出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/07/06 11:29:24」(JST)
| Phytolacca americana | |
|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Core eudicots |
| Order: | Caryophyllales |
| Family: | Phytolaccaceae |
| Genus: | Phytolacca |
| Species: | P. americana |
| Binomial name | |
| Phytolacca americana L. |
|
American Pokeweed (Phytolacca americana), or simply pokeweed, is a native herbaceous perennial plant of significant toxicity that is considered a semi-succulent[not verified in body] and that is large, growing up to 8 feet (2 metres) in height.
A member of the Phytolaccaceae, or pokeweed family, it presents simple leaves on green to purplish stems proceeding from a large white taproot; it bears flowers, green to white, that are followed by purple to almost black berries, which are a good food source for songbirds such as gray catbird, northern mockingbird, northern cardinal, and brown thrasher, as well as other birds and some small animals (i.e., to species that are unaffected by its human toxins).
P. americana or pokeweed—also known by a number of other names—is native to eastern North America, the Midwest, and the Gulf Coast, with more scattered populations in the far West.[not verified in body] It is considered a major pest species by farmers,[not verified in body] and that and the danger of human poisoning—its significant toxicity and its risks to human and animal health are consistently reported, with the whole of the plant toxic and increasing in toxicity through the year, with children at particular risk of its very poisonous purple-red ripe fruit—support arguments for eradication of P. americana. Even so, it is used as an ornamental in horticulture, and it provokes interest for the variety of its natural products (toxins and other classes), for its ecological role, its historical role in traditional medicine, and for some utility in biomedical research (e.g., in studies of pokeweed mitogen). In the wild, it is easily found growing in pastures, recently cleared areas, and woodland openings, edge habitats such as along fencerows, and in waste places.
Pokeweed is a member of the Phytolaccaceae, or broader pokeweed family, and is a native herbaceous perennial plant,[1] a semi-succulent[citation needed] that is large, growing up to 8 feet (2 metres) in height.[1] It presents branches, sometimes several, growing from the crown of a thick, white, fleshy taproot, each a "stout, smooth, green to somewhat purplish stem;" simple, entire leaves with long leafstalks alternate along the stem.[1]
Pokeweeds reproduce only by its seeds (large glossy black, and lens-shaped), contained in a fleshy, 10-celled, purple-to-near-black berry "with beautiful crimson juice;" the fruit develops from perfect, regular white or green flowers with 4-5 sepals absent petals that,like chokecherry develop in elongated clusters termed racemes.[1][2]The seeds have a long viability and can germinate after many years in the soil.
Birds are unaffected by the natural product pharmacopeia contained in the berries (see below),[citation needed] and eat them, scattering the seeds, though they are also found adventitiously in commercial seed (e.g., vegetable seeds packets).[1] The berries are reported to be a good food source for songbirds and other bird species and small animals unaffected by its toxins.[3] Distribution via birds is thought to accounts for the appearance of "single, isolated plants" in areas that had otherwise not been populated by pokeweed.[1]
P. americana is known as pokeberry,[1][4] poke root,[4] or inkberry,[1] also as Virginia poke or simply poke,[4][5] as pigeonberry,[4][5] or redweed or red ink plant,[5] or, in Chinese medicine, chuíxù shānglù (垂序商陸).[4][6][7] The plant is also referred to as poke sallet, and this and related terms can also refer to the cooked leaves of the plant, see Cultural significance below.
The information with regard to the overall and significant toxicity of this plant and the risks to human and animal health it poses is consistent and pervasive.[1][8][9][10][11] In summary, with regard to distribution through the plant: the poisonous principles are found in highest concentrations in the rootstock, then in leaves, and stems, and then in the ripe fruit,[8] the plant generally gets more toxic with maturity,[10] with the exception of the berries (which have significant toxicity even while green).[11]
With regard to human and animal (pet and livestock) toxicity, the Ohio Agricultural Research and Development Center (OARDC) staff scientists note that "[a]ll parts of common pokeweed are toxic... Roots are the most poisonous, leaves and stems are intermediate in toxicity (toxicity increases with maturity), and berries are the least toxic."[10] With regard to human poisoning they note:[10]
"Children are most frequently poisoned by eating raw berries. Infants are especially sensitive and have died from eating only a few raw berries... Adults have been poisoned, sometimes fatally, by eating improperly prepared leaves and shoots, especially if part of the root is harvested with the shoot, and by mistaking the root for an edible tuber. Research with humans has also shown that common pokeweed can cause mutations (possibly leading to cancer) and birth defects. Since the juice of pokeweed can be absorbed through the skin, contact of plant parts with bare skin should be avoided."
As summarized by Michael D.K. Owen, for the Iowa State University Extension Service:[1]
"Most authorities regard the plant as poisonous... Humans have been poisoned by eating parts of the root, which is the most poisonous part of the plant. Children are often attracted by the bright crimson juice of the berries and can be poisoned by eating the berries...
