar %age of cellulose found in plants & charophytes Peroxisome enzymes Sperm structure – flagella Formation of phragmoplast Phragmoplast – an alignment of cytoskeletal elements & Golgi-derived vesicles at a dividing cell’s midline Used in making cell plates during cell division Genetic evidence “Deep Green” Nuclear & chloroplast genes

Chapter 29 Plant Diversity What are the characteristics of plants? What adaptations do plants have for survival on land? Describe alternation of generations What is the evidence that plants evolved from charophytes (green algae)? How did plants evolve from green algae? Natural selection Algae best suited genetically for a drier climate (low water in a lake) could reproduce & pass along those genes to create a new population of better adapted “algae” What were the highlights/adaptations of plant evolution? Movement to land led to Bryophytes (mosses & worts) Tougher spores (sporopollenin) Jacketed gametangia Vascular tissue (ferns) Cells joined to transport water & nutrients Lacked seeds Development of seeds (Gymnosperms) More protection of embryo Embryo w/ food Development of flowers (Angiosperms) Complex reproductive structure

Figure 29.7 Highlights of plant evolution Bryophytes (nonvascular plants) Seedless vascular plants Seed plants Vascular plants Land plants Origin of seed plants (about 360 mya) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Charophyceans Liverworts Hornworts Mosses Lycophytes (club mosses, spike mosses, quillworts) Pterophytes (ferns, horsetails, whisk ferns) Gymnosperms Angiosperms

Table 29.1 Ten Phyla of Extant Plants