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Species Guide
All text and photographs © 1996,1997
Thomas W. Kimmerer

Family: Juglandaceae
Genera: CaryaJuglans
The following species are discussed in this guide:
Carya cordiformis Carya glabra
Carya illinoinensis Carya laciniosa
Carya ovata Carya tomentosa
Juglans cinerea Juglans nigra

Species bitternut hickory, Carya cordiformis
Species Name cordate (heart-shaped), referring to the fruit
Sites and Soils Bitternut grows on a wide range of sites, from alluvial bottoms to dry ridgetops, though large trees are generally confined to mesic sites on rich, well-drained soils.
Ecology Bitternut is the most common hickory, occurs on the widest array of sites, and has the largest range. It is the northernmost of all hickories. Bitternut is most often encountered in the understory of mesic sites, and it appears that relatively few make it into the canopy. When it does, it is a scattered tree. On drier sites small trees are common, canopy trees are not. Bitternut also occurs on alluvial bottoms, where it reaches considerable size. Bitternut is also the most tolerant of hickories, hence its common occurrence in the understory.
Life History Bitternut is the most tolerant hickory. It reproduces from seed, which are cached by squirrels. Seeds germinate in spring from seed banks, which may persist for years. Bitternut establishes well after major disturbance, but can establish in small gaps as well. Stumps will sprout after fire or logging, though not prolifically. On well-drained bottomlands, bitternut is fast growing, probably the fastest growing hickory. Lifespan is 150-200 years. Champion 171'x4'; typical 70'x1'-2'
Interactions Bitternut is ectomycorrhizal; wind pollinated. Seeds are bitter and generally ignored by squirrels if other foods are available.
Status Abundant; stable
Range Eastern Deciduous Forest, except extreme NE and Gulf Coastal Plain.
Kentucky status Abundant; stable
Kentucky range Entire state.
Uses Rough lumber and pulp.
Ornamental use Not much used.
Notes

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Species pignut hickory, Carya glabra
Species Name flexible (referring to the wood).
Sites and Soils Pignut can be found on almost any upland site on well-drained mesic to xeric, usually acidic, soils
Ecology Pignut hickory is one of the characteristic upland hickories of the Eastern Deciduous Forest, occuring on xeric (occasionally mesic) upland sites in mixture with black, scarlet and white oaks, mockernut and shagbark hickory, red maple and hard pines. It is an intolerant, gap-phase species occuring in mixture with these other species, never in pure stands.
Life History Pignut hickory reproduces from seed and stump sprouts. It is a mast-fruiting species, producing heavy seed crops at irregular intervals, though some seeds are borne every year. Seeds are cached by squirrels and germinate in spring. Seedlings survive for long periods only in gaps. Once established, pignut grows slowly, often becoming overtopped by red maple or oaks. Hickories live for only 100-200 years. In recent years, there has been considerable mortality of hickories following severe droughts of the 1980s. Champion 145'x4'; typical 60'x1'-2'
Interactions Ectomycorrhizal; wind-pollinated. Important food source for gray squirrels. Inedible by humans unless tannins are first extracted with hot water.
Status common; populations have declined since the ealy 1980s due probably to a series of millenial droughts. Mortality seems to be slowing in the last few years.
Range Eastern Deciduous Forest except extreme N and southern Mississippi River Valley.
Kentucky status Common; Many large trees were lost to drought in the 1980s, but regeneration appears to be good.
Kentucky range Entire state
Uses As for all hickories: tool handles, furniture, cabinets, sporting goods, etc. These uses are declining, and hickory is today considered a low value wood. Veneer use is increasing in importance, especially for face veneers, though all hickories suffer from ring shake. Ring shake is a separation of wood along the annual rings, and is a serious defect for thin veneers.
Ornamental use Some use on large sites. Use should be encouraged.
Notes

