Biology & Culture Of The Buffaloberry, Shepherdia argentea Pursh Nutt. (Elaeagnaceae)

 

Article by Richard G. St-Pierre, Ph.D.

 

This article is a web version of St-Pierre, R.G. 2008. Shepherdia argentea. In J. Janick and R.E. Paull (eds.). The Encyclopedia of Fruits and Nuts. CABI Publishing, Oxon, UK. pp. 343-345.

 

INTRODUCTION

 

Historical and Origins

 

The buffaloberry, Shepherdia argentea (Pursh) Nutt., Elaeagnaceae, is a fruit native to the great plains of North America and has a long history of use throughout this region. The buffaloberry was used by Native Americans and European settlers as an accompaniment to bison meat. The earliest recorded date of cultivation is 1818, and the buffaloberry was first introduced into commercial trade by G.J. and L.E.R. Lambrigger of Big Horn City, Wyoming, in the autumn of 1890.

 

World Production

 

Over 3.5 million seedlings (the equivalent of approximately 1663 ha) have been distributed across western Canada by the PFRA Shelterbelt Centre (Agriculture and Agri-Food Canada) in Indian Head, Saskatchewan, primarily for use in shelterbelts.

 

Uses and Nutritional Composition

 

Traditionally the fruit have been eaten raw or dried, particularly after they have received some exposure to frost. The fruit have also been used in pemmican, soup, puddings, juice, pies, preserves, and wines. Preservation methods include drying, freezing, and canning. The fruit also have been used for dyes, and during aboriginal ceremonial feasts to honour a girl's attainment of puberty. Thongs and laces have been made from shredded bark.

 

The buffaloberry is useful in shelterbelt plantings because of its high salt and soil pH tolerance, drought resistance, winter-hardiness, and nitrogen-fixing ability. Wildlife use the buffaloberry as a source of food and shelter. The sharp thorns make them useful as barrier plantings. The striking contrast of the silver foliage with the red fruit, winter persistence of the fruit, drought tolerance and low-maintenance give the species a high ornamental value. Buffaloberry fruit have ascorbic acid levels as high as 150 mg/100 g fruit. The fruit also have a high foaming ability due to their saponin content.

 

 

BOTANY

 

Taxonomy and Nomenclature

 

Previous Latin designations of Shepherdia argentea included Hippophae argentea, Lepargyraea argentea, and Elaeagnus utilis. Shepherdia argentea is commonly referred to as buffaloberry, or silver or thorny buffaloberry. The historical identification of bison with the plant accounts for its common name.

 

Description

 

The buffaloberry has a small, treelike growth habit, ranging in height from 1 to 6 m. The cultivar 'Sakakawea' reaches mature height in 15 to 20 years, with a crown width of 5 to 6 m. Specimens may attain 50 to 60 years in age. Natural stands of buffaloberry are typically thick groupings of tree-like shrubs.

 

The bark is smooth, whitish to grey-brown, becoming rough and dark with age. It may shred in long strips. Many older twigs terminate in stout thorns, 4 to 5 cm in length. Leaves are opposite, simple, smooth edged, and wedge-shaped. Individual leaves range from 2 to 5 cm in length with both sides having a covering of silver, waxy scales. Only the central vein is prominent. Absence of a rust coloured undersurface clearly separates this species from Shepherdia canadensis. Leaves emerge one to two weeks after flowering begins, and by late May or early June, they have reached full size. Shoot elongation continues until mid-August to early September. New growth averages from 17 to 54 cm per year.

 

The root structure of the buffaloberry is complex. It may have a taproot, which thickens at the top to form a root crown from which individual stems arise, or it may have irregularly spaced taproots, or branching roots which thicken into the root crown. Suckers form along the older roots to produce above-ground stems. Seedlings begin to produce suckers after as little as five years of growth The bark of the root is greyish-brown with few root hairs or rootlets.

 

Ecology and Climatic Requirements

 

The buffaloberry is native to the western and central North American Great Plains. The species is reported as far west as British Columbia and the Sierra Nevada Mountains of California, as far east as Iowa and Manitoba, as far south as New Mexico, and the northern boundary for the species is the northern grasslands (approximately 52°N latitude).

