To Wisley for a day’s immersion in limes, trees as easy to spot as they are hard to tell apart. I don’t usually delve this deep in botany, but when the R.H.S. Woody Plant Committee convenes a Study Day you are guaranteed the best and most experienced minds in the business: a taxonomic Test match.
In a barn-like building lined with specimens giving off the sweetest smells we spent the morning studying stellate hairs. There are 20+ species of Tilia in the world (the final count is pending; we shall be kept in suspense until the imminent publication of his Tilia monograph by Professor Donald Piggott, the gnomic leader of our discussion). Most of them come from Asia; where one species ends and another begins, either geographically or taxonomically, seems to remain pretty moot and is mainly determined by the hairs, if any, stellate or otherwise, on the underside of the leaves.
We have three native Tilia species in Britain (again, subject to the usual caveats), the small-leaved, the big-leaved and the common or hybrid limes. You know the common lime by its propensity to sprout from the base or anywhere up the trunk. We forgive it its messiness for its eventual monumental shape and size. Where exactly the dividing line between its two parents lies is less clear. It is some comfort to know that the herbalist Gerard’s Tilia was actually an elm, and that even the great Linnaeus’s type plant for Tilia was the hybrid T. x europaea….
My particular interest is in their offspring. In the past five years one or other of the three has been regenerating in the garden here. The trouble is that the saplings seem to correspond with none of them. They have larger leaves than T. cordata and hairier leaves than T. platyphyllos. On the other hand their young wood is purplish, not green like T. europaea. It’s back to the hairs and the magnifying glass, I’m afraid. But shall I grow them and cherish them? Of course, whatever they are.