If death occurs, it is usually due to paralysis of the respiratory organs... Because of the danger of human poisoning, pokeweed should be eradicated when discovered. This is especially true if the plants are in hedges, gardens, and other areas adjacent to a home where children may be attracted by clusters of berries."
A further well-referenced web reference on the toxicity states that pokeweed is to be avoided during pregnancy and notes that "children consum[ing] even one berry" requires that "emergency poison treatment... be instituted"; in terms of general exposure, it notes "plant sap can cause dermatitis in sensitive people" and that "it is strongly recommended that the people wear gloves when handling the plant."[12]
Regarding pet, livestock, an other animal poisoning, Owen notes that "[b]irds are apparently immune to this poison" and that [a]nimals usually do not eat the plant because of its bitter taste."[1] The OARDC scientists echo the lack of animal palatability, and note that "most animals avoid eating it unless little else is available, or if it is in contaminated hay. Horses, sheep and cattle have been poisoned by eating fresh leaves or green fodder, and pigs have been poisoned by eating the roots."[10]
Human deaths resulting from pokeweed consumption are currently uncommon,[citation needed] but cases of emesis and catharsis are known,[citation needed] and a child who consumed crushed seeds in a juice is reported to have died.[citation needed] Historically, pokeweed poisonings were common in eastern North America during the 19th century, especially from the use of tinctures as antirheumatic preparations and from ingestion of berries and roots that were mistaken for parsnip, Jerusalem artichoke, or horseradish.[13]
See the Natural products section for specific information about the known toxicities of the constituents of the plant.
Owen of Iowa State University further states:[1]
"If taken internally, pokeweed is a slow acting but a violent emetic. Vomiting usually starts about 2 hours after the plant or parts of it have been eaten. Severe cases of poisoning result in purging, spasms, and sometimes convulsions. If death occurs, it is usually due to paralysis of the respiratory organs. Cases of animal or human poisoning should be handled by a veterinarian or a physician." [emphasis added]
The OARDC staff scientists note that immediate and subsequent symptoms of poisoning from pokeweed include "a burning sensation in the mouth, salivation, gastrointestinal cramps, and vomiting and bloody diarrhea," and that depending upon the amount consumed, more severe symptoms can occur, including "anemia, altered heart rate and respiration, convulsions and death from respiratory failure."[10] If only small quantities of the plant or its extracts are ingested, people and animals may recover within 1 to 2 days.[10][14]
| This section may require cleanup to meet Wikipedia's quality standards. The specific problem is: that the dense factual information appearing is not verified in the 2 USDA sources (so Owen and tags were added). Note: As below, earlier text appeared as phrases, as if cut-and-pasted from bulleted source content. Please help improve this section if you can. (May 2015) |
Per Owen of Iowa State University, pokeweed "[u]sually... grows in rich pasture lands, in recently cleared areas, along fencerows, and in waste places and open spots in woodlands."[1] It is broadly distributed in these places and in fields, and is usually found in edge habitats.[citation needed]
It is adapted to coarse or fine soils with moderate moisture, high calcium tolerance but low salinity tolerance, pH tolerance from 4.7-8.[citation needed] The plant grows well in sun or shade, and readily survives fire due to its ability to resprout from the roots.[citation needed] Pokeweed seeds do not require stratification and are dispersed by berry-feeding birds.[citation needed]
Pokeweed is found in most of the United States, except the northern plains states, and the "Mountain States, Alaska and Hawaii".[original research?][this quote needs a citation] In recent years the plant appears to have increased in populated places.[citation needed][4][not in citation given][15][not in citation given]
| This section may require cleanup to meet Wikipedia's quality standards. The specific problem is: copyediting is required, because the cut-and-paste creating the section left it with bullet (non-sentence) content. Please help improve this section if you can. (May 2015) |
Plant Type:[citation needed] Perennial herbaceous plant which can reach a height of 10 feet (3 metres), but is usually 4 feet (1.2 metres) to 6 feet (2 metres). However, the plant must be a few years old before the root grows large enough to support this size. The stem is often red as the plant matures. There is an upright, erect central stem early in the season, which changes to a spreading, horizontal form later in the season with the weight of the berries. Plant dies back to roots each winter. Stem has a chambered pith.
Leaves:[citation needed] The leaves are alternate with coarse texture with moderate porosity. Leaves can reach sixteen inches in length. Each leaf is entire. Leaves are medium green and smooth with what some characterize as an unpleasant odor.
Flowers:[citation needed] The flowers have 5 regular parts with upright stamens and are up to 0.2 inches (5 mm) wide. They have white petal-like sepals without true petals, on white pedicles and peduncles in an upright or drooping raceme, which darken as the plant fruits. Blooms first appear in early summer and continue into early fall.
