Salal - Gaultheria shallon

Family: (Ericaceae - Heath Family) ^[E-flora]

Description

• General Creeping to erect.[IFBC]^[E-flora] "height very variable (0.2-5 m tall), with hairy, branches stems." ^[PCBC2004]
• Lifecycle Evergreen.^[PFAF] Perennial.^[WildPNW]
  
• Flowers The flowers are hermaphrodite (have both male and female organs) and are pollinated by Insects. ^[PFAF] "Inflorescences of 5-15 flowers...''[IFBC]^[E-flora] 7-10mm long.^[PCBC2004] White.[USDA]^[E-flora] Anthers awned.^[HNW]
  
• Fruits purplish-black at maturity. hairy, fleshy.[IFBC]^[E-flora] Seedy, 1/2 inch in diameter.^{[Derig WBOTW]}
  
• Leaves "Alternate, evergreen, thick, leathery, egg-shaped to egg-shaped-elliptic..."[IFBC]^[E-flora] "broadest at the base, and finely toothed." ^{[Derig WBOTW]} 3-10cm long and 2.5-5cm wide.^[HNW]
  
• Habitat Dry-wet forests & bogs. lowland and montane zones.[IFBC]^[E-flora] "Coniferous forests, rocky bluffs, to the seashore". ^[PCBC2004] It is quite tolerant of shade.^{[Tozer UWP]}
  
• Range Common in W BC, rare in SE B.C.[IFBC]^[E-flora] "Coastal Northwest from Alaska to California" ^{[Krumm PNBB]} Fully Naturalized in New Zealand ^{[NewZealandNaturalized]}
  
• Status Native. ^[E-flora]
  
• Ecological Indicator Shade-tolerant/intolerant. Occurs "...on nitrogen-poor soils; its occurrence decreases with increasing elevation and continentality." "Often dominant in open­canopy coniferous forests on water-shedding sites; forms thickets on cutover areas with relatively undisturbed forest floors. On nutrient-rich sites, restricted to decaying coniferous wood; on wet sites, on topographic prominences. Absent or sporadic in the shaded understory of immature, closed-canopy stands. Due to its extensive horizontal root system in the uppermost soil layer and decay-resistant foliage and roots, high cover of salal reduces available soil water and/ or decomposition of forest floor materials. These features hinder forest regeneration and growth, particularly on moisture-deficient sites." "...characteristic of Mor humus forms." (IPBC)^[E-flora]

Food

• Berries:
  • Wine made from salal. ^[Berries] Undoubtedly the most important traditional fruit of most Northwest Coast peoples. ^{[Turner, Kuhnlein]}
  • Historical: Used by Virtually all coastal peoples of British Columbia, southeastern Alaska, and Washington used them. ^{[Turner, Kuhnlein]}
  • Harvesting: The berries ripen in August, and often remain on the bushes into October. ^{[Turner, Kuhnlein]} "The fruit is produced over a period of several weeks in late summer[K]". ^[PFAF]
  • Preparation: "It makes good raw eating[K]. Fruit - raw, cooked or dried for later use[2, 3, 4, 183]. The fruit can also be made into preserves, pies, drinks etc[183]." ^[PFAF] Nowadays, people eat them fresh or make them into jam, jelly or syrup." ^[Haida] Cooking them with some lemon juice or a tart fruit improves the flavor. ^{[Seymour FNE]} "Dried salal berry cakes were prepared by soaking them in water overnight and kneading them in a bowl to mix them thoroughly." Then oil was poured over them. No water was drunk after a salal berry feast.^{[Turner,Bell2]}
  • Preservation: Can be readily cooked and dried in cakes, providing a year-round food source.^{[Turner, Kuhnlein]} Dried and used like raisins[183]. ^[PFAF] Boiled in large pots^[Haida] or traditionally, mashed and boiled with red hot rocks in bentwood cedar boxes.^{[Turner, Kuhnlein]} The cooked berries were then poured into rectangular wooden molds set on skunk-cabbage leaves and allowed to dry on racks over the fire into cakes. In winter these salal cakes were soaked in water, then eaten with grease.^[Haida] "usually reconstituted by soaking overnight...broken into small pieces, mixed with grease and eaten..."^{[Turner, Kuhnlein]}
  • Properties: Although they vary in taste and quality, they are usually sweet and juicy. ^{[Turner, Kuhnlein]} Sweet and juicy with a pleasant flavour [11, 95, 101]. ^[PFAF]
• Leaves:
  • The young leaves were chewed as a hunger suppressant. ^{[MPPW][Turner, Kuhnlein]}. A pleasant tea is made from the leaves[101]. ^[PFAF] Leaves toasted, pulverized, and applied to cuts.^{[Smith(1927)]}

