A woman takes a selfie in an alley of autumn-coloured gingko trees in Beijing, China, November 9, 2018. REUTERS/Thomas Peter

A woman poses for friends as they take pictures in an alley of autumn-coloured gingko trees in Beijing, China, November 9, 2018. REUTERS/Thomas Peter

Women pose for a group selfie in an alley of autumn-coloured gingko trees in Beijing, China, November 9, 2018. REUTERS/Thomas Peter

A woman poses for her friend taking pictures in an alley of autumn-coloured gingko trees in Beijing, China, November 9, 2018. REUTERS/Thomas Peter

Women take pictures in an alley of autumn-coloured gingko trees in Beijing, China, November 9, 2018. REUTERS/Thomas Peter

Frenchman Marc-Paul Baise presents a sexy coaster for his "Baise Bock" beer at a launching at a pub in Strasbourg, October 14, 2009. The beer, using Marc-Paul Baise's family name, French slang for "screwing", is brewed in small quantities and is flavoured with gingko and ginseng with claims of aphrodisiac properties. REUTERS/Vincent Kessler (FRANCE SOCIETY)

Frenchman Marc-Paul Baise presents a sexy coaster for his "Baise Bock" beer at a launching at a pub in Strasbourg, October 14, 2009. The beer, using Marc-Paul Baise's family name, French slang for "screwing", is brewed in small quantities and is flavoured with gingko and ginseng with claims of aphrodisiac properties. REUTERS/Vincent Kessler (FRANCE SOCIETY)

Frenchman Marc-Paul Baise presents a sexy coaster for his "Baise Bock" beer at a launching at a pub in Strasbourg, October 14, 2009. The beer, using Marc-Paul Baise's family name, French slang for "screwing", is brewed in small quantities and is flavoured with gingko and ginseng with claims of aphrodisiac properties. REUTERS/Vincent Kessler (FRANCE SOCIETY)

Frenchman Marc-Paul Baise presents a sexy coaster for his "Baise Bock" beer at a launching at a pub in Strasbourg, October 14, 2009. The beer, using Marc-Paul Baise's family name, French slang for "screwing", is brewed in small quantities and is flavoured with gingko and ginseng with claims of aphrodisiac properties. REUTERS/Vincent Kessler (FRANCE SOCIETY)

Frenchman Marc-Paul Baise presents a sexy coaster for his "Baise Bock" beer at a launching at a pub in Strasbourg, October 14, 2009. The beer, using Marc-Paul Baise's family name, French slang for "screwing", is brewed in small quantities and is flavoured with gingko and ginseng with claims of aphrodisiac properties. REUTERS/Vincent Kessler (FRANCE SOCIETY)

Frenchman Marc-Paul Baise presents a sexy coaster for his "Baise Bock" beer at a launching at a pub in Strasbourg, October 14, 2009. The beer, using Marc-Paul Baise's family name, French slang for "screwing", is brewed in small quantities and is flavoured with gingko and ginseng with claims of aphrodisiac properties. REUTERS/Vincent Kessler (FRANCE SOCIETY)

Frenchman Marc-Paul Baise presents a sexy coaster for his "Baise Bock" beer at a launching at a pub in Strasbourg, October 14, 2009. The beer, using Marc-Paul Baise's family name, French slang for "screwing", is brewed in small quantities and is flavoured with gingko and ginseng with claims of aphrodisiac properties. REUTERS/Vincent Kessler (FRANCE SOCIETY)

Frenchman Marc-Paul Baise presents a sexy coaster for his "Baise Bock" beer at a launching at a pub in Strasbourg, October 14, 2009. The beer, using Marc-Paul Baise's family name, French slang for "screwing", is brewed in small quantities and is flavoured with gingko and ginseng with claims of aphrodisiac properties. REUTERS/Vincent Kessler (FRANCE SOCIETY)

