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

Salix prolixa Andersson
Mackenzie willow (MacKenzie's willow)
Salicaceae (Willow family)

Introduction to Vascular Plants

© Jamie Fenneman  Email the photographer   (Photo ID #17046)

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Distribution of Salix prolixa
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Species Information

Click on the image below to view an expanded illustration for this species.

Dioecious shrubs, 1-5 m tall, not colonial; branches erect, flexible at base; twigs yellow- to red-brown, smooth or moderately hairy.
Alternate, simple, lance- or egg-shaped to narrowly oblong, 5-15 cm long, 1-5.3 cm wide, lower surface glaucous, smooth, upper surface dull, smooth or sparsely long-hairy on midrib, margins toothed, bases rounded or heart-shaped, tips tapered; leaf stalks without glandular dots at top; stipules leaflike.
Unisexual, lacking sepals and petals, borne in catkins which flower as leaves emerge, the catkins stout, on leafy twigs; floral bracts dark, smooth or hairy, hairs wavy; stamens 2; ovaries 1, smooth; styles 0.3-1 mm long.
Capsules which split open to release the seeds, each of which is surrounded by a tuft of hairs; stalks 1.3-4.2 mm long.
The twigs of this species are usually smooth, but plants with spreading-hairy twigs, the basis of the name S. rigida var. macrogemma, are common on Vancouver Island and are scattered elsewhere. Plants with hairy twigs are sometimes difficult to distinguish from S. barclayi.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
Blooming Period:
Early Spring
Fruit/Seed characteristics:
Colour: Yellow
Present over the Summer
Source:  The USDA

Habitat / Range

Moist forest openings, sand and gravel riverbars in the lowland, steppe and montane zones; common throughout BC; N to SE AK, S YT and NT, E to AB and S to WY, UT, NV and CA.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Salix prolixa

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres) 50 937 1825
Slope Gradient (%) 0 2 24
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
0 322 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
2 6 8
Modal Nutrient Regime
Number of field plots
 species was recorded in:
Modal BEC Zone Class
All BEC Zones (# of stations/zone) species was recorded in: BG(6), BWBS(20), CWH(1), ESSF(7), ICH(15), IDF(34), MS(12), PP(3), SBPS(7), SBS(49), SWB(3)


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 cordata var. mackenzieana Hook.
Salix eriocephala subsp. mackenzieana (Hook.) Dorn
Salix eriocephala subsp. prolixa
Salix eriocephala var. mackenzieana (Hook.) Dorn
Salix mackenzieana (Hook.) Barratt ex Andersson
Salix mackenzieana var. macrogemma Ball
Salix rigida subsp. mackenzieana (Hook.) E. Murr.
Salix rigida var. mackenzieana (Hook.) Cronquist
Salix rigida var. macrogemma (C.R. Ball) Cronquist

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References