Plant Adaptations for Living on Land
Plants were pioneers—the first organisms to colonize dry land.
Adapting for life on land required several key modifications.
- Typical Gymnosperm Cones
Pine tree
Gymnosperms are seed plants with a protected cone or other body for their seed embryos, such as conifers (evergreen trees), seed ferns, and cycads.
Pine tree
Gymnosperms are seed plants with a protected cone or other body for their seed embryos, such as conifers (evergreen trees), seed ferns, and cycads.
Plants originated in the nourishing environment of the water. Life on land required plants to develop a way to reduce water loss and the drying effects of desiccation. This protection came in the form of a waxy outer covering called a cuticle. The cuticle is a thin, impermeable covering that grows on the outside surface of the exposed parts of a plant. In addition to slowing water loss, the cuticle may sometimes protect a plant from the harmful effects of ultraviolet solar radiation—a danger that was more acute for the first land organisms than it is for today's because in the Early Paleozoic Era, Earth's atmosphere was still developing its protective ozone shield.
Typical Angiosperm
Plant body
Vertical section through flower Stamen
Angiosperms, the flowering plants, utilize flowers to attract pollinators, and some encase their seeds in fruits to aid in their dispersal.
Plants need to breathe; this, too, posed a challenge for the first inhabitants of the land. Now that they no longer were immersed in water, plants on land needed to develop a new physiological technique: a way to grab carbon dioxide molecules from the air. Plants evolved a network of tiny pores on their outer surfaces for this purpose. Called stomata, these pores enable an exchange of gases between the plant and the outside air, making photosynthesis possible.
Plants living in the water are held up or suspended by the buoyancy of the marine environment. On land, larger plants must lift themselves from the ground so that they do not collapse under their own weight. This is accomplished by a skeletonlike structure of stems, branches, and trunks that gives strength and shape to land plants. Early land plants evolved such structures and, as a result, expanded their habitable environment in a vertical direction. This dramatically—and literally—increased the range of terrestrial plants over and above the flat surface of the ground, making possible taller plants including trees.
The vascular systems of land plants were another key evolutionary innovation that enabled such plants to thrive. These systems improved the plants' ability to conduct water and nourishing minerals to different parts of their structures. Roots evolved as a specialized means to absorb water. These increasingly effective methods of providing food and energy led to the growth and diversity of all kinds of plants.
One final challenge for plants living on land was to find a means to reproduce effectively. In the marine environment, plants passed sperm to egg through the medium of water. Plants in a terrestrial habitat evolved many different solutions to the challenge of achieving the union of sperm and egg. Most of these solutions depend on reproductive cells called spores. Spores can be blown through the air, transported by available surface water, and transported by pollinating insects to make plant reproduction possible.
Many of these plant adaptations were mirrored by the evolution of invertebrate and vertebrate animals for life on the land. Plants
Photosynthesis
Water + light = chemical energy
Light energy
- Sugar leaves leaf
Chemical energy + carbon dioxide = sugar
Chemical energy + carbon dioxide = sugar
© Infobase Publishing
Plants nourish themselves through photosynthesis. Using a network of tiny pores, or stomata, on their outer surface enables plants to exchange gases with the outside air, allowing them to breathe.
share with some animal groups the internalization of vital body systems such as sexual organs, the development of a protective outer skin, and functions such as gas exchange.
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