Across the world, plants and flowers are increasingly reaching the brink of extinction. We get the chance the hold one of the rarest plants in the world, find out how invasive species are killing precious forests in New Caledonia, and check out a controversial scheme to keep back the encroaching sands of the Sahara desert.

The Green party leader Caroline Lucas, MP for Brighton Pavilion, talks to John Vidal about the evolution of the environmental movement: how Margaret Thatcher helped put the environment on the political map; the effect of the Rio Earth summit of 1992; and the rise of popular radical environmental movements in the UK

Deforestation of the Amazon has fallen to its lowest levels since records began, according to data recently released by Brazil's National Institute for Space Research.

The boost for the environment comes a week after president Dilma Rousseff was criticised for weakening the forest protection measures widely credited for the improvement, and two weeks before Brazil hosts the Rio+20 Earth summit.

Using satellite imagery, the institute said 6,418 sq km of Amazon forest was stripped in the 12 months before 31 July 2011 - the smallest area since annual measurements started in 1988.

Peter Kendall, the president of the National Farmers Union (NFU), has argued this week that the UK needs to consider building "super farms":

The challenge of feeding everybody with the constraints of climate change and weather shocks is so great we'll need a complete rethink.

Kendall believes that the acute shortage of farmland in the UK means that the largescale livestock farms seen in countries such as the US and Saudi Arabia - where one super dairy has a herd of 37,000 cows - should now be approved by planners.

This is about a few experimental versions, so we can see whether it lowers greenhouse gas emissions, see whether it's welfare friendly, see what the impacts are on the environment.

But, as Juliette Jowit's news story points out, "super farms" have their critics:

Concerns about large-scale animal farming fall into four categories: of animal welfare; of super units destroying small farms and rural communities; of farms straining soil and water resources and requiring mass transport of chemicals, generating more greenhouse gas pollution; and of such units being unsightly and emitting foul smells.