Plant Evolution and Classification Chapter 28

Adapting to Land The ability to prevent water loss: cuticle- waxy protective covering (also keeps our CO2) Three adaptations allowed plants to thrive on land. Cutilce-waxy protective covering used to prevent water loss; also keeps out CO2. Small plants that had stomata were able to survive. http://images.absoluteastronomy.com/images/topicimages/p/pl/plant_cuticle.gif

Adapting to Land 2. The ability to reproduce in the absence of water – spores and seeds http://static.howstuffworks.com/ http://www.nsf.gov/ http://www.wsu.edu:8080/

Spore vs seed A spore is haploid reproductive cell surrounded by a hard outer wall. Allowed the widespread dispersal of plant species. A seed is an embryo surrounded by a protective coat. Some seeds contain endosperm- tissue that provides nourishment for the developing plant. Seeds are more effective for dispersal than spores ex. Maple tree seeds

Adapting to Land The ability to absorb and transport nutrients – Vascular tissue – xylem and phloem . botit.botany.wisc.edu/

Vascular Tissue Vascular tissue transports water and dissolved substances from one part of the plant to another. It also provides support. Xylem- transports inorganic nutrients one way: roots to leaves Phloem- carries organic compounds/some inorganic compounds any way, any where Plants on land get their nutrients by absorbing them from the soil. Vascular tissue also helps support the plant

Nonvascular vs. Vascular Classifying Plants Nonvascular vs. Vascular On page 564, you can see the table that has all 12 phylums of plants. They can be divided into 2 main catagories: nonvascular and vascular.

Seedless Vascular Plants Nonvascular Plants Seedless Vascular Plants Gymnosperms Angiosperms Flowers Seeds Harden Vascular Tissue This is a hypothesis for the evolutionary relationships between plants and green algae. Reproduction by Spores Algal Ancestors

Nonvascular plants Have neither true vascular tissue nor true roots, stems, or leaves. 3 phyla Bryophyta Heptophyta Anthocerophyta

Vascular Plants Vascular, seedless Vascular, seed Whisk ferns Club mosses Horsetails Ferns Vascular, seed Cycads Ginkgoes Conifers Gnetophytes Flowering plants Monocots Dicots Gnetophytes are seed-bearing plants that can grow as shrubs, trees, or vines and share similarities with both gymnosperms and angiosperms.

Vascular Plants Have vascular tissue and true roots, stems, and leaves pky7thgradescience.pbworks.com

Seedless vascular plants Ferns – dominated the earth until about 200 million years ago.

Vascular Seed Plants Produce seeds for reproduction – embryo with a nutrient supply Have a greater chance of reproductive success When conditions are right the seed sprouts, or germinates Inside the tough, protective outer coat of a seed is an embryo and nutrient supply. There are 2 main groups of seed-bearing vascular plants: gymnosperms & angiosperms.

Gymnosperms 4 phyla Produce naked seeds Seeds are not enclosed and protected by fruits. Most are evergreen and bear their seeds in cones A cone is a reproductive structure composed of hard scales. The seed lie open on the surface of the scales.

Angiosperms 1 phyla – produces seeds that are enclosed and protected in fruits – called flowering plants Cones serve some of the same functions for gymnosperms that flowers serve for angiosperms. http://universe-review.ca/I10-22a-angiosperms.jpg

The Evolution of Angiosperms In many angiosperms, seeds germinate and produce mature plants, which in turn produce new seeds, all in one growing season. Gymnosperms often take 10 or more years to reach maturity and produce seeds. Angiosperms have the advantage over gymnosperms because they are able to reproduce new seeds in one growing season, whereas gymnosperm take a long time to mature.

The Evolution of Angiosperms The fruits of flowering plants protect seeds and aid in their dispersal.

The Evolution of Angiosperms Angiosperms also have a more efficient vascular system and are more likely to be associated with mycorrhizae than gymnosperms. Mycorrhizae are symbiotic associations that form between the roots of most plant species and fungi. These symbioses are characterized by bi-directional movement of nutrients where carbon flows to the fungus and inorganic nutrients move to the plant, thereby providing a critical linkage between the plant root and soil. www.greenmanconservation.co.uk

The Evolution of Angiosperms Angiosperms have an advantage by using animal pollination rather than the less-efficient wind pollination used by gymnosperms.

The Evolution of Angiosperms Angiosperms are more diverse than gymnosperms, so they occupy more niches. Aquatic Epiphytic Parasitic

Monocots and Dicots Based upon the number of cotyledons. Cotyledon: seed leaves in a plant embryo Flowering Plants are divided into Monocots and Dicots. The primary feature that distinguishes these 2 classes is the number of cotyledons. *Note that gymnosperms have 2 or more cotyledons. http://www.seedbiology.de/hormones.asp

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