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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
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