From Seed to Seed:
Plant Science for K-8 Educators

Adaptations for air. It is hard to imagine air being in short supply. And, in most cases, availability of air isn't a limiting factor in plant growth. Let's look at some cases where it is.

• The black mangrove grows in shallow water or mud, and sends out "air roots," or pneumatophores, that poke up above the water surface to take in air.
  
  
• The water lily has stomata on its upper leaf surface, instead of on the underside of the leaf like most plants.
  
  
  
• Many aquatic and wetland plants have interior chambers in the leaf petioles and stems through which oxygen diffuses to the plant roots.

Here are some other examples of interesting adaptations plants have for getting the air that they need

• Some plants growing in damp environments carry their stomata on raised stalks. This helps increase air circulation around the stomata and prevents them from being blocked by water drops.
  
  
• Plants growing fully submerged must meet their oxygen requirements from oxygen dissolved in the water. These plants often have highly dissected, or feathery, leaves. This characteristic dramatically increases the surface area of the leaf and maximizes the plants' ability to take in dissolved oxygen.
  
  
• You may have noticed small spots or lines on the bark of many woody plants' twigs. These small pores, consisting of loosely packed cork cells, are called lenticels. Lenticels provide a pathway for air to reach the twigs' growing tissues.