Chapter 29 Plant Diversity: How plants colonized land

Plant Origins Chlorophyta Plantae Ancestral eukaryote Rhodophyta Fungi Diplomonadida Parabasala Euglenozoa AlveolataStramenopila Cercozoa Radiolaria Amoebozoa Animalia Choanoflagellates Figure 28.4

See Fig Land plants evolved from Charophyceans (multicellular, eukaryotic, green- algae protists) Land plants Origin of land plants (about 475 mya) Ancestral green alga Charophyceans Liverworts Hornworts Mosses Lycophytes (club mosses etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties

See Fig Land plants evolved from Charophyceans (multicellular, eukaryotic, green- algae protists) Chara (a Charophycean pond alga) Land plants Origin of land plants (about 475 mya) Ancestral green alga Charophyceans Liverworts Hornworts Mosses Lycophytes (club mosses etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties

See Fig Land plants Origin of land plants (about 475 mya) Ancestral green alga Charophyceans Liverworts Hornworts Mosses Lycophytes (club mosses etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties The evidence consists of many derived homologies of cellular micro- structure and biochemistry (DNA, chlorophyll, etc.)

Evolutionary innovations: Colonization of land by the first bryophytes See Fig Bryophytes (nonvascular plants) Land plants Origin of land plants (about 475 mya) Ancestral green alga Charophyceans Liverworts Hornworts Mosses Lycophytes (club mosses etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties

Evolutionary innovations: Advent of a vascular system with the origin of vascular plants See Fig Bryophytes (nonvascular plants) Vascular plants Land plants Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Charophyceans Liverworts Hornworts Mosses Lycophytes (club mosses etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties Seedless vascular plants

Evolutionary innovations: Origin of seeds (embryo packaged with a supply of nutrients inside a protective coat) See Fig 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 etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties

Evolutionary innovations: Evolution of flowers (seeds develop inside chambers called ovaries, which originate in flowers that mature into fruits) See Fig 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 etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties

Evolutionary innovations: Alternation of generations See Fig 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 etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties

Review of chromosome number A diploid nucleus (2n) has two of each kind of chromosome A haploid nucleus (n) has only one of each kind of chromosome Human chromosomes from a diploid cell

No alternation of generations Animal Life Cycle: Diploid phase is dominant See Fig. 13.5

No alternation of generations Animal Life Cycle: Diploid phase is dominant See Fig Key Meiosis Fertilization Haploid Diploid n n n 2n Mitosis Zygote Diploid multicellular organism Gametes

Haploid No alternation of generations Fungal Life Cycle (shared by some protists): Haploid phase is dominant See Fig Meiosis Plasmogamy & Karyogamy n 2n Gametes or hyphae Key Diploid Mitosis n n n n Zygote-like cell Haploid multicellular organism Spores

Haploid See Fig Meiosis Fertilization n 2n Zygote Diploid multicellular organism (sporophyte) Gametes Key Diploid Mitosis Alternation of generations Plant Life Cycle (shared by some algae): 2n n n n n Haploid multicellular organism (gametophyte) Mitosis Spores Haploid or diploid phase is dominant, depending on the lineage

Haploid See Fig Meiosis Fertilization n 2n Zygote Diploid multicellular organism (sporophyte) Gametes Key Diploid Mitosis Plant Life Cycle (shared by some algae): 2n n n n n Haploid multicellular organism (gametophyte) Mitosis Spores Spore = reproductive cell that can develop into a new organism

Haploid See Fig Meiosis Fertilization n 2n Zygote Diploid multicellular organism (sporophyte) Gametes Key Diploid Mitosis Plant Life Cycle (shared by some algae): 2n n n n n Haploid multicellular organism (gametophyte) Mitosis Spores Gamete = reproductive cell that must fuse with another gamete

Fertili- zation Meiosis occurs in specialized cells to produce spores Mitosis results in gametophyte growth Mitosis occurs in specialized cells to produce gametes Mitosis results in sporophyte growth Alternation of generations

