| Aristolochia | |
|---|---|
| Aristolochia baetica | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Magnoliophyta |
| (unranked): | Magnoliids |
| Order: | Piperales |
| Family: | Aristolochiaceae |
| Subfamily: | Aristolochioideae |
| Genus: | Aristolochia L.[1] |
| Species | |
|
Over 500, see text |
|
| Synonyms | |
|
Hocquartia Dum. |
|
Aristolochia is a large plant genus with over 500 species. Collectively known as birthworts, pipevines or Dutchman's pipes, they are the namesake of the family (Aristolochiaceae). They are widespread and occur in the most diverse climates. Some species, like A. utriformis and A. westlandii, are threatened with extinction.
Isotrema is usually included here, but might be a valid genus. If so, it contains those species with a three-lobed calyx.
Contents |
Aristolochia is a genus of evergreen and deciduous woody vines and herbaceous perennials. The smooth stem is erect or somewhat twining. The simple leaves are alternate and cordate, membranous, growing on leaf stalks. There are no stipules.
The flowers grow in the leaf axils. They are inflated and globose at the base, continuing as a long perianth tube, ending in a tongue-shaped, brightly colored lobe. There is no corolla. The calyx is one to three whorled, and three to six toothed. The sepals are united (gamosepalous). There are six to 40 stamens in one whorl. They are united with the style, forming a gynostemium. The ovary is inferior and is four to six locular.
These flowers have a specialized pollination mechanism. The plants are aromatic and their strong scent[2] attracts insects. The inner part of the perianth tube is covered with hairs, acting as a fly-trap. These hairs then wither to release the fly, covered with pollen.
The fruit is dehiscent capsule with many endospermic seeds.
The common names "Dutchman's Pipe" and "Pipevine" (e.g. Common Pipevine, A. durior) are an allusion to old-fashioned meerschaum pipes at one time common in the Netherlands and Northern Germany. "Birthwort" (e.g. European Birthwort, A. clematitis) refers to these species' flower shape, resembling a birth canal. Some reference books[3][4] state that the scientific name Aristolochia was developed from Ancient Greek aristos (άριστος) "best" + locheia (λοχεία), "childbirth" or "childbed".
The species A. clematitis was highly regarded as a medicinal plant since the ancient Egyptians, Greeks and Romans, and on to until the Early Modern era; it also plays a minor role in traditional Chinese medicine. Due to its resemblance to the uterus, the doctrine of signatures held that "birthwort" was useful in childbirth. A preparation was given to women in labor to expel the placenta, as noted by the herbalist Dioscurides in the first century AD. Despite its presence in ancient medicine, Aristolochia is known to contain the lethal toxin aristolochic acid.
Aristolochia has been shown to be both a potent carcinogen and kidney toxin. Herbal compounds containing Aristolochia are classified as a Group 1 carcinogen by the International Agency for Research on Cancer.[5] Epidemiological and laboratory studies have identified Aristolochia to be a dangerous kidney toxin; Aristolochia has been shown associated with more than 100 cases of kidney failure.[6] Furthermore, it appears as if contamination of grain with European Birthwort (A. clematitis) is a cause of Balkan nephropathy, a severe renal disease occurring in parts of southeast Europe.[7]
In July 1999, two cases of nephropathy associated with the use of Chinese botanical preparations were reported in the United Kingdom. These preparations were shown to contain aristolochic acid. Biopsy samples showed extensive loss of cortical tubules with interstitial fibrosis. In 1993, a series of end-stage renal disease cases had been reported[8][9] from Belgium associated with a weight loss treatment, where Stephania tetrandra in a herbal preparation was suspected of being substituted with Aristolochia fangchi.[10][11] More than 105 patients were identified with nephropathy following the ingestion of this preparation from the same clinic from 1990-1992. Many required renal transplantation or dialysis. Subsequent follow up of these patients has shown they are at an increased risk of urological cancer.
Note that in TCM neither plant is used for prolonged weight loss treatments. Therefore, the term "Chinese-herb nephropathy" that was coined by Nortier et al. (N Engl J Med 2000; 342:1686-1692) is inaccurate. It gives the false impression that TCM promotes the use of such a herb, when in fact the Aristolochia was introduced into TCM formulations by subterfuge or error, and without the knowledge of TCM practitioners. See also Name confusion
Despite the toxic properties of aristolochic acid, naturopaths claim that a decoction of birthwort stimulates the production and increases the activity of leukocytes (white blood cells), or that pipevines contain a disinfectant which assists in wound healing. Also, Aristolochia bracteolata is colloquially known as "Worm Killer" due to supposed antihelminthic activity.
Aristolochia has also been used as a reptile repellent. A. serpentaria (Virginia Snakeroot) is thus named because the root was used to treat snakebite, as "so offensive to these reptiles, that they not only avoid the places where it grows, but even flee from the traveler who carries a piece of it in his hand".[12] A. pfeiferi, A. rugosa and A. trilobata are also used in folk medicine to cure snakebites. Aristolochic acid does indeed appear to bind and deactivate the Phospholipase A2 of certain snake venoms.
Aristolochia didyma, or "yawar panga" by its local name, is traditionally used in South America as a powerful purgative. It is sometimes taken to purify the body a few days before an Ayahuasca session.
Due to their spectacular flowers, several species are used as ornamental plants., notably the hardy A. durior of eastern North America, which was one of John Bartram's many introductions to British gardens; in 1761 Bartram sent seeds he had collected in the Ohio River Valley to Peter Collinson in London, and Collinson gave them to the nurseryman James Gordon at Mile End to raise. The vine was soon adopted for creating for arbors "a canopy impenetrable to the rays of the sun, or moderate rain," as Dr John Sims noted in The Botanical Magazine, 1801.[13]
Many species of Aristolochia are food for larvae of Lepidoptera, namely swallowtail butterflies. These become unpalatable to most predators by eating the plants. Lepidoptera feeding on pipevines include:
In Australia the invasive Aristolochia littoralis is fatal to the caterpillars of Ornithoptera euphorion and O. richmondia and threatens to displace their proper host, A. tagala.