 

The buffaloberry may be found bordering natural waterways, in valleys, around sloughs, and in plains or low meadows. The buffaloberry does not tolerate shade. It thrives in medium-textured, well-drained, moist soils but will survive under less favourable conditions. In general, the buffaloberry will tolerate saline, droughty and temporarily flooded soils. The buffaloberry is naturally found on non-saline to slightly saline soils with electrical conductivities ranging from 0.41 to 6.80 mmhos/cm, and is considered salt tolerant by both the PFRA (Agriculture and Agri-Food Canada) and the United States Department of Agriculture, Soil Conservation Service. The pH range of the soils on which the buffaloberry is naturally found varies from 6.3 to 7.7. The cultivar 'Sakakawea' is considered tolerant of high soil pH levels by the USDA Soil Conservation Service. Limits of tolerance for both salinity and soil pH have not been determined.

 

Seedlings are rare. Seedling growth is slow, increasing the likelihood of seedlings being grazed by wildlife. Seed is dispersed mainly by animals, but because the seed coat is soft, almost all viability is lost prior to seed deposition. Fire can seriously damage older stands of buffaloberry in which there is much dead wood. However, stands re-establish within a few years of fire damage. Rabbits, hares and deer can inflict damage by browsing on shoots less than two years in age. Shoots become armed with thorns after that time, making them largely resistant to browsing animals.

 

Reproductive Biology

 

Buffaloberry flowers are inconspicuous and apparently better able than other prairie species to withstand spring frosts. The flowers are small, 2 mm in diameter, lack petals, and have four brownish-yellow sepals. Flowers are produced singly or in clusters in the axils of two-year-old branches. Flowers emerge before the leaves, and unevenly throughout early spring. Clustered flowers open in sequence, consequently declining, and unopened flowers can be found on the same branch, giving the plant a long period for pollination and fruit ripening. The initiation of buds for the following year occurs from early July to mid-August.

 

Shepherdia argentea is dioecious. Staminate plants have larger, stouter buds than pistillate plants. Staminate flowers have eight stamens. Staminate plants average three flowers per cluster whereas pistillate plants average six flowers per cluster. Once opened, staminate blossoms are about twice the size of pistillate blossoms. Both staminate and pistillate flowers mature at about the same time. The most common pollinating insects observed have been wild relatives of the honeybee and leafcutter bee. Various unidentified small flies also have been observed on male and female flowers. In horticultural settings, one staminate to five or six pistillate plants is recommended for adequate pollination.

 

Fruit Growth and Development

 

The fruit are highly variable in colour, size, harvestability, and quality. Usually the colour is a bright reddish-orange, but yellow fruited plants are known. The cultivar 'Sakakawea' produces from 12 to 20% yellow fruit. Botanically, the fruit have been variously described as a drupe or as a fleshy perianth surrounding an achene. The fruit are single-seeded, each seed being dark and smooth. On average, a single fruit weighs 0.05 gm, and fruit range in diameter from 3 to 5 mm. Fruit begin to ripen about 107 days from first flowering, in the order that they were pollinated. They are considered ripe when fully yellow or red. This may occur from July to September and the fruit remain on the bush until frost or later, and after the leaves fall. Pistillate plants begin to bear fruit at four to six years of age, then produce abundantly for many years.

 

The taste of buffaloberry fruit collected before a frost is generally astringent or sour. A general bitterness is attributed to the presence of saponins. After exposure to frost, the taste improves as the sugar content rises. Yellow-fruited varieties appear to be sweeter. The fruit are pectin rich, with pectin content decreasing as the fruit age. Harvested fruit soon develop a strong, rather unpleasant odour and become sticky. The seed is easily chewed and consumed with the fruit.

 

 

HORTICULTURE

 

Propagation

 

Buffaloberry may be propagated via seed, cuttings or suckers. Seeds from mature fruit collected in late-September, are processed by wet maceration and recovered through flotation. Seed storage in a sealed container has been accomplished at 7° to 16°C and 30% relative humidity. Seed of the buffaloberry, at a moisture content of 13.1%, showed 97% germination after 42 months storage at 5°C. Stratified seed may be maintained in containers at 15°C. There are 110,000–870,000 dry seeds/kg. Germination of 50% has typically been reported, but 80 to 90% germination has been obtained with fresh seed. Stratification is not needed for autumn-planted seed. For spring-planted seed, stratification in a slightly moist medium for 3 months is recommended. Seeds should be sown at a rate of 30 to 50 viable seeds per 30 cm of row, to a depth of 6 mm, and mulched with about 1.3 to 2.5 cm straw. Germination occurs within 24 days of spring planting. Germination does not require light.

 

Suckers are easily separated from parent plants. Cuttings of the yellow-fruited genotypes, taken in late-July, have been rooted quite successfully using 0.8% indolebutyric acid (IBA), talc and thiram, a 1:1 sand:perlite mixture, and mist. There are no specific pruning or training requirements.

