Hi! Are you ready to learn trees? Yes? Awesome! Today we will take a walk through the Mirror Lake woodlot on the campus of The Ohio State University. This site is among the best remaining patches of woods at OSU; not more than a few acres, it features a shrub layer, spring wildflowers and warblers, and several large trees. The soil is well-drained, alkaline, and quite loamy. Come, as we dendrologize!

Trees of the Woodlot

Pawpaw (Asimina triloba)

This unique tree is the sole representative in Ohio of the Soursop family, Annonaceae. Preferring moist but well-drained rich soil, it can be found at the Mirror Lake woodlot growing as part of the understory. The elephant-skin gray bark and large, simple, alternate, magnolia-like obovate leaves set apart this tree from most you are likely to encounter in the eastern woods. Rotten-smelling red flowers appear on this tree in mid spring, later developing into fruits shaped like a mango and tasting similar to a banana!

Source: Lady Bird Johnson Wildflower Center

Pawpaw fruits near maturity in late August


Hackberry (Celtis occidentalis) 

Hackberry leaves and distinctive bark

This tree prefers berry basic soil, thriving in western Ohio where there is bedrock of high pH, and becoming less common on the acidic sandstone bedrock of eastern Ohio. Featuring simple, serrate, alternate, asymmetrical leaves, this tree could easily be mistaken for a basswood (Tilia spp.); the dark berries and distinctly textured bark set this tree apart. This tree can easily be spotted in the woodlot, where it composes most of the canopy.

Hackberry nipple galls visible on underside of leaves; fruits also shown.

Source: Missouri Botanical Garden

American Bladdernut (Staphylea trifolia)

Capsules in late summer; when ripe, they will turn brown.

True to its latin specific epithet, American Bladdernut is opposite as well as trifoliate, and a very distinctive understory shrub. In late summer, 3″ capsules develop in place of clusters of flowers. This understory shrub prefers some shade, with mesic, fertile soil high in organic matter. Interestingly, this shrub is capable of producing clonal thickets.

Source: Illinois Wildflowers

Red Maple (Acer rubrum)

No woods would be complete without at least a few red maples. Generalist from the driest hilltops to inundated swamps, Acer rubrum will find a way to grow and thrive there. This maple is similar to A. saccharinum, the Silver Maple, of which it hybridizes with to form a hybrid named Freeman’s maple, commonly planted as a street tree and showing potential in maple syrup production. Red Maple is distinguished from Sugar and Norway Maple by its v-notched margins and variable but smooth bark, and from silver maple by its shallower leaf sinuses. The branching pattern is opposite.

Source: Morton Arboretum

American Sycamore (Platanus occidentalis)

View of a large sycamore at the Woodlot

The planetrees, such as American Sycamore and London Planetree, have wonderful, distinctively flaky exfoliate bark with shades of white and yellow revealed underneath. The leaves are alternate, pubescent, and have palmate venation. The Water Lotus, Nelumbo, has been shown via DNA analysis to be much closer to Platanus than the Water Lilies, showing extreme divergence as well as convergent evolution. Planetrees are a classic bottomland tree, often co-occurring with Eastern Cottonwood. Sycamores are a good indicator of springs and seeps in hilly terrain.

Source: Peabody Museum of Natural History

Ohio Buckeye (Aesculus glabra)

The state tree of Ohio, this relative of the horsechestnut yields a showy inflorescence, opposite palmately compound foliage, and abundant spiny fruits. Ohio Buckeyes prefer moist, well drained soil, and does very well in the loamy forest soil of the woodlot. Ohio hosts three species of buckeye trees: the native Yellow (A. octandra), exotic Horsechestnut (A. hippocastanum), and Ohio Buckeyes. The buds may be told apart by the keeled bud of Ohio, and the sticky bud of horsechestnut.

Source: Ohio Division of Forestry

White Mulberry (Morus alba)

One form of the white mulberry leaf; distinctive bark in the background

The mirror lake woodlot, while a very nice escape from the city, shows signs of human impact. One interesting component of this woods is White Mulberry, an old-world species that has nearly replaced the native Red Mulberry on the landscape. This tree was brought to the new world by the British in an attempt to kickstart a silk industry, and it has since dispersed by birds throughout the continent. The berries range from white to black, and have a subtle flavor reminiscent of a black raspberry. The serrate, simple leaves are polymorphic; they may have one or more “thumbs”, lobes divided by variable sinuses. This tree may be considered a generalist; it grows in most anyplace that is disturbed, and waits patiently in the seed bank.

Source: Ohio Perennial and Biennial Weedguide

Common Buckthorn (Rhamnus cathartica)

Another nonnative component is this small tree or large shrub with its blue-black berries and rounded, finely serrate, opposite foliage. This tough and prolific nonnative shrub is able to colonize waste places through bird dispersal, and is a major invasive throughout Ohio. A cathartic drug may be made from its berries, hence the specific epithet.

Source: http://forestry.ohiodnr.gov/buckthorn

Northern Catalpa (Catalpa speciosa)

Catalpa, or Indian Cigar Tree, is one of the most interesting and beautiful species of the woodlot. Our largest representative of the Bignonicaeae, this is a native of the Mississippi valley that has been widely planted across the country for its showy flowers and huge, heart shaped foliage. Distinctive footlong “cigar” fruits appear after flowers disappear in early summer. Catalpa is once again quite generalist, and may be found as often in abandoned lots as in the woods. In a natural setting, Catalpa may be associated with fertile bottomlands.

Source: Natural Resources Conservation Service