How do hazelnut husks protect nuts from predators?

In the plant order Fagales, the hazelnut (genus Corylus) is protected by a husk that acts as a physical and chemical barrier against predators.12

While some species, such as Corylus ferox, feature long, protective spines on their husks, others utilize a different defense mechanism. Many hazelnut husks are covered in numerous multicellular, glandular hairs that exude a sticky substance. This adhesive secretion is believed to deter predators from consuming the nuts. Additionally, these husks—which are composed of modified bracts—serve as a structural casing that partially or completely encloses the fruit, providing a layer of protection as it develops.2