Fruit:[citation needed] A shiny dark purple berry held in racemous clusters on pink pedicels with a pink peduncle. Pedicles without berries have a distinctive rounded five part calyx. Fruits are round with a flat indented top and bottom. Immature berries are green, turning white and then blackish purple.
Root:[citation needed] Thick central taproot which grows deep and spreads horizontally. Rapid growth. Tan cortex, white pulp, moderate number of rootlets. Transversely cut root slices show concentric rings. No nitrogen fixation ability.[4][not in citation given][12][not in citation given][better source needed]
| This section may require cleanup to meet Wikipedia's quality standards. The specific problem is: current compiled list entries are not all necessarily important, and contain repeat appearances, misspellings, and likely hidden synonyms. Please help improve this section if you can. (May 2015) |
Various sources discuss notable chemical constituents of the plant.[16][full citation needed][better source needed] Owen of Iowa State University notes that the "entire pokeweed plant contains a poisonous substance similar to saponin" and that the "alkaloid phytolaccine also occurs in small amounts."[1] Heller at the National Library of Medicine notes the two natural products, the alkaloid phytolaccatoxin and phytolaccagenin, as contributing to human poisoning.[8] The Canadian Poisonous Plants Information System echoes the information about phytolaccine and phytolaccatoxin.[9]
Other toxic components include triterpene saponins based on the triterpene genins, phytolaccagenin as noted, and jaligonic acid, phytolaccagenic acid (phytolaccinic acid), esculentic acid, and pokeberrygenin,[17] and phytolaccasides A, B, D, E, and G, and phytolaccasaponins B, E, and G.[18][non-primary source needed][19]
Triterpene saponins isolated from the berries of pokeweed uncharacterized as to toxicity include esculentoside E; and phytolaccasides C and F, and oleanolic acid, and 3-oxo-30-carbomethoxy-23-norolean-12-en-28-oic acid.[17] Triterpene alcohols isolated include α-spinasterol and its glucoside, α-spinasteryl-β-D-glucoside, and a palmityl-derivative, 6-palmytityl-α-spinasteryl-6-D-glucoside, as well as a similarly functionalized stigmasterol derivative, 6-palmityl-Δ7-stigmasterol-Δ-D-glucoside.[17]
Other than starch and various tannins, other small molecule natural products isolated from pokeweed include canthomicrol, astragalin, and caryophyllene.[17] Seeds contain the phenolic aldehyde caffeic aldehyde.[20]
Proteins of interest include various lectins, protein PAP-R, and pokeweed mitogen (PWM),[citation needed] as well as a toxic glycoprotein.[9]
| This section requires expansion with: sourced information on the clear broader ecological roles played, and other horticultural uses. (May 2015) |
Pokeweed berries are reported to be a good food source for songbirds such as gray catbird (Dumetella carolinensis), northern mockingbird (Mimus polyglottos), northern cardinal (Cardinalis cardinals), and brown thrasher (Toxostoma rufum), other bird species including mourning dove (Zenaida macroura), and cedar waxwing (Bombycilla cedrorum), and small animals unaffected by its toxins, including raccoon, opossum, red and gray fox, and the white-footed mouse.[3][21]
Pokeweeds are used as sometime food sources by the larvae of some Lepidoptera species, including the giant leopard moth (Hypercompe scribonia).[22]
Some pokeweeds are grown as ornamental plants, mainly for their attractive berries;[citation needed] a number of cultivars have been selected for larger fruit panicles.[citation needed]
| This section requires expansion with: any valid modern uses based on strong secondary sources. (May 2015) |
There is interest in pokeweed mitogen (PWM) in lymphocyte simulation and anti-infective immunotherapy, and as an anticancer strategy, but effectiveness in human health has yet to be established.[23][24][25]
Pokeweed has been used as a folk remedy by Native Americans, as a purgative, emetic, and heart stimulant,[citation needed] and to treat cancer, itching, and syphilis.[citation needed] Owen notes that "Indians and early settlers used the root in poultices and certain drugs for skin diseases and rheumatism."[1]
In the period in which the aforementioned cases of poisoning occurred (see Toxicity), pokeweed had been used more broadly, for reported anti-rheumatic properties,[citation needed] and it appeared in 1820 in the U.S. Pharmacopoeia as a plant with analgesic and anti-inflammatory properties.[citation needed] The late 19th century herbal, the King's American Dispensatory, describes various various folk medical uses that led individuals to ingest pokeberry products.[26]
Poke is a traditional southern Appalachian food. The leaves and stems can both be eaten, but must be cooked. The leaves have a taste similar to spinach; the stems taste similar to asparagus. Traditionally, poke is boiled, then fatback is added and cooked some more to add flavor.
