Aesculus hippocastanum

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Aesculus hippocastanum
Aesculus hippocastanum, Horse-chestnut planted as a feature tree in a park
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Sapindales
Family: Sapindaceae
Genus: Aesculus
Species: A. hippocastanum
Binomial name
Aesculus hippocastanum
L.

Aesculus hippocastanum is a large deciduous tree, commonly known as horse-chestnut or conker tree.

Contents

Distribution [edit]

Aesculus hippocastanum is native to a small area in the Pindus Mountains mixed forests and Balkan mixed forests of South East Europe.[1] It is widely cultivated in streets and parks throughout the temperate world.

Growth [edit]

A. hippocastanum grows to 36 metres (118 ft) tall, with a domed crown of stout branches; on old trees the outer branches often pendulous with curled-up tips. The leaves are opposite and palmately compound, with 5–7 leaflets; each leaflet is 13–30 cm long, making the whole leaf up to 60 cm across, with a 7–20 cm petiole. The leaf scars left on twigs after the leaves have fallen have a distinctive horseshoe shape, complete with seven "nails". The flowers are usually white with a small red spot; they are produced in spring in erect panicles 10–30 cm tall with about 20–50 flowers on each panicle. Usually only 1–5 fruit develop on each panicle; the shell is a green, spiky capsule containing one (rarely two or three) nut-like seeds called conkers or horse-chestnuts. Each conker is 2–4 cm diameter, glossy nut-brown with a whitish scar at the base.[2]

Etymology [edit]

The common name "horse-chestnut" (often unhyphenated) is reported as having originated from the erroneous belief that the tree was a kind of chestnut (though in fact only distantly related), together with the observation that eating the fruit cured horses of chest complaints[3] despite this plant being poisonous to horses.

Uses [edit]

Cultivation for its spectacular spring flowers is successful in a wide range of temperate climatic conditions provided summers are not too hot, with trees being grown as far north as Edmonton, Alberta, Canada,[4] the Faroe Islands,[5] and Harstad, Norway.

This tree[6] and the red flowering cultivar A. hippocastanum 'Baumannii'[7] have gained the Royal Horticultural Society's Award of Garden Merit.

In Britain and Ireland, the nuts are used for the popular children's game conkers. During the two world wars, horse-chestnuts were used as a source of starch which in turn could be fermented via the Clostridium acetobutylicum method devised by Chaim Weizmann to produce acetone. This acetone was then used as a solvent which aided in the process of ballistite extrusion into cordite, which was then used in military armaments.

A selection of fresh conkers from a horse-chestnut

The nuts, especially those that are young and fresh, are slightly poisonous, containing alkaloid saponins and glucosides. Although not dangerous to touch, they cause sickness when eaten; consumed by horses, they can cause tremors and lack of coordination.[8] Some mammals, notably deer, are able to break down the toxins and eat them safely.[citation needed]

In the past, horse-chestnut seeds were used in France and Switzerland for whitening hemp, flax, silk and wool. They contain a soapy juice, fit for washing of linens and stuffs, for milling of caps and stockings, etc., and for fulling of cloth. For this, 20 horse-chestnut seeds were sufficient for six litres of water. They were peeled, then rasped or dried, and ground in a malt or other mill. The water must be soft, either rain or river water; hard well water will not work. The nuts are then steeped in cold water, which soon becomes frothy, as with soap, and then turns milky white. The liquid must be stirred well at first, and then, after standing to settle, strained or poured off clear. Linen washed in this liquid, and afterwards rinsed in clear running water, takes on an agreeable light sky-blue colour. It takes spots out of both linen and wool, and never damages or injures the cloth.

In Bavaria the chestnut[clarification needed] is the typical tree for a beer garden. Originally they were planted for their deep shade which meant that beer cellar owners could cut ice from local rivers and lakes in winter to cool the Märzen Lager beer well into summer. Nowadays guests enjoy the shade to keep their heads cool.