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Species sweet pecan, Carya illinoinensis
Species Name of Illinois (some authors use C. illinoensis, but the form used here is the correct one.)
Sites and Soils Mesic ridges in broad river bottoms, on well-drained soils which are only occasionally inundated.
Ecology Sweet pecan is a bottomland species of the Mississippi River valley and its tributaries, where it grows on well-drained ridges in bottoms, along with sweetgum, sycamore, water and willow oaks and other bottomland hardwoods. Like most bottomland species, sweet pecan is intolerant, weak-wooded, fast growing and short lived (to ca 100 years on bottomland sites).
Life History Sweet pecan reproduces from seed and stump sprouts. It is a mast-fruiting species, producing heavy seed crops at irregular intervals, though some seeds are borne every year. Seeds are cached by squirrels and germinate in spring on moist, but not hydric, sites. Growth is very rapid, the fastest of any hickory. Champion 180'x7'; typical 120'x4'
Interactions Ectomycorrhizal; wind-pollinated. Important food source for gray squirrels. Highly prized by humans, especially native Americans
Status common; populations in the original range have declined precipitously since the beginning of this century, as bottomland forests were converted for agriculture. At the same time, extensive plantations of sweet pecan were established throughout the south, and escapes from these plantations have extended the native range E. to the Atlantic coast. On balance, there is probably less sweet pecan than at the time of European settlement.
Range Southern Mississippi River Valley and its tributaries, incl. Missouri and Ohio; W. to central Texas, Oklahoma, E. Kansas and northeast Mexico (disjunct population).
Kentucky status Uncommon; formerly abundant in Miss. and W. Ohio river valleys, and grown in plantations in Fulton county. Drastically reduced by conversion to farmlands, and most natural stands and plantations are gone.
Kentucky range Mississippi and W. Ohio river valleys and their broader tributaries
Uses Wood is weaker than other hickories, suitable for flooring, furniture, veneer. Veneer use is increasing, but ring shake is a common defect. Pecan is one of the most important cultivated nuts of North America, grown primarily in Georgia and Texas, but also in most southern states and California.
Ornamental use Not widely used as an ornamental, and suffers from a number of foliar diseases which reduce its attractiveness.
Notes

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Species shellbark hickory, Carya laciniosa
Species Name shaggy
Sites and Soils Stream banks, lower slopes, riparian zones, on alluvial soils, often inundated in the winter. Also on better-drained upland sites particularly on limestone.
Ecology Shellbark hickory is a species of stream banks, lower slopes, riparian zones, and of moist limestone sites. It is also a scattered on drier upland sites provided that soil pH is neutral to alkaline. Shellbark hickory is intermediate in tolerance (more tolerant than other hickories except bitternut), and is very slow growing.
Life History Shellbark hickory reproduces from seed and stump sprouts. It is a mast-fruiting species, producing heavy seed crops at irregular intervals, though some seeds are borne every year. Seeds are cached by squirrels and germinate in spring. Once established, shellbark hickory grows very slowly, and is frequently overtopped by competition. Hickories live for only 100-200 years. In recent years, there has been considerable mortality of hickories following severe droughts of the 1980s. Champion 145'x4';typical 100'x1'-2'.
Interactions Ectomycorrhizal; wind-pollinated. Important food source for gray squirrels. Edible by humans, and prized by native Americans and early settlers; too slow growing to be cultivated.
Status common; populations have declined since settlement due to conversion of land for agriculture.
Range Midwest, Michigan to Tennessee, Arkansas, W. to eastern Kansas. Disjunct populations in New York, Pennsylvania, West Virginia, Tennessee.
Kentucky status Common; declining due to continued habitat loss; the most common hickory of the bluegrass, but not regenerating there
Kentucky range Entire state except Pine, Black mountains.
Uses As for all hickories: tool handles, furniture, cabinets, sporting goods, etc. Veneer use is increasing in importance, especially for face veneers, though all hickories suffer from ring shake. Ring shake is a separation of wood along the annual rings, and is a serious defect for thin veneers.
Ornamental use Rarely used. In Lexington Cemetery, it is a beautiful tree, and should be considered for large park sites.
Notes