Other Uses

• Cooking Tools:
  • The branches were widely used in pit cooking, to line the pit and intersperse between layers of food, and were also in stovetop kettle modifications of this cooking technique, and were cooked or smoked with fish and other foods as a flavoring. The branches were often used by Coastal peoples as soapberry whippers. ^{[Turner, Kuhnlein]}
• Dye:
  • A purple stain was made from the berries. It was intensified by adding Black Twinberry fruits. ^[PlantTech] "It is dark green[168]. A greenish yellow dye is obtained from the infused leaves.[257]" ^[PFAF]
• Floral Arrangements: "The plant is harvested for export and sold to florists worldwide for use in floral arrangements." ^[EMPofCan]

Medicinal Uses

• Berries: Dried salal berries were said to be a good blood conditioner and laxative.^{[Turner, Kuhnlein]} "Salal berries are incredibly high in flavonoids, and can be used as a free, nutritional therapy for strengthening capillaries in chronic skin and mucus membrane fragility; use a chunk twice a day."^[MPPW]
  • Harvesting: The "berries should be collected in early to mid-fall, when fully mature." ^[MPPW]
  • Preservation: The dried berries, whole or made into cakes, last until the next season." ^[MPPW]
• Leaves: "A poultice of the toasted, pulverized leaves has been applied to cuts[257]. A poultice of the chewed leaves has been applied to burns and sores[257]. The leaves have been chewed to dry the mouth[257]. An infusion of the leaves have been used as a stomach tonic and a treatment for diarrhoea, coughs, TB etc[257]." ^[PFAF]
  • Harvesting: "Although Salal is an evergreen, it is best to gather the young, reddish, zigzag branches from late spring to mid-fall. Bundle them and dry. "^[MPPW]
  • Preservation: "The leaves are good for several years." ^[MPPW]
  • Preparation: "The tea and the powdered herb are an effective astringent, hemostatic, and pain reliever when applied to scrapes, abrasions, burns, and insect bites. The herb isn't a major medicine, but it's common, comely, and effective against common problems in a commonsense fashion..." ^[MPPW] Bella Coola: Leaves toasted, pulverized by robbing, and applied to cuts.^{[Smith(1927)]}
  • Infusion: "A simple infusion of five or six crushed leaves is the easiest media for the medicine. "The leaf tea of salal was used as a stomach tonic for diarrhea, coughs and TB." "The tea is astringent and anti-inflammatory, both locally to the throat and upper intestinal mucosa, and, through the bloodstream, to the urinary tract, sinuses, and lungs. It is a safe, frequently repeatable tea for diarrhea, accompanied by heat, cramps, and moderate fever." Although there are stronger therapies, the tea helps scratchy, irritated coughs from allergies or dusty, dry air..." "For young children the tea is helpful for colic and gas pains resulting from subtle food hypersensitivities...". "...for adults with gastritis or a pre-ulcer stomach condition that causes distress two or three hours after meals..."."For bladder irritation, particularily in those types of cystitis that don't necessarily cause the urge to urinate but cause pain after urination, the tea is almost a specific." ^[MPPW]
  • Poultice: The powdered leaves can be applied topically as needed or mixed with water for a short-term poultice. ^[MPPW]

Ethnobotany

• Folk Use: Large leaves eaten by both newly wed husband and wife for a firstborn baby boy. ^[Moerman]
• Storage For Winter: "For drying, the berries were boiled and poured into half-inch thick wooden frames set on skunk cabbage leaves. The frames were rectangular and several feet long. When full they were placed on racks in the sun or over the fire to dry. The dried cakes were cut in short pieces and stored in boxes for winter. Before use, they were soaked in water..." ^{[Turner,Bell]} "They were mashed with a stone hammer, left to thicken for two nights, and then poured into cedar drying frames set on skunk cabbage leaves (Lysichitum americanum) and dried for two hours over an alder wood (Alnus rubra) fire. The resulting cakes were folded up and stored in wooden boxes near the fire.... If the cakes were being made to sell or for commoners at a feast, elderberry cakes were mixed with the berries before they were dried to make them "go further,".... Dried salal berry cakes were prepared by soaking them in water overnight and kneading them in a bowl to mix them thoroughly. Then oil was poured over them and they were eaten.... No water was drunk after a salal berry feast (Boas, 1921)." ^{[Turner,Bell2]}

