Flowering Plants: Cells and Tissues

• Flowering plants, also known as angiosperms, are diverse but share common structural features.
• Vegetative organs include all plant parts except reproductive structures.
• Vegetative organs facilitate growth and nutrition.
• Roots, stems, and leaves are vegetative organs.
• Most flowering plants contain a root and a shoot system.
• The root system consists of roots.
• The shoot system consists of stems and leaves.
• Flowers, seeds, and fruits participate in reproduction.

Cells and Tissues of Flowering Plants

• A cell is the basic unit of life.
• A tissue comprises specialized cells performing a particular function.
• Organs consist of multiple tissues.
• Meristem cells differentiate into daughter cells and persist as a meristem.
• Primary growth involves growth in length via apical meristems.
• Secondary growth refers to growth in width via lateral meristems.

Meristem Development

• Plant embryos develop meristem cells as their first cells.
• Undifferentiated cells divide indefinitely and differentiate into various cell types.
• Meristematic tissue enables continuous growth in flowering plants.
• Apical meristems at stem and root tips increase tissue length.
• Apical meristems give rise to three types of meristem that produce three specialized tissues.
• Epidermal tissue is a specialized tissue of the apical meristem.
• Ground tissue is a specialized tissue of the apical meristem.
• Vascular tissue is a specialized tissue of the apical meristem.
• Epidermal tissue forms the outer protective covering of a plant.
• Epidermis contains closely packed epidermal cells.
• Epidermal cells exposed to air have a waxy cuticle.
• Root epidermal cells contain root hairs.
• Root hairs increase the surface area of the root for water absorption.
• Epidermal cells of stems, leaves, and reproductive organs contain trichomes.
• Trichomes protect from sun and moisture loss.
• Trichomes discourage herbivory.
• Stomata are on the lower leaf surface.
• Periderm replaces the epidermis in older woody plants,
• Cork is a periderm component.
• Cork Cambium makes new cork.

Ground Tissue Types

• Ground tissue forms the bulk of a flowering plant
• Parenchyma cells are abundant and unspecialized cells within the plant organs
• Parenchyma cells can divide and give rise to more specialized cells
• Parenchyma cells contain chloroplasts and perform photosynthesis
• Collenchyma cells have thicker primary walls
• Collenchyma cells form bundles underneath the epidermis
• Collenchyma cells provide flexible support for immature regions of a plant
• Sclerenchyma cells have thick secondary walls impregnated with lignin
• Most sclerenchyma cells are nonliving at maturity
• The primary role of Sclerenchyma is to support mature regions of the plant
• Fibers are a type of Sclerenchyma cells and are long, slender, and grouped in bundles
• Sclereids are a type of Sclerenchyma cells and are shorter and varied in shape.
• The examples of Sclereids are seen in seed coats and nutshells

Vascular Tissue

• Two types of vascular tissues exist; xylem and phloem.
• Xylem transports water and minerals from the roots to the leaves.
• Xylem contains tracheids and vessel elements.
• Tracheids are long cells with tapered ends.
• Water travels across pits in the end and side walls of tracheids.
• Vascular rays between rows of tracheids conduct water across the plant's width.
• Vessel elements are larger and contain perforation plates in their end walls.
• Vessel elements form a continuous vessel for water and mineral transport.
• Phloem transports sucrose and organic compounds from the leaves to the roots.
• Sieve-tube members act as cells that conduct.
• Sieve-tube members contain cytoplasm but lack nuclei.
• Sieve plates are clusters of pores within the wall.
• Each sieve-tube member has a companion cell.
• Plasmodesmata connect sieve-tube members with companion cells.
• Companion cells contain a nucleus.
• Companion cells perform a transport function

Flowering Plant Organs

• Vegetative organs consist of the stem, branches, and leaves.
• The stem is the main axis of a plant that elongates and produces leaves.
• Nodes are areas where leaves attach to the stem.
• Internodes are regions between nodes.
• Terminal buds, found at the stem end, contain an apical meristem for producing new leaves.
• A stem has vascular tissue that transports water and minerals.
• Leaves are major parts of the plant and carry out photosynthesis.
• Foliage leaves are mainly broad and thin.
• The the wide portion of the foliage leaf is the blade.
• The stalk attaching the blade to the stem is the petiole.
• The leaf axil is the upper acute angle between the petiole and stem, where the axillary bud is found.
• Tendrils attach leaves to objects.
• Bulbs are leaves that store food.
• Monocots have cotyledons that act as transfer tissue.
• Nutrients are derived from the endosperm of the cotyledons.
• Root vascular tissue occurs in a ring in monocots.
• Leaves have parallel venation in monocots.
• Flower parts are arranged in multiples of three in monocots.
• Eudicots have cotyledons that supply nutrients to seedlings.
• Root phloem is between the xylem arms in eudicots.
• Leaves have netted venation in eudicots.
• Flower parts are arranged in multiples of four or five in eudicots.
• The terminal bud contains an apical meristem that produces leaves and tissue during the primary growth of the plant.
• Annual plants live for only one growing season.
• Resources are used to support vegetative structure, flower, and seeds in annual plants
• after seed dispersal annual plants cease to exist
• Perennial plants live for three or more seasons.
• Perennial plants expend energy in long term vegetative stability.
• Flower-inducing genes LEAFY and Apetala 1 differentiate annuals from perennials.
• The Apetala 1 gene turning on (helped by the LEAFY gene) stops vegetative growth in favor of flower production.
• Perennial growth can be induced in annuals with the blocking of flower-inducing genes.
• The root cap contains the root apical meristem.
• The zone of cell division contains primary meristems.
• The zone of elongation contains cells that lengthen and specialize.
• The zone of maturation contains fully differentiated cells.
• The epidermis, the outermost layer of the root.
• The cortex, composed of parenchyma cells facilitates water and mineral movement
• The endodermis forms a boundary between the cortex and the inner vascular cylinder
• The casparian strip of the endodermis
• The vascular tissue contains xylem and phloem
• The pericycle, mitotically active, initiates lateral root and branch development

