IVY

Hedera Helix

Ivy Family [Araliaceae]

14th April 2008, Duckington, Cheshire.

Photo: © RWD

25th Sept 2008, Silverdale, Cumbria.

Photo: © RWD

22nd Aug 2007, Llanfairfechan, North Wales.

Photo: © RWD

15th Dec 2008, Talkinhead, Cumbria.

Photo: © Jeremy Roberts

25th Sept 2008, Silverdale, Cumbria.

Photo: © RWD

22nd Aug 2007, Llanfairfechan, North Wales.

Photo: © RWD

25th Sept 2008, Silverdale, Cumbria.

Photo: © RWD

16th Sept 2009, Silverdale, Cumbria.

Photo: © RWD

19th March 2009, Appley Bridge, Lancs.

Photo: © RWD

19th March 2009, Appley Bridge, Lancs.

Photo: © RWD

22nd Aug 2007, Llanfairfechan, North Wales.

Photo: © RWD

Photo: © RWD

Photo: © RWD

POISON IVY Ivy is Not to be confused with: Poison Ivy (previously called rhus toxicodendron but now called toxicodendron radicans). The Americans call our Ivy English Ivy to distinguish it from their Poison Ivy, which is not an Ivy at all, but a highly toxic Rhus Tree or Toxicodendron, as are Japanese Lac Trees (toxicodendron vernicifera) and are possibly the most dangerous species of plants known. Although (English) Ivy is poisonous, it's poison is incomparable to that of Poison Ivy. The smoke from some species of burning Toxicodendron Trees easily has the potential to kill or seriously harm anyone in the neighbourhood. Just brushing against a branch or leaf can inflict a dangerous allergic and painful rash or wheal that is extremely reluctant to heal. Luckily, Poison Ivy does not grow naturally in Britain, but can be planted, as can Japanese Lac. Poison Sumach (toxicodendron vernix and Poison Oak (toxicodendron diversilobum) are other non-native trees that possess much the same poisonous substances as Poison Ivy to a greater or lesser extent. It should be pointed out that some common garden Sumach or Rhus Trees in Britain can also be very harmful (and the bark should not be touched, let alone the sap!), but are not quite in the same league as Poison Ivy or Japanese Lac.

The toxic compounds present in Toxicodendron Trees are Urushiols and Laccols, of which there are a whole series of each, differing only in the number and position of double bonds. Laccols and Urushiols themselves differ only in the length of their hydrocarbon side-chains, 15 carbon atoms for urushiols, and 17 for laccols. Urushiols and Laccols are not confined to just Toxicodendron Trees, but to other non-native plants too, including Ginko, Anacardiaceae (cashew nuts, etc), Melanorrhoeas and Chloraphora species.

Japanese Lac trees are famous for their ability to produce Japan or Black Japan, a lacquer used to give metallic bowls a shiny black coating in a process known as Japaning. The coating is due entirely to the polymerization of a whole profusion of differing and highly dangerous Urushiols and Laccols (collectively known as Urushioids) present in the sap of the Japanese Lac Tree. Once polymerized, the lacquer is quite safe and non-toxic.

The Urushoids shown above are based on Catechol with an added long carbon side-chain, R, on the meta position. In the case of Urushoids, the side-chain is 15 carbon atoms long, and in the case of Laccols it is 17 carbon atoms long. Both can have double bonds, and these are more prevalent at carbon-positions 8, 11 and 14, but can be at other positions. Both Urushiol (I) and Laccol (I) have no double bonds. There are two cis/trans isomers of Urushiol (III), whereas Laccol (III) is only present in one form. Note that there is no naturally occurring Laccol (IV). Just a small selection of Urushiols and Laccols are presented here, those most likely to be present in Toxicodendron Trees to a greater extent. The actual extent for each particular Toxicodendron varies: Urushiol (III) and Laccol (III) are the urushoids with the highest concentration in Poison Ivy.

The 15 and 17 carbon atom chains in Urushiols and Laccols respectively, are thought to be derived from Palmitic Acid and Stearic Acid respectively, with 16 and 18 carbon atoms respectively. Continuing this line of argument, it occurs to the author that Laccols (II) could be derived from Oleic Acid, and Laccols (III) from Linoleic Acid.

Because Poison Ivy does not occur naturally in Britain, but is nevertheless interesting, I have put this section in the Wild Flower Finder.

Not to be confused with: Poison Ivy!

Lookee-Likees :

Uniquely identifiable characteristics

Distinguishing Feature :

No relation to : Ivy Broomrape, Ground Ivy, Ivy-Leaved Toadflax, Ivy-Leaved Crowfoot or Ivy-Leaved Bellflower [plants with similar name]

The sap of Ivy, if it comes into contact with the skin, can cause dermatitis, sometimes with severe blistering and inflammation.

POLYACETYLENES
Falcarinols are naturally occurring acetylinic alcohols (note the two highly energetic triple bonds, extremely unusual in the natural world) present in (English) Ivy. They are strongly fungicidal, a natural defence from invading organisms. In their fungicidal role, they often function as phytoalexins, the mammalian equivalent being anti-bodies. In Ivy, they are both allergenic and irritant to humans. Another polyacetylene is also present: 11-dehydrofalcarinol. Falcarinol (aka Panaxynol) is present in Ivy and in Hemlock Water Dropwort (Oenanthe crocata) and causes contact dermatitis in certain individuals when the plants are handled.
Falcarinols also occur in the roots of carrots, their concentration increasing with prolonged storage. In carrots they can cause allergenic contact dermatitis, an occupational hazard for carrot pickers. Because of the highly reactive triple bonds, polyacetylenes such as these are very toxic.
The flowers of Ground Elder contain the highest concentration of falcarindiol, up to 9% by weight. Falcarindiol has been shown to possess anti-cancer activity. Some umbellifers also contain compounds containing triple bonded carbon atoms.

HEDERAGENIN
Hederagenin is a saponin and pre-cursor to many of the compounds present in Ivy, some of which are shown below. It is not a main component of Ivy. Bayogenin is almost identical except that an extra 'OH' is added on the carbon atom just above the left-most 'HO' group.

HEDERASAPONINS

Ivy also contains a number of hederasaponins, which, by partial hydrolysis and loss of sugars, leads to alpha-hederin, beta-hederin and hederacolchiside A1, which are being investigated for their possible use in treating lung cancer and leishmaniosis, caused by a water-borne parasite which lives in tropical areas.

ANY TEXT GOES HERE

Distribution
family8ivy family8Araliaceae

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Hedera