Willow trees and shrubs are part of the Salix genus. There are around 400 species of willows worldwide typically found near wetlands and on banks of rivers, ponds and streams. Of these, about 100 are native to North America, including the largest and most common, the black willow (Salix nigra). Although weeping willows (Salix babylonica) are very common as ornamental trees, such as the ones gracing the Public Garden lagoon, they are not native, but introduced species originally from China.
It is not easy to differentiate and identify individual willow species, but as a group they share some characteristics: leaves that grow in alternate pattern along the branch and are narrow, lance-shaped with finely serrated margins; catkin flowers that grow as separate male and female structures; branches that are flexible, weak, and often drooping, and root systems that are strong and aggressive contributing to rapid growth and re-propagation. Willows can sometimes grow at a rate of up to 10 feet per year!
The benefits of willow trees are many. Willows are among the earliest woody plants to leaf out in spring – as early as March if daytime high temperatures reach 10 °C (50 °F) for a few consecutive days! This makes willow flowers an early source of nectar and pollen for bees and hummingbirds. Willow bark has been used for centuries as natural pain-relievers as it contains salicylic acid, which is a compound from which aspirin was derived. The roots are deep, fast-growing and fibrous which makes them exceptional at stabilizing slopes and preventing erosion. Also, willow roots and shoots absorb heavy metals from the soil and even release substances that stimulate microbes in the soil that in turn break down organic pollutants. This is known as phytoremediation. Finally, the flexible branches are used in basketweaving and other crafts. |
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Outdoor Journal Activities |
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Head outdoors and read the book Wonderfully Wild by Jessica Stremer. In teams, students can map their outdoor space and create plans for rewilding it.
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Find any tree with branches at eye height for your students. Observe the buds on the tips of branches: feel the bumps and note their shape, gently scratch the tender bark, notice color and any markings on the twig, gently bend the branch to observe its flexibility. Make observational drawings in a science journal. Then, tie a ribbon on the end of a branch right behind the terminal bud and watch how it develops throughout the spring and summer. Revisit this branch often to make new observations.
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If you have access to willows, there are numerous activities to explore such as using willow leaves and bark to make dyes, twisting flexible branches into sculptural pieces or creating leaf prints.
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It is easy to take a willow cutting, place it in water and watch the roots develop! You can often find fresh willow cuttings at Trader Joe’s or nurseries with which to experiment. Take it further to investigate this claim, “Broken branches of willow trees have been known to grow into new trees, irrespective of their position in the soil!” Help your students devise experiments to test this statement and monitor progress.
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Willow roots contain a high proportion of rooting hormones, which is what allows roots to develop so quickly and densely. Rooting hormones are often used to help cuttings of other species develop roots. Students can make willow water to use as a rooting hormone and test efficacy with rooting indoor plant cuttings. Once the willow water is created, students devise experiments to test this willow superpower. Don’t forget to set up a control.
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Watch this video that explains genetic mutations and how it accounts for the weeping habit of trees.
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Magnolias In Bloom: Music Inspired by Nature |
April 11
3-4pm
Hunnewell Lawn
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Cherry Blossom Celebration |
April 18
1-4pm
Bradley Rosaceous Collection
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