Carlson3_BryophytesPteridophytes

Carlson3_BryophytesPteridophytes - Bryophytes,...

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1 Adaptations of Land Plants Professor: Thomas Carlson Bio 1B Fall ’07 2 Land Plants 3 Land Plants • 460 million years ago: – land plants evolved from aquatic green algae – the green algae were probably from fresh water • 400 million years ago: • 380 million years ago: first wood • 360 million years ago: first seeds • 260 million years ago: first vessels in vascular system • 125 million years ago: first flowers 4 Green Algae (Charophyta) (Figs 29.4, 29.7) progenitor to Green Land Plants Green Land Plants – cellulose cell wall – chlorophyll a and b – starch storage product in chloroplast – embryo protected by tissue of parent plant – alternation of generations 5 6
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7 Adaptations to Life on Land Apical Meristems of Shoots & Roots (Fig 29.5) Cuticle: waxy covering that retards desiccation (drying) Stomata: developed for gas exchange Pigments that protect plant against UV radiation Land Plants Optimize Photosynthesis – CO 2 from atmosphere is more available on land – LIGHT from sun is more available on land 8 9 Adaptations to Life on Land (Fig 29.5) Thick spore walls resist decay Gametangia: them from drying Archegonia: encloses eggs Antheridia: encloses sperms Embryos: young sporophytes contained within protective structure 10 11 Adaptations to Life on Land Vascular Tissue: Vascular tissue enables transport of water against gravity from tissues in contact with wet soil to tissues in contact with air: Hydroids (tiny channel through which water travels) in mosses (type of bryophyte) Tracheids
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Carlson3_BryophytesPteridophytes - Bryophytes,...

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