Systems in Plants

Why are plants important to us?

Plants have 2 obvious distinguishing features: (1) they are typically green in colour, and (2) they cannot move from place to place. Both of these features are directly related to the overall structure and functioning of plants.

Green colour – due to chlorophyll, a chemical used by plants for photosynthesis to make their own food

Anchored in one place – due to root structures

• Plants do not need to move around in search of food, unlike animals. However they must still perform many of the same functions as animals:

• Need to exchange gases with their surroundings

• Require an internal transportation system to move water and nutrients around

• Must have a way of reproducing

Hierarchy of Organization in the Plant Body

Two main body systems: root system, shoot system

Three main types of plant tissue systems: dermal, vascular and ground tissue

• The Root System: the system that anchors the plant, absorbs water and minerals and stores food

• Useful source of food (sweet potatoes, carrots, sugar beet), flavouring (ginger), fibre, natural remedies

• specialized to conduct photosynthesis and reproduce sexually;

• consists of the (a) leaf, (b) flower, (c) stem

(a) Leaf: • main photosynthetic structure of the plant –

carbon dioxide, water, light energy produce glucose and oxygen

• organelle that performs photosynthesis: chloroplast

• also for support, protection, reproduction and attraction

The Shoot System:

(b) Flower:

• Specialized structures for sexual reproduction: contain male or female reproductive structures, sometimes both

• Male reproductive structures: pollen grains; Female structures: eggs, fertilized by pollen

• After pollination, female flower parts from seeds (contained in the fruit)

(b) Flower:

• Pollination aided by (1) wind (e.g. grass, many trees), or (2) animals (e.g. carried by insects, bats, birds) – nectar and colourful flowers help attract animals to achieve pollination

• Uses: important source of food and flavourings

Flower under visible light (left) and UV light (right). Bees see UV light and are guided to the centre

(c) Stem:

• Supports branches, leaves and flowers

• Transports material through vascular tissue

• Uses: provides food (sugar cane, potatoes), wood and paper products, cork, linen, medicine

Tissue Systems:

• Dermal Tissue System: tissues covering outer surface of the plant

• Vascular Tissue System: tissues responsible for transporting materials within the plant

• Ground Tissue System: all other plant tissues