The Osage Orange of the Ciutadella

In late autumn this tree drops what look like green brains onto the path. The fruit of the Osage orange is the size of a grapefruit, yellow-green and almost fluorescent when fresh, its surface a mass of folds and channels, and it is inedible to more or less everything alive today. The usual explanation is that it fed animals that no longer exist, ground sloths and mammoths that swallowed the fruit whole and carried the seed away, which leaves the tree serving meals nobody has ordered for ten thousand years. It comes from a small range across Texas, Arkansas and Louisiana, where its wood made the finest bows in North America and gave both the Osage nation its trade and this tree its name. Europe imported it early in the 19th century and never took to it. Barcelona's specimen went into Parc de la Ciutadella around 1913 and now carries a trunk about two and a half metres around under a crown the city measures at anywhere from 13 to 19 metres. It is deciduous, so the timing matters: come in late October or November and the fruit is lying under it, with a few hanging on into winter after the leaves have gone.