Janet Dinsdale was a young, enthusiastic scientist whose life, in the 1990s, was taken over by Heath Lobelia. She was studying its germination and survival in Andrew’s Wood near Kingsbridge and at Redlake Meadows near Lostwithial, for her PhD at Plymouth University. She monitored the lives of over 2,000 plants in the grassy clearings of Andrew’s Wood and tried to answer the questions that ran through her head.

One was: “Why is Heath Lobelia so rare in Britain?” She discovered, by reading, that it grows only along the western coast of Europe, from Morocco in the south, along Portugal, Spain and France to southern England. There are only six sites where it grows in England.

She germinated seeds in the laboratory and found they only germinated if exposed to light. A few grass-cuttings over it or a bush growing up and shading it and the seed would not germinate. The next hurdle before germination was that it needed temperatures well over 20 degrees C before it would do so. Perhaps that is why Andrew’s Wood had a Lobelia bonanza\in 1976, when it was a hot summer? The final nail in the coffin was that although seeds germinated in Andrew’s Wood from March to September, only the seedlings that germinated in the spring survived their first winter. No wonder Heath Lobelia was rare.

Another question was: “Why does it suddenly emerge in thousands?”

Janet cut a turf 10cm deep from each of her twelve areas and counted how many seeds she could find. By extrapolating, she estimated there were 17,500 seeds per square metre, four times greater than any other in her samples.

She couldn’t believe it! Let’s join her in counting the flowers on a Lobelia spike. Count the flowers in this photo, which is just part of a spike. Janet counted thousands of spikes and she found that the average number of flowers on a spike was sixty. Amazingly each seed pod contained about 100 tiny, almond-shaped seeds – that is 6,000 seeds from each spike; three spikes could produce 18,000 seeds! No wonder that, when a set-aside field next door to the reserve was ploughed, in 1995, thousands of Lobelia turned the field blue. Lobelia can suddenly emerge in thousands because of the enormous seed-bank.

A third question was: “Why do these high numbers decrease so soon?” Partly, because unless new seeds are exposed to light they cannot germinate. Janet also discovered, by monitoring her plants in the reserve and at the university, that the maximum age for a Heath Lobelia plant was about six years;

most died well before that. The results of our fifty years of Lobelia counts show that most Lobelia bonanzas have dramatically shrunk after about six years.

So Janet’s advice to Devon and Cornwall Wildlife Trusts was to try to keep patches of bare, disturbed soil in the clearings for the seeds to germinate in the spring. She recommended grazing with cattle but not in the spring, cutting back invading scrub by hand or brush-cutters and rotational drastic soil disturbance.

For fifty years we have tried to do this but the willow and birch saplings get younger and stronger and we volunteers get older and weaker. Result: the scrub is more successful in its invasion and in the last six years Lobelia numbers have sunk to the lowest in fifty years.

But help has arrived. We have always had wonderful reserve officers from the Devon Trust but our latest reserve officers are not only young and enthusiastic they have some revolutionary plans, as well as needing our traditional hard-labour. Claire Inglis and Lineke Bosman have thrown themselves into this work and encouraged us volunteers, old and young, every second Thursday of every month.

They have asked John and Desley of Cows in Clover to bring in some Dexter cattle with very sophisticated cow-bells that instruct them where to graze and show us exactly where they have grazed. They are so special, Claire tells me they have names: Lilac, Delilah, Bo, Charlie and Cinderella. Cinderella and her friends, and the wintering woodcocks that hide during the day, have a message for us all, “Please keep your dogs on the lead and leave the gates closed.”

The latest and most revolutionary acquisition is a Roboflail, which Claire has persuaded Natural England to let us use in Andrew’s Wood for a few days. Lineke, its operator, tells me it is called Robbie. In three days this machine changed Aspen Clearing, from 80 percent scrub into a bare clearing with lots of bare patches. All it needs now is for us to rake up the cuttings so the Lobelia seeds can see the light. We are making dead hedges of the scrub branches which Claire knows will be good for the dormice, nesting birds, and lots of invertebrates; all part of the rich and beautiful mosaic of Andrew’s Wood.

Twelve years ago Aspen Clearing had a count of 2,234 Lobelia plants, this year it had 9. Next year, we hope it will turn blue again, thanks to Robbie, the cattle and us. Please join us one second Thursday - 10o’clock at the car park.