Guide to 6 Most Common Hickories of Eastern North America
Tied Species:Carya ovata, Carya laciniosa, Carya tomentosa, Carya cordiformis, Carya glabra, Carya illinoinensis,
Ecoregions:Eco-326, Eco-345, Eco-381, Eco-357, Eco-351, Eco-383, Eco-320, Eco-314, Eco-380, Eco-332, Eco-324, Eco-323, Eco-315, Eco-313, Eco-325, Eco-322, Eco-382, Eco-390, Eco-316, Eco-376, Eco-379,
Updated: Thu Apr 11 2024
There are 15-20 species of Hickory trees, the majority of which are native to North America. In this guide we are going to be looking at the 6 most common and widespread species of eastern North America.
Hickory trees provide so much value to their ecosystem in so many different ways. In the proper environment hickories, along with oaks, tend to become the dominant canopy species in the forest and act as a home to a multitude of different species. Hickory nuts are a great food source for people as well as many different animals including squirrels, opossums, and wild turkey. The wood is extremely strong and durable, it has traditionally been used for everything from tool handles, to baskets, to flooring. Hickory is also arguably the best wood to use as fuel. It burns longer and hotter than almost any other wood.
Generally it is not too hard to distinguish hickories from other tree species in the same range. Once you get a feel for their growth form, coupled with alternate branching, compound leaves, distinct nuts, and (sometimes)distinct bark, they are pretty unique in the environment. But if you need more clues, they can further be identified by their true end buds(on some other trees the terminal bud actually comes off to the side), solid piths(slice twig in half to check), and large obvious bud scars.
Once you have determined it is in fact a hickory tree, it can get a little tricky determining which exact species it is(not to mention hybrids). And while I'm not going to go over every species here, I'm going to give a comparison of the 6 most common and widespread species as a jumping off point into the world of hickories.
Species Summaries
Description: Shagbark hickories, as indicated by the name, have very shaggy bark that peels off in long strips. Mature trees typically grow between 60-90 feet tall and 2-3 feet and diameter, but can get bigger. They typically have 5-7 hairless leaflets(mostly 5) which are usually 8-14 inches long. The nuts are quite large growing between 1-3 inches with a thick husk. They have stout red-brown twigs that can be slightly hairy with end buds over 1/2 inch.
Similar Species: The only other hickory with shaggy bark with few leaflets is the Shellbark hickory, but it usually has 7-9 hairy leaflets and tan-orange twigs. Carya aquatica also has shaggy bark but 9-17 leaflets and small end buds. Carya ovalis sometimes has shaggy bark and similar leaflet count but has slender twigs and small end buds.
Description: Shellbark hickory is the other species we'll look at with shaggy bark. It typically gets bigger than Shagbarks growing to be 80-100 feet tall and 3-4 feet in diameter. It usually has 7-9 leaflets with hairy(sometimes hairless) undersides that are 15-22 inches long. The nuts grow roughly the same size as Shagbarks and also have thick husks. The twigs are stout, tan-orange, with large end buds.
Similar Species: Same as Shagbark.
Description: Mockernut hickories are similar to Shagbarks and Shellbarks in that they have stout twigs with large end buds and similar looking nuts, but the big difference is they have tight bark with deep, narrow fissures. They usually grow to be 50-80 feet tall and 18-24 inches in diameter. They typically have 7-9 leaflets with woolly undersides that are 8-15 inches long. Their nuts are similar to the species above at first glance but once opened are much smaller(hence the name Mockernut). Their twigs are also similar in size to above but more woolly.
Similar Species: It is the only hickory species with tight bark and end buds larger than 1/2 inch.
Description: Bitternut hickories have tight bark that typically forms a diamond pattern. They tend to grow 50-60 feet tall and 18-24 inches in diameter. They usually have 7-9 leaflets but can range from 5-11 and can be somewhat hairy. Leaves grow 6-12 inches. Their nuts are smaller than the species above and have a thin husk. The husk also has distinct ridges on them and, as you can guess by the name, have a bitter taste. Their twigs are slender and are distinct for their small(under 1/2") bright yellow buds that have paired, non-overlapping scales.
Similar Species: Pecans can look similar but typically have more leaflets(9-17) and hairier buds.
Description: Pignut hickories have tight bark with smooth ridges and typically grow 80-90 feet tall and 2-3 feet in diameter. They have leaves usually with 5 leaflets(sometimes 7) and are 6-12 inches long. I remember pignuts because their nut husk has a slender "snout" on one end, but I have also heard the name comes from pigs loving them so much. The nuts can be sweet, but sometimes bitter. They have slender, red-brown, hairless twigs with small end buds.
