The fruit of Justicia adhatodoides is the secret to the common name of pistol bush given to this tree. The immature green fruits seen in the picture develop to 3 cm club-shaped capsules.
Upon ripening, the capsules split open explosively with loud cracks resembling pistol shots. The seed dispersal is then performed by these mechanical distribution events. This may be observed from the end of summer to winter (Coates Palgrave, 2002; iNaturalist).