Chapter 15

PLANT STRUCTURES AND TAXONOMY

Chapter 15: Parts of a plant

Manufactures food by photosynthesis

Attracts insects for pollination

Contains seeds

Functions in sexual propagation of the plant

Anchors the plant and absorbs and stores food and water

Supports branches and transports food and water

Plant StructuresPlants are the backbone of the Agriscience industry. They are needed for crops to feed livestock, provide seeds for new crops for food, and landscaping inside and outside areas. Having a basic understanding of how plants function and what they need is a must.

Plants contain many parts and all are important to the health of the plant. The basic structures include:

1. Leaves - manufactures the food for the plant.2. Flowers - seed producing part, comes in many shapes and

colours.3. Stem - above ground (mostly) and provides support for the rest

of the plant.4. Roots - normally underground, anchors the plants and supplies

nutrients and water.

Roots• Often the largest part of the plant and the different kinds include:

1. Adventitious: Roots which often appear on above ground parts to help them climb or spread to other areas. • I.e. Virginia creeper, poison ivy

2. Taproot: Main root of the plant which grows straight down from the stem. It is thick and heavy and is often used as food by humans. • I.e. carrots, beets, radishes

• Advantage - able to survive droughts• Disadvantage - are not stabilizing to the soil

3. Fibrous: Generally thin, hairlike and numerous. They are often shallowbut spread sideways in the soil. • I.e. grasses, corn

• Advantage - stabilizes soil• Disadvantage - dries out quickly

The root itself has 3 main regions:1. The root cap or tip which is the tough part that

penetrates the soil.2. The area of cell division where cells multiply and begin to

grow in both directions.3. The area of maturation where cells become specialized

for certain jobs and roots hairs become seen. Root hairs are small roots which grow out from the main roots and help collect water and nutrients.

Two of the more important kinds of cells include the XYLEM and PHLOEM. Xylem carries water and nutrients up and around to the above ground parts. Phloem carries manufactured food down to the roots and around to other areas of the plant.

Stems Stems are the support for the plants. Above ground stems can be of two kinds:1. Woody - these are tough often covered with bark and can survive winter

conditions.2. Herbaceous - Succulent or soft, stems are usually green and can’t survive

winter conditions.

Stems which are below ground or along the ground are often modified and have specialized jobs. They include:

3. Bulbs - shortened stems which have modified leaves known as scales.• I.e. onions

4. Corms - thickened, compact, and fleshy.• I.e. gladiola

5. Rhizomes - thick stems which grow below the ground and give rise to new plants.• I.e. iris

6. Tubers - thickened underground stems that store carbohydrates.• I.e. potatoes

Parts of the Stem:

Terminal bud

Axillary bud

Flower bud

Leaf scar

Internode

NodeLenticels

Growthring

Leaves• The leaf is the main food manufacturing part of the

plant. It uses the sunlight in a process called photosynthesis to make this food. For this reason it exposes itself to as much sun as possible.

• There are a variety of leaf shapes, edges and arrangements. The edge of the leaf is referred to as the MARGIN and are named after the toothed pattern.

• There are many shapes of leaves depending on the species. Some of the more common are oval, needle-like, linear, and ovate.

• Some leaves are modified and colourful and showy. These leaves, called BRACTS are often mistaken for flowers. (I.e. poinsettia)

• Two types of leaves include simple and compound. A simple leaf has one single leaf coming from the stem. Compound leaves have two or more leaves coming from a single stem.

LEAF PARTS:

• There are two main parts of the leaf, the BLADEand the PETIOLE. The midrib is the vein that runs up the centre of the leaf supplying the “transportation route” for food.

Label the External anatomy of the Leaf

Answers

FLowers• Fruits and flowers are the most identifiable parts of

the plant. The fruit are actually a flower part which has enlarged and ripened. The primary function of a flower is to produce seeds to carry on the species. To understand how fruits and seed are developed we must first understand the flower parts.

• A developing flower or bud starts with a tightly bound group of sepals called a calyx. The sepalsprotect the flower parts needed for reproduction and will break open when the flower emerges.

• The petals, the brightly colored part help attract pollinators like insects and help lead the way to the reproductive parts. A flower contains both male and female parts in order to produce seeds.

• The male parts are together referred to as the Stamen. The stamen includes the filament which is the long, thin supports of the anther. The pollen or the reproductive cell is on the anther.

• The male parts are usually surrounding the female parts known as the Pistil. The pistil also has three parts, the stigma, the style and the ovary. The stigma collects the pollen where it travels down the style into the ovary where it will fertilize the ovules or female reproductive cells. These fertilized eggs will become the seeds. If a flower has all these parts it is a perfect flower. If any one of these parts is missing it is an imperfect flower.

• The pistil after fertilization becomes the fleshyfruit we eat. This fleshy part helps attract animals and humans to the seed to transport the seed to other areas.

• Fruit - a mature ripened ovary

• Vegetable - any part of the plant (roots, stem, leaf, flower) which is grown for food.

• Nut - a type of fruit.

Parts of a Flower

Parts of a Flower

Parts of a Flowering Plant

Killer Plants

Chapter 15: DefinitionsPlease use your textbook to find the definitions for the

following words: Cuticle Mesophyll Palisade Cells Spongy Layer Chloroplast Stoma Guard cells Upper epidermis Lower epidermis

Self Evaluation- Chapter 15

Copy & complete Parts A, B, & C on pages 289-291

Plants: Bill Nye (Part 1)

Plants: Bill Nye (Part 2)