Notes- Plants

Basic Characteristics of Plants

• Plants are members of the kingdom plantae.

• Plants are multicellular eukaryotes with cell walls made of cellulose. They are

autotrophs and have high levels of specializations.

• Most plants are autotrophs but a few can be parasites or predators.

What does a plant need in order to survive?

• Sunlight, Water (Photosynthesis)

• O2 for respiration and CO2 for photosynthesis

• Soil/minerals (Growth)

Evolution of Plants

• Before plants most organisms lived in the water.

• Plants changed the land in ways that allowed other organisms to

develop.

• The first plants developed from multicellular, photosynthetic green

algae living in aquatic environments.

• The first plants were very simple, similar to today’s mosses, and

required water to complete their life cycles.

• From these first plants many diverse groups of plants developed.

• Plants are divided into 4 groups based on the presence or absence of vascular tissue, seeds and flowers. The 4

groups are mosses, ferns, gymnosperms and angiosperms.

Mosses Ferns Gymnosperm Angiosperm

What are the major parts of the plant?

Leaf

• Site for photosynthesis

• Blade: Broad flat photosynthetic part of a leaf

1) Stomata: Pores in the blade allow for water evaporation and gas exchange

a. Guard cells open and close the stoma to prevent water loss

2) Veins: Tube-like structures that are used for transport

3) Petiole: structure that attaches leaf to stem

• Simple leaves have one blade.

• Compound leaves have two or more leaves called leaflets

1) Pinnate: Featherlike leaves with alternating along a petiole

2) Palmate: Several lobes radiating from one central point

Stem

Used for support and transportation

Contains vascular tissue

Sometimes used for storage

Absorb water and nutrients/anchor the

plant

1) Taproot: Single large central root

2) Fibrous roots: Clump of short

threadlike roots.

Flowers & Seeds

• Flowers are the reproductive organs of plants.

• Sexual reproduction occurs when pollen is carried from one flower to another

(pollination)

• Seeds house plant embryos

• Fruit protect and nourish seeds

Specialization in plants

• Plants are multi-cellular, eukaryotic, with cell walls. They are photosynthetic and have high levels of

specialization.

• Specialized cells have modifications that allow them to perform specific functions.

• Most specialized cells cannot survive on their own. Plants cells are similar to other eukaryotic cells in that they

have a nucleus, organelles and cytoplasm.

• Plant cells are different in that have a cell wall, chloroplast and a large central vacuole

• Plants have four types of tissues: Dermal, Vascular, Ground, Meristematic

Stomata

Plant Tissues

1. Dermal: Outermost layer used for protection

2. Vascular: Used for transport. There are two types xylem (water) and phloem (food).

3. Ground: All the remaining cells. Used for support, storage and sometimes photosynthesis.

4. Meristematic: Regions where new cells are produced leading to plant growth.

Stationary Existence

• Not being able to move creates problems for plants that mobile organisms do not have

• Plants must get all of the resources they need from where they are.

• Sexual reproduction is also complicated in that they have to get sex cells from one plant to another

• Plants have two phases in their life cycle a diploid (Sporophyte) and a haploid (gametophyte) stage.

• This process is called alternation of generations.

Reproduction in Plants

• Seedless Plants: embryo develops in the parent (no seeds)

• Seeded Plants: seeds to protect and nourish the embryo.

1) Gymnosperms: Seeds in cones.

2) Angiosperms: Seeds in fruits

Flowers

• The flower is the reproductive organ of

angiosperms

• Pistil/Carpel: Female parts of the flower. Made up

of the stigma, style and the ovary

• Stamen: Male parts of the flower. Made up of the

anther and filament

• Sepals and petals are the sterile parts of the flower

Filament Anther

Stigma Style

Ovary

Carpel

Petal Sepal

Ovule

Stamen