Significance

Description

Wolfberry species are deciduous woody perennial plants, growing 1-3 m high. L. chinense is grown in the south of China and tends to be somewhat shorter, while L. barbarum is grown in the north, primarily in the Ningxia Hui Autonomous Region, and tends to be somewhat taller.

The botanical division named to the upper right, Magnoliophyta, identifies plants that flower and the class Magnoliopsida represents flowering plants (Dicotyledons) with two embryonic seed leaves called cotyledons appearing at germination.

The order Solanales names a perennial plant with five-petaled flowers that are more or less united into a ring at the base; well-known members of the order include morning glory, bindweed, and sweet potato as well as the plants of the Solanaceae, mentioned below.

Lastly, Solanaceae is the nightshade family that includes hundreds of plant foods like potato, tomato, eggplant, wolfberry, peppers (paprika), crop commodities (tobacco), and flowers (petunia). Although the Solanales includes many plant foods, some members are poisonous (for example belladonna).

Leaves and flower

Wolfberry leaves form on the shoot either in an alternating arrangement or in bundles of up to three, each having a shape that is either lanceolate (shaped like a spearhead longer than it is wide) or ovate (egg-like). Leaf dimensions are 7 cm long by 3.5 cm wide with blunted or round tips.

One to three flowers (picture) occur on stems 1-2 cm in length. The calyx (eventually ruptured by the growing berry) is comprised of bell-shaped or tubular sepals forming short, triangular lobes. The corolla are lavender or light purple, 9-14 cm long with five or six lobes shorter than the tube. The stamens are structured with anthers that open lengthwise, shorter in length than the filaments (picture).

In the northern hemisphere, flowering occurs from June through September and berry maturation from August to October, depending on latitude, altitude, and climate.

Fruit

These species produce a bright orange-red, ellipsoid berry 1-2 cm long^{[11] photo}. The number of seeds in each berry varies widely based on cultivar and fruit size, containing anywhere between 10-60 tiny yellow seeds that are compressed with a curved embryo. The berries ripen from July to October in the Northern hemisphere.

Etymology

"Wolfberry" is the most commonly used English name, while gǒuqǐ (枸杞) is the Chinese name for the berry producing plant. In Chinese, the berries themselves are called gǒuqǐzi (枸杞子), with zi meaning "seed" or specifically "berry". Other common names are "the Duke of Argyll's Tea Tree"[3] and "matrimony vine".[4] Rarely, wolfberry is also known in pharmacological references as Lycii fructus, meaning "Lycium fruit" in Latin.

Although origin of the common name "wolfberry" is undefined, it may have derived from the Greek word for wolf, "lycos" (λύκος), first applied to tomato (Solanum lycopersicum with derivation of 'lyco' as wolf, plus 'persicum' as peach, i.e., "wolf-peach") by Carolus Linnaeus in 1753[12], the same year Lycium barbarum was entered into botanical nomenclature. Botanically related to tomato in family Solanaceae, wolfberry may have assumed its name from the more common, larger berry, tomato - the "wolf-peach". Why Linnaeus named tomato after the wolf remains unknown.

In the English-speaking world, "goji berry" has been widely used since the early 21st century as a synonym for "wolfberry". While the origin of the word "goji" is unclear, it is probably a simplified pronunciation of gǒuqǐ, the Mandarin name of the plant, developed by those marketing wolfberry products in the West.

Lycium, the genus name, is derived from the ancient southern Anatolian region of Lycia (Λυκία).[10] Interpreters of botanical nomenclature believe barbarum, the species name, indicates that the wolfberry was of foreign origin, perhaps originating outside Anatolia or China, or was deemed a plant not native to the region where it was first discovered.

Together, these names are used as specific botanical identifiers in binomial nomenclature for which barbarum is the specific epithet. The end abbreviation, L., refers to Linnaeus, who described the species in 1753 in Species Plantarum. L. chinense was first described by the Scottish botanist Philip Miller in the eighth edition of his The Gardener's Dictionary, published in 1768.

In Japan the plant is known as kuko (クコ) and the fruits are called kuko no mi (クコの実) or kuko no kajitsu (クコの果実); in Korea the berries are known as gugija (hangul: 구기자; hanja: 枸杞子)[13]; in Vietnam the fruit is called "kỷ tử" (杞子), "cẩu kỷ" (枸杞), "cẩu kỷ tử"(枸杞子) but the plant and its leaves are known more popularly as "củ khởi"; and in Thailand the plant is called găo gèe (เก๋ากี่). In Tibetan the plant is called dre-tsher-ma (), with dre meaning "ghost" and tsher-ma meaning "thorn"; and the name of the fruit is dre-tsher-mai-dre-bu (), with dre-bu meaning "fruit".

