Hickory is a common name for trees composing the genus Carya, which includes 19 species accepted by Plants of the World Online. The Angiosperm Phylogeny Group, however, considers the fruit to be a nut.

Taxonomy

Phylogeny

The oldest fossils attributed to Carya are Cretaceous pollen grains from Mexico and New Mexico. Fossil and molecular data suggest the genus Carya may have diversified during the Miocene. Modern Carya first appeared in Oligocene strata 34 million years ago. Recent discoveries of Carya fruit fossils further support the hypothesis that the genus has long been a member of Eastern North American landscapes, however, its range has contracted, and Carya is no longer extant west of the Rocky Mountains.

Fossils of early hickory nuts show simpler, thinner shells than modern species, with the exception of pecans, suggesting that the trees gradually developed defenses to rodent seed predation. During this time, the genus had a distribution across the Northern Hemisphere, but the Pleistocene Ice Age, beginning 2 million years ago, obliterated it from Europe. In Anatolia, the genus appears to have disappeared only in the early Holocene, probably related to human disturbance. The distribution of Carya in North America also contracted, and it completely disappeared from the continent west of the Rocky Mountains. It is likely that the genus originated in North America, and later spread to Europe and Asia.

  • Carya poilanei <small>Leroy</small> – Poilane's hickory
  • Carya sinensis <small>Dode</small> – Beaked hickory
  • Carya tonkinensis <small>Lecomte</small> – Vietnamese hickory

C. sinensis has sometimes been split out in a separate genus as Annamocarya sinensis, When this bark was mixed with maple bark, it produced a yellow dye pigment. The ashes of burnt hickory wood were traditionally used to produce a strong lye (potash) fit for soapmaking.

The nuts of some species are palatable, while others are bitter and only suitable for animal feed. Hickory nuts were a significant food source for indigenous peoples of the Eastern Woodlands of North America since the middle Archaic period. They were used by the Cherokee in Kanuchi soup, but more often edible oil would be extracted through crushing the nuts and then either straining or boiling the remains. Shagbark and shellbark hickory, along with pecan, are regarded by some as the finest nut trees. Pecans are the most important nut tree native to North America. Hickory is therefore used in a number of items requiring these properties, such as tool handles, bows, wheel spokes, walking sticks, drumsticks and wood flooring. Baseball bats were formerly made of hickory, but are now more commonly made of ash; however, it is replacing ash as the wood of choice for Scottish shinty sticks. Traditional lacrosse sticks are made out of hickory, however since the 1970s lacrosse sticks have switched to plastic heads on metal shafts. Hickory was also extensively used for the construction of early aircraft.

Due to its grain structure, hickory is more susceptible to moisture absorption than other species of wood, and is therefore more prone to shrinkage, warping or swelling with changes in humidity.

Hickory is also highly prized for wood-burning stoves and chimineas, as its density and high energy content make it an efficient fuel.

  • Philips, Roger. Trees of North America and Europe. Random House, Inc., New York. , 1979.
  • Carya images at the Arnold Arboretum of Harvard University Plant Image Database
  • Damery, Jonathan. "The Carya Collection." Arnold Arboretum of Harvard University website. Accessed 26 May 2020.