Transcript Stem Variation

Stems: Function
and Variation!!!
What are the functions of plant
stems?
1. Support
2. Transport: sugar, water, minerals
3. Storage: white potato (underground
stem) stores starch, cacti and succulents
store water
Types of Stems:
• Herbaceous-fleshy, green, soft, easily
broken
– Ex. Tulip, geranium,
– Beans, tomato
Types of Stems:
• Woody-grow year to year
– Hard, wood-like
– Ex. Trees: Maple, Oak
– Shrubs: grey dogwood, blackberry
Stem Anatomy
• Node: enlarged
portion of stem where
leaf develops
Stem Anatomy
• Internode: area between 2 nodes
Stem Anatomy
• Terminal Bud: at
the end of the stem
Stem Anatomy
Axillary or Lateral
Bud: on the side
Stem Anatomy
• Lenticels: spongy
areas on the surface
allow exchange of
gases
Stem Variation
I.
Divided into 2 groups
A. Above Ground Stems
1. Crown (fleshy lump of
compressed stems) Strawberry
Stem Variation
2. Spurs- small stems that grow out from the
main stem; common on fruit trees
Stem Variation
3. Stolon-horizontal stem that lies along
the top of the ground
Spider plant, Bermuda grass, strawberry
Stem Variation
4. Tendril- thin stem, twists around
objects for support
Ex. Peas, beans, grape, climbing plants
VIDEO EXAMPLE!
• http://www.youtube.com/watch?v=fGBIT4l
y-Vs
Stem Variation
5. Thorn- pointed/sharp, protection
Ex. Rose, blackberry
Stem Variation
B. Below Ground Stems
How do you tell a ROOT from an
underground stem?????
A root has no nodes……
B. Below Ground Stems
1. Tuber-an underground stem that stores
food
Ex. White Potato: eyes are nodes
B. Below Ground Stems
2. Rhizomes-grow horizontally underground
Ex. Thistles, Iris, Peonies
B. Below Ground Stems
3. Bulbs-shortened stems with thick fleshy
scales
Ex. Tulip, Lilly, Daffodil, Onion
Need a low temperature period to grow.
B. Below Ground Stems
4. Corm-solid stem base enclosed in dry,
scale-like leaves
Ex. Gladiolus and Crocus
Gladiolus
Why is Stem Variation Important?
1. Helps to ID plants
2. Used to propagate new plants
3. Crucial in the growth of
existing plants
• #1
• #2
• #3
• #4
#5 Which 2 stem variations does
this plant represent?
• #6
#7
#8
#9
# 10
#11 CROCUS: WHAT KIND OF
STEM?
NARCISSUS/PAPERWHITE
AMARYLLIS
• http://classes.aces.uiuc.edu/NRES103/con
tents.htm
• generalhorticulture.tamu.edu/.../lab2/ste
mm.html