Phytochemicals

• "Catechin and epicatechin, potent polyphenolic antioxidants, were identified in the EtOAc extracts of Gaultheria shallon....The high antioxidant capacity of Gaultheria shallon...is comparable to the values obtained for the reference compound, ascorbic acid...." ^[Acuna,2002]
• "On Gaultheria shallon as well as on Andromeda polifolia, galangin-3-methyl ether is the only flavonoid aglycone we could detect." ^{[Wollenweber,1984]}
• Epicuticular wax yields were found to be 0.04, 0.05, and 0.06%. Hydrocarbons in the wax were 18.9, 20.9, and 22.5%, respectively. ^{[salasoo1988]}

Nutritional

Tannins

Salal foliage yielded 1.53% (dry weight) of tannin. Other condensed tannin samples from untended shrubs showed 120.9 mg/g from the roots/rhizomes, 175.3 mg/g from the leaves, 130.4 mg/g from young stems, 55.3 mg/g from the old/woody stems, and 7.5 mg/g from the litter. In removal plots, the residual shoots showed 214.5 mg/g from the leaves and 114.9 mg/g from the stems.^{[Gross, PP2]}

Cultivation

"Prefers a moist but not boggy humus rich soil in shade or semi-shade[11, 182], but it can also succeed in full sun. A peat and moisture loving species, it requires a lime-free soil[11, 182]. One report says that it can succeed in dry shade[188] and another that it can withstand considerable drought once it is established[208]. Plants are hardy to about -20°c[184]. A vigorous suckering plant, it can be invasive when growing in good conditions, but responds to cutting back[1, 28]. It also succeeds when planted under trees[28, 49]. Plants in this genus are notably resistant to honey fungus[200]." ^[PFAF]

• Groundcover: "A ground cover plant for a shady position under trees, spreading slowly by means of suckers[188]. It should be spaced about 90cm apart each way[208]." ^[PFAF]
• Deer resistant plant ^[DeerResist]
• "In general salal is both resistant and resilient to many herbicides." ^{[Fraser et al.]}
• "Prescribed burning and logging can increase the growth of salal if the burn is light. Fire stimulates resprouting from roots and stem bases (sabhasri 1961). Only severe burns that eetrate sufficiently deep to kill the roots can reduce salal cover." ^{[Fraser et al.]}

"...shrubs such as salal (Gaultheria shallon) in coastal oceanic temperate rainforests and several Vaccinium species (particularly Vaccinium alaskaense) in high elevation forests have been reported to cause growth stagnation of conifers such as western red cedar (Tsuga plicata), western hemlock (Thuja heterophylla), Sitka spruce (Picea sitchensis) and Amabilis fir (Abies amabilis) (Bunnell, 1990; Messier, 1993; Fraser, 1993; Prescott, Weetman and Baker, 1996; Fraser, Turkington, and Chanway, 1993; Fraser, Chanway, and Turkington, 1995)." ^{[Zeng ASA]}

Forestry Effects

Detrimental

"Gaultheia shallon is a persistent and pervasive plant and is considered a serious competitor with coniferous species, particularly Douglas-fir (Pseudotsuga menziesii) on semi-xeric sites in low elevation coastal British Columbia (Tan et al. 1977; Stanek et al. 1979; Price et al 1986). On wetter sites. G. shallon competes with young planted seedlings of western red cedar (Thuja plicata), western hemlock (Tsuga heterophylla), Pacific silver fir (Abies amabilis) and Sitka spruce (Picea sitchensis) following clear-cut logging (Germain 1985; Weernan et al. 1990; Messier 1991)....salal can grow so rapidly that most plantable sites may become occupied and nearly impossible to clear manually." ^{[Fraser et al.]}

"It has been shown that salal is at least partially responsible for this poor growth during the first 15 years after plantation establishment, either by competing directly for nutrients (Germain, 1985; Messier and Kimmins, 1991a,b) or by inhibiting nutrient availability to trees (Germain, 1985; Weetman et al., 1990). On these sites, salal re-establishes itself quickly after disturbance, mainly by resprouting from old rhizomes already present in the undisturbed old-growth forest of western red cedar (Thuja plicata Donn) and western hemlock (Tsuga heterophylla(Raf.) Sarg. )." ^{[messier1991]}

