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Distribution of Salix exigua in the United States
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Malpighiales
Family: Salicaceae
Genus: Salix
Species: S. exigua
Background:
Salix exigua is a deciduous shrub or small tree that is commonly known as the narrow-leaf willow. Native to the United States, it is mostly found in the western part of North America from Mexico to British Columbia. The plant is a perennial, growing actively in the spring and summer months and reaching heights of up to 20 feet. It grows best along river beds and area that can accommodate its high water consumption. Salix is often used for erosion control in riparian habitats since it easily establishes in areas that are regularly flooded and is well adapted to sandy soils. The shrub grows at low to lower montane elevations of 0 to 5,500 feet.
Characteristics:
Salix has silvery-green foliage, and produces yellow flowers in the early spring that later form small white seeds. Branches have smooth reddish-brown bark with long thin alternate leaves that average 2-5 inches in length and are only ΒΌ inch wide. Leaves have serrated edges, with 1-5 teeth per centimeter and 2-7 millimeter petioles.
Reproduction:
The plant is dioecious, meaning that male and female flowers are produced on different plants. It produces both staminate (male) and pistillate (female) flowers. Upon maturation, seeds are dispersed by wind and can germinate within 12-24 hours under the right conditions. Salix spreads aggressively and will usually form dense thickets.