trees archive

Part I: Trees I Killed
–Managing Invasive Plants at the Ohio State Marion Prairie–

Since mid-summer 2023 I’ve been working at the Ohio State Marion Prairie at the Larry R. Yoder Prairie Learning Labratory up in Marion, about 40 mile north of Columbus. This is a nearly 12-acre reconsructed prairie that was initiated in the mid-1970’s by sowing seeds and planting plants from prairie remnants nearby. It is a thriving ecosystem used for nature study, education and relaxation by OSU studentsm, staff and faculy as well as the surrounding community. In the past few years, however, there have been way too many woody plants growing in what is supposed to be an area dominated by grasses and forbs. Bad!

To help remedy this (and to help out in other ways) the administrators there hired me to help control invasive plants. Here are some of the ones I’ve been battling.

White Mulberry
(Morus alba)

Whute mulberry is cropping up here and there in the Prairie, sith some rather large ones that previous stewards have seemingly encouraged. The photo below is at the west edge of the Prairie. White mulberry leaves are alternate in arrangement, simple in complexity, and with a margin that is coarsely toothed, and also varies from being entire to lobed, sometimes deeply so.

White mulberry leaves are alternate in arrangement, simple in complexity, and with a margin that is coarsely toothed, and also varies from being entire to lobed, sometimes deeply so.

Originally from Asia, Petrides (1958) tells us that white mulberry was brought here by the British prior to the American Revolution in an unsuccessful attempt to establish a silkworm industry.

Like raspberries and blackberries, mulberries are gtoups of many small fruits. Unlike those members of the rose family which are aggregate fruits, i.e., derived from a single flower with an apocarpous gynoecium, mulberries are multiples originating from head-like compact inflorescences. But what type of fruits are they multiples of? I had always  assumed that, like blackberries and raspberries, that they were drupes. Nope! According to H.A. Gleason in “The New Britton and Brown Illustrated Flora of the Northeastern United States and Adjacent Canada” (1968) tells us that the fruit is “…a short-cylindric syncarp resembling a blackberry, composed of the juicy, accrescent but not coherent calyces, each enclosing a small seed-like achene, with the remains of the styles protruding.” Hmm. Juicy calyces enclosing achenes, wow! Below see a closeup taken June 1, 2023. You can see that the juicy parts are separable.

black cherry
(Prunus serotina)

Like many of the weedy woodies here at the Prairie, black cherry is spread by birds. There were a few fairly large ones here until recently.

Black cherry leaves are alternately, simple, and crenate-serrulate (i.e., having rounded teeth). The shape is oblong-lanceolate.

If you scratch a black cherry twig and sniff, you get a distinct almond aroma. This is attributable to the presence of a cyanide compound. Information on the “Wild Foods 4 Wildlife web site (link)  while there are only trace amounts in the twigs and frsh leaves, dried foiage contains enough of the cyanide-containing “prussic acid” to kill livestock that might forage on downed black cherry branches.

cockspur hawthorn
(Crataegus crus-galli)

Yet another native plant, and indeed one that is valuble in low density, cockspur hawthorn is cropping up too much at the Prairie. Below is one that got cut down minutes after this photo  was taken.

The Ladybird Johnson Wildflower Center (link) tells us that this species has thorns that are among the longest of any of the hawsthorns.

Amur honeysuckle
(Lonicera maackii)

Perhaps the worst invasive in Ohio, and for sure the worst one here at the prairie, amur honeysuckle was, as detailed on this Ohio Department of Natural Resources web page (link) introduced to Ohio on the mid-1950’s and has since displaced native vegetation by its rapd growth facilitated by the bird-dispersed fruits.

The fruits are red berries, occuring in pairs iun the leaf axils.

As well explained in this article by David Taylor for the Kentucky Native Plant Society, Amur honeysuckle starts leafing out in March, long before native trees and shrubs, and the leaves don’t senesce until at least late October, giving the shrub an extra 5-8 weeks of photosynthetic activity. Moreover, it is somewhat frost-tolerant. These traits help make it invasive.

Callery pear
(Pyrus calleryana)

As described by Theresa Culley in this recent Ohio Invasive Plants Council newletter (scroll down) when there was just one cultivar in Ohio, the popular “Brafdord pear,” it was self-sterile, and thus didn’t seem to have invasive potential. But other cultivars, themselves self-sterile were cross-fertile with Bradford and other different ones, resulting in a profusion of trees spread through bird-dispersed fruits.

American plum
(Malus coronaria)

This is a native plant that nonetheless we are removong because the Prairie is meant to be dominated by herbaceous, not woody, plants.

 

The Ohio Deparment of Natural Resources, on this web page (link) tells is that an alternative name, “sweet crabapple,” refers to the scent of both the flowers and fruits, not the taste of the fruits) and greenish-yellow when mature, but make excellent jelly or jam due to their high pectin and high acid content. The whimsically remind us that “enough added sugar makes anything taste good.”

Tree of heaven
(Ailanthis altissima)

There is a large stand of this ultra-invasive Asian tree between the entrance road to the Prairie and Grave Creek. It’s the pale spindle-shaped area in the aerial photo below.

To properly eliminate TOH, you need to kill the trees first by using a “basal bark” treatment. This involves applying a concentrated (20%) solution of triclopyr (Garlon) mixed in basal oil to the base of the trees. After a couple months, if the trees are clearly dead dead dead, then you can cut them down. Here is wnat they look like about six weeks after treatment. Looking sad!

…but not sad enough, as a year later, the tops of some of the trees are all leafy again. Darn, but a second treatment ought to do the trick!

…and one that we don’t kill–bur oak!

bur oak
(Quercus macrocarpa)

Bur oak leaves are distinctively shaped: broadest above the middle, with margins that are lobed deeply in the lower half of the leaf, but shallowly in the upper half. True to its name–the specific epithet means “large fruited”–bur oak bears pretty mondo acorns, both in size and number, both in size and number. Moreover, the acorn caps are deep and heavily fringed.

An “oak savannah” is an open grassland with scatterered trees. Daughmer Prairie Savannah State Nature Preserve in north-central Ohio’s Crawford County, with towering majestic bur oaks that are over 200 years old is one of the best remaining oak savannahs in the United States.