Adaptations

Plants that are successful in the Arctic have developed ways to survive the winter and the often very dry desertlike climate. Many of the grasses have root systems that may extend 5-7 times further below ground than the plant is high. Some members of the rose and legume families have significant underground stem development, with much more of the plant below ground level than above. Several members of the daisy family have long tap roots with only a crown of leaves that lie close to the tundra. These plants are like dandelions and there are several native species of dandelions in the Arctic.

The leaves of monocotyledon species die back, building up a thatch of dead leaves that insulate and protect the growing shoots. This thatch also insulates ice that forms around the plants in the winter, so that plants that have been grazed and are less insulated often begin growing earlier in the summer and are more likely to flower. The leaves of many heath and woody rose species are leathery, often very close together on the stem, and modified in ways that retain water. The leaves survive for several years. When they die, they remain around the plant, forming a mulch that helps hold water near the plant. Herbaceous leaves of dicotyledon species larger than 1 cm long usually last only one season, are killed in the winter, and seen as ghosts of themselves lying on the tundra early in the following spring.

Many Arctic plants develop flowering stalks with the buds close to the tundra. Only when the flowers are ready to open, do the flowering stems become erect. This is striking in many grasses. Species that flower early in the season very often have buds with the outer surface of the sepals covered in dark hairs that appear to trap heat and assist the flowering process. The petals of Arctic plants may appear delicate, but many can be intact after snowfall and when the snow melts. The petals of Arctic poppies (Papaver species) and Dryas species are shaped like a satellite dish. They are heliotropic, that is, they point toward the direction of the sun as it moves across the sky in the 24 h daylight and, in doing so, focus the warmth toward the sexual center of the flower.

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