Horse-chestnuts have been threatened by the leaf-mining moth Cameraria ohridella, whose larvae feed on horse chestnut leaves. The moth was described from Macedonia where the species was discovered in 1984 but took 18 years to reach Britain.[9]

The flower is the symbol of the city of Kiev, capital of Ukraine.[10] Although the horse-chestnut is sometimes known as the buckeye, this name is generally reserved for the New World members of the Aesculus genus.

Medical uses [edit]

The seed extract standardized to around 20 percent aescin (escin) is used for its venotonic effect, vascular protection, anti-inflammatory and free radical scavenging properties.[11] [12] Primary indication is chronic venous insufficiency.[13] [12]A recent Cochrane Review found the evidence suggests that Horse Chestnut Seed Extract is an efficacious and safe short-term treatment for chronic venous insufficiency.[14]

Aescin reduces fluid leaks to surrounding tissue by reducing both the number and size of membrane pores in the veins.[medical citation needed]

Commonly used dose: Oral use, 250–300 mg extract standardized to around 20 percent aescin, or 50 mg purified β-aescin a day for 4 to 10 weeks, or 10-20 mg i.v. Topical as a cream with 2% aescin. The bioavailability of a film coated tablet of purified β-aescin with sustained release, as well as whole extract is reportedly high. Although these doses seem excessive based on a target value of no more than 340 μg aescin/kg and high bioavailability of oral intake, the above doses appear to be in common use.

Safety in medical use [edit]

Two preparations are considered; whole horsechestnut extract (whole HCE) and purified β-aescin. Historically, whole HCE has been used both for oral and IV routes (as of year 2001). The rate of adverse effects are low, in a large German study, 0.6 %, consisting mainly of gastrointestinal symptoms. Dizziness, headache and itching have been reported. One serious safety issue is rare cases of acute anaphylactic reactions, presumably in a context of whole HCE. Purified β-aescin would be expected to have a better safety profile.

Another is the risk of acute renal failure, "when patients, who had undergone cardiac surgery were given high doses of horse chestnut extract i.v. for postoperative oedema. The phenomenon was dose dependent as no alteration in renal function was recorded with 340 μg kg−1, mild renal function impairment developed with 360 μg kg−1 and acute renal failure with 510 μg kg−1". [15] This almost certainly took place in a context of whole HCE.

Three clinical trials was since performed to assess the effects of aescin on renal function. A total of 83 subjects were studied; 18 healthy volunteers given 10 or 20 mg iv. for 6 days, 40 in-patients with normal renal function given 10 mg iv. two times per day (except two children given 0.2 mg/kg), 12 patients with with cerebral oedema and normal renal function given a massive iv. dose on the day of surgery (49.2 ± 19.3 mg) and 15.4 ± 9.4 mg daily for the following 10 days and 13 patients with impaired renal function due to glomerulonephritis or pyelonephritis, who were given 20–25 mg iv. daily for 6 days. "In all studies renal function was monitored daily resorting to the usual tests of renal function: BUN, serum creatinine, creatinine clearance, urinalysis. In a selected number of cases paraaminohippurate and labelled EDTA clearance were also measured. No signs of development of renal impairment in the patients with normal renal function or of worsening of renal function in the patients with renal impairment were recorded." It is concluded that aescin has excellent tolerability in a clinical setting.[16]

Raw Horse Chestnut seed, leaf, bark and flower are toxic due to the presence of esculin and should not be ingested. Horse chestnut seed is classified by the FDA as an unsafe herb.[12] The glycoside and saponin constituents are considered toxic.[12]

Aesculus hippocastanum is used in Bach flower remedies. When the buds are used it is referred to as "chestnut bud" and when the flowers are used it is referred to as "white chestnut".

