Salix humilis Marsh.

prairie willow

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New England Distribution

Adapted from BONAP data

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North America Distribution

Adapted from BONAP data

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Facts About

The leaves of prairie willow have white and reddish hairs on the top surface (giving them a gray-green appearance) and white hairs on the undersurface. These hairs may help protect leaves from desiccation and solar heat, making this species more tolerant of drought than other willows. Short-tongued bees and flies visit the silky flowers for nectar. Caterpillars of many moths and butterflies, including the Striped Hairstreak (Satyrium liparops) eat the foliage. Many willows (Salix species) have bitter-tasting bark that contains derivatives of salicylic acid, the main compound in aspirin.

Habitat

Anthropogenic (man-made or disturbed habitats), forest edges, grassland, meadows and fields

Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Growth form
the plant is a shrub (i.e., a woody plant with several stems growing from the base)
Leaf type
the leaf blade is simple (i.e., lobed or unlobed but not separated into leaflets)
Leaves per node
there is one leaf per node along the stem
Leaf blade edges
  • the edge of the leaf blade has no teeth or lobes
  • the edge of the leaf blade has teeth
Leaf duration
the leaves drop off in winter (or they wither but persist on the plant)
armature on plant
the plant does not have spines, prickles, or thorns
Leaf blade length
30–100 mm
Leaf blade width
10–25 mm
Leaf stalk
the leaves have leaf stalks
Fruit type (general)
the fruit is dry and splits open when ripe
Bark texture
the bark of an adult plant is thin and smooth
Twig winter color
  • brown
  • green
  • red
  • yellow
Bud scale number
there is one scale on the winter bud, and it covers the scale like a cap
Show All Characteristics
  • Buds or leaf scars
    Bud scale number
    there is one scale on the winter bud, and it covers the scale like a cap
    Bud scar shape (Fraxinus)
    NA
    Collateral buds
    there are no collateral buds on the sides of the branches
    Leaf scar arrangement
    there is one leaf scar per node on the stem or twig
    Superposed buds
    there are no superposed buds on the branch
    Winter bud scales
    the winter bud is perulate (partially or completely covered with one or more scales)
    Winter bud stalks
    the winter buds have no stalks
  • Flowers
    Anther color
    there is a noticeable pink, reddish or purplish tint to the anthers
    Carpels fused
    the carpels are fused to one another
    Enlarged sterile flowers
    there are no enlarged sterile flowers on the plant
    Flower petal color
    NA
    Flower symmetry
    there is only one way to evenly divide the flower (the flower is bilaterally symmetrical)
    Hairs on ovary (Amelanchier)
    NA
    Hypanthium present
    the flower does not have a hypanthium
    Inflorescence position
    the inflorescences grow on the twigs
    Inflorescence type
    the inflorescence is an ament (catkin; slender, usually pendulous inflorescence with crowded unisexual flowers)
    Number of pistils
    1
    Ovary position
    the ovary is above the point of petal and/or sepal attachment
    Petal and sepal arrangement
    the flower lacks sepals and petals
    Petal appearance
    NA
    Petal fusion
    NA
    Sepal appearance
    NA
    Sepal cilia (Ilex)
    NA
    Sepal tip glands
    NA
    Sepals fused only to sepals
    NA
    Stamen number
    1 or 2
    Stamen position relative to petals
    NA
    Stamens fused
    the stamens are not fused to one another
  • Fruits or seeds
    Berry color
    NA
    Fruit type (general)
    the fruit is dry and splits open when ripe
    Fruit type (specific)
    the fruit is a capsule (splits along two or more seams, apical teeth or pores when dry, to release two or more seeds)
    Nut with spines (Fagaceae)
    NA
    Wings on fruit
    there are no wings on the fruit
  • Glands or sap
    Sap color
    the sap is clear and watery
    Stalked glands on fruit (Rosa)
    NA
  • Growth form
    Growth form
    the plant is a shrub (i.e., a woody plant with several stems growing from the base)
  • Leaves
    Hairs on underside of leaf blade
    • the underside of the leaf has hairs on it
    • the underside of the leaf has no hairs
    Hairs on upper side of leaf blade
    • the upper side of the leaf is fuzzy or hairy
    • the upper side of the leaf is not hairy, or has very few hairs
