Special Defenses

BASEic Botany

Plant Evolution

Over time plants have evolved with animals. The development of special defense structures allow plants to survive!

How plants ‘fight’

Can plants fight?

How do they keep herbivores and insects from eating them?

Plant Defenses

Physical defenses

Thorns

Spines

Chemical defenses

Resins

Odors

Toxins

Every plant is unique!

Thorns

Modified stems or branch

Can be simple or branched

Gymnosperm buxifolia - Thorns

Citrus Thorn

Spines

Modified leaves

Not only do they aid in defense they can help shade the plant from harsh environments

Fouquieria splendens - Spines

Spine Example

Iacacia xanthophloea

Review:

Thorns are modified ______________

Spines are modified ______________

Thorn or Spine?

Thorn or Spine?

Answer: Thorn

Thorn or Spine?

Thorn or Spine?

Answer: Spines

Thorn or Spine?

Thorn or Spine?

Answer: Thorn

Your Task is to sort through a bag of common plants that are found locally and determine if

they utilize thorns or spines. Be careful handling the plants!