The Black Walnut of the Tolsteegbrug

This tree poisons the ground under it. Black walnut roots leak juglone, a compound that stunts or kills a long list of plants that try to grow within reach, which is why anyone who inherits one gives up on tomatoes. In its native North America it is also the most valuable timber tree going, worth enough per log that thieves take them standing. This one is 19 metres tall with a trunk 332 centimetres around, measured by the canal-side survey of Utrecht's monumental trees. It stands by the Tolsteegbrug at the southern end of the singel, beside the building that housed the university's school of governance and organisation studies. The register dates its planting to somewhere between 1870 and 1890, so 136 to 156 years old, and the band is that wide because nobody wrote down the year. Autumn is when it makes itself known. The nuts come down in thick green husks the size of golf balls, and the husk stains whatever handles it a deep brown that takes a week to wear off, which is exactly what it was used for as a dye long before anyone in Europe planted the species to look at. The nut inside is worth eating and takes a hammer to reach. The canal route through Utrecht's monumental trees ends at this tree, which makes it a reasonable place to stop walking.