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Plants
- What is a plant?
- Kingdom Plantae
- Multicellular
- Eukaryotic
- Cell walls made of cellulose
- Carry out photosynthesis using
- green pigment
- chlorophyll
- Life cycle
- Alternation of generations
- haploid (N) gametophyte
- diploid (2N) sporophyte
- “-phyte” means plant
- gametes
- haploid cells
- fuse together to produce a diploid individual
- Many have vegetative (asexual) reproduction
- Survival Needs
- Sunlight
- use sun’s energy to carry out photosynthesis
- leaves are typically broad & flat
- arranged on stem to maximize light absorption
- Water & Minerals
- require a constant supply of water
- used up quickly when sun is shining
- absorb minerals with the water
- Gas Exchange
- oxygen for respiration
- carbon dioxide for photosynthesis
- Movement of Water & Nutrients
- roots – underground organs
- take up water & nutrients
- leaves – photosynthetic organs that contain 1 or more bundles of vascular tissue
- gathered into veins of xylem & phloem
- food is made here
- Early Plants
- For most of Earth’s history, plants did NOT exist!!
- First plants
- Evolved from organism similar to green algae
- First plants were still dependent on water to complete the life cycle
- Similar to today’s mosses
- simple in structure
- grew close to the ground
- common in damp, swampy regions
- PlantKingdom
- Four groups
- Based on three features
- water conducting tissues (no? yes? What are they?)
- seeds
- flowers
- science today
- classification based on plant DNA
- Project Deep Green
- Strong evidence that 1st plants evolved from green algae
- Lived in fresh water
- Bryophytes
- Nonvascular plants
- Mosses
- sphagnum mosses thrive in acidic bogs
- when dry it acts like a natural sponge
- thick layers of peat in the ground can be cut & used for fuel
- Seedless vascular plants
- Ferns
- most numerous
- have true roots, stems & leaves
- also includes club mosses & horsetails
- Evolution of vascular tissue
- xylem – carries water
- phloem – carries food
- both move fluid against pull of gravity!!
- Seed Plants
- Seeds can be found everywhere
- Gymnosperms
- most ancient surviving seed plants
- seeds are found on cones
- conifers
- most common (Phylum Coniferophyta)
- over 500 known species
- pines, spruce, fir, cedar, sequoia, redwoods, yews
- largest genus is Pinus (includes 100 species of pine tree)
- leaves are long and thin (needle like)
- reduces surface area
- cuts down on water loss due to evaporation
- most are “evergreen”
- exceptions are the tamarac/ larch & bald cypress
- lose needles every fall
- cycads
- tropical & subtropical areas
- Phylum Cycadophyta - large, palm like
- ginkgoes
- only one species survives today
- Ginko biloba (Phylum Ginkgophyta)
- Resistant to pollution
- Popular shad tree in urban areas
- gnetophytes
- Phylum Gnetophyta
- Genus Ephedra
- Angiosperms
- Phylum Anthophyta
- flower bearing plants make up 90% of all plants
- grasses, flowering trees & shrubs, wildflowers, cultivated flowers
- reproductive structures are the flowers
- attract bees, moths, hummingbirds to transport pollen
- Fruit
- Monocots v. Dicots
- Named for number of seed leaves (cotyledons)
- Monocots = one seed leaf
- Corn
- Wheat
- Lilies
- Orchids
- palms
- Dicots = two seed leaves
- Roses
- Clover
- Tomatoes
- Oaks
- Daisies
- Woody v. Herbaceous Plants
- Stem characteristics
- Woody
- Made of cells with thick cell walls
- Trees, shrubs, vines
- Herbaceous
- Stems are smooth & nonwoody
- Dandelions, zinnias, petunias, sunflowers
- Annuals, Biennials, & Perennials
- Annual
- Grow, mature, flower & die in one year
- Complete life cycle in one growing year
- Biennial
- Complete life cycle in two years
- Year one:
- germinate & grow roots
- very short stems
- Year two:
- grow need stems & leaves
- produce flowers & seeds then dies
- evening primrose, parsley, celery & foxglove
- Perennial
- Live for more than two years
- Slow, Grow, Go!!!
- Most have woody stems
- Do not require water for fertilization of gametes
- can live just about anywhere!!
- Reproductive structures
- cones & flowers
- pollen
- entire male gametophyte is contained here
- carried to female
- wind
- insects
- birds
- small animals
- pollination
- transfer of pollen
- seeds
- embryo of a plant in a protective covering
- seed coat
- surrounds & protects the embryo
- keeps seed from drying out
- some have special features that help dispersal
- some have seed coats that stick to fur or feathers
- after fertilization
- zygote in seed grows into a tiny plant
- embryo
- can remain in seed for a long time
- survival strategy
- Evolution of seed plants
- Most important adaptation was the seed
- Many moss & fern species have become extinct
- drier climate over time
- early seed plants moved everywhere on Earth
- formed dense forests & swamps
- most of eastern United States
- remains exist in the form of coal deposits!
- Vocabulary
- Gametophyte, sporophyte, bryophyte, vascular tissue, xylem, phloem, root, leaf, vein, stem, , gymnosperm, angiosperm, cone, flower, pollen grain, pollination, seed, embryo, seed coat, fruit, monocot, dicot, cotyledon, annual, biennial, perenial