Aesculus hippocastanum (Horse chestnut)

Aesculus hippocastanum (Horse chestnut)
Scientific classification
Kingdom: Plantae
Order: Sapindales
Family: Sapindaceae
Genus: Aesculus
Species: A. hippocastanum
Binomial name
Aesculus hippocastanum
Aesculus hippocastanum is a large deciduous tree, commonly known as horse-chestnut or conker tree.
Aesculus hippocastanum is native to a small area in the Pindus Mountains mixed forests and Balkan mixed forests of South East 
It is widely cultivated in streets and parks throughout the temperate world.
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 flowersare 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. 
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 despite this plant beingpoisonous to horses.
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, the Faroe Islands, and Harstad, Norway. 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. Some mammals, notablydeer, are able to break down the toxins and eat them safely Though the seeds are said to repel spiders there is little evidence to support these claims. The presence of saponin may repel insects but it is not clear whether this is effective on spiders. 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. Horse chestnuts can also be used to wash human hair.  By pouring about 3/4 cup of boiling-hot water and 1 grated horse chestnut into a closed bottle and shaking it, a frothy white liquid emerges. This can also be strained and later poured over the head in the shower.
In Bavaria the chestnut 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. 
The flower is the symbol of the city of Kiev, capital of Ukraine. 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
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.
 Primary indication is chronic venous insufficiency. A recent Cochrane Review found the evidence suggests that Horse Chestnut Seed Extract is an efficacious and safe short-term treatment forchronic venous insufficiency. 
Aescin reduces fluid leaks to surrounding tissue by reducing both the number and size of membrane pores in the veins.
Safety in medical use
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".  This almost certainly took place in a context of whole HCE. Three clinical trials were 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 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. 
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. 
Theglycoside and saponin constituents are considered toxic. 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".