The Basztowa Turkish Hazel

Turkish hazel is not the shrub its name suggests. Corylus colurna is a proper forest tree, native to southeast Europe and Asia Minor, capable of 25 metres and a neat conical crown, which is why cities plant it along streets when they want something tough and tidy. Krakow's protected list runs heavily to oaks, limes and planes, so a hazel on it is an oddity, and this one stands in Planty itself beside ul. Basztowa, close to the main station. It grows as two stems from one base, 165 and 120 centimetres round. The 165 is the larger stem rather than a single trunk, which is worth stating plainly: the two figures do not add together, and a two-stemmed tree reads as bulkier than either measurement on its own. The city registered it in 2008. Its age is not known. The growth-factor arithmetic used on the oaks and limes nearby needs a divisor matched to the species, and the only hazel figure in the standard tables is calibrated to common hazel, a multi-stemmed shrub with nothing like this tree's habit. Applying it would produce a number, not an estimate. If anyone holds a planting date for this corner of Planty, we would like to hear it.