Plant Organs and Tissues Mr. Ramos
Introduction to Plants • There are over 260,000 different species of flowering plants alone! • Plants are • multicellular, eukaryotic organisms. • Photosynthetic • Plants have a cell wall made of cellulose. • Plants take up water via capillary action.
Plant Classification Bryophytes are nonvascular. Tracheophytes are vascular Plants are classified as bryophytes and tracheophytes
Bryophytes and Tracheophytes • Bryophytes are plants that lack specialized tissues for the transport of water. They absorb substances directly from their surroundings. • Mosses, liverworts, & hornworts • Tracheophytes are vascular plants. They can be seeded or seedless. • Seeded: Flowering & non-flowering plants • Seedless: ferns • Vascular tissue transports water and nutrients. • Phloem transports food from the leaves down to other plant parts • Xylem moves water and nutrients from the ground upward in the plant.
Roots • Function of plant roots include • Anchoring and supporting the plant • Absorbing water & nutrients from the soil • Store food and water • Root Classification • Fibrous roots (monocots) • Taproot (dicots)
Stems • Stems transport materials between a plant’s root and its leaves and flowers. • Trees have hard, rigid stems called a trunk. These plants are called woody plants. • Plants with green, flexible stems are called herbaceous plants. These include grasses and garden plants.
Leaves • Leaves are the main organs that carry out photosynthesis. • Photosynthesis is a process by which plants use sunlight to make food from carbon dioxide and water. • Leaves have small openings called stomata where CO2 and O2 are exchanged. • Guard cells open and close the stomata.
Gymnosperms • Gymnosperms are the woody plants. • They are vascular plants that contain seeds. • One way to determine the age of a gymnosperm is by counting the number of tree rings. The rings are dead xylem.
Angiosperms • Angiosperms are the flowering plants. • They are vascular and contain seeds. • Angiosperms can be further divided into monocots and dicots. • Some flowering plants are woody: oak, cherry & walnut. The fruits develop inside the flowers
Seeds • A seed is a reproductive structure that contains a plant embryo. • In flowering plants, the seed stores food in parts called cotyledon, or seed leaves. • Angiosperms may have one or two cotyledons. • Monocots contain one seed leaf, or cotyledon. • Dicots contain two seed leaves or cotyledons.
Flower Anatomy • The male reproductive part is called the stamen. • The female reproductive part is called the pistil or carpel. • For sexual reproduction, pollen from the stamen must be transferred to the stigma. • The wind or animals can carry pollen to the stigma. This is called pollination.
Cones • Cones are structures that are adapted for sexual reproduction in conifers. • Male cones produce pollen & female cones produce eggs. • After fertilization, a seed develops. • Unlike the seeds of flowering plants, conifer seeds are not enclosed in protective fruit.
Spores • Nonvascular plants, such as mosses, reproduce by making & releasing spores. • A spore is a tiny, waterproof reproductive cell that can grow into a new organism if it falls on soil with the right conditions. • Seedless vascular plants, such as ferns, also reproduce with spores.
Life Cycle & Reproduction • Plants have an alternation of generation. • They spend half of their lives as haploids and part of their lives as diploid. • A gametophyte is a haploid plant that produces haploid gametes. • A sporophyte is a diploid plant that gives rise to haploid spores by meiosis. • Spores grow to be gametophytes.
Plant Life Cycle Meiosis Spores Mitosis Sporophyte N Gametophyte 2N N Fertilization Mitosis Sperm Egg N N Mitosis Zygote 2N