    Leaf blade base shape
    the base of the leaf blade is cuneate (wedge-shaped, tapers to the base with relatively straight, converging edges), or narrow
    Leaf blade base symmetry
    the leaf blade base is symmetrical
    Leaf blade bloom
    the underside of the leaf has no noticeable bloom
    Leaf blade edges
    • the edge of the leaf blade has no teeth or lobes
    • the edge of the leaf blade has teeth
    Leaf blade edges (Acer)
    NA
    Leaf blade flatness
    the edges of the leaf are curled under
    Leaf blade hairs
    • at least some of the hairs on the leaf blade are reddish-brown, and they do not have glands
    • the leaf blade has tangled or woolly-looking hairs, without glands
    Leaf blade length
    30–100 mm
    Leaf blade scales
    there are no scales on the leaf blades
    Leaf blade shape
    • the leaf blade is elliptic (widest near the middle and tapering at both ends)
    • the leaf blade is oblanceolate (lance-shaped, but with the widest point above the middle of the leaf blade)
    • the leaf blade is oblong (rectangular but with rounded ends)
    • the leaf blade is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
    Leaf blade texture
    • the leaf blade is coriaceous (has a firm, leathery texture)
    • the leaf blade is herbaceous (has a leafy texture)
    Leaf blade translucent dots
    there are no translucent dots on the leaf blade
    Leaf blade vein pattern
    the main veins of the leaf blade are pinnate (the secondary veins branch off at intervals from the main central vein) and non-arcuate (not arched towards the leaf tip)
    Leaf blade veins
    the leaf blade has one main vein running from the base toward the tip
    Leaf blade width
    10–25 mm
    Leaf duration
    the leaves drop off in winter (or they wither but persist on the plant)
    Leaf form
    the plant is broad-leaved (with broadly flattened leaf blades)
    Leaf lobe tips (Quercus)
    NA
    Leaf midrib glands
    the midrib of the leaf blade lacks glands on the upper surface
    Leaf stalk
    the leaves have leaf stalks
    Leaf stalk attachment to leaf
    the petiole attaches at the basal margin of the leaf blade
    Leaf stalk nectaries
    there are no nectaries on the leaf stalk
    Leaf stalk shape
    the leaf stalk is not flattened
    Leaf teeth
    • the edge of the leaf blade is entire (has no teeth or lobes)
    • the leaf blade margin has teeth, which themselves have smaller teeth on them
    • the leaf blade margin is serrate (with forward-pointing) or dentate (with outward-pointing) with medium-sized to coarse teeth
    • the leaf blade margin is serrulate (with forward-pointing) or denticulate (with outward-pointing) with tiny teeth
    Leaf teeth hairs (Carya)
    NA
    Leaf type
    the leaf blade is simple (i.e., lobed or unlobed but not separated into leaflets)
    Leaves per node
    there is one leaf per node along the stem
    Specific leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets
    Stipules
    • the plant has stipules
    • there are no stipules on the plant, or they fall off as the leaf expands
  • Place
    Habitat
    terrestrial
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • edges of forests
    • grasslands
    • man-made or disturbed habitats
    • meadows or fields
  • Scent
    Plant odor
    the plant does not have much of an odor, or it has an unpleasant or repellant odor
  • Stem, shoot, branch
    Aerial roots
    the plant has no aerial roots
    Bark texture
    the bark of an adult plant is thin and smooth
    Branch brittleness (willows only)
    the branches are flexible, and do not break easily
    Branch cross-section
    the branch is circular in cross-section, or it has five or more sides, so that there are no sharp angles
    First-year cane (Rubus)
    NA
    Lenticels on twigs
    there are no lenticels on the twigs, or they are very hard to see
    Pith shape
    the outline of the pith in a twig is roughly round
    Pith type
    the pith inside the twig is solid, completely filled with spongy tissue
    Short shoots
    there are no peg- or knob-like shoots present
    Twig bloom
    there is no bloom on the twig
    Twig hairs
    the twigs have hairs, but the hairs do not have glands
    Twig papillae (Vaccinium species only)
    NA
    Twig scales
    there are no scales on the twig surface
    Twig winter color
    • brown
    • green
    • red
    • yellow
    Wings on branch
    the branch does not have wings on it
    armature on plant
    the plant does not have spines, prickles, or thorns