If humans had alternation of generations

Further Adaptations of Land Plants Apical meristems Shoot Root See Fig. 29.5

Further Adaptations of Land Plants Multicellular, dependent embryos with placental transfer cells Embryo Maternal tissue See Fig. 29.5

Further Adaptations of Land Plants The spore mother cells of diploid sporangia produce protected (walled) haploid spores Spore Sporangium See Fig. 29.5

Further Adaptations of Land Plants Multicelluar, haploid gametangia produce gametes (in all but angiosperms) Archegonium: female gametangium Egg Archegonium See Fig. 29.5

Further Adaptations of Land Plants Multicelluar, haploid gametangia produce gametes (in all but angiosperms) Antheridium: male gametangium Sperm Antheridium See Fig. 29.5

Further Adaptations of Land Plants Characters for conserving water Waxy cuticle coating the epidermis

Further Adaptations of Land Plants Characters for moving water Lignified vascular tissues (found in all but bryophytes) Lignin

Further Adaptations of Land Plants Characters for moving water Phloem and xylem

I. Non-vascular Plants (Bryophytes) See Fig Dominant plants on Earth through the first 100 million years of land plants’ existence Bryophytes (nonvascular 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 etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties

I. Non-vascular Plants (Bryophytes) II. Vascular Plants A. Seedless See Fig Dominant plants in Carboni- ferous, i.e., today’s fossil fuels Bryophytes (nonvascular plants) Seedless vascular 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 etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties

I. Non-vascular Plants (Bryophytes) II. Vascular Plants A. Seedless B. Seed Plants See Fig Dominant plants on Earth today 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 etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties

I. Non-vascular Plants (Bryophytes) II. Vascular Plants A. Seedless B. Seed Plants i. Gymno- sperms ii. Angio- sperms See Fig 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 etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties

Bryophytes Gametophyte dominant; sporophyte dependent; gametophyte independent See Fig. 29.8

Bryophytes Meiosis Fertilization Key Haploid Diploid Male gametophyte Female gametophyte Gameto- phytes produce gametes by mitosis Antheridia Archegonia Sperm (flagellated) Egg See Fig. 29.8

Bryophytes Meiosis Fertilization Key Haploid Diploid Male gametophyte Female gametophyte Antheridia Archegonia Egg Zygote A zygote begins the sporo- phyte generation Mature sporo- phytes produce spores by meiosis See Fig Sporophytes Spores Sperm (flagellated) Sporangium

Bryophytes Moss gametophytes and sporophytes

Bryophytes Thin structure allows distribution of materials without vascular system Rhizoids anchor, but do not play a primary role in water and nutrient uptake

Phylum Hepatophyta - liverworts P. Anthocerophyta hornworts P. Bryophyta mosses Bryophytes

Ball or Spanish “moss” – an Angiosperm Bryophytes

Seedless vascular plants Sporophyte dominant; sporophyte initially dependent; gametophyte independent See Fig

Seedless vascular plants Meiosis Fertilization Key Haploid Diploid Gametophyte Antheridium Egg Sperm (flagellated) See Fig Archegonium Gametophytes produce gametes by mitosis

Fern prothallus = gametophyte Seedless vascular plants Gametophytes produce gametes by mitosis

Seedless vascular plants Meiosis Fertilization Key Haploid Diploid Gametophyte Antheridium Egg Sperm (flagellated) See Fig Archegonium Gametophytes produce gametes by mitosis

Seedless vascular plants Meiosis Fertilization Key Haploid Diploid Gametophyte Antheridium Egg Zygote Mature sporophytes Sperm (flagellated) See Fig Archegonium Young sporophyte Gametophyte A zygote begins the sporophyte generation

Seedless vascular plants Meiosis Fertilization Key Haploid Diploid Gametophyte Antheridium Egg Zygote Mature sporophytes Spores Sperm (flagellated) See Fig Archegonium Young sporophyte Gametophyte Sporangium Sorus Sporophyll Mature sporophytes produce spores by meiosis

Sori = clusters of sporangia Seedless vascular plants

See diagram on pg. 586 Homosporous spore production (most seedless vascular plants) Heterosporous spore production (some seedless vascular plants; all seed plants) Sporangium in sporophyll (2n) Single type of spore (n) Bisexual gametophyte Eggs Sperm

