When I was young all I knew about trees was that there were oaks and maples. I guess I thought there was one species of each. It was only when I took biology classes later in life that I found out that there were many (i.e. more than a hundred) species of each. The same is true of hickory trees, albeit there are only about 18 species worldwide. Hickories are part of the mature forest in this part of the northeast. Typical forest succession in this region starts with colonizing trees such as black cherry (very common in Pennypack Preserve), ash, and red cedar. These are overgrown by taller maple, beech, and tulip trees. Ultimately oaks and hickories predominate in the mature forest. Pennypack Preserve is still in transition from its agricultural and industrial days. Different stages of succession can be found in different areas of the preserve. One of the older areas in the preserve is around the Peak and Management Trails at the southern end. Hickories are more common there. I realized I didn’t know much about identifying hickory species, so I went out this afternoon to see what I could learn. I identified 3 hickory species in this area, but there could be additional species elsewhere in the preserve. This is what I found.
Mockernut Hickory (Carya tomentosa)
Saplings were common along Creek Road, with larger trees in the upland. The starting point to identifying hickories is to count the leaflets. Hickory leaves are compound, meaning each leaf is divided into several smaller leaflets. Different species have different numbers of leaflets. Typically mockernut hickories have 7 leaflets as seen in the photo.
Occasionally, more or fewer leaflets may be seen, so you need to look at multiple leaves on the same tree and decide what is typical. The full leaf is large, up to 20 inches or so, and the leaflets are up to 8 inches each. The bark is ridged as seen below.
Fortunately, I was able to find some of the nuts. This species could be confused with another Pennsylvania species, the Shellbark Hickory, but the latter produce much larger fruit and different bark. These Mockernut fruits were about 1 1/2 inches in diameter.
Bitternut Hickory (Carya cordiformis)
These were less common. Bitternut Hickories have 9 leaflets per compound leaf, but the whole leaf is much smaller, about 10 inches long. Individual leaflets are 3-6 inches.
The bark has vertical cracks, seen on this sapling.
Although I didn’t find any fruit, it is apparently very bitter and unpalatable, hence the name. On the other hand the wood is considered good for smoking meat.
Shagbark Hickory (Carya ovata)
This is the first (and only) hickory I learned to identify when I took Ecology as an undergraduate at the University of Michigan. There are 5 leaflets per leaf. Each leaf is 12 inches or longer with leaflets being about 4 inches in length.
Pignut Hickories also have 5 leaflets, but the leaves are smaller and the leaflets more narrow. Shagbark hickories are known for the bark which peels off in long strips as the tree ages.
Shellbark and Pignut Hickories can also have peeling bark, however.
In the fall, hickories are among the earliest trees to turn color. In a good year they can be a glorious yellow. This fall, look along the Management Trail to see them.