Ch28_Lecture-Spr11

Ch28_Lecture-Spr11 - 28 28 Plants without Seeds: from Water...

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Unformatted text preview: 28 28 Plants without Seeds: from Water to Land 28 Plants without Seeds: From Water to Land 28.1 How Did the Land Plants Arise? 28.2 How Did Plants Colonize and Thrive on Land? 28.3 What Features Distinguish the Vascular Plants? 29.4 What Are the Major Clades of Seedless Plants? 28.1 How Did the Land Plants Arise? Land plants are monophyletic all descend from a single common ancestor. One shared derived character (i.e. a synapomorphy) development from an embryo protected by tissues of the parent plant Also called embryophytes 28.1 How Did the Land Plants Arise? Land plants retain derived features they share with green algae: Chlorophyll a and b . Starch as a storage product. Cellulose in cell walls. Photo 28.2 Green algae of phylum Chlorophyta are most likely ancestors of plants. Figure 28.1 What Is a Plant? 28.1 How Did the Land Plants Arise? Plants can be defined in several ways Streptophytes include land plants and a paraphyletic group of green algae all retain egg within parents body Green plants : streptophytes plus all other green algae. All have chlorophyll b This textbook: plants refers only to land plants and derivatives 28.1 How Did the Land Plants Arise? Ten clades of land plants Vascular plants , or tracheophytes (seven clades) all have conducting cells called tracheids The seven groups of vascular plants constitute a clade www.sonoma.edu/users/c/cannon/ Figure 28.7 The Evolution of Todays Plants 28.1 How Did the Land Plants Arise? Nonvascular plants Remaining three clades liverworts, hornworts, and mosses These groups do not form a clade why? 28.1 How Did the Land Plants Arise? Charales (stoneworts) is thought to be the sister group of land plants based on synapomorphies: Both exhibit retention of egg in parent Plasmodesmata Branching, apical growth Similar peroxisome contents, mechanics of mitosis and cytokinesis, and chloroplast structure Figure 28.2 The Closest Relatives of Land Plants 28.2 How Did Plants Colonize and Thrive on Land? Plants first appeared on land between 400500 million years ago Adaptations were needed to survive in dry environments Large plants must transport water to all parts of plant Needed support in air Needed methods to disperse gametes 28.2 How Did Plants Colonize and Thrive on Land? Characteristics of land plants: The cuticle Stomata openings in stems and leaves; regulate gas exchange (except liverworts) Gametangia enclosing gametes 28.2 How Did Plants Colonize and Thrive on Land? Embryos in a protective structure Pigments that protect against UV radiation Spore walls containing sporopollenin Mutualistic relationships with fungi to promote nutrient uptake from soil 28.2 How Did Plants Colonize and Thrive on Land?...
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This note was uploaded on 06/06/2011 for the course BSC 2011 taught by Professor Presley during the Spring '11 term at FAU.

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Ch28_Lecture-Spr11 - 28 28 Plants without Seeds: from Water...

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