Horticulture Science Lesson 8 Understanding Stem Anatomy Monocots

Horticulture Science Lesson 8 Understanding Stem Anatomy

Monocots vs. Dicots • Way we classify plants • Monocot seeds have one seed leaf, Dicots have two seed leaves. • Monocots parts are in multiples of 3, dicots are in multiples of 4 or 5. • They also have different stem systems.

What are the functions of a stem? • Stems move water and minerals up from the roots to the leaves. • They also move food made from photosynthesis down to the roots.

How? • Water molecules are attracted to each other like magnets. • This is called COHESION. • Water molecules in plants travel through the XYLEM, a tube that runs through the stem by cohesion.

Function of a Stem • Stems leaves collect • Stems support the leaves. They hold the in the most efficient position to sunlight. are also used for food storage.

External Parts of a Stem • Lenticels- breathing pores • Terminal Bud- The end of the stem where growth is taking place. • Bud scale scars- Indicates a terminal bud has been located there. – Distance between the two shows one year of growth

– The leaf is attached to the stem at the node. – The area between leaves is called an internode. – At the node, just above where the leaf is attached, there is always a side bud called the lateral bud.

– On the outside of both terminal and lateral buds are small protective structures called bud scales.

– When the leaf falls off of the stem, it leaves behind a small scar just below the lateral bud. • This scar is called the leaf scar.

Internal Structures of a Stem • In MONOCOTS the stem structure is in bundles.

Internal Structure of a Stem • In dicots, the structure is made of rings.

Internal Structure • Xylem- Water and nutrients move UP the plant from the roots to the leaves through cohesion. • Phloem-Food and energy manufactured through photosynthesis moves from the leaves to the roots.

Internal Structure • Cambium-Builds new xylem and phloem cells. • In dicots, this causes the plant go grow in girth…. trees! • In monocots, the cambium doesn’t circle the outside of the plant, so it doesn’t continue to grow past maturity.

The Pith • The pith is the very center of the stem, it is from the Old English word meaning, “pit of the fruit”

Review • What is one way we classify monocots and dicots differently? • What is the function of the lenticels? • What is the process called that helps water travel upward through the xylem? • What is the purpose of the phloem? • What does the cambium do?

Task: Dissect a Flower! • You will need: white paper, flower, tape, marker, and a knife. • Cut the flower in half. • With one half, remove a petal, a stamen and pistil. Tape over it, label them and describe their function and the process of pollination. • Tape the other half to your paper and label the same parts, but also the sepal and any parts of the stem you can identify.