Introduction to Plants

Classification of plants Kingdom Plantae –Phylums Lycodiophyta (Club Mosses) Equisetophyta (Horsetails) Psilotophyta (Wisk Ferns) Polypodiophyta (Ferns) Cycadophyta (Cycads) Ginkgophyta (Ginkoes) Pinophyta (Conifers) Gnetophyta (Vessel-bearing Gymnosperms) Magnoliophyta (Flowering Plants)

Facts… critical to other life on this planet because they form the basis of all food webs Most plants are autotrophic earliest fossils found have been aged at 3.8 billion years scientific study of plants, known as botany identified about 350,000 extant (living) species of plants –~258,650 are flowering and ~18,000 bryophytes

What are plants? Multi-cellular organisms Make own food (photosynthesis) Have chloroplasts Have rigid cell walls made of cellulose Found all over the world

Plants provide: Food Oxygen Medicines Building materials Textiles (fibers) Coloring pigments

Plant Classification

Plants Without Seeds Need water to reproduce Reproduce with spores Include –Mosses –Ferns –Horsetails –Bladderworts

Plants with Seeds 2 types Found all over the world

Gymnosperms Means “naked seed” Often have cones & needle-like leaves Do not have flowers –Ex: conifers, gingko

Angiosperms Flowering plants Largest group –Moncots –Dicots

Monocots

Dicots

Evolution Principal photosynthetic organisms were microscopic cells floating below the surface of the water, closer to the sun’s rays As they multiplied, depleted resources of the open ocean, so colonies could be found nearer to the shores, in order to get minerals and nutrients from runoff About 650million years ago, diversity of these organisms abounded on the rocky shores, and some even integrated into multicelluar bodies

Evolution These new multicelluar photosynthetic forms developed a cell wall due to the rough waters of the rocky coastline As size increased, they developed internal structures that linked the photosynthesizing parts to the non- photosynthesizing parts

Evolution to land.. Oxygen & carbon dioxide not as abundant in the water, as it is not as free circulating as it is on land Critical factor to adapting to land is water resources Development of root systems to be able to keep plant stable on land and to seek out water resources without moving

Roots What do they do for the plant???

Are you Rooted? Roots help to keep plants in place. They spread out into the soil and “attached” themselves to the particles of the soil. Why do they reach and probe? –To find nutrients and water, thus in the end the plant gets anchored into the soil.

Root Hairs Water in the soil is taken up by root hairs and then passes from cell to cell to the xylem.

Types of Roots Generally grasses have this type of root Many roots extend into the soil from base of plant One or more large roots extending into the soil Smaller roots branch off Fibrous RootsTap Roots

Types of Roots Shallow roots –Desert roots –Quickly growing plants Deep underground roots –Areas with little rainfall Deep and Shallow Roots –Takes advantage of underground water sources and occasional showers.

Root Growth Amount of moisture in the soil Type of soil How quickly the plants grow and go to seed Type of rainfall in that area Type of plant – prop roots are used to help support the plant What does it depend on?

Lastly… Roots are used as food storage for plants. They store sugars and starches to help plants over winter. Sugar storage in roots also help to send up new shoots each spring, and to regenerate stems and leaves that were eaten or burned. Radishes, carrots, turnips – store large amounts of food in the form of starch in their roots. We eat these roots as a source of energy.

Plant Functions What do stems & leaves do for a plant???

Stems

Transport of Materials Phloem (2) –Carries sugars (food) up & down in plant Xylem (1) –Carries water & mineral up from roots to all parts of plants

Leaves

Photosynthesis Leaves collect sunlight, water and carbon dioxide to make sugar (food) for the plant The chemical equation for this process is 6 H2O + 6 CO2  C6H12O6 + 6 O2 sugar Sun energy

Respiration Leaves break down sugars to get energy This process releases excess water as waste The chemical equation is C6H12O6 + 6 O2  energy + 6 H2O + 6 CO2 Energy released To help plant grow sugar

Transpiration Taking in CO2 and releasing O2 and H2O as waste products after respiration