190 likes | 432 Views
Ch 17 Plants Colonization of Land. LM 444 . PLANT EVOLUTION AND DIVERSITY. Plants evolved from green algae Molecular, physical, and chemical evidence Indicates that green algae called charophyceans are the closest living relatives of plants. Figure 17.1A, B. Coleochate. Chara.
E N D
LM 444 PLANT EVOLUTION AND DIVERSITY • Plants evolved from green algae • Molecular, physical, and chemical evidence • Indicates that green algae called charophyceans are the closest living relatives of plants Figure 17.1A, B Coleochate Chara
Plants have adaptations for life on land • Plants are: multicellular photosynthetic eukaryotes
Plant Reproductive structures, as in flowers,contain spores and gametes Leaf performs photosynthesis Cuticle covering leaves and stemsreduces water loss; stomata inleaves allow gas exchange Stem supports plant and mayperform photosynthesis Surrounding watersupports alga Alga Whole algaperformsphotosynthesis;absorbs water,CO2, andminerals fromthe water Rootsanchor plant;absorb water andminerals fromthe soil Holdfastanchors alga • Plants have some specific adaptations • That are not found in algae Figure 17.2A
Obtaining Resources from Two Locations • Apical meristems • Are the growth-producing regions of a plant • Help maximize exposure to the resources in the soil and air
Maintaining Moisture • A waxy cuticle covers the stems and leaves of plants • And helps retain water • Stomata • Are tiny pores in leaves that allow for gas exchange
Plants have vascular tissue • Which helps distribute nutrients throughout the organism Figure 17.2B Xylem Phloem
Reproducing on Land • Many living plants • Produce gametes that are encased in protective structures “Gametangia”
Land plants Vascular plants Bryophytes(nonvascular plants) Seed plants Seedless vascular plants Mosses Hornworts Liverworts Angiosperms Gymnosperms Pterophytes(ferns and relatives) Lycophytes(club mosses and relatives) Origin of seed plants(about 360 mya) Origin of vascular plants(about 420 mya) Origin of land plants(about 475 mya) • Plant diversity reflects the evolutionary history of the plant kingdom • Some highlights of plant evolution Figure 17.3A
Bryophytes lack vascular tissue and include • The mosses, hornworts, and liverworts Figure 17.3B
Ferns are seedless vascular plants • With flagellated sperm Figure 17.3C
Seedless plants dominated vast “coal forests” • Ferns and other seedless plants • Once dominated ancient forests • Their remains formed coal Figure 17.7
Seed plants • Have pollen grains that transport sperm • Protect their embryos in seeds
Gymnosperms, such as pines • Produce seeds in cones Figure 17.3D
The seeds of angiosperms • Develop within protective ovaries Figure 17.3E
The structure of a fruit reflects its function in seed dispersal • Fruits are adaptations that disperse seeds Figure 17.11A–C