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10/1/2012 BI 103: Plants Plant Family History Taxon: A Ranked Hierarchy Kingdom: Plantae Phylum: Magnoliophyta Class: Magnoliopsida Order: Rosales Family: Rosaceae Genus: Malus Species: Malus pumila Adaptation to Land For a Plant: What are the differences between life on land and life in the water? Variation in temperature - fluctuation, not buffered by water Variation in moisture - no longer continuously bathed in water Nutrient availability - differences between water and soil and how nutrient uptake occurs Gravitational force - floating at the surface was sufficient to get to the sun Substrate - differences between water and soil Adaptation to Land What types of adaptations are needed to move from water to land habitat? Protection against water loss Cuticle to prevent water loss, stomata for regulation Ability to tolerate variation in temperatures Roots for anchoring to substrate and nutrient absorption Protection for gametes: specialized structures Gametes (sperm) do not require water Development of vascular tissue 1 10/1/2012 Bryophytes • Gametophyte generation dominant • true organs lacking • thallus (undifferentiated plant body) • rhizoids (root hair like structures) •unicellular or multicellular; anchorage function only •Pores: allow gas exchange; don’t close • conducting tissues absent or primitive • water required for fertilization Bryophytes: non vascular plants: Liverworts Gemmae cups Create liverwort Clones! 2 10/1/2012 Liverwort Bryophytes: Non vascular plants: Moss Bryophytes: Non-vascular plants: Moss Hornworts! 3 10/1/2012 Vascular plants: Derived adaptations Vascular tissue: conducts water and nutrients throughout the plant Plant organs: roots, stems, leaves Sporophyte generation dominate (plant spends more of its life in the sporophyte (2n) generation Lycophytes: “club mosses” Sporophyte dominate generation Vascular tissue Stems, roots, leaves! Strobilus: where spores are produced via meiosis 4 10/1/2012 Pterophytes (ferns and allies) • 11,000 extant species, mostly in the tropics; many extinct • Psilotales: whisk ferns(no roots) • Equisetales: horsetails • roots, stems & leaves present • sporangia variable in Sori, not strobilus TRENDS THROUGH TIME Pterophyte:Fern Life cycle Ancestral Derived Mosses & Liverworts Club mosses,horsetails, Plants we’ll cover next week… whisk ferns & ferns Non-vascular Spores Gametophyte-dominant Sperm require water Vascular Spores Sporophyte-dominant Sperm require water Vascular Seeds! Sporophyte-dominant Sperm don’t need water 5 10/1/2012 Moss Motile sperm Gametophyte-dominant Cuticle Homospory Gametophyte -dominant Liverworts Gammae cups Motile sperm Gametophyte-dominant Cuticle Gemmae cups Homospory Chlorophyta Green algae Ex: Chara Motile sperm Cuticle Strobili Gymnosperms Pterophytes Lycophyta Vascular tissue Motile sperm Sporophyte-dominant Cuticle Heterospory Roots and leaves Strobili Sori Pterophyta Vascular tissue Motile sperm Sporophyte-dominant Cuticle Heterospory Roots and leaves Sori Seeds Lycophytes Vascular tissue Sporophyte-dominant Roots and leaves Angiosperms Bryophytes Vascular tissue Green algae: Chlorophytes Land plants Gymnosperms Coniferophyta (pines and cone bearing trees) Cycads (palmlike) Ginkgos (ginkgo trees) Gnetophyta (gnetums) Gymnosperms: Ginkgo Long thought to be extinct in western civilization, until travelers from Germany found it while visiting temples in China and Japan. Flagellated sperm Dioecious (separate male and female plants) Fleshy outer covering to seed (not true fruit) 6 10/1/2012 Gymnosperms: Cycadophyta Flagellated sperm still, but use of pollen tube Palm-like plants, but have cones for reproduction Endangered by poaching and a black market Gymnosperms: Gnetophyta Ephedra Temperate regions except Australia Welwitchsia Namibia Gnetophyta: Welwitchsia Gnetum Old and New World Tropics • Flower-like structures • Vessels in xylem== not found in other Gymnosperms • double fertilization • Also loss of flagellated sperm and uses pollen tube. 7 10/1/2012 Gnetophyta: Ephedra in Utah Gnetophyta: Ephedra spp.== Mormon tea oNaked seeds oUse of pollen tube oThick cuticles oPhotosynthetic stems in Ephedra Gymnosperms: Coniferophyta Key characteristics: Loss of flagella on sperm, sperm conducted to egg by a pollen tube. Needle-like or scale like leaves Thick cuticle Recessed stomata Resin Cones 8 10/1/2012 What are the advantages of flowering? Discuss the question in groups of 2-3 students 5 min Angiosperms: the Flowering plants What are the advantages to the plant? Less inbreeding Higher probability the pollen will reach the right plant They don’t have to produce as much pollen Enlists partnerships with insects and other animals 9