Plant Parts - Stems

1. 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: • 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