"long-term results from a suite of silvicultural trials and associated ecological studies indicated that salal is not the fundamental problem for regenerating conifers on cedar-salal sites. Fertilization of cedar-salal sites caused a large and sustained response in tree growth regardless of the presence of salal, and growth responses to salal removal were much smaller than fertilization responses. Greenhouse experiments indicated that salal does not have allelopathic effects on germination or growth of conifer seedlings. In laboratory studies, salal did not demonstrate a greater capacity to take up organic N forms than the conifers, and molecular studies uncovered a vast diversity of mycorrhizal fungi associated with salal and hemlock roots. Together these findings indicate that the nutrient "short-circuiting" hypothesis, based on assumptions about ericoid versus non-ericoid mycorrhizal plants does not adequately describe the nutrition of plants in these ecosystems. We conclude that salal should be viewed as a symptom of the underlying problem of poor nutrient supply on cedar-salal sites, and that fertilization, rather than salal control, is the optimal solution for improving forest regeneration on these sites."^{[Prescott,2006]}

Beneficial

"Salal forms a very large rooting system with many fine roots and associated microorganisms (mycorrhizae and rhizophere bacteria) in only a few years following clearcutting. Therefore, salal maintains nutrients in the system that would otherwise have been leached and lost. Furthermore, the roots may act to reduce soil erosion on recently disturbed sites and contribute to the organic matter content of the soil (Sabhasri 1961). The leaves of salal also contribute to the organic matter content of the soil, as well as cycling nutrients back into the soil. When salai is abundant, the leaf litter is very large and may serve as a mulch, thus reducing evapotranspiration. This trait is particularly useful in dry habitats. Gaultheria shallon has also been recommended for coastal sand dune stabilization (Brown and Hafenrichtet 1962)." ^{[Fraser et al.]}

Floral Industry

"Salal began to be picked as floral greenery early in the 20th century, became the primary wild-harvested floral product in BC in the 1950s, and now comprises approximately 70% (Wills and Lipsey 1999) to 90– 95% (Ross 1998) of all wild-harvested floral greenery from the BC coast. Europe is the primary export market for salal, although large volumes are also shipped to Japan, distributed across North America or sold directly to local retailers on the Pacific coast (de Geus 1995; Ross 1998; Jones et al. 2002)." ^{[Cocksedge2006]}

"Florists use the leaves as a foliage supplement (trade name "lemon leaves") for cut flower arrangements (Anonymous 1970). Salal is also grown commercially in greenhouses. In 1980 salal had an annual retail value of approximately $2 million in BC (Hunt 1980)." ^{[Fraser et al.]} By 1997, an estimated 12,000 - 15,000 people were harvesting salal (part or full time). The gross revenue was $55-60 million CAD. ^{[cocksedge2006]}

"Salal is moderately shade tolerant and tends to grow best under partial shade (Bunnell 1990; Messier 1992), a condition that generally produces the most desirable commercial-quality product with long stems (45–76 cm) and suitable shade leaves for the floral industry (i.e., relatively thin, unblemished leaves with consistent green colouring)." ^{[cocksedge2006]}

"Based on this initial study, we conclude that (i) commercial salal harvesting from previously unharvested sites removes the equivalent of 1 year’s above-ground biomass increment, (ii) commercial salal harvesting increases the annual above-ground biomass in the subsequent year, and (iii) there is an increase in the total number of stems in the year after commercial harvesting." ^{[cocksedge2006]}

Mycorrhizal

• "Many ericaceous shrubs, including salal^1,9 and some conifers,¹⁰ can use their mycorrhizal associations to access organic forms of N and P, thus enhancing their competitive ability." ^{[Gross, PP2]}
• "The field roots of salal were highly colonized by the ericoid mycorrhizal fungi in terms of root colonization and cell colonization. The colonization rate was as high as 87% for root colonization and 91 % for cell colonization within the colonized roots. No statistically significant difference (at a = 0.01) of mycorrhizal colonization between the two forest types was found....Salal formed two kinds of root-fungus associations in axenic culture: typical ericoid mycorrhizae with 0. griseum and two unknown species, and atypical mycorrhizae with Acremonium strictum. ...Salal roots from both CH [(Cedar-Hemlock)]and HA [(Hemlock-Amabilis)] sites were extensively colonized by ericoid mycorrhizal fungi, and differences between the two sites in terms of root colonization or cell colonization intensity could not be detected. Studies show that low availability of mineral nitrogen and high organic nitrogen content can result in high intensity of colonization of ericoid mycorrhizae (Reed 1987) and that application of inorganic nitrogen can suppress ericoid mycorrhiza formation...The diversity of mycorrhizal fungi and high intensity of colonization suggest that ericoid mycorrhizal fungi are involved in the dominance of salal on CH clearcuts, although the dense mat of rhizomes inherited from the CH [(Cedar-Hemlock)] forests also plays a role." ^[Xiao&Berch]
• "Largent et al. (1980) reported that G. shallon can be associated with three different kinds of mycorrhizae: arbutoid, ericoid, and ectomycorrhizae." ^{[Fraser et al.]}

