Form and Structure of Plants Botany: the study of plants

What is a plant? Living organisms which are eukaryotic and multicellular Have organized tissues Have plastids (such as chloroplasts) Have cell walls containing cellulose

One reason the study of botany is so important to man is … Because all the food eaten by man comes directly or indirectly from green plants. About 2/3 of the food we eat comes directly from plants and 1/3 comes from animals which eat plants.

Ways Plants are Beneficial: Provide most of man's food Release O2 needed by man and animals Plants are raw materials for many manufactured goods Plants are a source of beauty

Misconceptions: All green things are plants. All plants are green. All plants are autotrophic.

morphology the shape or form of an organism

Anatomy the bodily structure of an organism (deals with how cells and tissues are put together)

Types of organs in plants Roots Stems Leaves flowers Flower Stem Leaf Root

Plant organs are determined by their relationships to nodes Node: a region where a leaf is or was attached

Plant organs are determined by their relationships to nodes Roots do not have nodes. Stems have nodes. Leaves do not have nodes but are attached to stems at nodes.

Roots Roots are the organs of the root system. A root system is all the roots of a plant.

Functions of Roots Anchors Absorbs Transports Stores food

Two Types of Root Systems Taproots Fibrous roots

Taproots commonly found in dicots penetrates the soil with very little branching often stores food (fleshy roots)

Taproots has one or a few main roots that are thicker and longer than the other roots of the plant examples: carrots and dandelions

Fibrous Root System commonly found in monocots have no main section but branch out into the soil in all directions

Fibrous Root System Has a cluster of roots that are approximately equal in size They branch several times Example: grasses

Types of stems Herbaceous stems Woody stems

Herbaceous stems Softer, more flexible type of stem Supported by cell walls and turgor pressure Woody plants often begin as herbaceous and then become woody as the grow older

Woody stems Hard and not very felxible Capable of supporting a lot of weight Examples: trees and shurbs

Stem Functions manufacture, support, and display leaves conduct materials

External Structures of Leaves Blade: the flat portion of a leaf Petiole: the stalk of a leaf; attaches leaf to stem Margin: the edge of a leaf’s blade Veins: the pipelines that carry food & water Node: place on stem where leaves are attached Margin

Stipule: a small leaflike or scalelike structure on a plant that helps to cover a leaf while it is devleoping External Structures of Leaves

Leaf Venation Two basic patterns of leaf venation: Parallel Venation Netted Venation

Parallel Venation A series of veins which originate at the stem and proceeds to the tip of the leaf Occurs in monocots – corn, grass, irises, orchids

Netted Venation Palmate: two or more main veins coming from a single point Examples: maple, ivy, geraniums Pinnate: if the veins branch off one large central vein called a midrib Examples: oaks, apple trees, African violets

Classification of Leaves Simple leaves Compound leaves

Simple or Compound? Simple Leaves: one blade on each petiole

Simple or Compound? Compound: more than one blade on each petiole Each small blade on a compound leaf is referred to as a leaflet

Sessile Leaves Sessile leaves lack petioles

Sessile Leaves Grasses and certain other monocots have sessile leaves that attach to the stem by way of a sheath that seems to wrap around the stem

Leaf Mosaic AlternateOpposite Whored Leaf mosaic: the arrangement of leaves on a stem

Leaf Mosaic Alternate Mosaic: leaves alternate from opposite sides of the stem (one petiole per node)

Leaf Mosaic Opposite Mosaic: two leaves grow from the same point on the stem (two petioles per node)

Leaf Mosaic Whorled Mosaic: three or more leaves grow from a single point on a stem (3 or more petioles per node)

Leaf Mosaic

Leaf Shapes LinearCordateDeltoidLobed Circular

Linear Leaf Shape long and narrow

Lobed Leaf Shape

Cordate Leaf Shape kidney or heart-shaped

Deltoid Leaf Shape deltoid-shaped

Circular Leaf Shape

Leaf Margins EntireSerrateUndulateDentate

Entire Leaf Margin smooth margin with no teeth

Serrate Leaf Margin toothed margins

Undulate Leaf Margin wavy margins

Dentate Leaf Margin teeth point out