Plant Anatomy

• Levels of organization   * Cells   * Tissues   * Organs
• There are three tissue systems in plants:   * Dermal tissues: Forms the outer protective coating of the plant   * Ground tissue: Performs most metabolic functions, such as photosynthesis, storage, secretion, and support   * Vascular tissue: Conducts fluids around the plant
• Each system is made up of different types of tissues
• Simple tissues: Made up of one type of cell   * Parenchyma cells:     * Found in epidermal and ground tissue systems     * Most common cell type in plants     * Thin walled     * Alive at maturity     * Some retain totipotency     * Responsible for most metabolic function   * Collenchyma Cells:     * Found in ground tissue     * Strong, thick, and flexible walls     * Alive at maturity     * Provides support to actively growing areas of the plant   * Sclerenchyma cells:     * Found in ground and vascular tissue     * Tough, thick walls that are strengthened with lignin     * Not alive at maturity     * Provide support to non growing parts of the plants     * Can either be fibbers or sclereids
• Complex tissues: Made up of multiple types of simple tissues   * Xylem:     * Composed of sclerenchyma and parenchyma     * Made of fibers, tracheids, and vessel membranes     * Fibers provide support while, tracheids and vessels conduct water     * Wood is composed of xylem.   * Phloem:     * Composed of sclerenchyma and parenchyma     * Made of sieve cells, sieve tube members, companion cells and fibers     * Companion cells are made of parenchyma cells and provide support     * Sieve cells and sieve tube members transport substances through the plant     * Sieve cells are found in gymnosperms, ferns, and horsetails     * Sieve tube members are found in most angiosperms   * Dermal Tissue:     * Epidermis is around one cell thick and is coated with a waxy cuticle or bark     * Include: guard cells, stomata, trichomes, and root hairs     * Root hairs occur in maturation zone and are an extension of an epidermal cell and thus are unicellular.   * Ground Tissue:     * Filler tissue     * Carries out photosynthesis, storage, and provide support     * Is composed of collenchyma, sclerenchyma, and parenchyma tissues
• Vascular Tissue:   * Xylem transports water and nutrients from the roots to the rest of the plant   * Phloem transports fluids, products of photosynthesis, and hormones around the plant   * Monocots and dicots have different arrangements of vascular tissue     * The arrangement of vascular bundles in dicots allows for secondary growth in woody stems. Vascular cambium will develop in between the xylem and the phloem which increases the diameter of the stem
• Regions of a growing root:   * Root cap: contain gravity sensing columella cells   * Zones of cell division, elongation, and maturation (differentiation)
• Types of roots:   * Fibrous roots: Many small roots. Ex. grasses   * Tap roots: One larger root with smaller roots coming off of it. Ex. Carrots
• The endodermis is at the edge of the stele, which includes all the vascular tissue.
• The Casparian strip is a waterproof layer that conducts water and minerals into the plasma membranes, instead of through spaces in the cell wall.
• The pericycle is inside this layer, and its meristematic tissue involved in secondary growth
• Roots can be specialized to perform specific functions   * Adventitious roots: Prop and buttress roots (not real roots)   * Aerial roots: Roots above ground   * Pneumatophores   * Storage roots ex. beets
• Epiphytic plants: Grow on trees and draw their nutrients from the air; not parasitic
• ​A plants stem provides support to all above ground structures
• Leaves develop from the apical meristem
• The point where leaves attach are called nodes, while the spaces in between are called internodes
• Stems can be specialized to perform specific functions   * Bulbs (tulips and onions)   * Rhizomes   * Runners and stolons (strawberries)   * Tubers (potatoes)   * Tendrils (vines in ivy, peas, pumpkins, ect)   * Cladophylls (cacti)
• Leaves are the photosynthetic organ of the plant
• Leaf patterns   * Alternate   * Opposite   * Whorled
• There are two types of leaves   * Microphylls: Small with one central vein   * Megaphylls: Typically larger with multiple viens
• Leaves can be specialized to perform specific functions   * Floral leaves​: Poinsettia   * Spines​: Cacti needles   * Reproductive leaves​: Some succulents   * Insectivorous leaves: Venus fly trap

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