Wetland Status

Usually occurs in non-wetlands, but occasionally in wetlands. (Wetland indicator code: FACU)

New England Distribution and Conservation Status

Distribution

Connecticut
present
Maine
present
Massachusetts
present
New Hampshire
present
Rhode Island
present
Vermont
present

Conservation Status

Exact status definitions can vary from state to state. For details, please check with your state.

Maine
unranked (S-rank: SNR)
Massachusetts
unranked (S-rank: SNR)

var. humilis

Massachusetts
unranked (S-rank: SNR)

var. tristis

Massachusetts
unranked (S-rank: SNR)

Native to North America?

Yes

Sometimes Confused With

Salix bebbiana:
leaf blades 1.7-3.9 times as long as wide (mean=2.8), never with red-brown hairs, and floral bracts tan to red at the apex (vs. S. humilis, with leaf blades 2.3-7.5 times as long as wide (mean=4), sometimes with red-brown hairs intermixed with the gray ones, and floral bracts dark at the apex).
Salix discolor:
leaf blades thinner, sparsely hairy to lacking hairs on the lower surface and fruiting catkins usually 40-108 mm long (vs. S. humilis, with leaf blades thicker, moderately to densely hairy on the lower surface and fruiting catkins usually 15-32 mm long).
Salix occidentalis:
leaf blades 2-5 × 0.7-1.2 cm, borne on leaf stalks 0.5-3 mm long, and fruiting catkins 10-18 mm long (vs. S. humilis, with leaf blades 3-10 × 1-2.5 cm, borne on leaf stalks 3-7 mm long, and fruiting catkins mostly 15-47 mm long).

Synonyms

  • Salix conifera Muhl.
  • Salix humilis var. angustifolia (Barratt) Anderss.
  • Salix muehlenbergiana Willd. var. angustifolia Barratt
  • Salix tristis Ait. var. glabrata (Anderss.) Anderss.

Family

Salicaceae

Genus

Salix

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Information from Dichotomous Key of Flora Novae Angliae

15.  Salix humilis Marsh. N

prairie willow. Salix conifera Muhl.; S. humilis Marsh. var. angustifolia (Barratt) Anderss.; 
 S. muehlenbergiana Willd. var. angustifolia Barratt; S. tristis Ait. var. glabrata (Anderss.) Anderss. • CT, MA, ME, NH, RI, VT; nearly throughout. Fields, roadsides, forest borders, sand plains, woodlands, often in well-drained soils. Salix humilis can be confused with S. cinerea ssp. oleifolia, especially when the ridges on decorticated branches are longer than usual (as does occasionally occur on New England material). The two taxa can be separated on the basis of plant height, leaf blade outline, stipules, anther color, and ovary pubescence. Salix humilis is 0.3–3 m tall, with leaf blades 2.3–7.5 times as long as wide, lacking or with rudimentary stipules on the first leaves (i.e., those that expand from the winter bud), has purple anthers that turn yellow in age, and has wavy or crimped hairs on the ovary. Salix cinerea ssp. oleifolia is 2–12 m tall, with leaf blades 1.8–4.3 times as long as wide, with foliaceous stipules on the first leaves, has yellow anthers, and ± straight hairs on the ovary.

10×15. Salix discolor × Salix humilis Salix ×‌conifera Wangenh. is an uncommon willow hybrid known from MA, ME, NH, RI, VT. It mostly closely resembles S. humilis in the thicker, reticulate-veiny, and abaxially tomentose leaf blades and pubescent branchlets but has more elongate carpellate aments, longer styles, and longer petioles that are intermediate between the parental species (27–55 mm long, 0.3–0.5 mm long, and 5–16 mm long, respectively, in the hybrid vs. 8–32 mm long, 0.2–0.4 mm long, and mostly 3–7 mm, respectively, in S. humilis).