1. The plant’s inner highway
Plant Parts - Stems
The plant’s inner highway
2001 AgriTeach.comTM (12901ms)

2. Why do plants have stems?
They have two functions:
moving materials (water, minerals, food)
supporting the rest of the plant
The stem has rings called “nodes”
the space in-between is called the “internode”
At each of the nodes is a “bud”

3. Stem Anatomy - External

4. Stem Anatomy - Internal
When a plantlet develops from a seed, it may have one or two seed leaves or “cotyledons”
Plants with one are “monocots”
Grasses - lawn grasses, corn, wheat, etc.
Plants with two are “dicots”
Other plants - trees, beans, alfalfa, etc.
Both types have different arrangements of their “vascualar bundles”
These are the veins and arteries of the plant

5. Vascular Bundles

6. Vascular Bundles The arrangement of the bundles: Inside the bundles:
Allows dicot stems to grow thicker & taller
Trees have active, living tissue around the outside of the trunk; inactive heartwood on the inside.
To make syrup, we tap the outside because it is busy moving sap (nutrients).
Limits monocots to a certain size
Inside the bundles:
xylem tissue moves materials up the plant
phloem moves materials down the plant

7. Plant Parts - Roots

8. Functions of the Roots
Anchor the plant
Absorb water and nutrients

9. Different Types of Roots
Tap Roots – one main root
Ex. Carrots
Function – storage of excess food
Fibrous Roots – branched roots
Spread out in the soil in search of water and nutrients
Root Hairs – tiny hair-like roots
Absorbs much of the water and nutrients for the plant.

10. Parts of a seed
Embryo - develop into all the different tissues that will ultimately make up the mature plant
Seed Coat - protects the internal parts of the seed
Endosperm - serves as a food source for the developing embryo

11. Parts of the Seed
endosperm

12. Germination
* When a seed sprouts and begins to grow

13. Monocot vs. Dicot
Dicot Germination
Monocot Germination