This shrub is 2-8' tall, often branching near the base and toward the
tips of older stems. Woody stems are terete and variably colored –
usually some shade of yellowish tan, brown, or gray. Young woody stems
are often short-pubescent, but they become glabrous with age. New
shoots are light green and short-pubescent. Alternate leaves occur
along young stems and shoots. The leaf blades are 1¾-4" long and ¼-¾"
across; they are narrowly lanceolate, oblanceolate, or oblong-elliptic in
shape and smooth to slightly crenate along their margins. The margins
are often revolute (curved downward) as well. The upper surface of the
leaf blades is medium green or grayish green and glabrous to sparsely
short-pubescent, while the lower surface (for this variety of Prairie
Willow) is short-pubescent and sometimes whitened. The petioles are
¼-½" in length and short-pubescent. At the base of the petioles,
lanceolate stipules are sometimes found.
Because Prairie Willow is
dioecious, different shrubs will develop either all male (staminate)
catkins or all female (pistillate) catkins from the bud scales along
twigs of the preceding year. Male catkins are ¼-¾" in length, becoming
longer as they mature. They are covered with silvery hairs at first,
but later become yellowish or reddish from the anthers of numerous florets. Each
male floret consists of a pair of stamens and a hairy bract. Female
catkins are ½-3" in length, becoming longer as they mature. Each female
catkin has several greenish female florets along its length. A female
floret consists of a greenish ovary about 4-8 mm. in length and a
hairy bract. The ovary is narrowly lanceoloid in shape with an
elongated beak; it is also short-pubescent with a pair of stigmata at
its apex. The male and female florets have neither petals nor sepals.
The blooming period occurs from early to mid-spring for about 1 week.
Afterwards, the female florets develop into seed capsules that become
light brown at maturity, when they split open to release tiny seeds
that are embedded in cottony hairs. These seeds are dispersed by the
wind. The root system is woody and branching. This shrub reproduces by
The preference is full or partial
sun, moist to dry-mesic conditions, and soil that is loamy, gravelly,
or sandy. New plants can be started by inserting cut-stems into the
ground during the spring, where they will form roots. Prairie Willow is
more tolerant of dry conditions than many other species in the genus.
It is relatively slow-growing for a willow, usually remaining less than 4'
tall, although sometimes Prairie Willow becomes larger when conditions
The native Prairie Willow
occurs occasionally throughout Illinois; it has been observed in most
counties. This variety of Prairie Willow is far more common than other
varieties within the state. Habitats consist of black soil
prairies, sand prairies, sandy shrub prairies, prairie remnants along
railroads, sandy and non-sandy savannas, sandy thickets, barren rocky areas along bluffs, and gravelly seeps. This
unusual willow can found in either moist lowland or drier upland areas.
The catkins of Prairie Willow attract
bees and flies, including Cuckoo bees (Nomada spp.
Andrenid bees (Andrena
Syrphid flies, Calliphorid flies, Muscid flies, and others. Among the
Andrenid bees, the following species are specialist pollinators
(oligoleges) of willows (Salix spp.): Andrena bisalicis
, and Andrena
. These insects seek nectar and pollen
from the florets of the catkins. Many other insects feed on the
foliage, bore through the wood, or suck plant juices from willows. The
following leaf beetles have been observed to feed on Prairie Willow:
(American Willow Leaf Beetle), Chrysomela
(Cottonwood Leaf Beetle),
(Striped Willow Flea Beetle). The Prairie Willow is
also the preferred host plant for the leafhopper Empoasca humilis
Other insect feeders include the larvae of wood-boring beetles,
weevils, the larvae of gall flies, plant bugs, stink bugs, aphids, the
larvae of sawflies, and the
caterpillars of many moths.
Caterpillars of the butterflies Satyrium
and Limenitis archippus
(Viceroy) feed on the leaves of willows, as do
the caterpillars of the skipper Erynnis
Among vertebrate animals, such birds as the Ruffed Grouse and
White-Crowned Sparrow feed on the buds and catkins of willows. Other
birds, such as the Northern Harrier, Wilson's Warbler, Yellow
American Goldfinch, Gray Catbird, and Willow Flycatcher, often
their nests in willow thickets. The twigs and leaves are often browsed
by White-Tailed Deer and Elk.
A sandy shrub prairie at Kitty Todd Nature
Preserve in NW Ohio.
The typical variety of Prairie Willow (Salix humilis humilis
described here. Two less common varieties, Smooth Prairie Willow (Salix
) and Sage Willow (Salix humilis microphylla
occur in Illinois. Unlike the typical Prairie Willow, Smooth Prairie
Willow has leaves that are hairless (or nearly so) and its young shoots
and stems are also hairless or less hairy. The margins of Smooth
Prairie Willow's leaf blades are also less likely to be revolute
(curved downward), otherwise it is almost identical to the typical
variety and occupies similar habitats. The Sage Willow is quite
different from the preceding two varieties in that it is a smaller
shrub only 1-3' tall with smaller leaves (about ¾-2" long)
and smaller catkins. It is also usually found in habitats that
more dry and barren than the preceding varieties. The Sage Willow has
been classified as a distinct willow species in the past (Salix
), but it is now regarded (rightly or wrongly) as a
Prairie Willow. In general, the rather variable Prairie Willow can be
distinguished from other willow species (Salix spp.
) by its
for drier habitats and small size, smooth to nearly smooth margins that
lack conspicuous and abundant teeth, its pubescent shoots and leaf
undersides (with the exception of var.
), and lanceolate