Aristolochia

My husband and I go to Garden Works quite often, but I've never seen before this plant. I have been amazed by unusual flowers of Aristolochia. 
 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.

Dutchman’s Pipe has an interesting pollination technique. The nectar inside the flower has a foul smell that attracts flies and once inside the curled flower the flies can’t escape. Because this is trick is reminiscent of many plants’ lure in order to feed off of insects, it may seem like this is the end of the fly. Not exactly. The fly hangs around inside the Dutchman’s pipe and dines on some nectar. At the same time, pollen from a previously visited blossom is transferred and pollination begins. Once the flower’s stamen has fully matured, the flower opens up and the fly is set free. Of course, he now carries the pollen from the mature stamen with him.

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. The scientific name Aristolochia was developed from Ancient Greek aristos (άριστος) "best" + locheia (λοχεία), "childbirth" or "childbed,", relating to its known ancient use in childbirth. The Roman orator Cicero records a different tradition, that the plant was named for the otherwise unknown individual with the common Greek name Aristolochos, who had learned from a dream that it was an antidote for snake bites.
Due to their spectacular flowers, several species are used as ornamental plants.  The vine was soon adopted for creating for arbors "a canopy impenetrable to the rays of the sun, or moderate rain." 

Requirements

Sunny (full sun) to shaded Position, protection from wind beneficial. Nutrient rich soil, fresh and moist with regular water provision, especially in sunny positions, to balance the high evapo-transpiration rate. The plants tolerate nearly everything, as long as they are watered regularly. Fertilising is beneficial. Aristolochia tomentosa (Woolly Dutchman's Pipe) is hardier and requires less attention.

Herbalism, toxicity and carcinogenicity
The species Aristalochia 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 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 upon delivery to expel the placenta, as noted by the herbalist Dioscurides in the first century CE. Despite its presence in ancient medicine, Aristolochia is known to contain the lethal toxin aristolochic acid.

The Bencao Gangmu, compiled by Li Shi-Zhen in the latter part of the sixteenth century, was based on the author’s experience and on data obtained from earlier herbals; this Chinese herbal classic describes 1892 "drugs" (with 1110 drawings), including many species of Aristolochia. For 400 years, the Bencao Gangmu remained the principal source of information in traditional Chinese medicine and the work was translated into numerous languages, reflecting its influence in countries other than China. In the mid-twentieth century, the Bencao Gangmu was replaced by modern Materia Medica, the most comprehensive source being Zhong Hua Ben Cao (Encyclopedia of Chinese Materia Medica), published in 1999. The Encyclopedia lists 23 species of Aristolochia, though with little mention of toxicity. The Chinese government currently lists the following Aristolochia herbs: A. manshuriensis (stems), A. fangchi (root), A. debilis (root and fruit), and A. contorta ( fruit), two of which (mou dou ling and quingmuxiang) appear in the 2005 Pharmacopoeia of the People's Republic of China.

In traditional Chinese medicine Aristolochia species are used for certain forms of acute arthritis and edema.

Despite the toxic properties of aristolochic acid, naturopaths claim that a decoction of birthwort stimulates the production and increases the activity of 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 taxa have also been used as reptile repellents. 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". A. pfeiferi, A. rugosa, and A. trilobata are also used in folk medicine to cure snakebites.

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