Similar Species: Carya pallida looks similar but typically has 7-9 leaflets and very small end buds(under 1/4"). Carya Ovalis is also quite similar, and sometimes considered a variation. It more often has 7 leaflets, which can be yellowish underneath, and can have looser bark. The nut husk also splits open farther down than the Pignut. Mockernut has stouter twigs and end buds. Carya texana is also similar but has distinct rusty-hairy twigs, buds, and leaf undersides.
Description: This might be the species that people are surprised to learn is a hickory, the Pecan. Pecan nuts are one of the most popular nuts out there and the tree is highly cultivated in North America. It may not be super common in the wild but they are out there. It is more common and more cultivated in the southern portion of this range but it can also thrive in the north-east under the right conditions. This is one of the largest hickory species typically growing 100-120 feet tall and 3-4 feet in diameter. It has leaves consisting of 9-17 leaflets and grow 12-20 inches long. Their bark is tight with vertical ridges. The nuts are longer than they are wide, have thin husks, and typically ridges along the husk joints. Their twigs are hairless but have small, yellow, hairy buds.
Similar Species: Carya aquatica is similar looking but has brown buds and shaggier bark. Bitternut hickory has hairless buds and usually 7-9 leaflets.
Comparisons
Leaves
Leaflets: mostly 5-7
Carya ovata - Shagbark: Usually 5 hairless leaflets.
Carya glabra - Pignut: Usually 5 hairless leaflets.
Leaflets: mostly 7-9
Carya laciniosa - Shellbark: Undersides can be hairless or tiny velvety hairs.
Carya cordiformis - Bitternut: Usually 7-9, sometimes 5 or 11. Undersides somewhat hairy.
Carya tomentosa - Mockernut: Undersides woolly.
Leaflets: mostly 9-17
Carya illinoinensis - Pecan: Usually hairless.
Bark
Bark: mostly shaggy
Carya ovata - Shagbark: Shaggy, long curled plates.
Carya laciniosa - Shellbark: Mostly shaggy, long curled plates. Sometimes tighter, but still peels and flakes.
Bark: mostly tight
Carya illinoinensis - Pecan: Flat scales and deep fissures.
Carya glabra - Pignut: Thin smooth ridges.
Carya cordiformis - Bitternut: Fine smooth ridges that form a diamond pattern.
Carya tomentosa - Mockernut: Deep narrow fissures.
Nuts
Nuts: thin husk
Carya illinoinensis - Pecan: Oblong, often in clusters of 3 to 6. Ridges along husk joint. Roughly 1-2.5 inches long by 1 inch wide.
Carya glabra - Pignut: Somewhat pear-shaped (narrows at the base). The husk usually must be split manually, as it rarely splits on its own. Approximately 1 inch long, slightly less wide.
Carya cordiformis - Bitternut: Ridged scaly husk. Bittern kernel. May be anywhere between 0.75 inch to 1.5 inches long.
Nuts: thick husk
Carya ovata - Shagbark: Occurring in pairs or solitary. Husk typically splits freely to the base when ripe. The kernel of the Shagbark is brown and sweet. They grow 1-3 inches long.
Carya laciniosa - Shellbark: Pretty much the same characteristics as Shagbark nuts.
Carya tomentosa - Mockernut: Very similar to the nuts above but husk may not split all the way to the base. Upon opening though, the shell is quite thick revealing a much smaller kernel.
Buds and Twigs
End Buds: under 1/2 inch long
Carya illinoinensis - Pecan: Buds yellow, hairy, 4-6 bud scales in pairs.
Carya glabra - Pignut: Bud scales overlapping, not in pairs. Twigs slender, hairless, and red-brown.
Carya cordiformis - Bitternut: Distinct bright yellow buds, scales in pairs. Twigs slender, mostly hairless, sometimes slightly hairy
End Buds: over 1/2 inch long
Carya ovata - Shagbark: Many overlapping bud scales. Twigs stout, red-brown, and slightly hairy
Carya laciniosa - Shellbark: Overlapping bud scales, hairy or hairless. Stout twigs
Carya tomentosa - Mockernut: Bud scales overlapping. Twigs stout and woolly
References
Petrides, G. A. (1998). A field guide to trees and shrubs: Northeastern and north-central United States and southeastern and south-central Canada (second). Houghton Mifflin.