Plant Diversity The Evolution and Classification of Plants
Warm-up: Write each Question and Answer for Each. What do I know about plants? True or False • All plants perform photosynthesis. • All plants need water and nutrients. • All plants reproduce using flowers. • All plants reproduce using seeds.
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 Land The 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 • Vascular System (transport) • Seeds • Flowers (enclosed seeds)
Slide # 7 Concept Map: Plants are divided 1st by whether or not they have a vascular system. Plants Bryophytes Has NO Vascular Tissue Has Vascular Tissue Tracheophytes
Bryophytes -NONVASCULAR Slide # 8 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
Typical Moss Plant (most common bryophyte) Slide # 9 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 # 11 Tracheophytes are divided into two groups by whether or not they reproduce with seeds. Tracheophytes Seeded Seedless Ferns use spores
Slide # 12 The Fern - a seedless vascular plant There are 11,000 species of ferns. • Contain a vascular system. • They grow in moist, shady habitats. • Has underground stems, roots, & large leaves called fronds. • Reproduce using spores, Not seeds. Sori
Slide # 13 Seed-Bearing Tracheophytes ADVANTAGE: Developed reproductive strategies that do not need water: • 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 have enclosed seeds -protected inside a fruit or if seeds are exposed to the environment. Tracheophytes Seeded Seedless Ferns use spores Gymnosperms Angiosperms “naked” or exposed seeds Flowers produce fruit w/ enclosed seeds
Slide # 15 Gymnosperms- “naked seed” • Cycad (Sago palm), • Ginkgo, • Conifer (pine, spruce, firs, cedars, sequoias, redwoods, junipers, yews, & cypress trees) Sago Palm Ginkgo Ginkgo
Sequoia Slide # 16 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 Pollen • Male cones produce pollen and the female cone produces eggsand seeds. • Pollen is inefficiently transferred by the wind. • Once mature, the scales on the female cone dry out and open scattering the seeds by the wind. Seed Cone 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 system of animals that eat the fruit (apple) • Spiny fruit- Velcro like projections attach to the fur of animals (cockleburs) Maple seeds: Winged fruit Burdock: Spiny fruit
Quiz Time • What did plants have to overcome to live on land? • What is the most primitive division of plants because they have no vascular system? • What is the most common example in this division and how do they reproduce? • Why are mosses so small? • What is the division of plants that contain a vascular system? • What did a vascular system do for plants size-wise? • How are mosses and ferns different? • How are mosses and ferns alike?
Quiz Time • How are Tracheophytes different from bryophytes? • How are tracheophytes divided? • What are the advantages of seeds over spores? • What other advantages did seed-bearing plants have over spore-bearing plants? • What are the two divisions of the seed-bearing tracheophytes?
Quiz Time • What does the term Gymnosperm mean? • What are the most common of the Gymnosperms? • What is the evolutionary importance of needles? • What structures do conifers use to reproduce? • Were are seeds located in the cone? • Even though wind-dispersal of pollen is inefficient, what did it allow plants to overcome?
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