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Species shagbark hickory, Carya ovata
Species Name ovate (referring to fruits)
Sites and Soils Uplands: poor, upper slopes; more mesic sites to the south; on acidic, well-drained soils.
Ecology Shagbark hickory is an upland species of poor sites, growing in mixture with other upland hickories, oaks, and pines. In the southern part of its range, it occurs on more mesic sites and may be found in coves and well-drained sites along stream and river banks. Moderately tolerant when young, shagbark hickory can often be found in the understory, but more mature trees are moderately intolerant. Gaps are essential to successful regeneration of shagbark hickory, and indeed of all hickories except bitternut.
Life History Hickories flower in spring and are wind pollinated. They are mast fruiting, bearing large seed crops at irregular intervals. Fruits ripen in fall and the nuts are eaten or cached by squirrels. Squirrels never remember where all their nuts are, so they are fairly effective planters of hickory nuts. The seeds germinate in spring of the following year, or may persist in the seed bank for a few years. After germination, the succulent shoots are often browsed by mammals, but new shoots are regenerated from the vigorous root system. This may occur for several years before the shoot system finally becomes established. Hickories stump and root sprout, especially after damage or death of the parent tree. Growth of all hickories is slow, though shagbark hickory is a bit faster than most. Hickories can live for 200-350 years.
Interactions Ectomycorrhizal; wind-pollinated. Important food source for gray squirrels.
Status Common; stable; Declines from the 1980's to the early 1990's, apparently due to millenial droughts, have abated.
Range Eastern Deciduous Forest except Gulf and Atlantic Coastal Plains, N. New England and N. Lake States.
Kentucky status Common; stable
Kentucky range Entire state, less common in the Buegrass than elsewhere.
Uses Formerly prized for tool handles, upland hickories are today minor commercial species with relatively low value.
Ornamental use Little used. Suited to large sites with deep soil.
Notes

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Species mockernut hickory, Carya tomentosa
Species Name Hairy
Sites and Soils Mockernut hickory is most commonly an upland species of mesic to xeric sites on acidic to alkaline soils. It is also found on upper terraces of broad riverbottoms.
Ecology Mockernut hickory is an intolerant gap-phase species which regenerates after major disturbance. It is slow growing, like most hickories.
Life History Mockernut hickory reproduces from seed and stump sprouts. It is a mast-fruiting species, producing heavy seed crops at irregular intervals, though some seeds are borne every year. Seeds are cached by squirrels and germinate in spring. Seedlings survive for long periods only in gaps. Once established, mockernut grows slowly, often becoming overtopped by red maple or oaks. Hickories live for only 100-200 years. In recent years, there has been considerable mortality of hickories following severe droughts of the 1980s.
Interactions Ectomycorrhizal; wind-pollinated. Important food source for gray squirrels. Nuts are sweet and delicious for human consumption.
Status common; populations have declined since the ealy 1980s due probably to a series of severe droughts. Mortality seems to be slowing in the last few years
Range Eastern Deciduos Forest except northern 1/4 and southern Missisppi River Valley.
Kentucky status common; Many large trees were lost in 1980s, but regeneration appears to be good.
Kentucky range Entire state
Uses As for all hickories: tool handles, furniture, cabinets, sporting goods, etc. Value is very low today. Veneer use is increasing in importance, especially for face veneers, though all hickories suffer from ring shake. Ring shake is a separation of wood along the annual rings, and is a serious defect for thin veneers.
Ornamental use Not available commercially.
Notes

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Species of Special Concern

Butternut populations are in precipitous decline due to a fungal disease, butternut canker, caused by Sirococcus clavigigneneti-juglandacearum. This fungus is of unknown origin. The disease was first observed in 1967 in Wisconsin. At present, the disease is epidemic throughout the range of butternut and is ravaging the species. Butternut is in Category C on the rare and endangered species list. The reduction in butternut populations is also due to overharvesting of this species, which produced fine hardwood for furniture. The Hardwood Forestry Fund is sponsoring research to develop canker resistant butternut trees. You can learn more about butternut canker from the US Forest Service . Overharvesting of butternut is also a major factor in its decline.

