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Ken Thompson 01 February 2018 12:00pm GMT Every year the BSBI (Botanical Society of Britain and Ireland) organises a New Year Plant Hunt (NYPH). Its mission is simple: identify and count all
the plants you can find in flower during a 3-hour walk in a four-day period over New Year. The results for 2018 have now been collated and analysed, and can be seen on an interactive map on
the BSBI website. The plant most frequently found (streets ahead of its nearest rival, and surely a great pub quiz question) was common daisy, _Bellis perennis_. But as ever, much of the
fun is in the detail, which quickly reveals that location is crucial. I write from south Devon, and one of the longest lists comes from just down the road on the coast at Brixham. On the
other hand, a list from Two Bridges in the middle of Dartmoor, only a few miles away but a long way uphill, consists of a single plant: common gorse. I’m not surprised; however hard you
look, I suspect it wouldn’t have been easy to get into double figures at Two Bridges. Nationally, the longest and third longest lists come from sites a few miles apart in the far west of
Cornwall, while second place goes to a list from Swanage. Mind you, the winners, from Phillack on the north coast of Cornwall, got up to 114 species by not only displaying an ability to
distinguish _Conyza floribunda_ (Bilbao fleabane) from _C. canadensis_ (Canadian fleabane), but they also recognised plants the rest of us have never heard of, such as _Polypogon viridis_
(water bent) and _Cyperus eragrostis _(pale galingale). But what the results mostly illustrate is that if you count or measure anything for long enough, interesting patterns emerge. The
NYPH is only in its 5th year, but it’s already clear, climate change notwithstanding, that what really matters is the weather in the period leading up to the hunt. The number of people
taking part has risen dramatically, but compared to the first three years, the average number of plants each group found was much lower in 2017 and 2018. Inspection of the weather records
reveals that those first three hunts were preceded by an unusually mild autumn/early winter, while the weather during the last two years has been much more normal, i.e. cold. The total
number of species found in flower this year was a whopping 532, which is far more than reference books would lead us to expect. It’s tempting to assume that this is a much larger number than
would have been found in the past, but since no-one was counting in, say, 1950 or 1960, the long-term pattern will only emerge when we’ve been doing this for quite a few more years. What
is already clear, however, is that the bulk of the ‘extra’ plants are not early, but late. That is, only a few of the unexpected plants found in flower at New Year are ones that we would
normally expect to find in flower later in the spring. Mostly the extra plants are summer or autumn-flowering species ‘left over’ from the previous year. In fact spring-flowering plants
generally need a period of cold before they can flower, and if winters become significantly warmer, it may even be that we will find fewer spring plants in flower at New Year in future. One
thing’s for sure, the NYPH is now an important fixture in the botanical calendar, and everyone is welcome to take part – you don’t have to be a BSBI member or an experienced botanist, and
even nil records are important, so it’s OK if you don’t find anything. Plenty of tips to get you started on the BSBI website, so make a note in your diary for 2019. _Ken Thompson is a plant
biologist with a keen interest in the science of gardening. His recent book _The Sceptical Gardener _is a collection of his columns for _The Telegraph_. Visit books.telegraph co.uk_