roots, stems and leaves...

9/24/2002:
Year 2 AppSci

PLANTS: Roots, Stems and Leaves

Objectives: By lesson end, students will be able to...

1. List the main functions of plant roots, stems and leaves – "What do roots, stems and leaves do?"
2. Draw and correctly label generalized root, stem and leaf diagrams – "Draw a typical root, stem and leaf."
3. Identify the different types of roots, stems and leaves – "Do all roots, stems and leaves look the same?"
4. Correlate the form of root, stems and leaves to their functions – "Why do roots, stems and leaves look like that?"

Materials:

• Roots: carrot, maize
• Stems: herb, bench, ginger, potato, cocoyam, onion and garlic (modified leaves, too)
  
• Leaves: cassava, bean, fern, cassia, simple leaf (netted cocoyam and parallel veined maize or grass)

Roots:

Functions
1. Absorb water and minerals from the soil
2. Fix/support the plant in the ground
3. Act as storage organs in some points

Variety
-Tap root system (e.g. carrot [see image above])
-Adventitious root system (e.g. maize [see image above])

Form
[see image above]


Stems:

Functions
1. Hold the leaves up, exposing them to the sunlight
2. Transport water and minerals through the plant
3. Act as storage organs in some plants

Variety
-Erect stems: herbs and trees
-Climbing stems: vines and some beans
-Creeping stems: sweet potato
-Underground stems: rhizomes (ginger), corms (cocoyam), tubers (potato) and bulbs (onion/garlic)

Form
[see image above]


Leaves:

Functions
1. Make food (photosynthesis)
2. Store food
3. Transport food to stems
4. Gas exchange (transpiration)

Variety
-Simple leaves: parallel (monocot, e.g. maize) amd netted (dicot, eg. cocoyam) venation
-Compound leaves: pinnate (palm frond), bipinnate (fern), trifoliate (bean) and digitate (cassava)

Form
[see image above]


Homework Assignment:

1. How can you distinguish between a storage root and an underground storage stem?
2. How does the form of a leaf relate to its function? (i.e. "why does a leaf look like that?")