New Yorkers collect fallen nuts from a Gingko Biloba tree during a foraging tour led by naturalist Steve Brill in Central Park in New York March 14, 2009. To confront the recession, a growing number of Americans are looking outside the traditional economy and turning to bartering, foraging and trash salvaging. "Wildman" Steve Brill, who leads foraging tours through New York's parks, said he's seen more people on his tours. Picture taken March 14, 2009. To match feature USA-CONSUMERS/THRIFT REUTERS/Jeff Zelevansky (UNITED STATES SOCIETY BUSINESS ENVIRONMENT)

Naturalist Steve Brill holds a gingko nut found on a foraging tour of edible plant life in Central Park in New York March 14, 2009. To confront the recession, a growing number of Americans are looking outside the traditional economy and turning to bartering, foraging and trash salvaging. "Wildman" Steve Brill, who leads foraging tours through New York's parks, said he's seen more people on his tours. Picture taken March 14, 2009. To match feature USA-CONSUMERS/THRIFT REUTERS/Jeff Zelevansky (UNITED STATES HEADSHOT SOCIETY BUSINESS ENVIRONMENT)

Naturalist Steve Brill holds a gingko nut found on a foraging tour of edible plant life found in Central Park in New York March 14, 2009. To confront the recession, a growing number of Americans are looking outside the traditional economy and turning to bartering, foraging and trash salvaging. "Wildman" Steve Brill, who leads foraging tours through New York's parks, said he's seen more people on his tours. Picture taken March 14, 2009. To match feature USA-CONSUMERS/THRIFT REUTERS/Jeff Zelevansky (UNITED STATES SOCIETY BUSINESS HEADSHOT)

A labourer walks amongst ginkgo trees at suburban Shanghai on an early winter day December 6, 2008. REUTERS/Aly Song (CHINA)

Ginkgo leaves are seen outside Beijing's Diaoyutai Guest House on an early winter day, November 16, 2008. REUTERS/Jason Lee (CHINA)

A child plays with his mother amongst ginkgo trees, outside Beijing's Diaoyutai Guest House on an early winter day, November 16, 2008. REUTERS/Jason Lee (CHINA)

People take a stroll under yellow gingko leaves in Tokyo December 4, 2006. REUTERS/Toshiyuki Aizawa (JAPAN)

A child sits on his father's shoulders while strolling beneath yellow gingko leaves in Tokyo December 4, 2006. REUTERS/Toshiyuki Aizawa (JAPAN)

A ginkgo leaf is seen in water outside the Diaoyutai Guest House on an early winter day in Beijing November 11, 2006. REUTERS/Jason Lee (CHINA)

A girl plays among ginkgo leaves outside the Diaoyutai Guest House on an early winter day in Beijing, November 11, 2006. REUTERS/Jason Lee (CHINA)

People view a painting by British artists Gilbert and George at the United Kingdom's arts Biennale pavilion in Venice. People view one of the "Gingko Pictures" multi-panel installations by British artists Gilbert and George at the United Kingdom's arts Biennale pavilion in Venice June 9, 2005. The arts festival is open to the public from June 12 - November 6. REUTERS/Chris Helgren

A Japanese girl plays with gingko leaves in Tokyo after record-breaking winds, gusting up to 144 km (90 miles) per hour, swept through the capital early December 5, 2004. The aftermath of the storm brought record high temperatures for the normally chilly month of December in Tokyo, rising up to 24.8 Celsius (77 Fahrenheit) shortly before noon, local media said. REUTERS/Yuriko Nakao YN/FA

A Japanese girl plays with gingko leaves in Tokyo after record-breaking winds, gusting up to 144 km (90 miles) per hour, swept through the capital early December 5, 2004. The aftermath of the storm brought record high temperatures for the normally chilly month of December in Tokyo, rising up to 24.8 Celsius (77 Fahrenheit) shortly before noon, local media said. REUTERS/Yuriko Nakao YN

People walk their miniature dachshunds on a carpet of gingko leaves in Tokyo after record-breaking winds, gusting up to 144 km (90 miles) per hour, swept through the capital December 5, 2004. The aftermath of the storm brought record high temperatures for the normally chilly month of December in Tokyo, rising up to 24.8 Celsius (77 Fahrenheit) shortly before noon, local media said. REUTERS/Yuriko Nakao YN/FA