Plants of Arctic Tundra Region
The growing season in the Arctic (lowland) tundra only ranges from fifty to sixty days per year because of the lack of light and heat. This growing season occurs during the summer, when temperatures average between 37°F and 54°F. All tundras, regardless of their location are characterized by grasses and grasslike plants (such as sedges), lichens, and dwarf forms of woody plants. Although there are about 1,700 kinds of plants in the Arctic tundras, there are no plants with deep root systems, such as trees. This is partially due to the low temperature and low precipitation, but mainly due to the layer of permanently frozen subsoil.
Conditions are most severe during the winter, but cool temperatures and strong winds during the summer also present problems to organisms in the tundra. Most of the plants are small and grow close to the ground. This helps them survive in the Arctic because the wind speed is slower near the ground due to friction between the wind and objects on the surface, including rocks and other plants. The air temperature near the ground is also warmer because the soil absorbs and radiates some heat from the Sun. To survive the cold winter, the above-ground growth of many plants dies, while their main growth and energy storage remains alive in their underground roots.
The coloration of organisms in the tundra is another adaptation to their cold environment. Since dark colors absorb sunlight and light colors reflect it, there are more dark plants than light plants in the tundra than in warmer environments. Many tundra plants are purple or blue. Light-colored flowers in the tundra are heliotropic, which means they turn to face the Sun to gather light and warmth.
To determine how the shape of flower petals helps seed production of some Arctic plants.
- 2-by-2-inch (5-by-5-cm) square of aluminum foil
- 2-by-2-inch (5-by-5-inch) square of black construction paper
- transparent tape
- desk lamp
- Overlap the edge of the foil and the black paper square. Secure with tape.
- Lay the combined strip on a table about 12 inches (30 cm) from a lamp, with the black paper facing the lamp.
- Bend up about 1 inch (2.5 cm) of the black paper facing the lamp. The bent edge should cast a shadow across the remaining black paper.
- Use the tape to secure the black paper to the table.
- Lift the aluminum foil strip and slightly squeeze the edges so that the foil curves. Change the height of the foil and its curve to form a spot of light in the center of the shaded black paper taped to the table.
Lifting the foil causes light to hit the shaded black paper. Curving the foil causes a spot of light to form in the center of the paper.
The light coloration of Arctic poppies and other light-colored flowers in this tundra is an adaptation to the cold environment. The flowers of these plants are heliotropic, which means they turn to face the sun to gather more light and warmth. Turning toward the Sun helps to direct sunlight onto the darker, shaded center of the flower, where the seeds are produced, and the shape of the leaves helps to focus the Sun's light on the flower's center. Insects that live in the center of these flowers also benefit from the sunlight focused here.