Tree of the Month, January 2024

Bitternut Hickory, Yellowbud Hickory, Swamp Hickory

Carya cordiformis

by Martin (Mort) Schmidt for Simply Living

Hickory is renowned for its toughness and resilience. Our seventh president, Andrew Jackson, was nicknamed “Old Hickory” because of his indomitable spirit. And Bitternut Hickory is a particular favorite of mine. Though not nearly as well known as Shagbark Hickory, Bitternut Hickory is instantly recognizable if you know what to look for. But first of all, be careful not to confuse Bitternut with Butternut, a close relative to Black Walnut. But all of the hickories and walnuts are in the walnut family, Juglandaceae, and all have nuts whose meat resembles a pair of human brains attached at their bases. 

Like the other hickories in Ohio, Bitternut Hickory has alternate compound leaves. Opposite leaves, branches, and buds are attached to the tree directly across from each other. Alternately-arranged leaves are attached at different points on the tree, similar to how our footprints alternate left, right, left, right. 

Alternate versus opposite. Drawing by Mort Schmidt. 

Hickories have pinnately compound leaves. Simple leaves are attached directly to the permanent parts of the tree, but compound leaves have multiple leaflets attached to a petiole (stem). The petiole is not permanent – it might remain on the tree for a while, but unlike twigs and branches, it lives for only one year on deciduous trees, and will never sprout new leaflets. But it’s not always obvious whether a slender part is temporary (a petiole) or permanent (a twig). What is obvious is that compound leaves have leaflets in more or less constant numbers. For example, Poison Ivy is easily recognized by groups of three leaflets; “Leaves of three, Let it be”. Bitternut Hickory leaflets are present in groups of 7, 9, or occasionally 11 leaflets. Its close relative, the Pecan tree (Carya illinoinensis}, has 9 to 17 leaflets. Other hickories in Ohio have 5 or 7 leaflets, rarely more. 

Pinnately- versus palmately-compound leaves. Drawings by Mort Schmidt. “Pinnate” means feather-like, and “palmate” means hand-like.

Bitternut leaflets are described as being lance-like or lanceolate, i.e., they’re an elongated, pointed oval, and they’re distinctly smaller and narrower than the leaflets of most other hickories. The leaflets have small teeth and turn yellow in the fall. 

Bitternut Hickory leaf. Notice that while this compound leaf is attached to the tree in an alternate pattern, its leaflets are opposite from one another. When determining whether a tree has alternately- or oppositely-arranged leaves, be sure to look at the whole leaf. Photo by Mort Schmidt.

Many people recognize mature Shagbark Hickory bark by its long, loose strips of bark. Mature Bitternut Hickory bark has a diamond pattern much like ash, but less deeply incised (and ash leaves and branches are opposite, while hickories are alternate). But all juvenile hickory bark, at least to my eye, looks alike, and resembles fingerprints or stretch marks on skin. 

Left to right – Mature Bitternut bark, mature ash bark, juvenile Bitternut Hickory bark. Photos by Mort Schmidt.

The most distinct trait of Bitternut Hickory is yellow buds. They’re especially obvious in winter when nature’s colors are muted, but the yellow buds are often visible in summer as well. Some sources, including the Wisconsin Department of Natural Resources Tree ID site, use “Yellowbud” as the common name for Carya cordiformis

Bitternut Hickory buds. Photo by Mort Schmidt.

The Bitternut Hickory’s fruit is far smaller than Shagbark’s. It’s also usually intact, because few animals like eating it. Bitternut nuts also differ in having four ridges or “wings”, whereas Shagbark nuts have four grooves. 

Bitternut nuts. Photo by Mort Schmidt.

Bitternut Hickories inhabitat moist soils, hence the common name, “Swamp Hickory”. Bitternut Hickory reaches a height of 80 feet at maturity, with a trunk diameter of 1.5 to 2 feet. Ohio’s Champion, located in Richland County, has a height of 115 feet, a diameter of 4.0 feet, and a crown width of 85 feet. According to the Illinois Wildflowers website, “Individual trees can live up to 200 years; they have to be at least 30 years old to produce nuts.” Bitternut Hickory is native to eastern North America and has the widest range of any hickory. The range map in Lucy Braun’s The Woody Plans of Ohio shows C. cordiformis in every one of Ohio’s counties except for Hocking. 

