gardens, particularly in Bavaria. Prior to the advent of mechanical refrigeration, brewers would dig cellars for lagering. To further protect the cellars from the summer heat, they would plant horse chestnut trees, which have spreading, dense canopies but shallow roots which would not intrude on the caverns. The practice of serving beer at these sites evolved into the modern beer garden. An inexpensive detergent for washing clothes can be made at home from conkers, and this is said to be an environmentally benign ('eco-friendly') detergent. Traditional medicine The seed extract standardized to around 20 percent aescin (escin) is possibly useful in traditional medicine for its effect on venous tone. A Cochrane Review suggested that horse chestnut seed extract may be an efficacious and safe short-term treatment for chronic venous insufficiency, but definitive randomized controlled trials had not been conducted to confirm the efficacy. Safety There is risk of acute kidney injury, "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 kidney function was recorded with 340 μg/kg, mild kidney function impairment developed with 360 μg/kg and acute kidney injury with 510 μg/kg". Raw horse chestnut seed, leaf, bark and flower are toxic due to the presence of aesculin and should not be ingested. Horse chestnut seed is classified by the FDA as an unsafe herb. The glycoside and saponin constituents are considered toxic. Other chemicals Quercetin 3,4'-diglucoside, a flavonol glycoside can also be found in horse chestnut seeds. Leucocyanidin, leucodelphinidin and procyanidin A2 can also be found in horse chestnut. Anne Frank tree A fine 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. Eleven young specimens, sprouted from seeds from this tree, were transported to the United States. After a long quarantine in Indianapolis, each tree was shipped off to a new home at a notable museum or institution in the United States, such as the 9/11 Memorial Park, Central H.S. in Little Rock, and two Holocaust Centers. One of them was planted outdoors in March 2013 in front of the Children's Museum of Indianapolis, where they were originally quarantined. Symbol of Kyiv The horse chestnut tree is one of the symbols of Kyiv, the capital