PLANTS Kingdom Plantae

Who Are The Plants? Plants= eukaryotic, multicellular, photosynthetic

LAND PLANT EVOLUTION Monocot Eudicot Gymnosperms (Naked seeds) Angiosperms (Seeds in flowers and fruit) Non-seeds Seeds Bryophytes (Non-vascular) Tracheophytes (Vascular) Green Algae

Origin of Land Plants? Evidence that Green Algae are the ancestors 1) DNA 2) Ch a & b 3) True starch inside chloroplasts 4) Diverse life cycles & reproduction Asexual & sexual phases Haploid & diploid stages

Green Algae as Land Plant Ancestors (5) Unicellular & multicellular species

First land plants were probably filamentous green algae growing along the edges of ponds that seasonally dried out. DNA evidence says land plants originated 500—600 mya. First land plant fossils 470 mya

Which Land Plant is Most Like the Ancestral Green Alga ? Green Algae Mosses Liverworts Hornworts

Answer Liverworts

Frist land plants were small and did not have vascular tissue. They were bathed in water or lived in moist environments. Called Bryophytes: moss, liverwort, hornwort.

LAND PLANT EVOLUTION Monocot Eudicot Gymnosperms (Naked seeds) Angiosperms (Seeds in flowers and fruit) Non-seeds Seeds Bryophytes (Non-vascular) Tracheophytes (Vascular) Green Algae

Overview of Plant Kingdom Land Plants

Important Characteristics Presence or absence of vascular tissue i.e. xylem and phloem Bryophytes (mosses, liverworts, hornworts) lack vascular tissue—small plants Tracheophytes (ferns and seed plants) have vascular tissue—can be large

What is vascular tissue? Specialized cells that conduct fluids and nutrients from place to place in the organism Xylem = cells specialized to carry H20 & minerals Phloem = cells specialized to carry H2O & sugar

Characteristics of Plants Xylem = cells specialized to carry H20 & minerals Phloem = cells specialized to carry H2O & sugar

Characteristics of Plants Xylem = cells specialized to carry H20 & minerals Phloem = cells specialized to carry H2O & sugar

Characteristics of Plants Life Cycles Alternation of Generations in Land Plants

Characteristics of Plants 3. Life Cycles Alternation of Generations in Land Plants

Characteristics of Plants 3. Life Cycles Alternation of Generations in Land Plants Both organisms are multicellular

Characteristics of Plants Alternation of generations

3 Challenges to living on land Body dries out (desiccation) Gravity collapses large organisms Gametes dry out and may not disperse properly How did the first land plants deal with these problems? Let’s look at the moss life cycle. They live in moist environments and they survive drying out—suspended animation

Look where mosses live

Look where mosses live

Look where mosses live

Haploid (gametophyte) generation is dominant In bryophytes

Look at moss close up

Characteristics of Plants Gametangia = gamete producing organs Antheridium ♂ Swimming Sperm Archegonium ♀ Eggs

Moss Sperm

Look at moss close up Gametophyte Generation Sporophyte Generation

Moss Life Cycle

How do sperm get to egg? Suggestions? 50% of moss species have different male and female plants that maybe several feet apart? Suggestions?

Can rain spread sperm? Experiment

Springtails crawl all over moss Can insects be responsible for sperm dispersal? Springtails crawl all over moss

Fertilization success With insects vs. without insects. With water spray vs. without water spray With insects & water vs. Without insects & water Fertilization success in C. purpureus and B. argenteum microcosms, measured as the fraction of microcosms that developed sporophytes (error bars, mean ± s.e.m.). The effects of springtail treatment (a), water spray treatment (b) and the interaction between these treatments (c) on fertilization success. Plus and minus symbols represent the presence and absence of springtails and water spray. n = 108 microcosms. *P < 0.05.

Moss survive by Living in moist environments and being able to become dormant when conditions are dry. They are dependent upon moist conditions for reproduction because they have swimming sperm but they are aided by rain, mist, and fog and by animal transport of sperm. Their dispersal over wide areas depends upon spores carried by the wind and animals

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