Seedless vascular plants Meiosis Fertilization Key Haploid Diploid Gametophyte Antheridium Egg Zygote Mature sporophytes Spores Sperm (flagellated) See Fig Archegonium Young sporophyte Gametophyte Sporangium Sorus Sporophyll

Seedless vascular plants See diagram on pg. 586 Homosporous spore production (most seedless vascular plants) Heterosporous spore production (some seedless vascular plants; all seed plants) Sporangium in sporophyll (2n) Single type of spore (n) Bisexual gametophyte Eggs Sperm Megasporangium in megasporophyll (2n) Megaspore (n) Female Gametophyte (n) Microsporangium in microsporophyll (2n) Microspore (n) Male Gametophyte (n) Eggs (n) Sperm (n)

Evolution of: Leaves (principal photosynthetic organs of vascular plants) Seedless vascular plants

Evolution of: Roots (principal organs that anchor vascular plants and absorb water & nutrients) Seedless vascular plants

Evolution of: Vascular tissues (conduits that distribute water & nutrients within vascular plants) Seedless vascular plants

Phylum Lycophyta “Club mosses” Seedless vascular plants

Phylum Pterophyta Horsetails E.g., Equisetum Seedless vascular plants

Strobilus – a group of sporophylls forming a cone Phylum Pterophyta Horsetails Seedless vascular plants

Phylum Pterophyta Whisk ferns Seedless vascular plants

Phylum Pterophyta Ferns Terrestrial species are found on the ground Seedless vascular plants

Phylum Pterophyta Ferns Resurrection fern is an epiphytic species, i.e., it grows on other plants Seedless vascular plants

A modern community

Seedless vascular plants A diorama of an ancient community

Seedless vascular plants A fossil stump of a seedless vascular plant

I. Non-vascular Plants (Bryophytes) II. Vascular Plants A. Seedless B. Seed Plants i. Gymno- sperms ii. Angio- sperms See Fig 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 etc.) Pterophyte (ferns, horsetails, whisk fern) Gymnosperms Angiosperms Hashed lines indicate uncertainties

The Life Cycle of Animals – Illustrated for Humans Generation 1 Multicellular individuals; Diploid (2n) cells Unicellular gametes; Haploid (1n) cells Generation 2 Specialized cells undergo meiosis to produce gametes Gametes fuse during fertilization to become a zygote AYAY aXaX Aa XY From the single-celled zygote stage onward, cells undergo mitosis to increase the number of cells in the maturing individual. Unicellular zygote; Diploid (2n) cell Muticellular individuals; Diploid (2n) cells AXAX aXaX AA XY Aa XX AA XX Aa XY Gen. 3 Aa XX

The Life Cycle of Fungi – Illustrated for Bread Mold Several generations Diploid (2n) zygote Several generations Haploid (1n) cells of hyphae Multiple rounds of asexual reproduction possible; all cell divisions occur by mitosis. Brief inter- generational zygote stage Haploid (1n) cells of hyphae Zygotic meiosis Multiple rounds of asexual reproduction possible; all cell divisions occur by mitosis. Fusion of compatible hyphae to form a zygote Aa +- a-a- Haploid (1n) spore A+A+ a-a- a-a- a+a+

The Life Cycle of Plants (Alternation of Generations) – Illustrated for a Dioecious Flower Generation 1 Multicellular sporophyte Unicellular spores Generation 2 Specialized cells undergo meiosis to produce spores Gametes fuse during fertilization to become a zygote aBaB Aa Bb Single-celled spores undergo mitosis to increase the number of cells in the maturing gametophyte. Mature gametophyte produces gametes by mitosis Multicellular gametophyte AbAb Haploid (1n) cells AbAb aBaB Unicellular gametes Generation 3 Diploid (2n) cells Multicellular sporophyte Diploid (2n) cells Unicellular spores of gametophyte Haploid (1n) cells Pollen grain Embryo sac Gen. 4 AA bb Aa Bb Aa Bb Unicellular zygote aa BB Specialized cells undergo meiosis to produce spores AbAb aBaB