Plant Evolution and Diversity Reading: Chap. 30 A. Plants: fundamentals I. What is a plant? What does it do? A. Basic structure and function B. Why are plants important? - Photosynthesize C. What are plants, evolutionarily? -CO2 uptake D. Problems of living on land -O2 release II. Overview of major plant taxa - Water loss A. Bryophytes (seedless, nonvascular) - Water and nutrient uptake B. Pterophytes (seedless, vascular) C. Gymnosperms (seeds, vascular) -Grow D. Angiosperms (seeds, vascular, and flowers+fruits) Where? Which directions? II. Major evolutionary trends - Reproduce A. Vascular tissue, leaves, & roots B. Fertilization without water: pollen C. Dispersal: from spores to bare seeds to seeds in fruits D. Life cycles Æ reduction of gametophyte, dominance of sporophyte Fig. 1.10, Raven et al. B. Importance of plants C. Where do plants fit, evolutionarily? 1. Food – agriculture, ecosystems 2. Habitat 3. Fuel and fiber 4. Medicines 5. Ecosystem services How are protists related to higher plants? Algae are eukaryotic photosynthetic organisms that are not plants. Relationship to the protists What are the defining traits of plants? - Multicellular, eukaryotic, photosynthetic autotrophs - Cell chemistry: - Chlorophyll a and b - Cell walls of cellulose (plus other polymers) - Starch as a storage polymer - Most similar to some Chlorophyta: Charophyceans Fig. 29.8 Points 1. Photosynthetic protists are spread throughout many groups. 2. Plants are most closely related to the green algae, in particular, to the Charophyceans. Coleochaete 3. Plantae has expanded to include green algae, red algae and glaucophyte Chara algae. What is in common? 1 - Apical meristem “Land” plants only C&R 29.3 - Multicelluar gametangia: antheridia an “Land” plants only d archegonia - Alternation of generations (sporic life cycle) (some butAll not “Land” all green plants algae) 30.13 Moss life cycle C&R 29.6 The Phylogeny of Green Plants Bacteria Archaea - Multicellular, dependent embryos Eukarya Rhodophyta (red algae) Ulvophyceae (ulvophytes) “Land” plants only Coleochaetophyceae (coleochaetes) Charaphyceae (stoneworts) Green plants Green algae Hepaticophyta (liverworts) Nonvascular plants Anthocerophyta Seedless vascular plants (hornworts) Bryophyta Land plants (mosses) 29.17a Lycophyta (lycophytes) Vascular plants Psilotophyta (whisk ferns) Æ Sphenophyta (horsetails) “Embryophytes” Pteridophyta (ferns) Gymnosperms Seed plants Cycadophyta Chloroplasts containing chlorophyll (cycads) Ginkgophyta Ability to live on land (ginkgo) Other conifers Vascular tissue (redwoods et al.) Gnetophyta Angiosperms (gnetophytes) Seeds Pinophyta (pines et al.) Flowers Anthophyta (angiosperms) a + b and β -carotene D. Problems of land life: 30.14 Adaptations for living in air 30.20 2 1. Desiccation of plant 2. Resource acquisition - water and minerals Fig. 30.10 REE, Fig. 1.10 - Roots - Water conservation - epidermis w/cuticle, REE, Fig. 1.10 stomata, guard cells 4. No water for reproduction 3. Light acquisition a. gamete dispersal and desiccation b. spore dispersal and desiccation C&R Fig. 29.7 a. Surface area - Leaves b. Fight gravity - Support c. Fluid transport - Vascular tissue, xylem and phloem Fig. 1.10 - Fertilization and dispersal that are independent of water (some). II. Overview of Taxa 1. Bryophytes Liverworts (Hepaticophyta) Hornworts Mosses (Bryophyta) ~6500 species, moist (Anthocerophyta) ~12,000 species, environments ~100 species widespread 3 Bryophyte ecology: Bryophyte ecology: b. Global carbon cycle a. Groundcover and epiphytes Groundcover Epiphytes B. Seedless vascular plants (Pteridophytes) What’s new? 1. Vascular tissue, true leaves, true roots 2. Sporophyte dominant Lycophyta Psilotophyta Sphenophyta Pterophyta - “club mosses” 30.17b Other SVP developments: true leaves Other SVP developments: true roots Moss phyllids http://www.palaeos.com/Plants/Bryophyta/Bryophyta.html Angiosperm, Fig. 29.10 Club moss, REE Fig. 19-3 4 Figure 30-9 Bacteria Archaea C. Seed plants - Gymnosperms Eukarya Rhodophyta (red algae) Ulvophyceae (ulvophytes) Coleochaetophyceae (coleochaetes) Charaphyceae (stoneworts) Green plants Green algae Hepaticophyta (liverworts) Nonvascular plants Anthocerophyta Seedless vascular plants (hornworts) Bryophyta Land plants (mosses) Lycophyta (lycophytes) Vascular plants Psilotophyta (whisk ferns) Sphenophyta (horsetails) Pteridophyta (ferns) Gymnosperms Seed plants Cycadophyta Chloroplasts containing chlorophyll (cycads) Ginkgophyta Ability