Bloodroot (Sanguinaria canadensis) is a perennial, herbaceous flowering plant native to eastern North America from Nova Scotia, Canada southward to Florida, United States. It is the only species in the genus Sanguinaria, and is included in the family Papaveraceae and most closely related to Eomecon of eastern Asia.
Bloodroot is also known as bloodwort, red puccoon root, and sometimes pauson. Bloodroot has also been known as tetterwort in America, although that name is used in Britain to refer to Greater Celandine.
Bloodroot is a variable species growing from 20 to 50 cm tall, normally with one large, sheath-like basal multi-lobed leaf up to 12 cm across. The flowers are produced from March to May, with 8-12 delicate white petals and yellow reproductive parts. The flowers appear over clasping leaves while blooming. Plants are variable in leaf and flower shape and have in the past been separated out as different subspecies due to these variable shapes; currently most taxonomic treatments lump these different forms into one highly variable species. Bloodroot stores sap in an orange colored rhizome, that grows shallowly under or at the soil surface. Over many years of growth, the branching rhizome can grow into a large colony. Plants start to bloom before the foliage unfolds in early spring and after blooming the leaves expand to their full size and go summer dormant in mid to late summer. Plants are found growing in moist to dry woods and thickets, often on flood plains and near shores or streams on slopes, they grow less frequently in clearings and meadows or on dunes, and are rarely found in disturbed sites. The flowers are pollinated by small bees and flies, seeds develop in elongated green pods 40 to 60 mm in length and ripen before the foliage goes dormant. The seeds are round in shape and when ripe are black to orange-red in color. Deer will feed on the plants in early spring.
Caution: the sap is toxic; see below for further details.
Bloodroot is one of many plants whose seeds are spread by ants, a process called myrmecochory. The seeds have a fleshy organ called an elaiosome that attracts ants. The ants take the seeds to their nest, where they eat the elaiosomes, and put the seeds in their nest debris, where they are protected until they germinate. They also get the added bonus of growing in a medium made richer by the ant nest debris.
The double flowering forms are prized by gardeners for their large showy white flowers, which are produced very early in the gardening season. Bloodroot flower petals are shed with in a day or two of pollination so the flower display is short lived. The double forms bloom much longer than the normal forms, the double flowers are made up of stamens that have been changed into petal looking like parts, making pollination more difficult.
Bloodroot produces morphine-like benzylisoquinoline alkaloids, primarily the toxin sanguinarine. The alkaloids are transported to and stored in the rhizome. Comparing the biosynthesis of morphine and sanguinarine, the final intermediate in common is (S)-reticuline.   A number of plants in Papaveraceae and Ranunculaceae, as well as plants in the genus Colchicum (family Colchicaceae) and genus Chondodendron (family Menispermaceae), also produce such benzylisoquinoline alkaloids.
Plant geneticists have identified and sequenced genes which produce the enzymes required for this production. One enzyme involved is CYP80B1, which produces (S)-3'-hydroxy-N-methylcoclaurine from (S)-N-methylcoclaurine.
Sanguinarine kills animal cells by blocking the action of Na+/K+-ATPase transmembrane proteins. As a result, applying bloodroot to the skin may destroy tissue and lead to the formation of a large scab, called an eschar. Bloodroot and its extracts are thus considered escharotic.
In spite of supposed curative properties and historical use by Native Americans as an emetic, internal use is inadvisable. Although applying escharotic agents, including bloodroot, to the skin is sometimes suggested as a home treatment for skin cancer, these attempts can be severely disfiguring. Salves derived from bloodroot cannot be relied on to remove an entire malignant tumor. Microscopic tumor deposits may remain after visible tumor tissue is burned away, and case reports have shown that in such instances tumor has recurred and/or metastasized.
On 13 Aug 2005, U.S. news media reported that Dan Raber (of Georgia, United States) came under felony investigation for dispensing bloodroot paste to women with various ailments including breast cancer. It was reported that nine women developed disfiguring destruction of skin and underlying tissue. Reports also indicated that Lois March, M.D., who is a practicing physician in Cordele, Georgia, has also come under U.S. FDA investigation for her role in prescribing pain medication to Raber's disfigured customers while their use of bloodroot was ongoing. 
The United States FDA has approved the inclusion of sanguinarine in toothpastes as an antibacterial or anti-plaque agent.    Currently, it is believed that this use may cause leukoplakia, a premalignant oral lesion. On 24 Nov 2003, the Colgate-Palmolive Company of Piscataway, New Jersey, United States commented by memorandum to the United States Food and Drug Administration that then-proposed rules for levels of sanguinarine in mouthwash and dental wash products were lower than necessary. However, this conclusion is controversial.
Some animal food additives sold and distributed in Europe such as Phytobiotics' Sangrovit contain sanguinarine and chelerythrine. On 14 May 2003, Cat Holmes reported in Georgia Faces that Jim Affolter and Selima Campbell, horticulturists at the University of Georgia College of Agricultural and Environmental Sciences, were meeting with Phytobiotics to relate their research into commercial cultivation of bloodroot. It is also used in the mole remover Dermatend.
Bloodroot extracts have also been promoted by some supplement companies as a treatment or cure for cancer, but the U.S. Food and Drug Administration has listed some of these products among its "125 Fake Cancer 'Cures' Consumers Should Avoid".
The plant was used as a dye and for an herbal remedy by the native population. A break in the surface of the plant, especially the roots, reveals a reddish sap.
In physician William Cook's 1869 work The Physiomedical Dispensatory is recorded a chapter on the uses and preparations of bloodroot. described tinctures and extractions, and also included at least the following cautionary report:
Greater Celandine (Chelidonium majus), a member of the Poppy family (Papaveraceae) was used in Colonial America as a wart remedy. Bloodroot has been similarly applied in the past. This may explain the multiple American and British definitions of "Tetterwort" in 1913.