Salicaceae (Willow Family)

Dioecious (unisexual) trees or shrubs.
Leaves deciduous (falling), alternate, simple (not compound), stipulate (leaf appendages).
Flowers born in male or female catkins.
Each flower subtended by a tiny bract (leaf like structure).
Stamens (male parts) 1 to many.
Stigmas (femlae parts) 2-4 often 2-lobed, ovaries solitary.
Fruit a dihiscent (spliting open) capsule (dry fruit) containing numerous small seeds each with a tuft of long silky down.

Natural History:

The genus Salix (Willow) is a very taxonomicaly difficult group. Experts have a difficult time deciding exactly what is a species, and amateurs have a hard time getting to know them.
Plants rely on wind for both pollination and seed dispersal.

Family Size:

World:

Genera: 2-3

Species: 350-500

North America:

Genera: 2

Species:

Yukon:

Genera: 2

Species: 36

Salicaceae Genera

Populus (Poplar)

Trees.
Buds often resinous, covered with several scales.
Flowers in drooping catkins. Appearing in early spring and maturing as leaves expand.
Male flowers with several to many stamens on a broad disk.
Female flowers with 2-4 stigmas.

World= 40 sps.

N.A.= ? sps.

Yukon= 2 sps.

Salix (Willow)

Decumbent shrubs, to erect shrubs, to small trees.
Flowers in erect catkins. Expanding before or with (rarely after) the leaves.
Male flowers with 2-8 stamens.
Female flowers with 2 entire or divided stigmas.
A taxonomicaly difficult genus. Species names are often changing. Subspecies elevated to species or vice versa.

World= 300+ sps.

N.A.= ? sps.

Yukon= 34 sps.

Central Yukon= 23 sps.

Salix alaxensis (Alaskan Willow)

Salix lanata (Woolly Willow)

Salix pulchra (Flat-leaved Willow)

Salix reticulata (Net-veined Willow)

Illustrated Key To Salicaceae Species

Note: Move cursor over image for note on what to look for. Click on image to enlarge.

Populus balsamifera (balsam poplar)

Populus tremuloides (trembling aspen)

Decumbent (trailing) Shrub Willows: (generally less than 30cm tall)

Salix arctica (arctic willow)

Salix Phlebophylla (skeleton willow)

Salix polaris (snow-bed willow)

Salix reticulata (net-viened willow)

Salix rotundifolia (mountain roundleaf willow)

Salix myrtillifolia (myrtle-leaved willow)

Shrub Willows: (generally between 30cm to 2m tall)

Salix barrattiana (barratt's willow)

Salix candida (hoary willow)

Salix brachycarpa (short capsuled willow)

Salix glauca (blue-green willow)

Salix hastata

Salix exigua (sandbar willow)

Salix pseudomyrsinites (tall blueberry willow)

Tall Shrub Willows: (generally more than 2m tall)

Salix lanata (richardson's/woolly willow)

Salix pseudomonticola (false mountain willow)

Salix planifolia (plane leaved willow)

Salix pulchra (flat-leaved willow)

Salix scouleriana (scouler's willow)

Salix alaxensis (alaskan willow)

Salix barclayi (barclay's willow)

Salix lucida (western shining willow)

Salix arbusculoides (little tree willow)

Salix bebbiana (bebb's willow)

Dicotomous Key To Salicaceae Species

A: Trees; Flowers in drooping catkins: Populus (Poplar)

B: Leaves wide lanceolate; Petioles (leaf stem) round, will roll between fingers: Populus balsamifera (Balsam Poplar)
B: Leaves Orbicular with pointed tip; Petioles flatened, will not roll between fingers: Populus tremuloides (Trembling Aspen)

A: Small trees to dwarf shrubs; Flowers in erect catkins: Salix (Willow)

C: Decumbent shrubs less than 20cm high:

D: Pistils (female parts) pubescent (hairy):

E: Leaves underside glaucous:

F: Leaf venation (viens) very obvious and distinclty net like: Salix reticulata
F: Leaf venation not obvious nor distinctly net like: Salix arctica

E: Leaves underside not glaucous:

G: Leaves persistent (not falling off) becoming skeletonized: Salix phlebophylla
G: Leaves not persistent nor becoming skeletonized: Salix polaris

D: Pistils glabrous (not hairy):

H: Forest habitat; Leaf margins crenate-dentate (toothed): Salix myrtillifolia
H: Arctic habitat; Leaf margins mostly entire (not toothed): Salix rotundifolia

C: Erect shrubs more than 20 cm high to small trees:

I: Catkins expanding before leaves:

J: Pistils glabrous (not hairy):

K: Stipules persistent for many years; Branchlets densely pubescent: Salix lanata
K: Stipules not persistent; Branchlets glabrous: Salix pseudomonticola

J: Pistils pubescent (hairy):

L: Leaf underside glaucous (waxy coat):

M: Leaves pubescent: Salix barrattiana
M: Leaves mostly not pubescent:

N: Stipules narrow and long; Leaves and stipules persistent: Salix pulchra
N: Stipules tiny; Leaves and stipules not persistent: Salix planifolia

L: Leaf underside not glaucous:

O: Stipules linear and persistent: Salix alaxensis
O: Stipules minute or abscent: Salix scouleriana

I: Catkins expanding with or after leaves:

