Native Species News!

by Lynn Richardson, vice-chair, Woodcroft Eco-friendly Landscape Committee; member, New Hope Audubon Bird-friendly Habitat Committee

Nothing says summer like black-eyed Susans! These sunshine-bright, easy-to-grow flowers attract numerous little wasps, flies, and other pollinators to your garden, many of which help control garden pests. Native plants like the black-eyed Susan support beneficial insects in ways that other plants plants can’t. And we must support these beneficial insects because if they disappear, our extinction will not be far behind.


Two different plants are commonly called black-eyed Susans. Their botanical names are Rudbeckia hirta and Rudbeckia fulgida. Rudbeckia fulgida is a perennial plant that spreads by underground runners. It stands 2-4 feet tall and generally flowers from midsummer to early fall. Rudbeckia hirta is an annual or short-lived perennial that spreads by seed. New plants that pop up are easily dug and moved to where you want them. They flower most of June into July. Both of these species prefer full sun and a not-too-rich soil. Goldfinches love the seeds!


Many garden centers carry these plants. Be sure to ask whether the plants you’re planning to buy have been treated with neonicotinoids (“neonics”), a group of widely used insecticides that are absorbed by plants and can be present in pollen and nectar, making them toxic to bees. The local sources of Rudbeckia hirta and fulgida listed below do not use neonics.


Where to buy it
Cure Nursery, Pittsboro https://www.curenursery.com
Mellow Marsh Nursery, Siler City https://www.mellowmarshfarm.com/
North Carolina Botanical Garden, Chapel Hill (check with them for availability of seeds and plants) http://ncbg.unc.edu/


An interesting aside—How do bees find the nectar?
The dark center or eye of the black-eyed Susan flower head is made of hundreds of tiny flowers filled with nectar that bloom from the eye’s outer rim inward. The yellow pollen along the outer ring of the eye in the photo above indicates that those flowers are in bloom. When a pollinator insect visits, it rotates around this ring, drinking nectar from each bloom. If you look carefully, you’ll see a slight darkening toward the base of the yellow petals that forms a bulls-eye around the disk. An ultraviolet pigment that bees can see (and humans can’t) causes this darkening, which leads them to the nectar and pollen at the flower’s center. Amazing, huh?
 
Resources consulted for this article include “Maryland Grows Blog” by Sara Tangren, Ph. D., Sr. Agent Associate, Sustainable Horticulture and Native Plants, and Christa Carignan, Coordinator, University of Maryland Extension, Home & Garden Information Center  https://marylandgrows.umd.edu/2018/09/14/black-eyed-susans-attract-pollinators-and-other-beneficial-insects/

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Invasive Plant of the Month—Japanese Stiltgrass

 by Lynn Richardson, vice-chair, Woodcroft Eco-friendly Landscape Committee; member, New Hope Audubon Bird-friendly Habitat Committee

What is it?
Japanese stiltgrass (botanical name Microstegium vimineum) is a delicate, sprawling grass 1/2 to 3 1/2 feet high. Slender flower stalks that develop in September go to seed from late September through early October, unleashing 100 to 1000 seeds per plant. Seeds remain viable in the soil for three to five years. A native of several Asian countries including Japan, Korea, and China, stiltgrass was first identified in Tennessee around 1920. It was used as packing material for goods imported from China, which was probably how it was introduced into the United States.

In residential areas across Durham, fast-growing Japanese stiltgrass grows in lawns, landscape beds, vegetable gardens, and natural areas. Like other invasive plants, it thrives in a wide variety of habitats—from sunny to shady and moist to dry. Hay, soil, and potted plants may contain stiltgrass; wind, water, animals, humans, and vehicles all spread the seed, which are light and float easily. The seeds may survive and germinate even after long periods in water.

 
Why it’s a problem
Stiltgrass forms extensive patches, displacing native species that can’t compete with it. Areas filled with Japanese stiltgrass are less biologically diverse, and provide less native wildlife habitat. Left unchecked, Japanese stiltgrass can overtake and smother native vegetation in three to five years. Japanese stiltgrass may change soil chemistry so that the seeds of our native trees, shrubs, and wildflowers don’t germinate, making it a threat to the future of our forests. If a native seed does manage to germinate, the stiltgrass may shade the tiny plant out. When deer browse native plants in stiltgrass-infested areas, they open up even more room for it to spread. Unfortunately, they don’t eat stiltgrass!

How to remove it
Entire stiltgrass plants can easily be removed by grabbing the plant close to the ground and tugging firmly. Hand-pull in August and September, when plants are tall and branched. If you pull in July or earlier, you’ll need to keep an eye on the weeded area to catch any new plants that emerge, since pulling may expose buried seeds to light and jumpstart their germination. Late summer pulling is best because any new seedlings don’t have enough time to get established before cold weather. As weeding too early has its drawbacks, so does weeding too late! Be sure to weed before mid- to late September, when the plant goes to seed.

Plants pulled before they set seed can be left on site; plants with seeds should be bagged and placed in the garbage. When in doubt, bag them. You will need to continue pulling each year until the seed bank is exhausted, which may take several years. If your yard has low areas that seeds can wash into or if your neighbor has an infestation, you may not be able to permanently eradicate the plant. Keeping on top of what wanders into your yard will help keep the problem from getting out of hand.
Mowing is another option. It’s best to wait until late summer (roughly mid-August to mid-September) to cut stiltgrass. Mowing at this time will remove the inconspicuous flower before its seed matures while not allowing the plant time to flower and set seed again. Plants cut earlier in summer respond by regrowing and flowering soon after cutting.

I had great success last summer weed-eating the big infestation in my backyard natural area down to the ground, then covering it with a thick layer (4-6 inches) of mulch. This year the few plants that are emerging are easily pulled out. Another option is to plant a thick stand of wildflowers such as obedient plant or grasses such as river oats that will crowd out almost all stiltgrass.