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Willow Tree Adaptations

Famous for their wide canopies and ornamental beauty, willow trees have been planted across Asia, Europe and North America beside lakes and streams. Although the casual willow fancier may only be familiar with the weeping willow, willow trees come in many varieties. The species is highly adaptable, and new subspecies appear to suit each new environment.

Weeping Willow
- Weeping willows are planted as ornaments by water.
  
  The best-known type of willow tree is the weeping willow, with its long, trailing branches forming an umbrella-like canopy dropping almost all the way to the ground. Native to China, it grows best on river banks and other wet places, and it has adapted to grow wide, shallow root networks that spread densely over a large area. Weeping willow roots can grow over land or in shallow water. The tree can grow in alkaline soil or acidic, clay, loam or even sand.
Corkscrew Willow
- The corkscrew willow, also known as the Pekin or Hankow willow, can also grow in many different kinds of soil. Like the weeping willow, it has adapted for watery habitats, and it grows best in damp earth. It grows quickly and reaches about 30 feet in height before it cracks under its own fragility and dies. To sustain its relatively brief life cycle, the corkscrew willow's roots grow aggressively, branching out through damp topsoil like those of the weeping willow.
Arctic Willow
- The arctic willow has adapted to the frozen tundra.
  
  Like other willow trees, the arctic willow grows a wide, shallow network of roots. However, this willow does so because the ground below the topsoil is frozen in its habitat, the North American tundra. The plant grows across the soil rather than vertically, staying near the ground that has been warmed by the sun. It has adapted to be poisonous to insects during its growing season, and it has hairs on its leaves to keep them warm and to trap moisture.
White Willow
- White willow leaves are white because of a layer of fine hairs.
  
  White willows have evolved fine white hairs on their leaves to increase their surface area, thereby catching more light for photosynthesis. Like all willows, it is able to adjust to a variety of pH levels in the soil, but it needs a lot of water and sunlight. The white willow can hybridize, meaning that two species can mix and create a new species. This trait allows the tree to quickly adapt to changes in its environment. All willows can hybridize, which is why there are so many subspecies of willow tree. In fact, there are 300 subspecies of the white willow alone.

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