P: Pistils (female parts) glabrous (not hairy):

Q: Leaf underside not glaucous (no waxy coat):

R: Leaves 10 times longer than wide: Salix exigua
R: Leaves much less than 10 times wider than long:
- S: Plant low usually less than 0.6m; Styles 0.3-0.5mm long:Salix myrtillifolia
- S: Plant erect usually more than 0.6m; Styles 0.5-0.9mm long:Salix pseudomyrsinites

Q: Leaf underside glaucous (waxy coat):

T: leaf margins entire (not toothed): Salix hastata
T: Leaf margins serrate, serrulate, or crenate (toothed):

U: Petiole (leaf stem) with two small glands at base: Salix lucida
U: Petiole with stipules up the 1cm long: Salix barclayi

P: Pistils pubescent (hairy):

V: Leaf underside having silky soft hairs, not glaucous: Salix arbusculoides
V: Leaf underside glaucous:

W: Pistilate (female) catkins short, 2cm long or less: Salix brachycarpa
W: Pistilate catkins 3cm - 5cm long:

X: Pistilate catkins loosly flowered: Salix bebbiana
X: Pistilate catkins more densly flowered: Salix glauca

Charactaristics Chart Key To Salicaceae Species

Note: The following chart is adapted from Bruce Bennett (2010): Chart Key for Willows of Tombstone Park.

Note: Identifying the following 6 charactaristic for your specimen will help identify it to species or narrow it down to 2 or 3 choices.

Species	Stature	Catkin timing	Pistil Pubescence(hairs)	Leaf Underside Colour	Leaf Pubescence	Distinguishing Charactaristic
Salix arctica (arctic willow)	Decumbent	With leaves	Pubescent	Green	Sparse	Long many flowered catkins
Salix Phlebophylla (skeleton willow)	Decumbent	With leaves	Pubescent	Green	Glabrescent	With marcescent leaves becoming skeletonized
Salix polaris (snow-bed willow)	Decumbent	With leaves	Pubescent	Green	Glabrescent	Short fewer flowered catkins
Salix reticulata (net-viened willow)	Decumbent	With leaves	Pubescent	Glaucous	Both	Leaves round or oval with distinct net veination
Salix rotundifolia (mountain roundleaf willow)	Decumbent	With leaves	Glabrous	Green	Glabrescent	Leaves round or oval with marcescent leaves
Salix myrtillifolia (myrtle-leaved willow)	Decumbent-Shrub	With leaves	Glabrous	Green	Glabrescent	Decumbent or low shrub
Salix barrattiana (barratt's willow)	Shrub	Before leaves	Pubescent	Glaucous	Pubescent	Twigs and branches black and ragged from old stipules
Salix candida (hoary willow)	Shrub	Before leaves	Pubescent	Glaucous	Pubescent
Salix brachycarpa (short capsuled willow)	Shrub	With leaves	Pubescent	Glaucous	Glabrescent	Capsules short beaked, catkins loosely flowered
Salix glauca (grey-leaved willow)	Shrub	With leaves-After leaves	Pubescent	Glaucous	Pubescent	Branchlets pubescent to white villous
Salix hastata	Shrub	With leaves	Glabrous	Glaucous	Glabrescent	Thicket forming; rust coloured hairs on leaf midrib
Salix exigua (sandbar willow)	Shrub	With leaves	Glabrous	Green	Both	Leaves very narrow, 10x longer than wide
Salix pseudomyrsinites (tall blueberry willow)	Shrub	With leaves	Glabrous	Green	Glabrescent
Salix lanata (richardson's/woolly willow)	Shrub-Tall Shrub	Before leaves	Glabrous	Glaucous	Both	Branches ragged with old stipules
Salix pseudomonticola (false mountain willow)	Tall Shrub	Before leaves	Glabrous	Glaucous	Glabrescent	Branchlets yellow-green; leaves thin translucent when young
Salix planifolia (plane leaved willow)	Shrub-Tall Shrub	Before leaves	Pubescent	Glaucous	Glabrescent
Salix pulchra (flat-leaved willow)	Shrub-Tall Shrub	Before leaves	Pubescent	Glaucous	Sparse	With marcescent leaves and old stipules
Salix scouleriana (scouler's willow)	Tall Shrub	Before leaves	Pubescent	Green	Glabrescent	Leaves rust colour beneath
Salix alaxensis (alaskan willow)	Tall Shrub	Before leaves	Pubescent	Green	Pubescent	Twigs and branches copiously velvety tomentos
Salix barclayi (barclay's willow)	Shrub-Tall Shrub	With leaves	Glabrous	Glaucous	Both	Thicket forming; twigs yellow-green villous
Salix lucida (western shining willow)	Tall Shrub	With leaves	Glabrous	Glaucous	Both	2 small glands at base of leaves
Salix arbusculoides (little tree willow)	Tall Shrub	With leaves	Pubescent	Green	Pubescent	Twigs smooth, reddish; leaves long narrow
Salix bebbiana (bebb's willow)	Tall Shrub	With leaves	Pubescent	Glaucous	Both	Capsules long beaked; catkins loosely flowered

Salicaceae : Willow Family

Taxonomy | Illustrated Key | Dichotomous Key | Chart Key | Genera | Family Traits

Salicaceae Taxonomy

Scientific Name:

Salicaceae Traits

Description: