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Rhubarb

2007 Schools Wikipedia Selection. Related subjects: Food and agriculture;
Plants

                  iRhubarb
         Scientific classification

   Kingdom:  Plantae
   Division: Magnoliophyta
   Class:    Magnoliopsida
   Order:    Caryophyllales
   Family:   Polygonaceae
   Genus:    Rheum
             L.

                                   Species

   About 60, including:
     * R. nobile
     * R. officinale
     * R. palmatum
     * R. rhabarbarum
     * R. rhaponticum

   Rhubarb is a perennial plant that grows from thick short rhizomes,
   comprising the genus Rheum. The large, somewhat triangular leaf blades
   are elevated on long, fleshy petioles. The flowers are small,
   greenish-white, and borne in large compound leafy inflorescences.

Cultivation and use

   The plant is indigenous to Asia, and many suggest that it was often
   used by the Mongolians; particularly, the Tatars tribes of the Gobi.
   Varieties of rhubarb have a long history as medicinal plants in
   traditional Chinese medicine, but the use of rhubarb as food is a
   relatively recent innovation, first recorded in 17th century England,
   after affordable sugar became available to common people.

   Rhubarb is now grown in many areas, primarily for its fleshy petioles,
   commonly known as rhubarb sticks. In temperate climates rhubarb is one
   of the first food plants to be ready for harvest, usually in mid to
   late Spring (April/May in the Northern Hemisphere, October/November in
   the Southern). The petioles can be cooked in a variety of ways. Stewed,
   they yield a tart sauce that can be eaten with sugar or used as filling
   for pies (see rhubarb pie), tarts, and crumbles. This common use led to
   the slang term for rhubarb, "pie plant" (piestengel in German). Cooked
   with strawberries as a sweetener, rhubarb makes excellent jam. It can
   also be used to make wine.

   In former days, a common and affordable sweet for children in parts of
   the United Kingdom was a tender stick of rhubarb, dipped in sugar. In
   the UK the first rhubarb of the year is grown by candlelight in dark
   sheds dotted around the noted " Rhubarb Triangle" of Wakefield, Leeds
   and Morley.
   A Homemade Rhubarb Pie
   Enlarge
   A Homemade Rhubarb Pie

   In warm climates, rhubarb will grow all year round, but in colder
   climates the parts of the plant above the ground disappear completely
   during winter, and begin to grow again from the root in early spring.
   It can be forced, that is, encouraged to grow early, by raising the
   local temperature. This is commonly done by placing an upturned bucket
   over the shoots as they come up.

Species

   The plant is represented by about 60 extant species. Those most
   commonly used in cooking are the Garden Rhubarb (R. rhabarbarum) and R.
   rhaponticum, which, though a true rhubarb, bears the common name False
   Rhubarb. The drug rheum is prepared from the rhizomes and roots of
   another species, R. officinale or Medicinal Rhubarb. This species is
   also native to Asia, as is the Turkey Rhubarb (R. palmatum). Another
   species, the Sikkim Rhubarb (R. nobile), is limited to the Himalayas.

   Rhubarb is used as a strong laxative and for its astringent effect on
   the mucous membranes of the mouth and the nasal cavity.

   Rheum species have been recorded as larval food plants for some
   Lepidoptera species including Brown-tail, Buff Ermine, Cabbage Moth,
   Large Yellow Underwing, The Nutmeg, Setaceous Hebrew Character and
   Turnip Moth.

Toxic effects

   Rhubarb
   Enlarge
   Rhubarb
   Rhubarb flower.
   Enlarge
   Rhubarb flower.

   Rhubarb leaves contain poisonous substances. Rhubarb leaf poisoning is
   most often caused by oxalic acid, a corrosive and nephrotoxic acid that
   is abundantly present in many plants. The LD50 for pure oxalic acid is
   predicted to be about 375 mg/ kg body weight, or about 25 g for a 65 kg
   human. While the oxalic acid content of rhubarb leaves can vary, it
   averages about 0.5%, so a rather unlikely five kilograms of the
   extremely sour leaves would have to be consumed to reach an LD50 dose.
   In the petioles, the amount of oxalic acid is much lower, especially
   when harvested before mid-June (in the northern hemisphere), but it is
   still enough to cause slightly rough teeth.

   The roots and stems are rich in anthraquinones, such as emodin and
   rhein. These substances are cathartic and laxative, which explains the
   sporadic abuse of Rhubarb as a slimming agent. Anthraquinones are
   yellow or orange and may colour the urine.

Other uses of the word

   It is or was common for a crowd of extras in acting to shout the word
   "rhubarb" repeatedly and out of step with each other, to cause the
   effect of general hubbub. As a result, the word "rhubarb" sometimes is
   used to mean "length of superfluous text in speaking or writing", or a
   general term to refer to irrelevant chatter by chorus or extra actors.

   Possibly from this usage, possibly from a variant on " rube", or
   perhaps some of both, the word also denotes a loud argument. The term
   has been most commonly used in baseball.

   In the 1989 film Batman, The Joker ( Jack Nicholson) tells Bruce Wayne
   ( Michael Keaton) to "never rub another man's rhubarb". The term was
   used as a threat to Bruce Wayne warning him to leave both men's love
   interest Vicki Vale ( Kim Basinger) alone.

Trivia

   Rhubarb is sometimes considered a vegetable (based on its appearance
   and being a close relative of Sorrel) and sometimes considered a
   (culinary) fruit (based on how it is eaten).

   "Donkey Rhubarb" is used as a term when referring to the drug-oriented
   uses of cannabis. For example, the word takes the place of words such
   as "weed" or "pot" in some places in Canada.

   Rhubarb, specifically in the form of the ficitious product
   "Be-Bob-A-Re-Bob Rhubarb Pie", is frequently mentioned in ' A Prarie
   Home Companion'. In the 2006 film adaptation of the program, the pies
   are not mentioned, but rhubarb itself is, including an explanation of
   the source of the name.
   Retrieved from " http://en.wikipedia.org/wiki/Rhubarb"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