Cultivation

The majority of commercially produced wolfberries come from the Ningxia Hui Autonomous Region of north-central China and the Xinjiang Uyghur Autonomous Region of western China, where they are grown on plantations. In Zhongning County, Ningxia, wolfberry plantations typically range between 100 and 1000 acres (or 500-6000 mu) in area.

Cultivated along the fertile aggradational floodplains of the Yellow River for more than 600 years, Ningxia wolfberries have earned a reputation throughout Asia for premium quality sometimes described commercially as "red diamonds".[14] Government releases of annual wolfberry production, premium fruit grades, and export are based on yields from Ningxia, the region recognized with:

* The largest annual harvest in China, accounting for 42% (13 million kg, 2001) of the nation's total yield of wolfberries, estimated at approximately 33 million kg (72 million lb) in 2001.
* Formation of an industrial association of growers, processors, marketers, and scholars of wolfberry cultivation to promote the berry's commercial and export potential.
* Ongoing horticultural research conducted on the wolfberry plant at the Ningxia Research Institute, Yinchuan (see References: Gross et al., 2006, chapter 9).
* The nation's only source of therapeutic grade ("superior-grade") wolfberries used by practitioners of traditional Chinese medicine.[15]

In addition, commercial volumes of wolfberries grow in the Chinese regions of Inner Mongolia, Qinghai, Gansu, Shaanxi, Shanxi and Hebei. The oblong, red berries are very tender and must be picked carefully or shaken from the vine into trays to avoid spoiling. The fruits are preserved by slowly drying them in the shade on air exchange tables or by mechanical dehydration employing a progressively increasing series of heat exposure over 48 hours.

Wolfberries are celebrated each August in Ningxia with an annual festival coinciding with the berry harvest (it was first held in Ningxia's capital, Yinchuan, but is now held in Zhongning County, an important center of wolfberry cultivation for the region).[16]

China, the main supplier of wolfberry products in the world, had total exports generating US$120 million in 2004. This production derived from 82,000 hectares farmed nationwide, yielding 95,000 tons of wolfberries.[17]

Pesticide and fungicide use

Organochlorine pesticides are conventionally used in commercial wolfberry cultivation to mitigate destruction of the delicate berries by insects. Since the early 21st century, high levels of pyrethroid insecticide residues (including fenvalerate and cypermethrin) and fungicide residues (such as triadimenol), have been detected by the United States Food and Drug Administration in some imported wolfberries and wolfberry products of Chinese origin, leading to the seizure of these products.[18] Due to the demand for organic products in the West, some Chinese growers are beginning to experiment with integrated pest management and to explore the possibility of obtaining organic certification, something that has not yet been publicly disclosed for Chinese wolfberry farms and products.

Some Western resellers may state that their wolfberries are organically grown when in fact they are not. The Green Certificate claimed by some wolfberry marketers to be the equivalent of the United States Department of Agriculture's "USDA Organic" seal[19] is in actuality simply an agricultural training program for China's rural poor.[20] China's Green Food Standard,[21] administered by the Chinese Ministry of Agriculture's China Green Food Development Center, does permit some amount of pesticide and herbicide use.[22][23][24]

Despite some claims that wolfberries sold in Europe, the United States, and Canada meet organic standards[citation needed], there is no public evidence for standardized organic certification of wolfberries from the Asian regions where they are commercially grown. Often, these berries are marketed as Tibetan or Himalayan Goji Berries that have been "wild crafted" or "wild harvested". On the contrary, however, Tibet's agriculture conventionally uses fertilizers and pesticides, and neither wolfberries ("goji") of Tibetan or Himalayan origin sold outside Tibet nor organic certification of such berries have been proved[25].
 

Tibetan goji berry

Since the early 21st century, the names "Himalayan Goji berry" and "Tibetan Goji berry" have become common in the global health food market, applied to berries claimed to have been grown or collected in the Himalaya region [26] (or sometimes "the Tibetan and Mongolian Himalayas"[27], a misnomer because the Himalayas do not extend into Mongolia, which lies approximately 1500 km (1000 miles) to the northeast)[28]. Although none of the companies marketing such berries specifies an exact location in the Himalayas or Tibet where their berries are supposed to be grown, Earl Mindell's website states that his "Himalayan" Goji products do not actually come from the Himalayas, but instead from Inner Mongolia, Ningxia, and the Tian Shan Mountains of western Xinjiang, China[29].

