Plant Diversity The Evolution and Classification of PlantsMore free powerpoints at http://www.worldofteaching.com
Slide # 3 PLANT CHARACTERISTICS • Multicellular eukaryotes • Photosynthetic autotrophs containing chloroplasts. • Non-mobile (fixed to one spot) • Cell walls made of cellulose • Responds to environment and grows through the use of hormones
Slide # 4 Plants Make the The Move to LandThe ancestors of plants were multicellular green algae. They were completely immersed in water & dissolved minerals. To move onto land, plants had to solve these problems: How to get chemical resources (water, minerals, oxygen, and carbon dioxide) separated into air and soil How to transport resources within the plant. How to prevent from drying out How to reproduce without water
Slide # 5 Some Adaptations (solutions)- Have body parts extending into both air and soil Develop a vascular system to transport resources in plant Have a protective layer – cuticle (waxy outer layer) to keep from drying out Specialized structures for reproduction including spores & seeds that do not dry out
Slide # 6 Plants are classified based on whether or not they have 1. Vascular System (transport) 2. Seeds 3. Flowers (enclosed seeds)
Slide # 7 Concept Map: Plants are divided 1st bywhether or not they have a vascular system. PlantsHas NO Vascular Has Vascular Tissue Tissue Bryophytes Tracheophytes
Slide # 8 Bryophytes -NONVASCULAR Most primitive plants Found in moist, shady areas NO vascular (transport) system Small size due to no vascular tissue No true roots, stems, or leaves Needs water for reproduction. Reproduces using spores, -a water-proof single cell that can grow into a new organism. Most common example: Mosses
Slide # 9 Typical Moss Plant (most common bryophyte) Spores form inside the capsule. Notice the problem of nutrient separation into air and soil is solved with underground and above ground parts. (Although NO TRUE roots, stems or leaves are present)
Slide # 10 Tracheophytes -Vascular Plants-• Contains two types of specialized vascular tissues for transport within the plant: – Xylem- transports H20 up from roots. – Phloem- transports food made during photosynthesis and nutrients to where they are needed in the plant.• Presence of a vascular system allowed plants to become tall.• Has specialized organs: roots, stems, and leaves.
Slide # 11Tracheophytes are divided into two groups by whether or not they reproduce with seeds. Tracheophytes Seedless Seeded Ferns use spores
Slide # 12 The Fern - a seedless vascular plant Thereo Contain a vascular are system. Sori 11,000 specieso They grow in moist, of ferns. shady habitats.o Has underground stems, roots, & large leaves called fronds.o Reproduce using spores, Not seeds.
Slide # 13 Seed-Bearing TracheophytesADVANTAGE: Developed reproductive strategies that do not need water:2. Seed contains • A fully developed embryo • Food supply for embryo • A water-proof seed coat to keep from drying out• Sperm transferred in water-proof pollen through pollination by wind or animals.• Developed seed-bearing structures: Cones and Flowers
The two Seeded Tracheophyte groups are divided by whether or not they haveenclosed seeds -protected inside a fruit or if seeds are exposed to the environment. Tracheophytes Seedless Seeded Ferns use Gymnosperms Angiosperms spores “naked” or Flowers produce exposed fruit w/ enclosed seeds seeds
Slide # 16 Sequoia Gymnosperms-Conifers• Most common gymnosperms are Conifers• Conifers have leaves called needles or scales have a reduced surface area and thick waxy coat on the needle to reduce water loss and prevents freezing. Juniper Pine
Slide # 17 Conifer• Reproduction Male cones produce Pollen pollen and the female cone produces eggs and seeds.• Pollen is inefficiently transferred by the wind.• Once mature, the scales on the female cone dry Seed out and open scattering Cone the seeds by the wind. Pollen Cone
Slide # 18 Angiosperms- “enclosed seeds”• These are flowering plants the encourage direct and efficient pollen transfer (smell, color and offering nectar)• Pollinators are flying insects, birds, and bats that transfer pollen from flower to flower.• Flowers contain ovaries, which is where eggs/seeds are produced.• A fruit is the pollinated ovary containing mature seeds.
Slide # 19 Fruit can aid in dispersal of seed to reduce competition with parent plant.• Winged fruit – glides to new location (maple fruit)• Floating fruit – can float to new locations (coconut)• Fleshy fruit - sweet bright colored fruit have seeds that survive the digestive Maple seeds: Winged fruit system of animals that eat the fruit (apple)• Spiny fruit- Velcro like projections attach to the fur of animals (cockleburs) Burdock: Spiny fruit