Short answers, pulled from the story.
The name "hickory" derives from a Native American word in an Algonquian language, possibly Powhatan. It is a shortening of words such as pockerchicory or pocohicora, which may have referred to the hickory nut itself or to a milky drink made from those nuts. The genus name Carya comes from the ancient Greek káryon, meaning "nut."
Plants of the World Online accepts 19 species of hickory within the genus Carya. Twelve are native to North America and seven are native to Southeast Asia, in China, Indochina, and the Assam region of northeastern India. Eleven of the North American species occur in the United States.
Dried hickory nuts are 64% fat, 13% protein, 18% carbohydrates, and 3% water. A 100-gram serving supplies 2749 kilojoules of food energy and provides 220% of the daily value for manganese, along with significant amounts of several B vitamins.
Hickory wood is uniquely hard, stiff, dense, and shock resistant. No other commercial wood combines all four of those properties at once. This makes it the material of choice for tool handles, bows, walking sticks, drumsticks, wheel spokes, and wood flooring, and it is the current preferred wood for Scottish shinty sticks.
Modern Carya first appeared in Oligocene strata 34 million years ago, and the oldest fossils attributed to the genus are Cretaceous pollen grains from Mexico and New Mexico. The Pleistocene Ice Age, beginning around 2 million years ago, erased the genus from Europe entirely.
Several moth species use hickory as a larval food plant, including the luna moth, the regal moth (whose caterpillars are called hickory horn-devils), the hickory tussock moth, and the walnut sphinx. The hickory leaf stem gall phylloxera (Phylloxera caryaecaulis) also depends on hickory, forming galls on its stems and leaves each spring.