Flora and fauna of the Athens County area, and occasionally habitats outside Ohio. Subject matter will consist of both interpretive material and taxonomic issues in plant and animal identification.

Monday, November 4, 2013

Hickories of Ohio

It's that time of year where I'm not out with the camera much. I often look through my photos in order to come up with a topic to post. I had put this together before I realized fellow blogger Andrew Gibson did an excellent post on the subject a couple years back at Natural Treasures of Ohio. Andy emphasized winter condition in his post, and I simply hope to expand on that.

There are six species of hickory in our region. Rather than memorizing them, there are three ways you can spilt them into different groups.

1) Are there 5 or commonly 7-9 leaflets?
2) Is the bark shaggy or tightly criss-crossed?
3) Is the fruit husk thick or thin?

We'll start with the two shaggy looking species. The more common one is the Shagbark Hickory, Carya ovata. It is found from bottomlands to ridgetops. The bark forms long shaggy or warped plates that separate from the trunk.

Because young Shagbarks do NOT have shaggy bark, it pays to look at other characters. The twigs are dark brown and dirty hairy. The buds are elongate or bullet shaped. The bottom scales are black to purple, and the upper scales are light colored.

Sometimes there may be seven leaflets, but Shagbark most often occurs with 5 leaflets. The name ovata comes from the terminal leaflet often being broader than other hickories. The fruit has thick husks, and is considered the most edible of all the hickories here in the north. In the south, another hickory has high commercial value, Carya illinoiensis, otherwise known as the Pecan.

Another thick husked fruit with compound leaves. At first glance, it looks just like the picture above.

Looking at the bark, it too seems to match Shagbark. This is Kingnut Hickory, Carya laciniosa. One thing to consider, 99 out of 100 times, this species will be restricted to wet bottomlands only. Beyond that you need to look closer at a few details.

Unlike Shagbark, Kingnut always shows 7-9 leaflets. Another common name for this species is Shellbark Hickory.

The buds are similar to Shag, dark below and light above, but pay attention to the new growth twigs. Shagbark is dark brown, dirty hairy. Kingnut twigs are tan, beige, flesh toned, or just call them light colored. Except in early spring, the twigs are hairless. The lenticles are often lined in orange.

While any hickory can retain its rachis stems, Kingnut is notorious for keeping them on throughout the winter. Another thing Kingnut does more so than any other hickory, it also holds the old bud scales. You can see them peeled back against the base of the twig.

Three other hickories have this tight look to the bark. Scissor shaped, criss-crossed, or X shaped. I have never met anyone who can reliably tell Mocker, Pig, and Bitter apart strictly by the bark alone. At certain ages there are subtle differences, but as they grow older, even those characters don't usually hold up. So it's important to look at the other parts of the tree.

Bitternut Hickory, Carya cordiformis, has 7-9 leaflets. By itself, that doesn't do much, since Mockernut has also 7.

The unique characteristic are the buds. Both terminal and lateral buds are a sulfur or mustard yellow. They are the only hickory in the north with these valvate or naked buds.

If you can't reach the branches to check buds, look on the ground for fruit. Bitternut fruit are oval rather than perfectly round. Like the Pignut, they are thin husked. Unlike Pignut, the fissures have raised ridges or wings. Most find the thin husked hickories not very tasty, hence the name Bitternut.

Regardless of which you may choose to crack open and eat, be aware they are susceptible to pests. Here is the grub of the Hickory Nut Weevil, Curculio caryae, chewing it's way out of the shell. These beetles spend the season eating the inside, then crawl out and bury themselves in the dirt till the following year before pupating into adults. They are related to the same Weevils that attack Plum, Chestnut, and Oak acorns.

Mockernut Hickory, Carya tomentosa. Another 7-9 leaved hickory with thick fruit. If these characters start to overlap, look for something that stands out as different.

Carya tomentosa refers to the hairy texture of the twig and leaf rachis. The more you look at these though, the more you can see something else that sticks out. The buds are shaped like the Taj Mahal or like a Hershey Kiss candy.

Besides the shape, the other thing to look for is that there are NO dark scales around the base of the bud. Early in the season they do have them, but they are deciduous and drop off come late summer and fall.

Our third tight barked species is Pignut Hickory, Carya glabra. Here in the north Pignut usually has 5 leaflets. In the south, it is more common to see them with 7. To remember both 5 leaved species, I think of what former colleague Ned Maxson used to tell students. When in the woods, look for "five shaggy pigs".

Pignut is the second thin husked, oval fruit. It does NOT have wings on it like the Bitternut. The shape often resembles a pig face and snoot.

Students sometimes call this a Shagbark, thinking they see two toned buds. Remember, on Shagbark the lower scales are dark, and upper portions light. On Pignut, one whole side of the bud may be dark.

Pignut twigs and buds are skinnier and smaller than the other hickories. To some, that's all relative. Their twigs are dark brown like Mockernut and Shagbark, but look again. The term glabra means smooth. There is no hair on the new growth portions. This is especially evident when shining in the sun.

That smooth appearance continues into the leaves. The rachis is also hairless on Pignut.

That brings us to out last hickory. Click on the photo if it's not large enough. Look at the bark. This one seems it can't decide on whether to call itself tight or shaggy. This is the least common species. Considered by some as just a Pignut variety, most texts elevate it to a valid species. It's known as Sweet Pignut, Carya ovalis.

Sweet Pig is said to have slightly larger and more stout twigs and buds. In my observations, this is true, but still a minute character. Sweet Pig almost always has seven leaflets instead of 5. Another common name is Red Hickory. The bases of the rachis are usually red, then brown further up. Since this photo was taken in November, I wouldn't use this as proof. One needs to check during the summer.

It is written that ovalis fruit splits all the way to both ends, and that glabra only splits half way. I've seen thousands of Pignuts, and I don't believe this is reliable.

An appropriate third common name applied to this species is the False Shagbark Hickory. The bark is tightly X shaped, but portions tend to start breaking away. Not in long shaggy strips, but just enough to catch your attention. It's the first thing I look for if I'm thinking Sweet Pignut.

Hickories do have habitat preferences, but by no means are they restricted to one site. Only Kingnut needs to keep its feet wet in bottomlands. All the others I have seen growing within a few feet of each other throughout our slopes and ridges.


  1. great post, Dennis! I've been meaning to update my outdated post with leaf and fruit characteristics/photos. looking forward to more treatments. I have a half dozen or so treatments to get published over the winter. hope it happens!

  2. Love these posts - they bring me back. I spent some time on a mesic slope with Andrew one day and I found a grove of black maples. They all had the textbook wing on the base of the petiole. Love the woody species.

  3. Thanks for all your posts about trees. I took Dendro with you years ago and now work as a utility forester. My co-workers and I enjoy reading your posts from time to time.