Range map of Carya cordiformis. Image from U.S. Geological Survey

While the Bitternut fruit is undesirable to people and animals, the wood is very useful. Hickory is known for its hardness and toughness, and the hickories are the hardest commercially-available lumber in Ohio. Bitternut Hickory lumber has a Janka hardness of 1,500 lbf and a density of 0.74 g/cc, according to the Wood Database, compared to the median of my list of 73 Ohio trees of 1,075 lbf and 0.64 g/cc. 

The true hickories (Shagbark, Kingnut, Pignut, and Mockernut – Carya. ovata, C. lacinosa, C. glabra, and C. tomentosa), like oak and ash, are ring-porous. That is, the large pores are packed into tight bands aligned with the annual rings. In diffuse-porous woods, such as maple and beech, the pores are distributed evenly and are not aligned parallel to rings. The pecan hickories, including Bitternut Hickory and Pecan have semi-ring-porous structure, in which pores are tightly spaced along the annual rings early in the year, but more spread out later in the year. Examples of the three porosity types are available here. Bitternut Hickory and Pecan wood are less hard than the true hickories, but still very hard. And at the lumber yard, Bitternut is generally combined with the true hickories.  

Ring-porous woods readily split parallel to grain. Ironically, this is a strength, not a weakness for slender items, such as tool handles, chair spindles, and the likes, as long as the grain is parallel to the object’s length. Ash is the lightest and softest of these ring-porous woods, and hickory is the densest and hardest. Consequently, rake and shovel handles are typically made of ash, because they don’t need a lot of shock resistance, and hickory is too heavy. Hickory is preferred for hammer and ax handles, because it offers greater shock resistance and its greater weight is less detrimental in shorter handles. (Baseball bats are typically made of ash. Hickory is less likely to break, but too dense for most batters – unless you’re Babe Ruth. One of his hickory bats is on display at the Louisville Slugger Museum in Louisville. However, some sources indicate that hickory bats were more common in Ruth’s day. Today professional players often use maple, which tends to shatter on impact but provides good distance. The replacement cost isn’t a factor in professional sports).  

The hickories have low durability (rot resistance), and are not good for outdoor applications. Hickory’s hardness makes it a good choice for flooring and furniture. Hickory also shares with ash and oak the ability to steam-bend, making it desirable for some furniture applications. Like other dense woods, hickory has a high fuel value, and because it splits well parallel to grain, it makes ideal firewood. Despite Bitternut Hickory’s unpalatable nuts, many consider it the best of the hickories for smoking meat and other foods. 

Historically, hickory’s hardness, shock resistance, and long grain made it the preferred wood for wagon-wheel spokes. Last month’s Tree of the Month article discussed how traditional Windsor chairs were made with multiple woods to take advantage of their various properties. Similarly, wagon wheels were made of multiple woods to exploit the advantages of each. Spokes were often made of hickory, and they were driven into hubs of elm. Elm is not nearly as hard as hickory, but its cross grain made it unlikely to split when spokes were driven into it at various angles. The settlers didn’t eat Bitternut Hickory nuts, but they did extract their oil to fuel lamps. The Natives prized hickory for making bows. 

According to the Native American Ethnobotany Database, the Iroquois made considerable use of Bitternut Hickory, including as a food additive. The nut meats were boiled and the liquid was used as a drink. The nut meats were also added to breads, puddings, soups, and sauces. Presumably, the bitterness was reduced by boiling or leaching mets, or by simply using them sparingly. The Iroquois also used Bitternut bark to make chair seats. The Database also cites the use of Bitternut bark infusions by the Meskwaki people for use as a laxative. And the Omaha people took advantage of Bitternut’s strength and bending properties to make snowshoes. 

Although mammals have little interest in the nuts of Bitternut Hickory, the nuts often have small worm or insect holes in them. Hickory foliage, including Bitternut, is consumed by a number of insects. In fact, Catocala subnata (Youthful Underwing), is said to feed on the foliage of Bitternut Hickory exclusively, according to the Illinois Wildflowers website. And because hickories attract insects, they also attract insectivorous birds. 

Despite hickory’s reputation for strength and resilience, none of the United States have adopted any variety of hickory as its state tree. Nevertheless, hickory is revered as lumber and fuel, and Bitternut Hickory will warm your heart when you spot its bright yellow buds in an otherwise colorless winter landscape. 

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On January 12 at 2:00 pm, Mort Schmidt and Park Ranger Scott Felker will lead a winter tree ID walk at the Three Creeks Metro Park, leaving from the Confluence Area. Visit the Metro Parks Calendar for updates. 

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You can also listen to my talks on Ohio Broadleaf Tree Identification on YouTube, Part 1 and Part 2

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