Marshwood Vale, Dorset: Producing black acorns is a sign of stress. Immature seeds die mid-growth, with the stalk withering on the twig
Marshwood’s oaks are shedding an unexpectedly large crop of black acorns this autumn. These are stunted stubs of nut with an eggshell sheen, barely rising in their brown cups. Long stalks show they are from pedunculate or English oaks, Quercus robur, one of the commonest native hedgerow trees.
I’ve found many under one particular oak that’s about 400 years old, whose massive, twisting, almost curly, branches overspan the lane. Its lower trunk has developed a huge burl, a woody, swollen growth, caused by long-ago injuries and beetle attacks.