As noted by the OARDC staff scientists:[10]
"Children are most frequently poisoned... [and] Infants are especially sensitive and have died from eating only a few raw berries. Although boiled young shoots have been eaten as greens and berries cooked in pie, ingestion of any part of the plant cannot be recommended. Adults have been poisoned, sometimes fatally, by eating improperly prepared leaves and shoots, especially if part of the root is harvested with the shoot, and by mistaking the root for an edible tuber." [emphasis added]
As summarized by Owen of Iowa State University:[1]
"Most authorities regard the plant as poisonous. Humans have been poisoned by eating parts of the root, which is the most poisonous part of the plant. Children are often attracted by the bright crimson juice of the berries and can be poisoned by eating the berries... Because of the danger of human poisoning, pokeweed should be eradicated when discovered. This is especially true if the plants are in hedges, gardens, and other areas adjacent to a home where children may be attracted by clusters of berries."
Although all parts of the plant are considered toxic and the root is never eaten and cannot be made edible,[citation needed] the late 19th century herbal, the King's American Dispensatory, describes various various folk medical uses that led individuals to ingest pokeberry products,[26] and festivals still celebrate the plants use in its historical food preparations (see below). Authorities[who?] advise against eating pokeweed even after thrice boiling, as traces of toxins may still remain,[citation needed] and all agree pokeweed should never be eaten uncooked.[citation needed]
Plant toxins from Phytolacca are being explored as a means to control zebra mussels.[27][28]
The toxic extract of pokeweed berries can be processed to yield a red ink or dye.[29][better source needed]
| Nutritional value per 100 g (3.5 oz) | |
|---|---|
| Energy | 84 kJ (20 kcal) |
|
Carbohydrates
|
3.1 g
|
| Sugars | 1.6 g |
| Dietary fiber | 1.5 g |
|
Fat
|
0.4 g
|
|
Protein
|
2.3 g
|
| Vitamins | |
| Vitamin A equiv.
beta-carotene
lutein zeaxanthin
|
(54%)
435 μg (48%)
5200 μg1747 μg
|
| Thiamine (B1) |
(6%)
0.07 mg |
| Riboflavin (B2) |
(21%)
0.25 mg |
| Niacin (B3) |
(7%)
1.1 mg |
| Vitamin B6 |
(9%)
0.111 mg |
| Vitamin C |
(99%)
82 mg |
| Vitamin K |
(103%)
108 μg |
| Trace metals | |
| Calcium |
(5%)
53 mg |
| Iron |
(9%)
1.2 mg |
| Magnesium |
(4%)
14 mg |
| Manganese |
(16%)
0.336 mg |
| Phosphorus |
(5%)
33 mg |
| Potassium |
(4%)
184 mg |
| Sodium |
(1%)
18 mg |
|
Link to USDA Database entry
|
|
|
|
| Percentages are roughly approximated using US recommendations for adults. Source: USDA Nutrient Database |
|
The cultural significance of poke sallet, the cooked greens-like dish made from pokeweed, and the rural poverty reflected in its history,[citation needed] is indicated by the popularity and coverage received by the 1969 hit swamp rock song "Polk Salad Annie", written and first performed by Tony Joe White.[30][31][32][33][better source needed] The opening lyrics run:
Ah, [s]ome of you all never been down South too much
Some of you all never [Incomprehensible]
I' gonna tell you a little story
So you'll understand where I'm talking about
Down there, we have a plant that grows out in the woods and the fieldsAnd it looks some like a turnip green
Everybody calls it Polk salad, now, that's Polk salad
Polk... salad...
Used to know a girl that lived down there andShe'd go out in the evenings and pick a mess of it
Carry it home and cook it for supper
'Cause that's about all they had to eat
But they did all right...[34][33]
The song was covered tens of times, most famously by Elvis Presley (going on to appear in many tens of his albums),[35] by Big Twist and The Mellow Fellows, Tom Jones, Johnny Hallyday, Bill Carlisle, Joe Dassin, and others.[33][better source needed][36][37]
Poke sallet festivals are held annually in several small southern communities, in remembrance of the plant and its historic role, festivals that have evolved to be local community celebrations only remotely related to the plant as a food or medicinal (e.g.,[38] and individual festival references below). Published locations for the continuing festivals include:
Young pokeweed leaves boiled repeatedly to reduce toxins, with water discarded after each boiling, give the "poke sallet" or "poke salit" of these events,[citation needed] but see sections on Toxicity and Food uses above.
| This section requires expansion with: sourced general explanation of if and when this plant might serve to meet nutritional needs, and how toxicity is therein avoided. (May 2015) |
Bearing toxicity information in mind (see section above), nutritional information for boiled and drained pokeberry shoots has been reported (see box).
Bearing toxicity information in mind (see section above), nutritional information per 100 grams dry weight of shoots has been reported:[12][better source needed]
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| リンク元 | 「ヨウシュヤマゴボウ」「Phytolacca americana」 |
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