VMBO Year 3 · Ecology · Section 6.6

Adaptations in plants

How do plants fit their environment?

Plants need water, carbon dioxide and sufficient light for photosynthesis. Stomata are small pores in the leaf surface controlling gas exchange. Carbon dioxide enters for photosynthesis, while oxygen and water vapour can leave. The number, position and opening of stomata affect the balance between gas exchange and water loss.

Dry and moist environments

Plants adapted to dry conditions often have features that reduce water loss:

• Relatively few stomata, sometimes sunk below the surface.
• A thick waxy cuticle.
• Small leaves, rolled leaves or thick water-storing leaves.
• Hairs that help reduce air movement near the surface.

Plants in moist environments may have larger, thinner leaves, a thinner cuticle and less deeply sunken stomata. These are general patterns; species vary and other conditions also matter.

Aquatic plants

Floating leaves usually have stomata on their upper surface, where they contact the air. Fully submerged leaves generally lack stomata and exchange gases through their surface. Many aquatic plants have internal air spaces or air channels that help transport oxygen to roots in waterlogged, oxygen-poor soil.

Adaptations to light

Sun plants grow best in relatively bright conditions, such as open fields. Shade plants tolerate lower light levels, for example on a forest floor. Shade-adapted leaves are often broad, thin and dark green, helping capture limited light. Sun plants often have thicker leaves able to use stronger light.

Climbing towards the light

Climbing plants use other structures for support, reaching brighter conditions without building a thick self-supporting trunk. Some attach using aerial attachment roots; others use tendrils that coil around supports. Most climbers obtain water and nutrients through their own roots. Parasitic plants that take substances from another plant are a separate case; climbing alone does not make a plant parasitic.