Lifestyle: Most hickories begin flowering at about age twenty, and they start bearing heavy nut crops at about age forty. Thereafter they produce abundantly at about three-year intervals, so a meager crop in any given year is not unusual.
The male catkins and the small, wind-pollinated, female spikes appear on the same tree shortly after the leaves unfold. Leaves turn gold in autumn.
Hickories have deep taproots, making them stand firm in the wind. Their big buds and five to seventeen leaflets (depending on species) are often pungently fragrant when crushed. Like other nut trees, the leaf scars below the buds bear eccentric faces by which you may identify the various species in winter. A twig in cross section shows the pith in five-pointed star form.
Hickories grow slowly and live two hundred to three hundred years. These trees are moderately shade tolerant. Though they may produce stump sprouts after cutting or fire, they don't actually clone. Shagbark and bitternut species produce the allelopathic toxin juglone, though to a lesser extent than black walnut.
Associates: With oaks, hickories formed one of the dominant climax forest types of eastern North America. Wherever upland hickories grow, look for black, red, or white oaks. Hickories also share many animal associations with oaks, butternut, and black walnut.
Spring, summer. Prominent insect feeders on leaves include several butterfly and moth caterpillars. The banded hairstreak butterfly larva (Strymon falacer) is green or brown and sluglike. Of moth caterpillars, look for several underwing species, plump in the middle and tapering toward both ends. A tufted, gregarious species is the hickory tussock or tiger moth (Halisidota caryae). The hickory leafroller (Argyrotaenia juglandana), pale green-translucent, feeds inside the leaf rolls it makes. The elm spanworm (see American Basswood) can defoliate hickories.
Leaf and petiole galls are fairly numerous, most of them created by Phylloxera aphids and Caryomyia gall gnats. They may be pouchlike, cone shaped, warty, or pleated along leaf veins. A common twig gall, caused by the aphid Phylloxera caryaecaulis, looks like a partially opened hickory nut.
A tree that loses its leaves in early summer, showing dead tops and branches, may be infested with hickory bark beetles (Scolytus quadrispinosus) . The dark brown beetles, hickory's most injurious insect pests, bore into leafstalks, buds, and green nuts, then lay eggs beneath the bark, where larvae tunnel at right angles to the female's egg gallery. This butterfly-shaped series of tunnels is easily seen on dead, barkless trunks. The larvae, which sometimes girdle the tree, emerge through perforations in the bark.
Twig girdlers and twig pruners are common trimmers of hickory (see Red Oak).
Inspect green nuts that drop early; if the shells have circular cavities, they probably
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