Episode 128: Good Plant/Bad Plant Retrospective (Part 1)

This retrospective episode consists of previously aired short segments that have been compiled here as they all relate to a common topic. It’s called Good Plant/Bad Plant because each segment focuses on two plants: one that support pollinators, birds and other animals and one plant, or plant group, that is an invasive or noxious weed.

In this episode (Part 1 of 3), Master Gardener Volunteer, Tim Kennelty, covers native species like oaks, monarda, serviceberry, and willows. But he also advises against invasive species such as Japanese knotweed, Japanese stiltgrass, Asian bittersweet, and Asian bush honeysuckle.

In the first segment, oaks (genus quercus) and Japanese knotweed are put under the microscope. The mighty oak refers to the many oak trees that are native to New York. Oaks can grow to about 100 feet and can live from 200 to 400 years. Oaks are generally relatively easy to grow and thrive in well drained acidic soil in full sun. They're really beautiful, majestic trees, often with attractive fall foliage in shades of red, gold, and orange. Oaks support more than 500 different caterpillar species, which of course turn into butterflies and moths, but are critical food for young birds as well. And they produce acorns that are eaten by squirrels, deer, turkey and other birds.

If the oak is the king of beneficial plants, the queen of invasive plants is Japanese knotweed. It can grow from three to 15 feet and has bamboo like stems. Knotweed thrives in disturbed areas like drainage ditches, wetlands, streams, woodland edges, and along roadsides. It spreads rapidly through underground rhizomes. Knotweed forms dense thickets that crowd out and shade native vegetation, reducing species diversity while also adversely impacting ecosystems and wildlife. Management includes repeated cutting, and most likely will require herbicide application.

The second segment in this episode focuses on monarda and Japanese stiltgrass. Monarda didyma, known by a number of different common names including bee bam, Oswego tea and bergamot, is native to eastern North America. It is a great addition to butterfly gardens and bird gardens. By contrast, Japanese stiltgrass ( Microstegium vimineum ) is a widespread invader of woodlands, roadsides and trails. It is an annual grass, but a prolific seeder, that germinates in the spring and dies back each fall. Once introduced, it is extremely difficult to remove from a site.

Serviceberry and Asian bittersweet are featured in the next segment. Amelanchier spp. is a native North American shrub that is sometimes grown as a small tree. There are many species of this native that grow in full sun to part shade, have small five-petalled white flowers that emerge before or at the same time as the leaves, and have small edible berries that darken to a deep reddish-purple to black when ripe. Oriental bittersweet ( Celastrus orbiculatus) is a woody, deciduous, perennial vine has since naturalized and become an extremely aggressive, capable of damaging natural areas. It chokes out desirable native plants by smothering them with its dense foliage and strangling stems and trunks.

Willows and Asian bush honeysuckle are the conversation topics for the last segment in this episode. Most, shrubs and trees of the Salix genus, are mostly native to north temperate areas and are valued as ornamentals, as well as for their shade, moisture control, and wildlife attributes. By contrast, invasive bush honeysuckles originated in Eurasia and Eastern Asia, and were introduced in the U.S. for ornamental landscaping, erosion control, and wildlife habitat. Unfortunately, bush honeysuckles self-seed aggressively and rapidly escape into natural areas. Although the fruits have poor nutritional value for wildlife, birds disperse them widely. Native vegetation is displaced as bush honeysuckle blocks sunlight and exudes chemicals into the soil that are toxic to other plants.

Learn more about these plants on this episode of Nature Calls: Conversations from the Hudson Valley. Stay tuned for Part 2 and Part 3 of this Good Plant/Bad Plant Retrospective series.

Host: Jean Thomas

Guest: Tim Kennelty

Photo by: Tim Kennelty

Production Support: Linda Aydlett, Deven Connelly, Teresa Golden, Xandra Powers, Annie Scibienski