How Did Plants Adapt to Life on Land?

The first types of plant to adapt to land were the ancestors of green algae. They adapted through the evolution of body support, transport of materials such as water, fertilization, and the development of the embryo.

The first step to adapting to land was the development of body support. Originally, the plants only floated on water using gas-filled vesicles. In order to grow tall, the plants developed rigid cell walls and other supportive tissues. Plants originally absorbed nutrients from the surrounding environment, but on land, a plant must absorb water and nutrients from the soil and transport it to its limbs. Since the plants began to use rigid cell walls to grow taller, a system of vessels, or tubes, were developed to transport materials.

Plants also developed leaf cells that produce food, stem cells that provide support and root cells that absorb and transport nutrients from the soil. Originally, plants could only fertilize in aquatic or moist environments, allowing the sperm to swim to the eggs. The development of sporophytes produce gametophytes, and gametophytes produce either sperm in pollen grains or eggs in the ovaries.

The pollen allows the plants to reproduce using wind transport instead of water. The development of the seed provides water and nutrients to the embryo in non-aquatic environments, preventing the embryo from drying out. The seeds also allow the transport of embryos away from the parent without requiring water.