 

Nutrition and Fertilization

 

Specific fertilizer requirements for the buffaloberry have not been determined. However, the buffaloberry is considered a good choice for poor soils as it has the capacity to fix atmospheric nitrogen.

 

Diseases and Pests

 

Mature stands of the buffaloberry are rendered weak and susceptible to wind damage once they are infected by white heart rot (Fomes ellisianus), which is specific to the buffaloberry and widespread. Infection occurs through damaged branch stubs. Advanced symptoms are manifested by the appearance of a 'conk', a hard, dry, dark-brown fruiting body in the shape of a hoof, growing from branch stubs and on stems. Control involves pruning well below the site of infection. Younger plants are infected by a fungal canker, Cucurbitaria sp. Leaf spots are caused by Cylindrosporium shepherdiae and Septoria shepherdiae. A powdery mildew is caused by Sphaerotheca castagnei and Sphaerotheca humilis. Rusts are caused by Puccinia caricis-shepherdiae and Puccinia coronata. These fungi are not considered significant pathogens.

 

Leaf-feeding insects commonly found on the buffaloberry in North and South Dakota include Datana sp., and Erannis tiliaria (linden looper). Some plants have been severely defoliated by Japanese Beetles (Popillia japonica) in Tennessee. The cecropia moth caterpillar (Hyalophora cecropia) is credited with partially defoliating young buffaloberry plantings as well. Two psyllids, Paratrioza arborensis and Psylla magnicauda, have been noted. Root feeders include larvae of the june beetle (Phyllophage sp.), and click beetle (Elateridae). Premature fruit drop is caused by the buffaloberry maggot (Rhagoletis sp.) Another insect, known as the buffaloberry fruitworm (Carposina niponensis ottawana) has also been noted.

 

Handling and Postharvest Storage

 

Harvesting represents one of the major drawbacks to the widespread use of buffaloberry fruit. The thorns are sharp and numerous. The fruit ripen unevenly, are small, and often adhere quite strongly to the branches. Many older trees are too tall for convenient picking, and the dense irregular growth of the plant can make it difficult to reach all of the fruit. The traditional method is to lay a cloth on the ground under the bush and then to beat the bush with a stick, once air temperatures have decreased to about -10°C, as frozen fruit fall off very easily. Otherwise the method demands more effort than hand picking and is more harmful to the bush.

 

Main Cultivars and Breeding

 

Two cultivars of buffaloberry currently exist: ‘Gold-eye’ (yellow fruited), developed in Morden, Manitoba, and ‘Sakakawea’, developed by the Soil Conservation Service of the USDA for revegetation of disturbed areas.

 

 

LITERATURE CITED AND FURTHER READING

 

Anon. 1985. ‘Sakakawea’ silver buffaloberry. Publication 1364. United States Department of Agriculture (USDA), Soil Conservation Service, Bismark, North Dakota, USA.

Hayes, P.A., Steeves, T.A., and Neal, B.R. 1989. An architectural analysis of Shepherdia canadensis and Shepherdia argentea: patterns of shoot development. Canadian Journal of Botany 67:1870–1877.

Hayes, P.A., Steeves, T.A., and Neal, B.R. 1990. An architectural analysis of Shepherdia canadensis and Shepherdia argentea (Elaeagnaceae): the architectural models. Canadian Journal of Botany 68:719–725.

Knudson, M.J., Haas, R.J., Tober, D.A., and Darris, D.C. 1987. Improvement of chokecherry, silver buffaloberry, and hawthorn for conservation use in the Northern Plains. In: Tuskan, G.A. (ed.). Proceedings of the Fifth North Central Tree Improvement Conference. Fargo, North Dakota, USA. pp. 163–177.

Krishnan, S., and Hughes, H. 1991. Asexual propagation of Shepherdia canadensis and S. rotundifolia. Journal of Environmental Horticulture 9:218–220.

Looman, J. 1984. The Biological Flora of Canada. 4. Shepherdia argentea (Pursh) Nutt., buffaloberry. Canadian Field Naturalist 98:231–244.

Thilenius, J.F., Evans, K.E., and Garrett, E.C. 1974. Shepherdia Nutt. buffaloberry. In: Schopmeyer, C.S. (ed.). Seeds of Woody Plants in the United States. Agriculture Handbook No. 450. US Department of Agriculture (USDA), Forest Service. Washington, D.C. pp. 771-773.

Turner, N.J., and Szczawinski, A.F. 1988. Edible Wild Fruits and Nuts of Canada. National Museum of Natural Sciences, Ottawa, Ontario, Canada.