ST. LOUIS - Four of the world's leading botanical institutions are working on a catalogue of every plant in the world, with plans to make the inventory of at least 400,000 species available for free online by 2020.

Those involved in the project say at least 100,000 plant species worldwide are threatened by extinction.

Plans for the catalogue called the World Flora were announced Monday by the St. Louis-based Missouri Botanical Garden, New York Botanical Garden and two British institutions, the Royal Botanic Garden Edinburgh and Royal Botanic Gardens, Kew.

The catalogue will include scientific information and images for every known species, with new ones added as they are discovered.

Officials at the botanical organizations say developing the catalogue is partly aimed at helping halt the loss of plant biodiversity around the world.

Check out some of our favourite eco-friendly Canadian celebrities.

• Ryan Gosling

  GREEN THUMBS UP: He saves the ladies, breaks ups fights and has a long list of memes that make us fall in love with him over and over again. We also love this animal-loving actor for defending chickens and turkeys in factory farms and calling out KFC and McDonads on behalf of PETA.
  Actor Ryan Gosling attends the premiere of 'The Ides Of March' held on September 27, 2011 in Beverly Hills, California.

• Measha Brueggergosman

  GREEN THUMBS UP: With a voice this powerful, we're not surprised Canadian opera singer Measha Brueggergosman has green energy within her. Brueggergosman has pledged to make her life more green with the World Wildlife Fund, by buying green appliances, draft-proof windows and sticking to a green energy supplier.
  Singer Measha Brueggergosman arrives at the Canada For Haiti Benefit on January 22, 2010 in Toronto, Canada.

• Justin Bieber

  GREEN THUMBS UP: Canadian sensation Justin Bieber received an eco-friendly car for his 18th birthday last month, assuring us the young adult will continue to go green for years to come. The $100,000 Fisker Karma electric car was given to him by his manager Scooter.
  Singer Justin Bieber speaks during interview with Elvis Duran for 'The Elvis Duran and the Morning Show' on March 24, 2012 in West Hollywood, California.

• Pamela Anderson

  GREEN THUMBS UP: Long-time PETA activist and vegetarian Pamela Anderson has stripped for ad campaigns, worn a lettuce bra and starred in anti-fur video campaigns.
  Actress Pamela Anderson attends a press conference on March 22, 2012 in West Hollywood, California.

• Rachel McAdams

  GREEN THUMBS UP: Canadian beauty Rachel McAdams is no 'mean girl.' The actress co-owns a green lifestyle site, Green Is Sexy, and says she's not a typical materialistic gal.
  Actress Rachel McAdams attends the premiere of Sony Pictures' 'The Vow' at Grauman's Chinese Theatre on February 6, 2012 in Hollywood, California.

• James Cameron

  GREEN THUMBS UP: Even though there has been some outcry for James Cameron's use of private jets, the director says the motive behind "Avatar" was to send out an environmental message.
  James Cameron arrives at the world premiere of Titanic 3D in central London on March 27, 2012.

• Avril Lavigne

  GREEN THUMBS UP: Canadian rocker Avril Lavigne has worked for Reverb, a non-profit environmental music-based organization that promotes green tours.
  Singer Avril Lavigne attends the Picksie 2.0 launch party at Lucky Strike Lanes & Lounge on November 22, 2011 in New York City.

• Ryan Reynolds

  GREEN THUMBS UP: Actor Ryan Reynolds is one face behind Nissan's "Innovation For Endurance" campaign focusing on environmental innovators. By the way Ryan, even though you mention Teddy Roosevelt's passion to protecting the parks of America as your inspiration, we hope you can bring some of that green lovin' back home.
  Ryan Reynolds attends the 'Safe House' premiere at the SVA Theater on February 7, 2012 in New York City.

• Barenaked Ladies

  GREEN THUMBS UP: This band was named one of the most eco-friendly rockers by Rolling Stone Magazine in 2010. The Barenaked Ladies started "green touring" back in 2004 before it got cool and sold recyclable CD cases.
  Kevin Hearn, Ed Robertson, Jim Creeggan and Tyler Stewart of Barenaked Ladies pose on the red carpet at the 2011 Juno Awards.

• Ellen Page

  GREEN THUMBS UP: As a environmental activist, this Canadian actress told MotherJones.com she gets excited by permaculture, Bill McKibben, and ecovillages. If that wasn't enough, Page also vouches for organic products and speaks out against the spreading toxins in Halifax.
  Actress Ellen Page arrives at the premiere of IFC Midnight's 'Super' at the Egyptian Theatre on March 21, 2011 in Hollywood, California.

• Alanis Morissette

  GREEN THUMBS UP: Singer Alanis Morissette says she has solar panels, drives a hybrid and loves to shut off the lights in the house.
  Alanis Morissette arrives at the American Music Awards in Los Angeles on November 20, 2011.

• Liz Trinnear

  GREEN THUMBS UP: Canadian VJ Liz Trinnear is also another young'un in the environmental fashion world. For the 2011 Junos and Lollapalooza, Trinnear pledged to go green for six weeks with her clothing, beauty and even her drinks.
  MuchMusic VJ Liz Trinnear poses at the 2010 Much Music Video Awards in Toronto.

