|
Rheum palmatum
 Rheum palmatum is a species of flowering plant in the knotweed family Polygonaceae. It is commonly called Chinese rhubarb,[1][2] ornamental rhubarb,[3] Turkey rhubarb[2] or East Indian rhubarb.[2] Rheum palmatum is a herbaceous perennial related to the edible rhubarb. It is primarily used in traditional medicine, and as an ornamental subject in the garden. TaxonomyAgnia Losina-Losinskaja proposed classifying it in the section Palmata in the Flora SSSR in 1936.[4] In the 1998 Flora Republicae popularis Sinicae A. R. Li maintains this classification for this species.[5] Description  Its lobed leaves are large, jagged and hand-shaped, growing in width to two feet, but sometimes up to a full meter (3ft 3in) in width and length). The tiny pink flowers are in panicles up to five feet (1.5 meters) in height.[6] Chinese rhubarb has thick, deep roots.[7] Similar speciesThe species Rheum tanguticum is closely related to R. palmatum.[8] R. palmatum can be distinguished from R. × hybridum, the garden rhubarb we eat, by size; while garden rhubarb only grows to a few feet in height, Chinese rhubarb can grow to six feet.[7] KaryotypyR. palmatum has a chromosome count of 2n=22.[5] DistributionIt is native in the regions of western China, northern Tibet, and the Mongolian Plateau.[7] Folk medicine Rheum tanguticum, Rheum palmatum, R. rhabarbarum and R. officinale and a few others, are all harvested for their roots, which are used as a herbal medicine.[8] Rheum palmatum (or dahuang) is an important crop that has been used in traditional Chinese medicine for over 2,000 years.[9] The dried roots of Chinese rhubarb became one of the most prominent items traded along the Silk Road.[7] Imported roots of various rhubarb species were widely used in Europe for hundreds of years before the identity of the plant was eventually discovered.[7] Some of the common names associated with Rheum palmatum – "Russian rhubarb", "Turkey rhubarb", and "Indian rhubarb" – are directly affiliated with the trade routes for rhubarb from China.[7] The root is known for its purported purging effects and suppressing fever.[7] In ancient China, rhubarb root was taken to try to cure stomach ailments and as a "cathartic" (an agent used to relieve constipation), and used as a poultice for "fevers and edema" (swelling caused by fluid retention in the body tissues).[7] It was given its Latin name by Carolus Linnaeus in the year 1759 and first grown in Britain around 1762.[7] The first International Symposium on Rhubarb was held in China in 1990. Its objective was to verify the scientific data and treatment of Chinese Rhubarb used by Chinese pharmacopoeias.[7] Health risksPregnant women should avoid all intake of the plant since it may cause uterine stimulation.[7] If taken for an extended amount of time, adverse effects include: "hypertrophy of the liver, thyroid, and stomach, as well as nausea, griping, abdominal pain, vomiting, and diarrhea."[7] Though the root of the Chinese rhubarb is a key facet of herbal medicine, its leaves can actually be poisonous if consumed in large amounts due to the oxalic acid content.[7] Patients with "arthritis, kidney problems, inflammatory bowel disease, or intestinal obstruction" should refrain from consumption.[7] CultivationOrnamental use With its large palmate leaves and tall panicles of pink flowers, Rheum palmatum is a bold statement plant for the temperate garden, that grows up to 2.5 m (8.2 ft) tall and broad. It is hardy down to −20 °C (−4 °F).[10] It is propagated by seed in the spring, or by root division in spring or autumn.[8] It grows best in full sunlight in well-drained soil.[8] The following cultivars have gained the Royal Horticultural Society's Award of Garden Merit:-[11]
Farming as medicinal herbSince it is the roots and rhizome which serve as this plant's source of medicinal usage, special care is taken in their preparation.[7] When 6–10 years old, the rhizomes of these plants are removed from the ground in the autumn when both its stems and leaves changed to yellow wild.[8] Furthermore, the lateral rootlets and the crown are removed, leaving only the root.[8] Any debris around the root is cleaned off, the coarse exterior bark removed, and the root cut and divided into cube-like pieces to increase its surface area, thereby decreasing the time needed for drying.[7] References
 Wikimedia Commons has media related to Rheum palmatum.
|
||||||||||||||||||||||||||||
Portal di Ensiklopedia Dunia
