Sandbar Willow (LA Urban Forest Program)

Sandbar Willow

Salix exigua

Summary ⁶

Salix exigua (sandbar willow, narrowleaf willow, or coyote willow; syn. S. argophylla, S. hindsiana, S. interior, S. linearifolia, S. luteosericea, S. malacophylla, S. nevadensis, and S. parishiana) is a species of willow native to most of North America except for the southeast and far north, occurring from Alaska east to New Brunswick, and south to northern Mexico.

Alternative names ⁷

Sandbar willow, gray willow, narrow-leaved willow, dusky willow, pussywillow

Description ⁸

More info for the terms: adventitious, alliance, root crown, shrub, succession

This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g. [85,89,113,125,188]).

Narrowleaf willow is a native [49], winter-deciduous [23,49] shrub that grows up to 33 feet (10 m) tall [49,54,65,71,85,96,109,125,188]. More commonly, narrowleaf willow is 6.5 to 20 feet (2-6 m) tall [24,53,67,80] with many erect shoots [67]. Individual stems arise singly or a few together and form large colonies from spreading roots [71,113]. Lateral roots of narrowleaf willow produce root sprouts in profusion, often in long rows. These shoots elongate rapidly in spring [187]. Narrowleaf willow also resprouts from the root crown [49].

Individual stems often only live 10 years, though some may reach 20 years. Shoot length, leaf length, number of leaves per shoot, and mean internode length all decrease with age [192].

Narrowleaf willow is alternately described as "deep rooted" [37] and shallow rooted [24]. Roots are woody and spreading [49], forming an extensive root system, especially with the development of large clones [99].

Narrowleaf willow leaves are linear to linear-elliptic and acute at both ends [6,53,85,96,109,125]. Leaf size ranges from 0.8 to 6 inches (2-15 cm) long and 0.1 to 0.8 inch (3-20 mm) wide [6,6,24,53,65,67,85,113,155].

Narrowleaf willow produces flowers in catkins 0.6 to 4 inches (1.5-10 cm) long [49,54,65,67,109]. Catkins are first produced with or just after leaves, though flowering may occur in succession throughout the summer [24,113].

Narrowleaf willow is both drought resistant [118] and very tolerant of flooding; it can withstand flooding for periods of 2 or more growing seasons. "Very tolerant" species usually exhibit good adventitious or secondary root growth during periods of flooding [27,155,162,185]. The ability to generate new roots on the original root or submerged stem is important to willows. Elevated soil-water tables result in severely restricted root development and eventual death of the root system. However, adventitious rooting above the flooded soil is abundant in many species of willow and a new root system develops above the soil-water table [107], which likely contributes to narrowleaf willow's flood tolerance. A greenhouse study of rooted cuttings found that narrowleaf willow cuttings inundated with water for 152 days displayed 72% and 43% increases in shoot and root elongation, respectively [4]. Another greenhouse study found gradual declines in the water table (0.4 to 0.8 inch (1-2 cm)/day) promote root elongation and shoot growth of narrowleaf willow compared to a constant water table, while abrupt declines in water table (>0.8 inch/day) reduce growth and survival [5]. In Texas, narrowleaf willow forms a woodland alliance that is flooded throughout most of the growing season. When flooding subsides, soils often remain relatively saturated [155].

Willows are very frost tolerant. Mature leaves and winter-dormant stems are capable of surviving temperatures of -4 oF (-20 oC) and -94 oF (-70 oC) respectively. However, frosts during the early growing season can cause severe damage to the fast-growing shoots. Temperatures <28 oF (-2 oC) will kill the elongation zone soon after exposure. Lateral buds below the damaged shoot rapidly form new shoots [107].

Fuentes y créditos

(c) Don Loarie, algunos derechos reservados (CC BY), http://www.flickr.com/photos/57556735@N08/7876017582
(c) Matt Lavin, algunos derechos reservados (CC BY-SA), http://www.flickr.com/photos/35478170@N08/5001878120
(c) Don Loarie, algunos derechos reservados (CC BY), http://www.flickr.com/photos/57556735@N08/7876023248
(c) icosahedron, algunos derechos reservados (CC BY), subido por icosahedron
(c) Bob Dodge, algunos derechos reservados (CC BY), subido por Bob Dodge
Adaptado por earthwatchtrees del trabajo de (c) Wikipedia, algunos derechos reservados (CC BY-SA), http://en.wikipedia.org/wiki/Salix_exigua
(c) USDA NRCS National Plant Data Center, New Mexico Plant Materials Center, & Idaho Plant Materials Center, algunos derechos reservados (CC BY-SA), http://eol.org/data_objects/1393813
Dominio Publico, http://eol.org/data_objects/24638976