Download - Plant Parts
Parts of the plant and their functions
Importance of plants
• Without plants life on earth would not exist
Plants:
• Primary source of food for people and animals
• Produce oxygen
• help to keep us cool
• renew the air
Plants:
• slow wind speed
• provide a home for wildlife
• beautify surroundings
• perfume the air
• furnish building materials and fuel
Parts of a plant
• Four basic parts–leaves
–stems
–roots
–flowers
Leaves
• the food factory of the plant
• produce the food used by the plant or stored for later use
Shape and size of leaves
• vary among plants
• used for identification of plants
Leaf arrangement
• alternate
• opposite
• whorled–arranged in a circle around the
stem
External leaf structure
• petiole - leaf stalk
• leaf blade (leaf)–has veins
–forms structural framework of the leaf
Midrib
• large center vein from which all other leaf veins extend
Margins
• edges of leaves
• assists in plant identification
Internal leaf structure
• epidermis–skin of the leaf
–single layer of cells
–protects leaf from loss of too much moisture
Guard Cells
• open and close the small pore on the underside of the leaf
Stomates
• allow the plant to breathe and transpire–give off moisture
Chloroplasts
• contain chlorophyll
• located inside the food making cells
Photosynthesis
• process by which CO2 and H2O in the presence of light are converted to sugar and oxygen
Chemical formula
• 6CO2 + 6H2O
• -----> in reaction with sunlight and chlorophyll ------>
• C6H12O6 (glucose) + 6O2
food
• manufactured in the leaves moves downward through the stem to the roots–used by the plant
–stored in stem or root and leaf in the form of sugar, starch or protein.
Respiration
• plants respire 24 hours a day
• consume O2 and give off CO2
• plants produce more O2 through ps. Than they consume during respiration and growth.
Stems
• have two main functions–movement of water and minerals
from the roots upward and movement of manufactured food down
Stem functions
• support of leaves and reproductive structures
Stems also
• used for food storage and reproduction of plants involving cuttings
• Green stems manufacture food just as leaves do
External Stem Structure
• lenticels- breathing pores
• bud scale scars-indicate where terminal bud has been located previous year.
Leaf Scars
• shows where leaf was attached
• Distance between the two represents one year of growth.
Internal Stem Structure
• phloem- bark, carries manufactured foods down.
• Xylem- wood, carries water and minerals up.
• Cambium- separates the 2 and produces all new cells.
• Characteristic of dicots
Internal Stem Structure
• dicot- dicotyledon, a plant with 2 seed leaves
Monocot
• Monocotyledon - a plant with one seed leaf.
• Have vascular bundles, contain both xylem and phloem in each small bundle
Monocot
• stems have no cambium
• cells enlarge to create size of mature stem
Economic Importance
• food
• building materials
Roots
• Usually underground• functions:
–anchor plant and hold upright–absorb water and minerals form
soil and conduct to stem–store food, & propagation
Root Structure
• internal
–similar to stems
–older roots have xylem, phloem and cambian
external
–root cap
•produces continuous supply of new cells
•protects roots as they push through soil
Structure
• root hairs
–absorb moisture and minerals
• small roots
Functions other than water and mineral absorption
• cash crops for food
–carrots
–beets
–radishes
–sweet potatoes• propagation
Type of root systems
• fibrous-grasses
–easier transplanting
–shorter, smaller, more compact
• lap root-carrot
–longer and fewer roots
Flowers, Fruits, and Seeds
• pollination- color of flower attracts insects to fertilize flower– beginning of fruit and seed formation
• fruits and seed are attractive to birds who eat and spread seeds.
– Reproduces plant– some seeds carried on animals coats
Parts of the Flower
• differ in size, shape, and color, some basic parts
• sepal
–green leaf-like part, covers and protects bud before opening
Petals
• are actually leaves
• usually bright colors to attract pollinating insects.
Parts of the Flower
• stamens
–male part of flower
–has two parts
•filament-stalk
Anther
• anther- sac-like structure on top of filament, contains pollen
Parts of the Flower
• Pistil - female part
• in the center of flower
• has three parts
Pistil
• three parts
• stigma - top - sticky
• style - tube leading from stigma to ovary
Ovary
• egg cells develop here
• grows to become fruit or seedcoat
Types of Flowers
• complete
–contains 4 main parts
Incomplete
• does not have all 4 main parts
Perfect
• has stamens and pistils
Imperfect
• lacks stamens or pistils
Types of Flowers
• monoecious
–stamens and pistils are found in separate flowers on the same plant
•ex: Corn
dioecious
• male or staminate flowers found on one plant, female or pistilate flowers on another plant
• ex: holly