In
Hazel trees, the nut is surrounded by a short leafy husk (which is technically an
involucre). This leaf-like husk encloses most of the nut. It starts off green and will fade to brown at the end of the season. Usually, the ripe nut falls out of (or can be separated from) the husk some 7–8 months after
pollination has occurred. In some places, both shells and the husks of walnuts (
Juglans regia ) which are produced as waste crops during the fruit harvesting and processing, are sometimes burned as fuel for heating purposes. In 2019, it has been demonstrated that the walnut green husk could be valued as a source of different natural bio-active compounds with excellent
antioxidant and
antimicrobial properties. As well as cosmetic uses. An organic compound Naphthalenone, (derivative of
Naphthalene) is found in green walnut husks of
Juglans mandshurica for various uses.
Juglans nigra, black walnut, husks have antioxidant potential. Confusingly, Walnut husks are also called
hulls as well.
Rhagoletis juglandis, also known as the 'walnut husk fly' is a common pest of walnuts. The larvae are small and live under the surface of the husk of the walnut. They cause damage to the fruit and husks which then become difficult to remove. The husk fly also infests ripe
apricot and
peach fruits, usually if infested walnuts are located within flying distance. Some fruit shell and hull derived
bio-adsorbents have also been used for
wastewater treatment purposes. For example, the
almond hull and shell have been used to remove metals such as
Pb,
Cd, and
Co in various quantities. Iranian almond (
Prunus amygdalus ) hulls have antioxidant and anti-radical properties. The
coconut husk and shells can be used for fuel and are a source of
charcoal. In Thailand, the coconut husk is used as a potting medium to produce healthy forest tree
saplings. A dried half coconut shell with husk can be used to buff floors. It is known as a
bunot in the Philippines and simply a "coconut brush" in
Jamaica.
Coir, also called
coconut fibre, is a
natural fibre extracted from the outer husk of coconut. ==Husking and dehulling==