Quercetin 3,4'-diglucoside, a flavonol glycoside can also be found in horse chestnut seeds.[17]

Anne Frank Tree [edit]

A famous specimen of the horse-chestnut was the Anne Frank Tree in the centre of Amsterdam, which she mentioned in her diary and which survived until August 2010, when a heavy wind blew it over.[18][19]

Bonsai [edit]

The horse-chestnut is a favourite subject for bonsai.[20]

Diseases [edit]

Gallery [edit]

  • Leaves and trunk

  • Foliage and flowers

  • Close-up of flowers

  • Trunk

  • Germination on lawn

References [edit]

Notes

  1. ^ Euro+Med Plantbase Project: Aesculus hippocastanum
  2. ^ Rushforth, K. (1999). Trees of Britain and Europe. Collins ISBN 0-00-220013-9.
  3. ^ Lack, H. Walter. "The Discovery and Rediscovery of the Horse Chestnut". Arnoldia 61 (4). 
  4. ^ Edmonton
  5. ^ Højgaard, A., Jóhansen, J., & Ødum, S. (1989). A century of tree planting on the Faroe Islands. Ann. Soc. Sci. Faeroensis Supplementum 14.
  6. ^ http://apps.rhs.org.uk/plantselector/plant?plantid=66
  7. ^ http://apps.rhs.org.uk/plantselector/plant?plantid=67
  8. ^ Lewis, Lon D. (1995). Feeding and care of the horse. Wiley-Blackwell. ISBN 9780683049671. Retrieved 2011-10-21. 
  9. ^ Lees, D.C.; Lopez-Vaamonde, C.; Augustin, S. 2009. Taxon page for Cameraria ohridella Deschka & Dimic 1986. In: EOLspecies, http://www.eol.org/pages/306084. First Created: 2009-06-22T13:47:37Z. Last Updated: 2009-08-10T12:57:23Z.
  10. ^ Kiev
  11. ^ Diehm C, Trampisch HJ, Lange S, Schmidt C. Comparison of leg compression stocking and oral horse-chestnut seed extract therapy in patients with chronic venous insufficiency. Lancet. 1996;347:292–4.
  12. ^ a b c d Horse Chestnut, Memorial Sloan-Kettering Cancer Center
  13. ^ http://nccam.nih.gov/health/horsechestnut NCCAM.nih.gov Horse Chestnut page
  14. ^ Pittler MH, Ernst E., Cochrane Database Syst Rev. 2012;11:CD003230
  15. ^ Supplementary drugs and other substances: Aesculus. In: Martindale. The Complete Drug Reference, 32nd edn. Pharmaceutical Press, 1999: 1543–4.
  16. ^ Sirtori CR (September 2001). "Aescin: pharmacology, pharmacokinetics and therapeutic profile". Pharmacol. Res. 44 (3): 183–193. doi:10.1006/phrs.2001.0847. PMID 11529685. 
  17. ^ Quercetin-3,4′-diglukosid, ein Flavonolglykosid des Roßkastaniensamens. Wagner J, Naturwissenschaften, 1961, Volume 48, Issue 2, page 54, doi:10.1007/BF00603428
  18. ^ Sterling, Toby (24 August 2010). "Anne Frank's 'beautiful' tree felled by Amsterdam storm". The Scotsman. Retrieved 24 August 2010. 
  19. ^ Gray-Block, Aaron (23 August 2010). "Anne Frank tree falls over in heavy wind, rain". Reuters. Archived from the original on 24 August 2010. Retrieved 24 August 2010. 
  20. ^ D'Cruz, Mark. "Ma-Ke Bonsai Care Guide for Aesculus hippocastanum". Ma-Ke Bonsai. Retrieved 2011-07-05. 
  21. ^ "Extent of the bleeding canker of horse chestnut problem". UK Forestry Commission. Retrieved 2010-01-09. 
  22. ^ a b http://www.suffolkcoastal.gov.uk/yourdistrict/trees/chestnuts/default.htm
  23. ^ "Other common pest and disease problems of horse chestnut". UK Forestry Commission. Retrieved 2010-01-09. 
  24. ^ "Bleeding Canker". Royal Horticultural Society. 11 November 2009. Archived from the original on 16 January 2010. Retrieved 2010-01-09. 

External links [edit]

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