Monocot Roots

• The ground tissue of root includes a pith surrounded by a vascular ring.
• They share growth zones with eudicot roots, but do not undergo secondary growth.
• Pericycle, endodermis, cortex, and epidermis are in them.
• In primary roots a fleshy taproot grows straight down.
• The role of the taproot is to store food.
• Fibrous root systems leverage slender, lateral branches
• The role of the fibrous root system is to anchor the plant to the surrounding soil
• Fibrous roots are found in monocots
• Adventitious roots grow out of organs on the shoot system rather than the root system.
• Prop roots and aerial roots are adventitious.
• Mycorrhizae are symbiotic root relationships.
• Mycorrhizae feature roots and fungi.
• Fungus transports water and minerals, and a plant provides sugars in mycorrhizae.
• Root nodules contain nitrogen-fixing bacteria.
• Bacteria in nodules reduce atmospheric nitrogen in nodule roots.
• Plants get nitrogen from bacteria, which receive carbohydrates from the plant.
• Anatomy of a woody twig includes the terminal bud, and shoot tip protected by bud scales.
• Each spring, a dropping of bud scales leaves a scar.
• Each scar represents a year of growth.
• A shoot apical meristem generates new cells that elongate and increase stem length
• It is protected by a terminal bud
• Enveloped by leaf primordia
• Specialized primary meristems
• Protoderm produces epidermis
• Ground Meristem forms pith and cortex
• Procambium makes the primary xylem and phloem
• Mature vascular bundles contain vascular cambium.
• Mature nonwoody stems exhibit only primary growth.
• The outermost tissue includes a waxy cuticle.
• Stems have distinctive vascular bundles.
• Herbaceous eudicots contain vascular bundles inside a distinct ring.
• Monocots contain are vascular bundles scattered throughout their stems
• Woody plants have three distinct regions: bark, wood and pith
• Primary growth increases the length of the plant.
• Secondary growth increases the girth.
• Cork, cork cambium, cortex, and phloem are in bark.
• Tree bark is often removed but doing so is harmful to the host as they need it to transport organic nutrient.
• Girdling in trees lead to their death.
• Girdling is caused by the removal of bark from around the tree.
• Cork cells are impregnated with suberin.
• Gas exchange is impeded at all tree areas, save lenticels.
• Wood is secondary xylem that builds up year after year.
• Vascular cambium is dormant during winter.
• Trees exhibit annual rings made up of spring and summer wood.
• Summer wood has a lower proportion of vessels than spring wood. Heartwood
• The inner annual rings of older trees are called heartwood.
• Heartwood no longer functions in water transport.
• Stolons are aboveground horizontal stems.
• New plants are produced as nodes touch the ground as they develop.
• Rhizomes are underground horizontal stems.
• Rhizomes contribute to asexual reproduction.
• Tubers are enlarged portions functioning in food storage
• Corms are underground stems that produce new plants during the next season Humans make use of stems
• Sugar cane is used to produce table sugar.
• Cinnamon and quinine are produced from bark.
• Wood is used to produce paper and building materials.
• Leaves are major components of plants and conduct photosynthesis.
• Photosynthesis requires water, carbon dioxide, and sun.
• Foliage leaves are typically thin and broad.
• Blade, petiole and a leaf axil are parts of foliage leaves
• Tendrils and bulbs are are forms of leaves
• The arrangement of leaves are variable
• Deciduous plants loose all of their leaves

Leaf Layers

• Upper and lower epidermis
• waxy cuticle
• trichomes Lower epidermis has stomata for gas exchange
• Eudicot leaves contain mesophyll
• Palisade is classified in mesophyll
• In spongy, also part of part of mesophyll, the irregulalar cells share boundries that surround air spaces
• Leaves capture light energy in chloroplasts
• leaves contain many chloroplasts

Leaf Stem Arrangement

• The leaves are arranged in alternate, opposite, or whorled patterns
• The portions of leaves wide enough to be described a simple or compound
• Leaves adapt to their environments
• Leaves exist as shade, spins and climbing leaves
• Plants are specialized for catching insects