Prairies and Savannas on the Grady Tract

Common buckthorn (Ramnus cathartica), female with unripened berries.

Common buckthorn (Ramnus cathartica), female with unripened berries.

Breezy and cool—it was a great day for a hike. On our way down the wooded path to the Grady Knoll and Greene Prairie, it is hard not to notice and mention two of our most prolific understory invasive plant species: common buckthorn (Rhamnus cathartica) and tartarian honeysuckle (Lonicera tatarica). Both of these shrubs leaf out early and shade out the native plants. In addition, they produce large amounts of juicy berries that are widely spread as birds feed on fruits, eat the flesh, and poop (“plant”) the seeds all over.

You might notice the word “cathartica” in the Latin or binomial species name of common buckthorn. It earns that name as the berries can have a laxative effect, especially berries that are not fully ripened. Good for the plant, not so good for the birds that are the main consumers of this fruit. Buckthorn was brought here from Eurasia as an ornamental and hedgerow plant in the later 1800s. The birds in Eurasia that evolved with this plant know not to eat unripened berries. Our local birds and other animals haven’t learned to recognize the importance of timing their foraging. In addition to the laxative effect, they also don’t get full nutritional value from unripened berries.

There has been some clearing done in the forest areas west of the trail. I used to call this side “pokeweed alley.” Although pokeweed is a native plant, and not usually as invasive as buckthorn or honeysuckle, its juicy berries are eaten by birds that “plant” its seeds. (Pokeweeds, buckthorn, and honeysuckle also gain advantage with higher than average germination rates.) American pokeweed (Phytolacca americana) is usually about six feet tall at maturity. It has a large taproot and thick semi-succulent stems. Clusters of small white and green flowers grow from a raceme at the top of the stem. Today, only a few plants still had flowers. Soon the bright red berries will develop and continue to ripen into dark purple juicy berries.

The shaded path up to the Grady Knoll has a very instructive array of poison ivy. People seemed to appreciate getting a refresher in recognizing this plant. Each plant may look slightly different and change as it grows and matures—but there are tell-tale signs that you can look for. We looked for the “leaflets of three,” shaped in pointed ovals with prominent venation, and usually one of the three leaflets has a thumb-like indentation. The three leaflets together make up a compound leaf.

The deer like this forested area. We saw hoof prints from a deer in this area a few days ago. Unfortunately, buckthorn and honeysuckle aren’t their preferred foods. Robins, chickadees, catbirds, chipmunks, and squirrels created a chirping, whistling, caroling, rustling symphony along the wooded path. We also heard some sparse but clear calls and song from an eastern towhee and a red-bellied woodpecker.

During Saturday morning work parties and other projects, volunteers and staff clear invasive species in natural areas and weed in the Longenecker Gardens and Native Plant Gardens. There has been a lot of restoration work in the Grady Tract woodlands, and it will be interesting to see if we encourage a more diverse understory here. One good sign is that after clearing some buckthorn, honeysuckle, and pokeweed, Joe-Pye-weed (Eupatorium maculatum), an understory plant that we like to see in the woods, has started to gain some territory in this shaded area.

As we made our way out into the sunny areas of the oak savanna knolls, we got nice whiff of common milkweed (Asclepias syriaca). Someone described what monarch caterpillars looked like, and across the trail inching its way up a stem was a distinctive banded black, yellow and white caterpillar. Further up the trail we saw an adult monarch. Although not a preferred host plant for the monarch eggs, butterfly-weed (Asclepias tuberosa), as the name implies, is an important food source for many butterflies. All the milkweeds have a beautiful and distinctive flower structure. And now is a great time to catch the bright orange flowers of butterfly-weed and the pale white-pinkish flowers of common milkweed.

On the knoll we also caught some of the final blooms of tall beard-tongue (Penstemon digitalis), interspersed with an interesting grass that will “needle” its spiky seed into the sandy soil, needle or porcupine grass (Stipa spartea). Black-eyed Susans (Rudbeckia hirta), spiderwort (Tradescantia ohiensis), sand cress (Arabis lyrata), common yarrow (Achillea millefolium), common St. John’s-wort (Hypericum perforatum), fleabanes (Erigeron), and sulphur cinqefoil (Potentilla recta) were in bloom. We await the flowers of stiff goldenrod—plants are healthy and prolific, but not yet in bloom. And, we saw the leaves of wild lupines (Lupinus perennis), but need to come out a bit earlier in the season to see the flowers.

The trail into Greene Prairie was a bit wet and muddy, but we carefully made our way. Along the boarded path as you enter, you are sure to find a cast of familiar characters: sensitive fern (Onoclea sensibilis), prairie blue-eyed grass (Sisyrinchium campestre), alumroot (Heuchera richardsonii), swamp saxifrage (Saxifraga pensylvanica), prairie phlox (Phlox glaberrima), Northern bedstraw (Galium boreale), butterfly-weed (Asclepius tuberosa), Robin’s fleabane (Erigeron pulchellus), daisy fleabane (Erigeron strigosus), and downy phlox (Phlox pilosa).

In the wetter areas were islands of various willows and gray dogwood shrubs (Cornus racemosa). As we looked out to the middle of the prairie, we saw the last blooms and some seed pods of white wild indigo (Baptisia alba). We could see the preparations for the flower show to come—rough blazing-star (Liatris aspera) about to bloom, and hundreds of prairie dock (Silphium terebinthinaceum) that have set their deep roots, grown their course elephant-ear sized and shaped leaves, and will soon send up 10–12 foot tall stalks with yellow-rayed composite flowers that will nod toward the summer sun (if the rain ever stops). Similarly prolific, but not yet in bloom, are the lead-plants (Amorpha canescens). They are shrub-like plants with silvery pale leaves and tight spikes of bright violet flowers dotted with orange anthers. Compass plant (Silphium laciniatum) is a close relative of prairie dock, with large oak-shaped leaves. It is just beginning to send up stalks and flowers that are similar to prairie dock flowers. Great show today, and more to come. Hope to see you out there.

—Paul Borowsky