E-Flora BC: Electronic Atlas of the Flora of British Columbia

Salix petrophila Rydb.
Rocky Mountain willow (alpine willow)
Salicaceae (Willow family)

Introduction to Vascular Plants
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Distribution of Salix petrophila
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Species Information

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General:
Dwarf shrubs, 2-10 cm tall, layering; branches decumbent or trailing, flexible at base; twigs yellowish, smooth or sparsely hairy.
Leaves:
Alternate, simple, very narrowly elliptic to elliptic, lance- or egg-shaped, 2-4.4 cm long, 0.7-2 cm wide, lower surface glaucous, sparsely long soft-hairy to nearly smooth, hairs white, upper surface dull or shiny, long soft-hairy to nearly smooth, margins entire, bases and tips pointed to rounded; leaf stalks without glandular dots at top; stipules absent, rudimentary, or leaflike.
Flowers:
Unisexual, lacking sepals and petals, borne in catkins which flower as leaves emerge, the catkins stout, on leafy twigs; floral bracts tawny to light brown, hairs straight or wavy; stamens 2; ovaries 1, hairy; styles 0.4-1.6 mm long.
Fruits:
Capsules which split open to release the seeds, each of which is surrounded by a tuft of hairs; stalks 0.2-0.8 mm long.
Notes:
This species is often included in S. arctica but it seems to be sufficiently distinct to warrant specific rank. Its exact distribution in S BC is not yet known. It sometimes has its filaments and anthers flushed with purple. For a separation from S. arctica and S. cascadensis see Table 1, page 60.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Mesic rocky slopes in the subalpine and alpine zones; common in S BC; E to S AB and S to NY, PA, IN, IL, IA, NE, CO and WA.

Source: The Illustrated Flora of British Columbia

Climate

The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Synonyms and Alternate Names

Salix arctica subsp. petraea (Andersson) A. Löve & D. Löve & Kapoor
Salix arctica var. caespitosa (Kennedy) L. Kelso
Salix arctica var. graminifolia (E.H. Kelso) L. Kelso
Salix arctica var. petraea (Andersson) Bebb
Salix arctica var. petrophila (Rydb.) L. Kelso
Salix brownei var. petraea (Andersson) Bebb
Salix caespitosa Kennedy
Salix petrophila var. caespitosa (Kennedy) C.K. Schneid.

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References