Willow
Willows are diverse trees and shrubs of the genus Salix.
They are typically deciduous trees and shrubs found on moist soils in cold and temperate regions, known for their watery bark sap rich in salicin, soft wood, and fibrous roots.
- type_species
- Salix alba
- habitat
- Moist soils in cold and temperate regions
- flowering
- Dioecious, with male and female catkins on separate plants
- leaf_out
- Among earliest woody plants to leaf out in spring
- oldest_fossils
- Early Eocene of North America
Lore & Background
Willows have been known since antiquity, with the generic name Salix used by the Romans and possibly derived from a Celtic language meaning 'near water'. Willows are classified into subgenera, though the exact divisions remain in flux; morphological studies suggest 3 or 5 subgenera, while phylogenetic studies indicate some should be combined. The oldest fossils are from the early Eocene of North America, with European occurrences from the Early Oligocene.
Reader's Guide
Willows are significant for their ecological roles and human uses. They provide early pollen for bees, are browsed by various animals, and are used by beavers for dam building. The plants reproduce both by tiny, wind- and water-dispersed seeds and vegetatively from stumps and branches. Willows are extensively cultivated for hedges, landscaping, and bioenergy, and are known for taking root readily from cuttings. However, some species have become invasive in Australia, where they are considered weeds of national significance. The bark and leaves have been mentioned in ancient texts from Assyria, Sumer, Egypt, and Ancient Greece for folk medicine. Willows also host numerous aphid species and are affected by rust fungi of the genus Melampsora.
Did You Know?
- The dwarf willow (Salix herbacea) rarely exceeds 6 cm in height.
- Willow leaves drop when day length shortens to about 10 hours and 25 minutes.
- Willows are among the earliest woody plants to leaf out in spring.
- The type species for the genus Salix is Salix alba.
Frequently Asked Questions
What are Willow's key traits?
Willows are recognized for their soft wood, fibrous root systems, and a watery bark sap that is rich in salicin. They are also among the earliest woody plants to push out new leaves each spring.
How does Willow reproduce?
The genus is dioecious, meaning each individual plant is either male or female and bears only one type of catkin. Successful seed set therefore depends on cross-pollination between separate plants.
Where does Willow grow?
Willows are native to moist soils in cold and temperate regions around the world. They are typically deciduous, shedding their foliage each autumn.
How far back does Willow's fossil record go?
The oldest willow fossils identified to date come from the Early Eocene of North America, making the genus one of the more ancient lineages in the temperate tree world.
More in Tree Species 1-15
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