Intro to Horticulture

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Intro to Horticulture

• Parts of the plant and their functions

Environmental Science
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Functions of leaves

• .

1. Critical for photosynthesis (the process by
which plants produce their food).
2. Aid in the process of transpiration which is
necessary in order for plants to cool themselves.

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3. Leaves can store some food which can later
be transferred to other areas of the plant.
4. Sometimes, leaves can be used in asexual or
vegetative propagation.
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External Leaf Structures

• Leaves are consist of petiole and blade
• Blade is comprised of veins and a midrib
• The veins of the leaf form its structural
  framework

• .

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Internal Leaf Structures

• Epidermis
• Cuticle
• Waxy substance covers the leaves and stems
• Waterproof layer that keeps water in plants

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Principal Tissues of the Leaf

• Epidermis (cont)
• Stomata
• Openings in the epidermis mainly located on
  underside of leaves
• Exchange of gases

• Guard Cells
• Two cells located on each side of stomata
• Open and closes stomata

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Chloroplast

• More in cells located in the center of the leaf
• The chloroplast contains chlorophyll which gives
  the plants the green color
• Manufactures food for the plant though
  Photosynthesis
• Beginning of the food chain for most living things

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Photosynthesis
CARBON DIOXIDE WATER LIGHT ENERGY GLUCOSE
OXYGEN

• Food manufactured by this process goes down to
  the roots thought the stem. It is either used by
  the plant or stored as a starch, sugar, or protein

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Respiration

• Plants respire 24 hours/day just as animals
• In this process they consume carbon dioxide and
  give off oxygen

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What is the purpose of the stems?

• Two main Functions
• The movement of materials- water, minerals, food
• Support the leaves and reproductive structures
• Can be used for food storage
• Ex. Irish potato

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What are the types of stems?
1) Woody Stem trees, shrubs, perennials 2)
Grass Stem hollow or filled 3) Herbaceous Stem
like wood but softer (clover, alfalfa) 4)
Modified Stem
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Types of Modified Stems

• Bulbs (onion)
• Tubers (potato)
• Stolons above ground runner (strawberry)
• Rhizomes below ground runners (field bindweed or
  creeping jenny)

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What is the Terminal Bud?

• Terminal bud tries to make plant grow taller or
  longer
• if we remove terminal bud, the plant will be
  shorter and thicker
• Can you think of why we would want to do this??
• What kind of plants could we do this on??

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Internal Stem Structure

• What does the Xylem Carry
• Water and minerals travel up
• What about the Phloem
• Manufactured food travels down the plant
• What does the Cambium do?
• Separates the xylem and the phloem
• Thin, green, actively growing tissue located
  between the bark and the wood of a plant

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Monocot vs. Dicot

• Dicot stem may continue to increase in diameter
  because the cambium builds new phloem cells on
  the outside and new xylem cells on the inside
• Ex. Trees
• Monocot have vascular bundles which contain both
  xylem and phloem and no cambium
• This would make it more limited in size
• Ex. corn

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Why should we care?

• The stems of some plants we use as food
• Irish potato and asparagus
• Others are used in building materials
• Lumber from the tree trunks

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Roots

• Roots function
• Anchor the plant and hold it upright
• Absorb water and minerals from the soil and
  conduct them to the stem
• Store large quantities of plant food
• Propagate or reproduce some plants

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Fibrous root vs. tap root

• Fibrous root system
• Much easier to transplant
• More spread out
• Tap root system
• Longer fewer roots
• End of root contains many root hairs

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Functions of Fruit
1. Protect the seeds inside the ripened ovule
(fruit).
2. Provide nutrients to the soil and to a newly
germinated seedling.
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3. Aid in the dissemination/spreading of seed by
providing food for animals.
Animals eat the fruit and seeds. After the
fruit is digested, the seeds pass out in the
animals feces at another location.
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4. Some plants have dry, dehiscent fruits which
split open to disseminate seeds.
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What is the purpose of seeds

• To continue the plant process
• There are two types
• Monocots
• dicots

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Monocot and dicot
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