1. Stems
S7-3-1

2. 2 Functions of a Stem
Transport water, minerals, and food between roots and leaves (via phloem and xylem)
Hold leaves up to receive sunlight

3. 2 types of stems
Herbaceous-green and soft, bendable (sunflower, peas, grass)
Woody—contain wood (hard substance made of thickened xylem); rigid and strong (roses, maples, firs)

4. Parts of a woody stem Outer bark—old phloem, gives protection
Phloem—innermost bark
Cambium—where growth occurs
Xylem
-Sapwood—active xylem
-Heartwood—clogged xylem that doesn’t transport but gives support
Pith—soft center core; contains large, thin-walled cells that store water and food

5. Uses of stems Wood—building houses, furniture
FYI: ¾ used for construction
Paper products—including cardboard
Fuel—many homes burn wood for heat
FYI: 1 ton/year used for fuel
Medicines:
Aspirin—pain reliever, from willow bark
FYI: Many Native American tribes chewed on willow bark for its pain relieving properties long ago
Hydrocortisone—reduces swelling, from yam tubers
Taxol—cancer treatment drug, from yew bark
Foods (more info on this later)
Willow tree

6. Specialized stems #1 Allows plant to spread to new places
Ex. Vines, morning glories, creeping jennies
Stolon: A stem that grows horizontally above the ground and produces roots and shoots to create new plants. Also called runners.
Ex. Strawberries

7. Specialized stems #2 It’s such a big category,
Water storage—some plants store large amounts of water in their stem to prepare for dry conditions
Ex. Cacti
Food storage . . .
It’s such a big category,
it needs a separate page!!

8. We like to eat some stems!
Specialized stems #3
We like to eat some stems!
Asparagus
Celery
Sugar cane
Rhubarb

9. Specialized stems #4
Our most
common tuber . . .
Tubers—underground stems used for food storage and reproduction
Ex. potato (the ‘eyes’ will grow new stems)
The stem “swells” to
store food for the plant
The green plant grows above ground with tubers
growing
under-
ground
POTATOES!
The tubers may then be dug up and eaten

10. Questions: Answer on a separate piece of paper
List the 2 functions of a stem.
What type of stem does a tulip have?
What type of stem does an oak have?
What type of vascular tissue is bark made of?
What is the difference between heartwood and sapwood?
List 3 uses of stems (not foods).
Why do cacti store a great deal of water?
Out of the 4 listed, name your 2 favorite “stem foods.”
Why do some plants use tubers?
Why does a plant with a longer stem have a competitive advantage?