Carpathian Walnut Catkin
A catkin or ament is a slim, cylindrical flower cluster, with inconspicuous or no petals, usually wind-pollinated but sometimes insect-pollinated. It contains many, usually unisexual flowers, arranged closely along a central stem that is often drooping.
Ah, that's a catkin? I think I learned that in Botany class, but forgot it long ago.
IIRC pokeberry produces that flower-fruiting structure.