Species butternut, Juglans cinerea
Species Name ash gray (for the bark)
Sites and Soils Rich, mesic sites following disturbance, on well-drained acidic to alkaline soils.
Ecology Butternut is a small, scattered tree of rich mesic sites. Intermediate in tolerance, it is a gap phase species, whose associates include black cherry, American beech, Northern red oak, yellow-poplar, sugar maple, yellow birch and eastern white pine.
Life History Butternut produces mast crops of heavy seeds, which germinate below the parent tree or are dispersed over short distances by squirrels. Germination of the few seeds which survive predation is good, and the seeds buried by squirrels can form a seed bank. Butternut is moderately intolerant, and growth is slow. Lifespan was rarely longer than 100 years, and is now much less. Champion 110'x5'; typical 50'x1.5'
Interactions Ectomycorrhizal; wind pollinated; severly infected by butternut canker caused by the fungus Sirococcus clavigigneneti-juglandacearum.
Status Formerly common; declining due to overharvesting and the ravages of butternut canker.
Range Eastern Deciduous Forest except in Atlantic & Gulf Coastal Plain and lower Mississippi River valley; there are many disjunctions in the range which do not show on distribution maps.
Kentucky status Common at the time of European settlement; now rare and declining.
Kentucky range Entire state
Uses Butternut wood is prized for cabinetwork, gunstocks and furniture. Never abundant, the species has been devastated by overharvesting and disease, and there is very little wood left on the market. Nuts are delicious, and were prized by Native Americans and European settlers. Orange dye was obtained from fruit husks, and root bark was used in folk medicine. Syrup was made from sap, but yields were lower than for sugar maple.
Ornamental use Rarely used, as form is not particularly attractive and the large rachises and fruits make the tree "trashy." Does not grow in compacted soil.
Notes

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Species black walnut, Juglans nigra
Species Name black (for the dark wood)
Sites and Soils Mesic: coves, stream banks, lower slopes, hedgerows, rich old fields, on well-drained rich acidic to alkaline soils
Ecology Black walnut is among the most characteristic midwestern trees. Though an early successional species on rich sites, it persists late enough in forest succession to be a component of many forest types. It is abundant in hedgerows and oldfields, as well as river bottoms and coves. In the open, walnut has a short main stem with a broad crown. With even moderate competition, walnut forms a tall, stately tree. On poor sites, walnut will become established and persist, but will not become a canopy tree and is eventually snuffed out by competition.
Life History Black walnut produces seed crops every year, and heavy seed crops intermittently. Seeds are highly sought by squirrels, which cache seeds by burying them. Germination occurs the following year. Seeds can form a long-term seed bank. Black walnut is intolerant and grows moderately fast. First reproduction may occur by ten years. Few walnuts live longer than 200 years, though a few persist for up to 250 years. Stems are usually short and forked unless grown with competition. Champion 150'x8'; typical 80'x2'-3'.
Interactions Walnut seeds are an important food item for grey squirrels. Walnut leaves are host to a number of insects and diseases, which cause the leaves to drop in late summer. Black walnut is famous for its allelopathic inhibition of the growth of nearby plants. Despite this, the effect is not commonly observed in the field. Ectomycorrhizal, wind pollinated
Status Common, stable, but reduced by overharvesting.
Range Eastern Deciduous Forest except absent from most of Northeast and lower Mississippi Valley, Gulf Coastal Plain.
Kentucky status Common, stable, but reduced by overharvesting. Abundant in the Bluegrass.
Kentucky range Entire state
Uses Black walnut is the premier hardwood species in North America, and one of the most valuable woods in the world. Supplies of quality walnut are declining, as a result of overharvesting. Attempts to grow walnut in plantations for fine wood production have met with limited succcess. Walnut wood is dark and hard, but workable, with fine grain. It is prized for gunstocks, furniture and face veneer. The nuts are collected throughout the midwest, and are used in baking and ice cream making.
Ornamental use Not commonly used. Generally too large, and too trashy, for ornamental consideration. However, it is culturally important, and its use in parks and other large sites should be encouraged. There are many in Lexington, Kentucky, probably planted by squirrels from remnant trees.
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