Clade Angiosperms Scientific name Juglandaceae Rank Family | ||
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Lower classifications Walnut Tree, Hickory, Pecan, Pterocarya, Platycarya | ||
Juglandaceae
The Juglandaceae are a family, known as the walnut family, of trees, or sometimes shrubs, in the order Fagales. Various members of this family are native to the Americas, Eurasia, and Southeast Asia. Members of the walnut family have large, aromatic leaves that are usually alternate, but opposite in Alfaroa and Oreomunnea. The leaves are pinnately compound or ternate, and usually 20–100 cm long.
Contents
The trees are wind-pollinated, and the flowers are usually arranged in catkins.
The nine or ten genera in the family have a total of ca 50 species, and include the commercially important nut-producing trees walnut (Juglans), pecan (Carya illinoinensis), and hickory (Carya). The Persian walnut, Juglans regia, is one of the major nut crops of the world. Walnut, hickory, and gaulin are also valuable timber trees.
Systematics
The known living genera are grouped into subfamilies, tribes, and subtribes as follows:
The only member of the genus Alfaropsis I.A.Iljinsk., Alfaropsis roxburghiana (Wall.) I.A.Iljinsk. is a synonym for Engelhardia roxburghiana Wall. (or perhaps vice versa).
The only member of the genus Annamocarya A.Chev., Annamocarya sinensis (Dode) J.-F.Leroy, may be a member of Carya.
Fruits
Some fruits are borderline and difficult to categorize. Hickory nuts (Carya) and walnuts (Juglans) grow within an outer husk; these fruits are sometimes considered to be drupes or drupaceous nuts, rather than true botanical nuts. "Tryma" is a specialized term for such nut-like drupes.
The fruits of the Juglandaceae are often confused with drupes but are accessory fruit because the outer covering of the fruit is technically an involucre and thus not morphologically part of the carpel; this means it can not be a drupe but is instead a drupe-like nut. These odd nuts fall into two different types: in the walnut genus (Juglans), it is a pseudodrupe and in the hickory genus (Carya), it is a tryma.