Although Lycium species do grow in some regions of Tibet, commercial export production of wolfberries in the Tibetan Himayalas must be a myth[11] fabricated for a marketing advantage, as this mountain range bordering the Tibetan Plateau is a region inhospitable to commercial cultivation of plant foods of any kind. In the Himalayan foothills, bleak desolation is unrelieved by any vegetation beyond sparse, low bushes[30], whereas eastern valleys and plains of the Tibetan Plateau at lower altitude support growth of wild Lycium chinense[31].

The Tibetan Plateau, comprising most of Tibet north and east of the Himalayas, lies at more than 3000 m (10,000 ft) in altitude, with poor soil and arid climate conditions unfavorable for fruit crops. Defined by the geography of Tibet, particularly in the western Himalayas, cold nighttime temperatures averaging -4°C year round [32] with six months of continual frost[33] would inhibit plant bud development and prevent fruit formation. Existing in Tibet are minimal subsistence agriculture and impoverished crop management and transportation facilities unsupportive of commercial berry production. Although limited fertile regions suitable for food crops exist in the valleys of Lhasa, Shigatse, Gyantse, and the Brahmaputra River, there are no objective economic, scientific, or government reports on the commercial production of Lycium berry species from these Tibetan regions[34].

Importance of cultivar

Described in ancient Chinese texts, gǒuqǐ (wolfberry, named Lycium barbarum L. in 1753) has existed in China over recorded history and has likely been used to make hybrid plants dozens of times across Asia, as attested by some 90 species of boxthorn, wolfberry's genus.

Although several wolfberry marketers state that their "Tibetan goji" is a specific species, given variously as Lycium eleganus, Lycium eleganus barbarum, or Lycium eleagnus, no such species exist. Elaeagnus (Silverberry or Oleaster) is a genus of about 50-70 species of flowering plants in the Elaeagnaceae family. The vast majority of Elaeagnus species are native to temperate and subtropical regions of Asia, including Elaeagnus umbellata, which grows near the Himalayas and bears an orange-red berry possibly confused with Lycium barbarum.

Some Internet authors claim Lycium eleagnus barbarum (another nonexistent species) is the original Lycium barbarum or an improved cultivar of it.[35] However, Lycium and Elaeagnus are sufficiently disparate genera that successful cross-breeding is unlikely. Further, there is no evidence in the International Code of Nomenclature for Cultivated Plants of a Lycium species of Elaeagnus or vice versa.[36] [37]

United Kingdom

Archibald Campbell, 3rd Duke of Argyll (1682–1761) delighted in growing exotic trees and shrubs in his garden at Whitton in Middlesex, England (he was nicknamed the "Treemonger" by Horace Walpole) and introduced the plant into the United Kingdom in the 1730s where it is known as Duke of Argyll's Tea Tree. It was and still is used for hedging, especially in coastal districts. Its red berries are attractive to a wide variety of British birds.[12]

The plant continues to grow wild in UK hedgerows. On 15 January 2003, the Department for Environment, Food and Rural Affairs (of the United Kingdom Government) launched a project to improve the regulations protecting traditional countryside hedgerows, and specifically mentioned Duke of Argyll's Tea Tree as one of the species to be found growing in hedges located in Suffolk Sandlings, Hadley, Bawdsey, near Ipswich, and Walberswick.[13]

The wolfberry has been naturalized as an ornamental and edible plant in the UK for nearly 300 years. On June 18, 2007, the FSA (UK Food Standards Agency) stated that there was a significant history of the fruit being consumed in Europe before 1997, and has removed it from the Novel Foods list [38]. It is now legal to sell the goji berry in the UK as a food as reported by the British Food Standards Agency [39].(also see discussion below, Marketing claims under scrutiny in Europe).

Importation of mature plants

Importation of wolfberry plants into the United Kingdom from most countries outside Europe is illegal, due to the possibility that alien plants could be vectors of diseases attacking native members of the Solanaceae family, such as potato or tomato.[14]

Uses

Wolfberries are almost never found in their fresh form outside of their production regions, and are usually sold in open boxes and small packages in dried form. The amount of desiccation varies in wolfberries: some are soft and somewhat tacky in the manner of raisins, while others may be very hard. Wolfberries with a vibrant orange-red color may have been treated with sulfites. Wolfberries are usually used directly, and do not need to be rehydrated prior to use.

