10.3Plant Structures

* Means Vocabulary word

Roots

• Roots: • anchor a plant in the ground, • absorb water and minerals from the soil,• sometimes store food

Root Types

• There are 2 Root types:• 1) Fiberous- many similar sized roots that

form a dense, tangled mass• They take a lot of soil when pulled out of the

ground• EX: lawn grass, corn, onions

Root Types

• Tap Root System• Long, thick main root• Many small roots branch off of the main root• Very hard to pull out of the ground• Ex: Carrots, dandelions, cacti

Root StructureRoots have many structures.

*Root cap: protects the root from injury as the root grows through soil

Stems

• 2 main functons:• 1) to carry substances between the plants

roots and leaves• 2) provides support for the plant and holds up

the leaves so they are exposed to the sun

Stem Structure

• 2 types:• 1) Woody Stems• -hard and rigid (ex: maple tree)

Stem StructureThe woody stem of a tree contains many different structures. What are the active xylem and phloem on the tree trunk?

*Cambium: layer of cells that produce new phloem and xylem

Wood Stem Structure

phloem

Xylem

Stems

• Type 2: • Herbaceous• -contain no wood and are often soft• Ex: daisies, ivy, asparagus

Annual Rings

• Show a tree’s yearly growth• Are made from XYLEM

– Spring: large with thin cell wall (rapid growth)-light brown color

– Summer: small with thick cell wall (slow growth)-dark brown color

You an add up the pair of bands to find out how old a tree is!

Annual Rings

• The width of the XYLEM can tell a scientist about the amount of rainfall– Rainy year: wide rings– Dry year: very narrow rings

– Becauase of this scientist can tell when an area had a drought many years ago

– Ex: in southwestern US scientist found droughts occurred in: 840, 1067, 1379, 1632!

Annual Rings

• Knowing what you just learned how old is this tree and was there ever a drought??

Leaves

• Leaves capture the sun’s energy and carry out the food making process of photosynthesis

Leaf Structure

• The top and bottom of a leaf protect the inside cells

• Inside of these layers are the veins that house: Xylem and Phloem

• The surface layers of the leaf have small openings called stomata

Leaf Structure

• *Stomata: small pore that opens and closes to control when gases enter and leave the cell

• When the stomata is open: carbon dioxide enters & oxygen/water vapor exit

Leaves

• *Transpiration: the process by which water evaporates from a plant’s leaves

• Plants would lose to much water during a day via transpirations to sustain life (ex: corn plants lose 4 liters of water during summer day)

• Because of this the stomata is used to make plants not dry out- control open/closing

Seeds

• Inside a seed is a partially developed plant. If a seed lands in an area where conditions are favorable, the plant sprouts out of the seed and begins to grow

Seed Structure

• 3 major parts– 1) Embryo– 2) Stored food– 3) Seed coat

Seed Structure

• *Embryo: the young plant that develops from the zygote, or fertilized egg

• Already has the beginnings of roots, stems, leaves

Seed Structure

• Stored Food:• The food used by an embryo until

photosynthesis can begin– Food is stored in cotyledon in most plants

• While in others its stored outside the embryo

Seed Structure

• Seed Coat– The outside covering of a seed– Acts like plastic wrap: protects embryo from

drying out

embryocotyledon

Seed Coat

Seed Dispersal

• Dispersal is the term used to describe the scattering of seeds

• Methods:– Animals– Barb structures– Water– Wind – Ejection

Seed Dispersal

• Animals: – animals eat plants that contain seeds-the seed

goes through the digestive system-animal defecates and seed grows in new area

• Barb Structures: – A structure that has hooks/barbs and hooks to

fur/clothing and falls off in a new area

Seed Dispersal

• Water– Seeds fall into rivers and oceans

• Wind-light weight seeds are dispersed by gust of wind

• Ejection– Plant ejects their seed and force scatters the

seeds into many directions

Seed Dispersal

• Say which picture demonstrates each seed dispersal

Germination

• *Germination: process that occurs when the embryo begins to grow and pushes out of the seed

• Process:– 1) Seed absorbs water– 2) Embryo uses stored food to begin growing– 3) Roots grow (1st downward)– 4) Stem and leaves grow upward

Germination

• Label the steps:

2

4

43

31

Structures of a Flower

• *Flower: the reproductive structure of an angiosperm

• A typical flower contains sepals, petals, stamen, and pistils

• *Pollination: the transfer of pollen from male reproductive structures to female reproductive structures

• Ex. of pollinators: birds, bats, insects, bees, flies

Structure of a Flower

• Sepals and Petals• *Sepals- a leaf like structure that encloses and

protects the bud of a flower• *Petals-a colorful, leaf like structure of some

flowers

Structure of a Flower

• *Stamens-the male reproductive part of a flower

Structure of a Flower

• *Pistils-the female reproductive part of a flower

• *Ovary-a flower structure that encloses and protects ovules and seeds as they develop– An ovary may contain one or more ovules

Style: a slender tube that connects The stigma to a hollow structure at the Base of the flower

Structures of a Typical Flower

Sepals

Petals

Stamens

Pistils