Chapter 22 Plant Diversity

What is a plant? Include examples like trees, moss, flowers, bushes, grass, crops, etc Multicellular eukaryotes Have cell walls, chloroplasts & chlorophyll Autotrophs (produce their own food through photosynthesis) Vary in size from less than 25 micrometers to over 117 meters tall Can survive in all types of environments

What do plants need to survive? Sunlight chloroplasts/chlorophylls Water roots or osmosis through rhizoids Gas exchange leaves Transportation of nutrients and water to its parts Vascular tissue or rhizoids

Evolution of Plants algae Bryophytes (moss) ferns gymnosperms Aquatic & nonvascular algae nonvascular Bryophytes (moss) Nonseeded vascular ferns Seeded &Vascular gymnosperms angiosperms

Adaptations of Bryophytes Bryophytes are able to get the water they need through osmosis They are also able to tolerate harsh environments as long as water is available

Groups of Bryophytes Mosses Liverworts Hornworts The most common group Dependent on water Liverworts Hornworts

Plant Classifications: Seed Plants Angiosperms Gymnosperms 250,000 species Have flowers (reproductive structures) Seeds are protected in seed coats inside the fruit Can be further classified into two major groups: monocots and dicots Can also be classified based on life span: annuals (one year life span), biennials (two year life span), and perennials (many years life span) 700 species Seeds are protected in cones Includes gnetophytes, cycads, ginkgoes, and conifers

Reproduction in Bryophytes All bryophytes reproduce with alternating generations of gametophytes and sporophytes The gametophyte stage is when the plant cells produce gametes (sex cells) (these are haploid); when the plant is haploid. This is also the dominant stage (the one your most familiar with) The sporophyte stage is the diploid stage. When gametophytes produce spores

Adapting to Land The development of vascular tissue had enabled plants to occupy more land since its now out of her home.

The phyla of spore-bearing plants Club Mosses Horsetails Ferns

Life Cycle of a Fern Ferns during the sporophyte stage produce spores which are haploid The spores are carried by pollinators The spores then germinate and turn into gametophytes The gametophytes produce gametes which will undergo fertilization in the presence of water

Reproductive advantage of seed plants The life cycle of seed-bearing plants are similar to that of seedless plants Unlike the seedless plants, seed plants do not require water for fertilization of the gametes – so seed plants can live virtually anywhere, while seedless plants must remain near an adequate water source

Evolution of Seed Plants Seed plants evolved to the number it is today because Seeds provided protection for the embryos Seeds provided an initial food source for the embryos Seeds allowed plants to wander far from “home” because they didn’t require a water source.

Gymnosperm Groups Gnetophytes Cycads Ginkgoes Conifers

Angiosperms Traits Life Spans Have seeds enclosed in protective structures Seeds turn into fruit Annual = one year life span Biennial = two year life span Perennial = more than two year life span

Plant Classification: Angiosperms Monocots Dicots Seeds = one cotyledon Leaves = parallel veins Flower parts = in multiple of 3’s Stems = vascular bundles scattered throughout stem Roots = fibrous roots Seeds = two cotyledon Leaves = branched veins Flower parts = in multiple of 4’s or 5’s Stems = vascular bundles arranged in a ring Roots = taproots