CHAPTER III:

OVERVIEW OF PLANT

STRUCTURE

TOPIC:An Overview of Vascular

Plant Organs

BY : Patricia Clariza Santos MLS-1D ( Group II)

Organ consist of several types of tissues adapted as a group to perform a particular functions.

Vascular plants have three organs:

ROOTS

STEMS

LEAVES

Bryophytes and some seedless vascular plants have structures that can be called:-“stemlike”-“leaflike”-“rootlike”But not considered to be true stems, leaves and roots.

The list of plants is much shorter than the list of animal organs. While some botanists refer to reproductive structures such as :

- SEEDS- CONES- FLOWER as (organs)

Most reserve the term solely for stems, leaves and roots.

Stems position leaves

for maximum

photosynthesis

Photosynthesis – is the process by which plants certain other organisms use solar energy to make their own food by transforming carbon dioxide and water into sugars that store chemical energy.

Stem is any part of a plant that supports leaves or reproductive structures.

BRANCHES

Leaves function in both

photosynthesis and

transpiration

Leaf or a leaves – is the main photosynthetic organ of modern plants.

Cacti – most photosynthetic plant that occurs in the thick stems, which stores water.

Some pressure is a “push” from the roots, but a “pull” from the leaves that is the main force that moves water in most plant. This “pull” come from the loss of water through the pores in leaves.

Transpiration – the evaporation of water from the plants, pulls water and mineral nutrients up from the roots to the leaves.

- The chemistry of water helps explain how transpiration moves large amounts of water through the plants.

Roots anchor the plant

and absorb water and

minerals

Roots have two main function :

- Anchoring the plant in the soil-Absorbing water and minerals

The absorption takes place only near the very tips of the roots, through trichomes.

Root Hairs

Which means the tiny extensions of root epidermal cells that greatly increase the amount of root surface area.

- In addition to anchorage and absorption, many roots store food for the plant.

Even though roots frequently store food, they do not actually produce it. Because they are usually NON-PHOTOSYNTHETIC and in fact usually grow away from the light.

Vascular tissue system continues between :

Roots

Stem

Leaves

Needs sugar and other organic nutrients produced in leaves.

While leaves and stem needs water and minerals obtained by the roots.

Xylem carries water and minerals from the roots.

Phloem carries food from the leaves to the rest of the plant.