Kingdom: Plantae

The World as We Know It Would Not Exist Without plants without plants and other photosynthesizers, sunlight would only provide light and heat Only photosynthesizers can turn sunlight into sugars and body tissues Oh yeah, and there’d be little to no oxygen either…I like oxygen

Characteristics of ALL Plants Your book says MOST plants are multicellular. This implies that some are unicellular but when I learned it, ALL plants were multi-cellular If you were unicellular but behaved like a plant…we called you algae and stuck you in the Protist kingdom to be consistent we’ll include algae I guess

Anyway The combination of being multicellular and photosynthetic is rare outside of the plant kingdom The most distinctive feature of plants is their reproductive cycle Plants have a sporophyte and a gametophyte generation

Plants Have a Two Generation Life Cycle This means that plants produce separate diploid and haploid generations that alternate with each other The diploid generation is called the sporophyte and produces haploid spores by meiosis These haploid spores grow via mitosis to produce the haploid generation called the gametophyte

The Gametophyte plant body... Is haploid and produces haploid gametes these gametes fuse to produce a diploid zygote This zygote develops into the diploid sporophyte, thus continuing the life cycle this life cycle is described as alternation of generations

Evolution Connection The trend seems to be an increase in prominence of the sporophyte generation accompanied by a decreasing size of the gametophyte me remember them. good times.

Origins of Plants The ancestors of all plants were most likely photosynthetic, aquatic protists (ancient algae) Algae appeared about 500 million years ago they lack true roots, leaves, stems, and complex reproductive structures such as flowers and cones Algal gametes are shed directly into the water

Algae Have complex life cycles they can vary considerably between and within the different algal divisions

In Chara, a green pond algae, the haploid gametophyte generation is dominant In Fucus, the diploid sporophyte generation is dominant In Ulva, the sporophyte and gametophyte are visually indistinguishable In giant kelp, the the the the sporophyte can be hundreds of feet long but the gametophyte is microscopic

Algae Are Classified by Their Color The colors are based on the pigments in the algae The pigments are usually red or brown they absorb the green violet and blue light that readily penetrates the water The combination of these pigments and green chlorophyll gives algae their colors

Rhodophyta These red algae derive their color from red pigments that mask the green chlorophyll they are mostly marine and always multicellular Some species deposit calcium carbonate which contributes to the formation of reefs they are used to produce agar and carrageenan

4000 species

Phaeophyta These are the brown algae They contain brownish yellow pigments When combined with chlorophyll they make brown to olive-green colors they almost entirely marine and always multicellular Some giant kelp beds form undersea forests and provide shelter, food, and breeding areas for a variety of animals

1500 species

Chlorophyta Yeah that’s right, it’s green algae Mostly multi-cellular, there are a few uni-cellular species Large variety of shapes and sizes Some even form colonies that are an intermediate form between uni and multi cellularity

This is also spyro gyra

Ancestral Green Algae Probably Gave Rise to Terrestrial Plants 1. Green algae uses the same types of chlorophyll and accessory pigments in photosynthesis as land plants do 2. Green algae store food as starch and have cell walls made of cellulose, similar in composition to those of land plants 3. Most live in fresh water where they were subjected to pressures that led to adaptations for the challenges of life on land

How Did Plants Invade Land? When plants first made the transition to land, it was barren and inhospitable to life However it was full of sunlight and CO2 These conditions are ideal for plants and coupled with no predators or competitors, plants flourished and diversified

Transition From Water to Land Lead to Increased Complexity What challenges did plants face on land?

The Resulting Adaptations 1. Roots or rootlike structures anchor plant absorb water and nutrients 2. Vascular tissues for moving water, nutrients and the products of photosynthesis 3. The polymer lignin stiffening substance supports plant’s body

continued 4. Waxy cuticle 5. Stomata (singular, stoma) covers leaves and stems limits desiccation 5. Stomata (singular, stoma) pores that open to allow for gas exchange can close to reduce water loss

Protection and Dispersal of Sex Cells and Developing Plants In aquatic plants and algae gametes and zygotes can be carried by water or they can swim Life on land does not allow for this Life on land requires a means for dispersal that does not require water and a way of protecting embryos from desiccating

These Challenges Were Met By pollen, seeds, flowers and fruit Dry microscopic pollen can be carried by the wind Flowers entice pollinators Seeds provide waterproof protection and nourishment for embryos Fruits are highly instrumental in seed dispersal

Two Major Groups of Land Plants Bryophytes- non-vascular plants straddles the boundary between land and aquatic life tracheophytes- Vascular plants completely adapted to life on land