Propagation

"The seed requires a period of cold stratification. Pre-chill for 4 - 10 weeks and then surface sow in a lime-free compost in a shady part of the greenhouse and keep the compost moist[78]. The seed usually germinates well, usually within 1 - 2 months at 20°c, but the seedlings are liable to damp off. It is important to water them with care and to ensure that they get plenty of ventilation. Watering them with a garlic infusion can also help to prevent damping of[K]. Prick out the seedlings into individual pots when they are about 25mm tall and grow them on in light shade in the greenhouse for at least their first winter[K]. Plant them out in late spring or early summer. The seedlings are susceptible to spring frosts so might need some protection for their first few years outdoors. The leaves remain very small for the first few years[11]. Cuttings of half-ripe wood 3 - 6cm long, July/August in a frame in a shady position. They form roots in late summer or spring[78]. A good percentage usually take. Division in spring when new growth is about 7cm tall. Divided plants can be rather slow to get established[182]. We have found that it is best to pot up the clumps and grow them on in a shady position in a cold frame until they are rooting well. Plant them out in the spring."^[PFAF]

• "The plant produces numerous seeds but the most significant and effective form of colonization is through vegetative spread." ^{[Fraser et al.]}
• "Despite the large quantity of seeds produced and the many seeds which germinate, seedling survival is very low (Haeussler et al. 1990)." ^{[Fraser et al.]}
• "Salal readily forms new plants from cuttings of the stem and roots (Sabhasri 1961)" ^{[Fraser et al.]}
• "Salal's survival strategy appears to be to build a large biomass of rhizomes in the clearcut to store carbohydrates which will permit it to survive under very dense stand covers for many years. This strategy allows salal to 'wait' until stand self-thinning occurs and the canovy opens up, whereas other species without such below-ground storage would be eliminated.^{[messier1991]}

Gaultheria - Wintergreen

Shrub, glabrous or short- or long-hairy, glandular or not, often smelling of wintergreen, generally rhizomed. Stem: prostrate to erect, rooting at nodes or not. Leaf: alternate, evergreen, leathery, entire to serrate. Inflorescence: raceme, each flower with 1 bract, 2 bractlets, or flowers 1 in leaf axils, each with 4–10 bractlets; pedicel jointed to flower. Flower: sepals generally 5, fused; petals 5, fused, cylindric, urn-, or bell-shaped, white to red; stamens (5,8)10, anthers dehiscing by 2 short, slit-like to rounded pores, awns (0,2)4, sometimes reduced; ovary superior or 1/2-inferior, chambers (4)5, placentas axile, at top. Fruit: capsule, loculicidal or irregularly dehiscing, generally ± enclosed by fleshy, colorful calyx (or a berry and/or with non-fleshy calyx). Seed: few to many per chamber, appendages 0.
± 130 species: circum-Pacific, eastern North America, eastern Brazil, Himalayas. (J.F. Gaulthier, botanist, physician, Quebec, 1708–1756) [Middleton 1991 Bot J Linn Soc 106:229–258] ^[Jepson]

Local Species;

1. Gaultheria humifusa - alpine-wintergreen ^{[E-flora][PCBC][TSFTK]}
2. Gaultheria ovatifolia - western tea-berry ^{[E-flora][PCBC][TSFTK]}
3. Gaultheria shallon - Salal ^{[E-flora][PCBC][TSFTK]}

Uses of Other Related Sp

Gaultheria fragrantissima (Wintergreen), oil composed of 99.2-99.5% methyl salicylate.^{[Radulovic et al.]}
Gaultheria humifusa (Alpine Spicywintergreen), "Used to make a black dye."^[UMDEth]
Gaultheria ovatifolia (Western Teaberry), Fruit eaten fresh, or stewed and made into sauce.^[UMDEth]