Medicinal

Wolfberries have long played important roles in traditional Chinese medicine (TCM) where they are believed to enhance immune system function, improve eyesight, protect the liver, boost sperm production and improve circulation, among other effects.[15]

In TCM terms, wolfberries are sweet in taste and neutral in nature. They act on the liver, lungs, and kidneys and enrich yin. They can be eaten raw, consumed as juice or wine, brewed into an herbal tea photo 1photo 2 or prepared as a tincture. The berries are also used in traditional Korean medicine, traditional Japanese medicine and traditional Tibetan medicine.

Wolfberry leaves may be used to make tea[40] and Lycium root bark (called dìgǔpí; 地骨皮 in Chinese)photo for TCM treatment of inflammatory and some types of skin diseases. A glucopyranoside and phenolic amides isolated from wolfberry root bark have inhibitory activity in vitro against human pathogenic bacteria and fungi [41][42].

An early mention of wolfberry occurs in the 7th century Tang Dynasty treatise Yaoxing Lun. It is also discussed in the 16th century Ming Dynasty Compendium of Materia Medica of Li Shizhen.

From marketing literature for wolfberry products including several "goji juices", a reputation exists for wolfberry polysaccharides having extensive biological effects and health benefits, although none of these has been proved by peer-reviewed research. A May 2008 clinical study published by the peer-reviewed Journal of Alternative and Complementary Medicine indicated that parametric data, including body weight, did not show significant differences between subjects receiving Lycium barbarum berry juice and subjects receiving the placebo. The study concluded that subjective measures of health were improved and suggested further research in humans was necessary.[16]

Wolfberry polysaccharides show antioxidant activity in vitro[17] and might also have biological activities in vivo currently under research (20 publications on this topic since 1991; PubMed, February 2007). As a source of dietary fiber, however, polysaccharides would yield products from bacterial fermentation in the colon, such as several short-chain fatty acids, e.g., butyric acid, which may provide health benefits.[18][19]

Although the macromolecular structure of wolfberry polysaccharides has not been elucidated, preliminary structural studies appear to indicate that they exist in the form of complex glycoconjugates .[20][21]

Wolfberry fruits also contain zeaxanthin, an important dietary carotenoid selectively absorbed into the retinal macula lutea where it is thought to provide antioxidant and protective light-filtering roles.[22][23] A human supplementation trial showed that daily intake of wolfberries increased plasma levels of zeaxanthin.[24]

Several published studies, mostly from China, have also reported possible medicinal benefits of Lycium barbarum, especially due to its antioxidant properties,[25] including potential benefits against cardiovascular and inflammatory diseases,[26][27] vision-related diseases[28] (such as age-related macular degeneration and glaucoma[29]), having neuroprotective properties[30] or as an anticancer[31] and immunomodulatory agent.[32]

However, in the west, none of this research has been scientifically verified, confirmed in clinical studies, or accepted by regulatory authorities.

Safety issues

A published case report described a 61-year-old Chinese woman who experienced an elevated international normalized ratio (INR) after drinking a tea made from wolfberry fruit. Further in vitro testing revealed that the tea inhibited warfarin metabolism. These observations indicate a potential herbal-drug interaction between warfarin and wolfberry.[33] Another case report describes an 80-year-old Chinese woman on a chronic stable dose of warfarin who experienced two episodes of an elevated INR after drinking wolfberry tea.[34]

Atropine, a toxic alkaloid found in other members of the Solanacea family, occurs naturally in wolfberry fruit. The atropine concentrations of berries from China and Thailand are variable, with a maximum content of 19 ppb, below the likely toxic amount.[35]

Culinary

As a food, dried wolfberries are traditionally cooked before consumption. Dried wolfberries are often added to rice congee,photo as well as used in Chinese tonic soups, in combination with chicken or pork, vegetables, and other herbs such as wild yam, Astragalus membranaceus, Codonopsis pilosula, and licorice root.photo 1photo 2 The berries are also boiled as an herbal tea, often along with chrysanthemum flowersphoto and/or red jujubes, and packaged teas are also available.photo Various wines containing wolfberries (called gǒuqǐ jiǔ; 枸杞酒) are also produced,[36][37][38] including some that are a blend of grape wine and wolfberries.photo At least one Chinese company also produces wolfberry beer, and New Belgium Brewery makes an ale with wolfberries used as flavoring.photo Since the early 21st century, an instant coffee product containing wolfberry extract has been produced in China.photo 1photo 2photo 3

Young wolfberry shoots and leaves are also grown commercially as a leaf vegetable.photorecipe

In the West, dried wolfberries are also eaten hand-to-mouth as a snack, in the manner of raisins or other dried fruit. Their taste has an accent of tomato and is similar to that of dates, dried cranberries or raisins, though drier, more tart, less sweet and with an herbal scent. Dried wolfberries are also used frequently in raw food diets.