From BBC News:
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).
“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. “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.”