to live on land (ginkgo) Other conifers Vascular tissue (redwoods et al.) Gnetophyta Angiosperms (gnetophytes) Seeds Pinophyta 1. Gymnosperms: Who are they? (pines et al.) Flowers Anthophyta (angiosperms) a + b and β -carotene Conifers Phyla: Biggest Ginkgophyta - 1 genus, 1 species: Giant sequoia Cycadophytabiloba - ~100 species Conifers - 550 species: Pinophyta & “other” Gnetophyta(redwoods, - 3 genera, cypresses, 70 spp. junipers, etc.) Tallest? Coast redwood Ginkgo Conifers Conifers highest oldest Bristlecone pine – 4795 in 2007 Conifers Furthest north White spruce 5 Conifers Most photographed Monterey cypress Conifers Widespread (boreal forest, temperate rain forest)Conifers Very important timber species 3. What’s new? http://www.pc.gc.ca/canada/nature/archives/2003/fe/ Wet conditions ART_IMAGES/map_boreal.gif Black spruce a. Secondary growth b. Continued g’phyte reduction c. Pollen and heterospory d. Seeds Conifers D. Seed plants: Angiosperms Dry conditions (Phylum Anthophyta) Juniper Red algae Ulvophytes Coleochaetes Stoneworts Green algae Liverworts Nonvascular plants Hornworts Land plants~270,000 species Seedless vascular plants Mosses Vascular plants Heterospory Lycophytes Whisk ferns Horsetails Gymnosperms Ferns Seed plants Cycads Simple gametangia Retention of egg on parent Thick-walled spores Ginkgo Complex gametangia RetentionAlternation of embryo of generations on parent Redwoods et al. Sporophyte-dominated life Gnetophytes Heterospory Pollen Seeds Pines et al. Angiosperms Flowers Fruit cycle Fruit Figure 30-26 6 1. Who are they? 2. Why are they important? Monocots: ~ 60,000 spp. a. Most diverse phylum, huge radiation Lilies, orchids, b. Base of many terrestrial food webs grasses, palms c. Basis of agriculture Dicots: Fruits Most of the rest Vegetables Trees, shrubs, forbs Grains Eudicots and ‘other’ d. Secondary compounds – drugs, medicines A. What is “vascular tissue” III. Major Evolutionary Trends and what does it do? 1. Xylem A. Structure: Vascular tissue, leaves, & roots - water and nutrients up from B. Reproduction: Fertilization without water: pollen roots to stem, leaves: one way - hollow C. Reproduction: Dispersal of progeny: from spores to bare seeds to seeds in fruits - dead at maturity - secondary cell walls, lignin D. Life cycles Æ reduction of gametophyte, dominance of sporophyte 2. Phloem - photosynthate from leaves to roots, shoots, meristems - living at maturity - no secondary cell walls 3. Evolutionary Sequence Observed in Water- Conducting Cells Simple water- First vascular tissue Tracheids Vessel elements conducting cells Ends have gaps in secondary cell wall (inside) Ends have gaps through primary and secondary cell walls Primary wall Primary wall Primary wall Primary wall (with cellulose) (with cellulose) (with cellulose) (with cellulose) Lignin Secondary wall Secondary wall (with lignin) (with lignin) Little structural Some structural Increased structural Found in gnetophytes support. Found in support. Found support. Found in and angiosperms fossils and present- in fossils all vascular plants day mosses 7 B. Fertilization without water 4. Secondary growth 1.pollen and heterospory a. In Gymnosperms b. (lateral meristem - draw) Conifer life cycle 29.14d Co-evolution with animals 2. Flowers - more efficient fertilization (pollination) Stamen = microsporangia Ovule = megasporangium plus integuments Carpel = stigma + style + ovary Petals and sepals = modified leaves, attract pollinators C&R, 30.13 Many crops depend on natural pollinators Darwin’s Hawk Moth http://www.pbs.org/wnet/nature/bestofnature/video.html US Postal Service http://www.berkeley.edu/news/media/releases/2006/10/25_pollinator.shtml http://encarta.msn.com/media_461530192_761578331_-1_1/Darwin's_Hawk_Moth.html 8 C. New mode of dispersing progeny 1. Seeds Seed formation Incorrect color in “c” - should be C&R, Fig. 30.2 blue for food supply, which is haploid (megagametophyte). Conifer life cycle 29.14d 2. Fruits - more efficient dispersal Fruits - different kinds Wind-dispersed Animal dispersed - eaten Pine seed Animal dispersed - riding Coevolution with animals Water-dispersed C&R, 30.15 30.20, 30.25 3. Angiosperm life cycle 2. Bryophyte life cycle and structure a. ovule inside carpel b. smaller g’phyte 1. G’phyte vs. s’phyte c. Double fert: 2. Archegonia and endosperm - 3n antheridia d. After fert: 3. Water for fert. Ovule Æ seed 4. Embryo on g’phyte Ovary wall Æ fruit 5. Spores for dispersal 6. Roots and leaves? Fig. 30.17a 9.