Black Walnut

Black walnut is a deciduous tree of the walnut family, native to the middle and east of North America, where it grows mostly beside rivers and streams; it reached Europe, probably in 1629. It can grow thirty to forty metres tall, with grey-black bark cut into ridges that make a diamond pattern and long pinnate leaves of fifteen to twenty-three leaflets. Its round fruit is a hard, ridged brown nut inside a semi-fleshy husk, which Kynes describes as yellow-green, and the leaves, twigs and husks all have a sharp, spicy smell. The kernels are eaten for their strong flavour, though the thick shell makes them hard to get out, and the dark, straight-grained heartwood is prized for furniture, gunstocks and coffins. The husks hold juglone, plumbagin and tannin, which stain pavements, patios and the fingers of whoever shells the nuts, and early American settlers dyed hair with their brownish-black colour. The tree has long been said to poison nearby plants such as apples, tomatoes, pines and birches with the juglone it releases, although research since 2019 has questioned how far that holds. As a herb, the hull and the leaf are the parts used. Kynes describes it within her Walnut entry, beside the English walnut.