Juglandaceae

Defining Characteristics

• Alternate , pinnately compound, aromatic leaves (fragrant when crushed)
• Monoecious — male flowers in pendulous catkins, female flowers solitary or in small terminal clusters
• Fruit a large nut enclosed in a husk derived from the involucre and/or perianth
• Pith of twigs chambered (Juglans) or solid (Carya)
• Trees often produce allelopathic compounds (especially juglone in Juglans)

Notable Genera

• Juglans (walnut — ~20 species)
• Carya (hickory, pecan — ~20 species)
• Pterocarya (wingnut)

Notes

All species produce large, edible nuts — walnut, pecan, and hickory are commercially important. Valued timber trees with strong, shock-resistant wood. Juglone, produced by walnut trees, inhibits the growth of many other plant species ( allelopathy ), making under-planting difficult.