Juglandaceae

Large, pinnately compound, aromatic leaves on trees; tiny wind-pollinated flowers on separate male catkins and female spikes ripen into a large nut enclosed in a thick, fleshy-then-hardening outer husk.

Roots and fallen leaves release juglone, a natural chemical that suppresses the growth of many other plants nearby — a defensive strategy called allelopathy that makes walnut trees poor garden neighbours.

To check whether a plant belongs to Juglandaceae, compare the leaf arrangement, leaf type, flower symmetry, fruit type, and one distinctive marker together. A single feature can mislead; the family pattern is the combination.