Hickory

For other meanings of Hickory please see Hickory (disambiguation).

  Trees in the genus Carya (from Ancient Greek kary "nut") are commonly known as Hickory. The genus includes 17-19 species of deciduous trees with pinnately compound leaves and large nuts. A dozen or so species are native to North America (11–12 in the United States, 1 in Mexico), and 5–6 species from China and Indochina.

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Another Asian species, Beaked Hickory, previously listed as Carya sinensis, is now treated in a separate genus Annamocarya, as Annamocarya sinensis.

Hickory flowers are small yellow-green catkins produced in spring. They are anemophilous and self-incompatible. The fruit is a globose or oval nut, 2–5 cm long and 1.5–3 cm diameter, enclosed in a four-valved husk which splits open at maturity. The nut shell is thick and bony in most species, thin in a few, notably C. illinoinensis; it is divided into two halves which split apart when the seed germinates.

Species and classification

In the APG system, genus Carya (and the whole Juglandaceae family) has been recently moved to the Fagales order.

North America

• Carya sect. Carya — typical hickories
  • Carya floridana Scrub Hickory
  • Carya glabra Pignut Hickory
  • Carya myristiciformis Nutmeg Hickory
  • Carya ovalis Red Hickory (treated as a synonym of C. glabra by Flora N. Amer.)
  • Carya ovata Shagbark Hickory
    • Carya ovata var. australis (syn. C. carolinae-septentrionalis) Southern Shagbark Hickory
  • Carya laciniosa Shellbark Hickory
  • Carya pallida Sand Hickory
  • Carya texana Black Hickory
  • Carya tomentosa (syn. C. alba) Mockernut Hickory

• Carya sect. Apocarya — pecans
  • Carya aquatica Water Hickory
  • Carya cordiformis Bitternut Hickory
  • Carya illinoinensis Pecan
  • Carya palmeri Mexican Hickory

Asia

• Carya sect. Sinocarya — asian hickories
  • Carya dabieshanensis Dabie Shan Hickory (may be synonymous with C. cathayensis)
  • Carya cathayensis Chinese Hickory
  • Carya hunanensis Hunan Hickory
  • Carya kweichowensis Guizhou Hickory
  • Carya poilanei Poilane's Hickory
  • Carya tonkinensis Vietnamese Hickory

Hickory is used as a food plant by the larvae of some Lepidoptera species. These include:

• Brown-tail (Euproctis chrysorrhoea)
• the Coleophora case-bearers C. laticornella and C. ostryae.
• Regal moth (Citheronia regalis), whose caterpillars are known as hickory horn-devil
• Walnut Sphinx (Amorpha juglandis)

Another insect that uses the hickory tree as a food source is the hickory leaf stem gall phylloxera (Phylloxera caryaecaulis). Phylloxeridae are related to aphids and have a similarly complex life cycle. Eggs hatch in early spring and the galls quickly form around the developing insects. Phylloxera galls may damage weakened or stressed hickories, but are generally harmless. Deformed leaves and twigs can rain down from the tree in the spring as squirrels break off infected tissue and eat the galls, possibly for the protein content of the phylloxera, or possibly because the galls are fleshy and tasty to the squirrels.

Uses

Hickory wood is extremely tough, yet flexible, and is valued for tool handles, bows (like yew), wheel spokes, carts, drumsticks, golf club shafts (sometimes still called hickory stick, even though made of steel or graphite), walking canes etc. and for punitive use as a switch or rod (like hazel), and especially as a cane-like hickory stick in schools. Baseball bats (also used as substitute paddle or even modified for physical punishment) were formerly made of hickory but are now more commonly made of ash. Hickory is also highly prized for wood-burning stoves, because of its high caloric content. Hickory wood is also a preferred type for smoke curing meats. In the Southern US, hickory is popular for cooking barbecue, as hickory grows abundantly in the region, and adds flavor to the meat. Hickory is sometimes used for hardwood flooring due to its durability and character.

A bark extract from shagbark hickory is also used in an edible syrup that is similar to maple syrup, with a slightly bitter, smoky taste.

The nuts of some species are palatable, while others are bitter and only suitable for animal feed. Shagbark and Shellbark Hickories, along with the Pecan, are regarded by some as the finest nut trees.

When cultivated for their nuts, note that because of their self-incompatibility, clonal (grafted) trees of the same cultivar cannot pollenize each other. Two or more different cultivars must be planted together for successful pollination. Seedlings (grown from hickory nuts) will usually have sufficient genetic variation.

See also

• Walnut