• Mia Kirshner

  GREEN THUMBS UP: Canadian actress Mia Kirshner reportedly supported Canada's oilsands protest in 2011. We can respect her passion.
  Mia Kirshner arrives at the 63rd Venice International Film Festival's gala opening, 30 August 2006, at the Lido in Venice.

• Michael Buble

  GREEN THUMBS UP: Canadian Michael Buble has a way with words -- even when he's discussing climate change and greener driving with environmentalist David Suzuki and actress Emily Blunt.
  Michael Buble attends the 2011 Rockefeller Center Christmas tree lighting on November 30, 2011 in New York City.

• Hayden Christensen

  GREEN THUMBS UP: Hayden Christensen loves to get his hands dirty. The Canadian actor bought a farm north of Toronto in 2007 and couldn't wait to fill his land with farm animals and drive around his Bobcat.
  Actor Hayden Christensen attends the Cinema Society screening of 'Vanishing On 7th Street' at IFC Center on February 7, 2011 in New York City.

• Bryan Adams

  GREEN THUMBS UP: Vegan, singer and photographer Bryan Adams is another celebrity behind PETA's campaign on animal rights and promoting a meatless lifestyle.
  Canadian musician Bryan Adams performs at the Dasrath stadium in Kathmandu on February 19, 2011.

• Nelly Furtado

  GREEN THUMBS UP: We've seen singer Nelly Furtado spreading the love with her dark concert during Earth Hour in 2008, but she also fundraised for The Land Conservancy of British Columbia by working on a handmade quilting project.
  Singer Nelly Furtado attends the Opening Night Gala during the 35th Toronto International Film Festival at Metro Square.

• Malin Akerman

  GREEN THUMBS UP: Canadian actress Malin Akerman says she has been an environmentalist since childhood by volunteering for environmental organizations, driving a hybrid and installing solar panels in her rental home.
  Malin Akerman attends the LACOSTE launch of Women's Spring/Summer 2012 Collection held at The Sunset Tower on March 21, 2012 in West Hollywood, California.

• Sarah Chalke

  GREEN THUMBS UP: Actress Sarah Chalke has been dubbed as a green mommy by purchasing and using organic products like bedding and wooden toys, according to Ecollywood. Are we surprised? Not really. Chalke was also once an environmental reporter as a teen for the Canadian show KidZone.
  Actress Sarah Chalke attends the Premiere of Summit Entertainment's 'Man On A Ledge' at Grauman's Chinese Theatre on January 23, 2012.

• Jessi Cruickshank

  GREEN THUMBS UP: Canadian television personality Jessi Cruickshank knows a thing or two about fashion. She told Chatelaine magazine she loves eco-shopping for organic cottons and sustainable prints. She has also designed eco-friendly t-shirts for Free The Children.
  MTV hosts Jessi Cruickshank (L) and Dan Levy attend MTV's 'The Hills Live: A Hollywood Ending' Finale event held at The Roosevelt Hotel on July 13, 2010 in Hollywood, California.

• Keanu Reeves

  GREEN THUMBS UP: After shooting "The Day The Earth Stood Still," Reeves told The Sun UK he recycles, owns solar panels and has joined the cause for rainforest conservation.
  Keanu Reeves attends the 'Side By Side' Premiere during day seven of the 62nd Berlin International Film Festival at the Haus der Berliner Festspiele on February 15, 2012 in Berlin, Germany.

• Joshua Jackson

  GREEN THUMBS UP: You may remember Joshua Jackson as the voice of Jesse Grass, a hunky environmentalist on an episode of "The Simpsons." But this real life tree hugger loves cycling, owns a hybrid and a biodiesel truck.
  Actor Joshua Jackson attends the 'Lay the Favorite' premiere during the 2012 Sundance Film Festival held at Eccles Center Theatre on January 21, 2012 in Park City, Utah.

• Adam Beach

  GREEN THUMBS UP: "Arctic Air" actor Adam Beach has been seen opposing pipelines in British Columbia and joining forces with the First Nations of Canada for land rights.
  Actor Adam Beach attends the Premiere of Universal Pictures 'Cowboys & Aliens' during Comic-Con 2011 at San Diego Civic Theatre on July 23, 2011 in San Diego, California.

• Nina Dobrev

  GREEN THUMBS UP: "Vampire Diaries" star Nina Dobrev is not only a humanitarian, but she also urged her fans to get more green with the "Increase Your Green" campaign in 2010.
  Actress Nina Dobrev attends the 9th Annual John Varvatos Stuart House Benefit on March 11, 2012 in West Hollywood, California.

• Drake And K-Os

  TWO GREEN THUMBS UP: Canadian musicians Drake and K-Os both toured green in 2010 for Drake's "Away From Home Tour," with greener technologies, like biodiesel fuel, biodegradable products on the tour bus and backstage, and an 'Eco-Village' to give more information about green options to audience members.
  Actress Nina Dobrev attends the 9th Annual John Varvatos Stuart House Benefit on March 11, 2012 in West Hollywood, California.