Salix petrophila

Rydberg

Bull. New York Bot. Gard. 1: 268. 1899.

Common names: Rocky Mountain willow
IllustratedEndemic
Basionyms: Salix arctica var. petraea Andersson in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 16(2): 287. 1868,
Synonyms: Salix arctica subsp. petraea (Andersson) Á. Löve, D. Löve & B. M. Kapoor Salix arctica var. petrophila (Rydberg) Kelso Salix petrophila var. caespitosa (Kennedy) C. K. Schneider
Treatment appears in FNA Volume 7. Treatment on page 81. Mentioned on page 63, 82.

Plants 0.02–0.1 m, forming clones by layering. Stems decumbent or trailing; branches yellowbrown, gray-brown, or redbrown, (often weakly glaucous, dull or slightly glossy), glabrous; branchlets yellow-green or yellowbrown, usually glabrous, sometimes pilose to glabrescent. Leaves: stipules absent or rudimentary; petiole 2–13 mm (longer than subtended bud); largest medial blade usually amphistomatous, very narrowly to broadly elliptic, oblanceolate, or obovate, 19–44 × 7–21 mm, 1.5–4.6 times as long as wide, base cuneate or convex, margins flat, entire, apex acute, acuminate, convex, or rounded, abaxial surface pilose to glabrescent, hairs wavy, adaxial dull or slightly glossy, pilose or sparsely villous to glabrescent; proximal blade margins entire; juvenile blade villous or pilose abaxially, mainly on margin. Catkins: staminate (ca. 50 flowers), 18–32 × 6–13 mm, flowering branchlet 3–13 mm; pistillate moderately densely to loosely flowered, (18–80 flowers), slender or stout, 18–59 (–70 in fruit) × 6–15 mm, flowering branchlet 2–40 mm; floral bract tawny or brown, 0.5–3.6 mm, apex acute or rounded, entire or 2-fid, abaxially hairy or ciliate, hairs straight or wavy. Staminate flowers: abaxial nectary 0–0.2 mm, adaxial nectary oblong, narrowly oblong, or square, 0.4–1.2 mm, nectaries distinct; filaments distinct or connate less than 1/2 their lengths; anthers ellipsoid, short-cylindric, or globose, 0.4–0.8 mm. Pistillate flowers: adaxial nectary oblong, square, narrowly oblong, or ovate, 0.5–1.2 mm, equal to or longer than stipe; stipe 0.2–0.8 mm; ovary pyriform or obturbinate, sparsely to densely villous, beak gradually tapering to styles; ovules 6–12 per ovary; styles 0.4–1.6 mm; stigmas flat, abaxially non-papillate with rounded or pointed tip, or broadly to slenderly cylindrical, 0.28–0.36–0.6 mm. Capsules 3.6–5 mm. 2n = 76.


Phenology: Flowering Jul–Aug.
Habitat: Alpine snowbeds, meadows, talus slopes and open dry pool beds in spruce-fir forests
Elevation: 1700-4000 m

Distribution

V7 84-distribution-map.gif

Alta., B.C., Calif., Colo., Idaho, Mont., Nev., N.Mex., Oreg., Utah, Wash., Wyo.

Discussion

Salix petrophila is often included in S. arctica (G. W. Argus 1993), but southern cordilleran populations, extending as far north as southern British Columbia and Alberta, seem to be a distinct taxon (Argus 1997). The exact northern limit of this species still needs to be established, but in Alberta it does not seem to extend north of Waterton Lakes National Park, except for a population on springy slopes above Agness Lake, Banff National Park. Suitable alpine habitats between Waterton Lakes and Banff national parks, e.g., Mt. Armstrong, Tornado Mountain, and Crowsnest Pass, should be explored for S. arctica and S. petrophila.

Selected References

None.

Lower Taxa

None.

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

... more about "Salix petrophila"
0 cm0 mm <br />0 m <br /> (0.02 cm0.2 mm <br />2.0e-4 m <br />) +
pilose +  and glabrescent +
ovate +, oblong +  and square +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.12 cm1.2 mm <br />0.0012 m <br />) +
sparsely villous;glabrescent +
glossy +  and dull +
red turning yellow +
globose +, short-cylindric +  and ellipsoid +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.08 cm0.8 mm <br />8.0e-4 m <br />) +
ciliate +  and hairy +
2-fid (?) +, Entire (?) +, Rounded (?) +, Acute (?) +, Convex (?) +  and Acuminate (?) +
George W. Argus +
Rydberg +
convex +  and cuneate +
Salix arctica var. petraea +
tapering +
pilose +  and villous +
toothed +  and 2-fid +
persistent +
redbrown +, gray-brown +  and yellowbrown +
pilose +  and glabrescent +
subglobose +  and globose +
0.2 cm2 mm <br />0.002 m <br /> (4 cm40 mm <br />0.04 m <br />) +
0.36 cm3.6 mm <br />0.0036 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
flowered +, pistillate +  and staminate +
1.8 cm18 mm <br />0.018 m <br /> (5.9 cm59 mm <br />0.059 m <br />) +
pendulous +, spreading +  and erect +
stout +  and slender +
0.6 cm6 mm <br />0.006 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
Rocky Mountain willow +
Alta. +, B.C. +, Calif. +, Colo. +, Idaho +, Mont. +, Nev. +, N.Mex. +, Oreg. +, Utah +, Wash. +  and Wyo. +
1700-4000 m +
connate +  and distinct +
brown +  and tawny +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.36 cm3.6 mm <br />0.0036 m <br />) +
pistillate +  and staminate +
bisexual +  and unisexual +
spherical +
Alpine snowbeds, meadows, talus slopes and open dry pool beds in spruce-fir forests +
straight +
unbranched +  and spicate +
subterminal +  and axillary +
membranaceous +
1.9 cm19 mm <br />0.019 m <br /> (4.4 cm44 mm <br />0.044 m <br />) +
obovate +, oblanceolate +  and elliptic +
0.7 cm7 mm <br />0.007 m <br /> (2.1 cm21 mm <br />0.021 m <br />) +
arranged +  and alternate +
marcescent +
deciduous +
2-7[-10]-carpellate +
obturbinate +  and pyriform +
glandular-dotted +
flat;convex;flat;convex +
0.2 cm2 mm <br />0.002 m <br /> (1.3 cm13 mm <br />0.013 m <br />) +
Flowering Jul–Aug. +
Bull. New York Bot. Gard. +
overlapping +
distinct +
Illustrated +  and Endemic +
branched +, sympodial +, monopodial +  and branching +
trailing;decumbent +
non-papillate +
cylindrical +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.08 cm0.8 mm <br />8.0e-4 m <br />) +
caducous +  and persistent +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.16 cm1.6 mm <br />0.0016 m <br />) +
persistent +  and deciduous +
ferruginous +  and white +
Salix arctica subsp. petraea +, Salix arctica var. petrophila +  and Salix petrophila var. caespitosa +
Salix petrophila +
Salix sect. Diplodictyae +
species +
pointed +  and rounded +
sympodial +, branching +  and heterophyllous +