Gaultheria procumbens (Wintergreen), is used for its analgesic qualities, draining qualities and opening of the nasal passages. ^{[Tilgner HMHE]} Carminative, tonic, antiseptic and aromatic. ^[PDR] Berries and young tender leaves eaten. The leaves make a very pleasant tea.^{[Medsgar EWP]} "The leaves should not be swallowed, but when gently chewed, they produce a perfectly wonderful Wintergreen flavor..."^{[Angier FFWE]}
The entire plant contains oil of wintergreen. This oil has numerous uses, was once extracted from the plant by means of steam distillation and "is only present in small quantities in the fresh plant". "More is formed by enzyme action after the plant wilts and the cell walls start to break down. The plants were left to ferment for a day or so before being distilled, to allow more oil to form."^{[Tozer UWP]} Monotropitoside (Gaultherin) changes into methyl salicylate when the plant is dried.^[PDR]

Caution: Those allergic to aspirin should probably avoid it. ^{[Tozer UWP]}

References

• Acuna,2002 - Antioxidant Capacities of Ten Edible North American Plants, Ulyana Munoz Acuna, Daniel E. Atha, Jun Ma, Michael H. Nee and Edward J. Kennelly, Phytother. Res. 6, 63-65 (2002)
• cocksedge2006 - Short-term response of salal (Gaultheria shallon Pursh) to commercial harvesting for floral greenery Wendy Cocksedge, Brian D. Titus
• DeerResist - Guardeners Guide to Preventing Deer Damage, This booklet was prepared by the California Department of Fish and Game’s Wildlife Programs Branch, with assistance from the Minnesota Department of Natural Resources, Farmland Wildlife Resource Unit., THE STATE OF CALIFORNIA, Arnold Schwarzenegger, Governor
• E-flora -http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Gaultheria%20shallon, Gaultheria shallon, Accessed April 11, 2015
  • USDA Gaultheria shallon, US Dept. of Agriculture, http://plants.usda.gov/core/profile?symbol=gash
• Fraser et al. - Fraser, L., Turkington, R. and Chanway, C. P. 1993. The biology of Canadian weeds. 102. Gaultheria shallon Pursh. Can. J. Plant Sci. 73:- 1233-1247.
• [Jepson] Walter S. Judd, 2013. Gaultheria, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=26490, accessed on Jun 10 2014
• messier1991 - Messier, C. and Kimmins, J.P., 199I. Above-and below-ground vegetation recovery in recently clearcut and burned sites dominated by Gaultheria shallonin coastal British Columbia. For. Ecol. Manage., 46: 275-294.
• PFAF http://www.pfaf.org/user/Plant.aspx?LatinName=Gaultheria shallon, Accessed April 11, 2015
• Prescott,2006 - The role of salal in forest regeneration problems in coastal British Columbia: problem or symptom? by Cindy E. Prescott and Toktam Sajedi, JANUARY/FEBRUARY 2008, VOL. 84, No. 1 — THE FORESTRY CHRONICLE
• Radulovic et al. Comparative Study of the Leaf Volatiles of Arctostaphylos uva-ursi (L.) Spreng. and Vaccinium vitis-idaea L. (Ericaceae), Niko Radulovi?, Polina Blagojevi? and Radosav Pali?, September 2010, Molecules 2010, 15, 6168-6185; doi:10.3390/molecules15096168
• salasoo1988 - Epicuticular Wax Hydrocarbons of Ericaceae in the Pacific Northwest of U.S.A., Biochemical Systematics and Ecology, Vol. 16, No. 7/8, pp. 619-622, 1988.
• salasoo1989 - Epicuticular Wax Hydrocarbons of Ericaceae in British Columbia, Biochemical Systematics and Ecology, Vol. 17, No. 5, pp. 381-384, 1989.
• Xiao&Berch - Diversity and Abuncance of Ericoid mycorrhizal fungi of Gaultheria shallon on Forest Clearcuts, Guoping Xiao and Shannon M. Berch, Can. J. Bot. 74: 337-346 (1996).
• Wollenweber,1984 - Novel Epicuticular Leaf Flavonoids from Kalmia and Gaidtheria (Ericaceae), Eckhard Wollenweber and Gisela Kohorst, Z. Naturforsch. 39c,710-713 (1984)