The descendants of Charles Darwin are retracing his footsteps by surveying wild flowers in the meadows around his former home at Down House, in Kent.
Randal Keynes (r) gets to work with Johannes Vogel from the Natural History Museum
In June 1855, Darwin began a study of the local plants, which supported his theories on evolution and was mentioned in his book On the Origin of Species.
Now, three generations of the Darwin family - aged from 21 months to 78 years - have begun a repeat survey.
It should show how flowering plants have changed over the past 150 years.
The descendants are Erasmus Darwin (great grandson), Randal Keynes (great, great grandson), Sarah Darwin (great, great granddaughter), Chris Darwin (great, great grandson), Allegra Darwin (great, great, great, granddaughter) and Leo Darwin Vogel (great, great, great grandson).
They have been joined in the 2005 survey by scientists from the Natural History Museum and conservationists from English Heritage.
It will record a range of flora, including cowslips, red clover, yarrow and yellow vetchling.
It was from his study at Down House that Charles Darwin worked on his scientific theories of evolution.
They culminated in his book - On the Origin of Species by Means of Natural Selection - which revolutionised biology.
Gill Stevens, UK biodiversity manager at the Natural History Museum's department of botany, said the naturalist used the area around the house as his outdoor laboratory.
Darwin at Down House in 1881
"It was where he did his experiments and where he did his thinking," she told the BBC News website.
"It was probably the first biodiversity audit in history. He wanted to show the degree of diversity in our British plants on a small plot - they were his words from his notebook."
Speaking in the meadows of Down House, Randal Keynes spoke about the circumstances of his great, great grandfather's audit.
"It was in this field that Darwin went with the governess - the children's governess - and simply counted the number of different kinds of plant that were growing in the field.
Down House was Darwin's main scientific workplace after his voyage on HMS Beagle
"And he realised that the number and the pattern made a very important point about how species diverge as they evolve; and this is the key to the modern idea of biodiversity."
He added: "He was being helped in the survey by Joseph Hooker, who was to become director of the Royal Botanic Gardens at Kew.
"Darwin wasn't himself an experienced botanist; and he wrote to Hooker in his excitement right at the beginning of the survey, 'I have just made out my first grass - hurrah, hurrah! I must confess that fortune favours the bold, for as luck would have it, it was the easy Anthoxanthum odoratum' [sweet or scented vernal grass]."
The survey is using the same methods as Darwin - basically wandering through and doing a grand sweep - alongside modern botanical techniques.
All the flowering plants will be collected over a one-year period as part of a wider programme of activities to train wildlife and conservation enthusiasts.
The plants helped to underpin Darwin's ideas
"These meadows are incredibly valuable to our understanding of the natural world," said Johannes Vogel, keeper of botany at the Natural History Museum.
"The survey provides a rare insight into changes over the course of 150 years and will help us conserve these historically important meadows."
Charles Darwin lived at Down House from 1842 to 1882. It is now a museum managed by English Heritage and a proposed World Heritage Site.
(All images are courtesy of the Natural History Museum)