Salix irrorata

Andersson

Öfvers. Kongl. Vetensk.-Akad. Förh. 15: 117. 1858.

Common names: Blue-stem or dewy-stemmed willow
Illustrated
Treatment appears in FNA Volume 7. Treatment on page 155. Mentioned on page 95, 96, 98, 136, 153, 156.

Shrubs, 2–7 m, (multistemmed, sometimes forming clones by stem fragmentation). Stems: branches (highly brittle or not at base), redbrown to violet, usually glaucous, glabrous; branchlets yellowbrown, (strongly glaucous or not), glabrous, sparsely velvety, or tomentose. Leaves: stipules absent or rudimentary on early ones, foliaceous or rudimentary on late ones, apex acute; petiole convex to flat adaxially, 4–14 mm, velvety adaxially; largest medial blade lorate, narrowly oblong, narrowly elliptic, or narrowly oblanceolate, 47–115 × 8–22 mm, 3.5–7.7 times as long as wide, base cuneate or convex, margins flat to slightly revolute, entire and gland-dotted, serrulate or crenate, apex acuminate, acute, or convex, abaxial surface glaucous, glabrous, sparsely tomentose, or short-silky, hairs wavy, adaxial slightly to highly glossy, glabrous or pilose; proximal blade margins entire or serrulate; juvenile blade yellowish green or reddish, glabrous or sparsely villous abaxially, hairs white. Catkins flowering before or just before leaves emerge; staminate stout or subglobose, 15–34 × 8–22 mm, flowering branchlet 0 (–2) mm; pistillate densely flowered, stout or slender, 14–43 × 7–12 mm, flowering branchlet 0–4 mm; floral bract brown or black, 1.3–2.5 mm, apex rounded, abaxially hairy, hairs straight or wavy. Staminate flowers: adaxial nectary narrowly oblong to oblong, 0.3–0.8 mm; filaments connate less than to more than 1/2 their lengths; anthers yellow or purple turning yellow, ellipsoid or shortly cylindrical, 0.4–0.7 mm. Pistillate flowers: adaxial nectary narrowly oblong to oblong, 0.3–0.7 mm; stipe 0.4–1 mm; ovary pyriform, beak slightly bulged below styles; ovules 9–12 per ovary; styles 0.3–0.9 mm; stigmas flat, abaxially non-papillate with rounded tip, 0.15–0.28–0.6 mm. Capsules 3.5–4 mm. 2n = 38.


Phenology: Flowering mid Mar-mid May.
Habitat: Streams, wet meadows
Elevation: 1400-3000 m

Distribution

V7 179-distribution-map.gif

Ariz., Colo., N.Mex., Wyo., Mexico (Baja California), Mexico (Chihuahua), Mexico (Coahuila), Mexico (Durango), Mexico (Sonora)

Discussion

Salix irrorata is very closely related to S. lasiolepis. The two are here maintained as separate species primarily because S. irrorata is a diploid and S. lasiolepis a tetraploid, and also because of their largely allopatric ranges (G. W. Argus 2007). Studies of sawflies (Euura Newman) by P. W. Price (pers. comm.) show that the same species of Euura can successfully reproduce on either willow. The only morphological character that separates the two is that in S. irrorata branchlets and branches are very strongly glaucous, whereas in S. lasiolepis they are not glaucous. Some plants have weakly glaucous stems (wax not visible except by polishing or only as sparkling crystals); this may be infraspecific variability or evidence of hybridization.

Hybrids:

Salix irrorata forms natural hybrids with S. drummondiana, S. geyeriana, and S. lasiolepis var. lasiolepis.

Salix irrorata × S. lasiolepis var. lasiolepis: This putative hybrid occurs in Arizona and New Mexico. It is characterized mainly by weakly glaucous branches.

Selected References

None.

Lower Taxa

None.

"-0.6mm" is not declared as a valid unit of measurement for this property.

... more about "Salix irrorata"
21 +, 4 +, 1 +, 16 +  and 29 +
short-silky +, tomentose +, glabrous +  and glaucous +
narrowly oblong +  and oblong +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.07 cm0.7 mm <br />7.0e-4 m <br />) +
purple turning yellow +  and yellow +
cylindrical +  and ellipsoid +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.07 cm0.7 mm <br />7.0e-4 m <br />) +
Rounded (?) +, Convex (?) +, Acute (?) +  and Acuminate (?) +
George W. Argus +
Andersson +
convex +  and cuneate +
Salix sect. Vetrix +
tapering +
reddish +  and yellowish green +
ferruginous +  and white +
serrulate +  and entire +
villous +  and glabrous +
toothed +  and 2-fid +
persistent +
flowered +  and pistillate +
0 cm0 mm <br />0 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
tomentose +, velvety +  and glabrous +
subglobose +
slender +  and stout +
0 cm0 mm <br />0 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
intermediate +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
pendulous +, spreading +  and erect +
Blue-stem or dewy-stemmed willow +
Ariz. +, Colo. +, N.Mex. +, Wyo. +, Mexico (Baja California) +, Mexico (Chihuahua) +, Mexico (Coahuila) +, Mexico (Durango) +  and Mexico (Sonora) +
1400-3000 m +
black +  and brown +
0.13 cm1.3 mm <br />0.0013 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
pistillate +  and staminate +
bisexual +  and unisexual +
Streams, wet meadows +
straight +
unbranched +  and spicate +
subterminal +  and axillary +
membranaceous +
hemiamphistomatous +, amphistomatous +  and hypostomatous +
4.7 cm47 mm <br />0.047 m <br /> (11.5 cm115 mm <br />0.115 m <br />) +
oblanceolate +, elliptic +, oblong +  and lorate +
0.8 cm8 mm <br />0.008 m <br /> (2.2 cm22 mm <br />0.022 m <br />) +
arranged +  and alternate +
marcescent +
deciduous +
gland-dotted +
crenate +, serrulate +, flat +  and slightly revolute +
rudimentary +
2-7[-10]-carpellate +
pyriform +
glandular-dotted +
convex;flat +
0.4 cm4 mm <br />0.004 m <br /> (1.4 cm14 mm <br />0.014 m <br />) +
Flowering mid Mar-mid May. +
Öfvers. Kongl. Vetensk.-Akad. Förh. +
overlapping +
distinct +
Illustrated +
redbrown +  and violet +
decumbent;erect +
non-papillate +
cylindrical +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
caducous +  and persistent +
distinct +  and connate +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.09 cm0.9 mm <br />9.0e-4 m <br />) +
persistent +  and deciduous +
Salix irrorata +
Salix sect. Mexicanae +
species +
rounded +
sympodial +, branching +  and heterophyllous +