Tag Archive | invasive plants

Ornamental Grasses – Part 1

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Ornamental grasses add color and texture to landscaping

Frequently overlooked and under-appreciated by most gardeners, ornamental grasses can add beautiful height, texture, and even fragrance. While it is true that the majority of ornamental grasses do best in full sun, a number will also tolerate shade as long as it is not too heavy and their other cultural needs are met.

Grasses for Part Sun

Among the useful grasses or grasslike plants are tufted hair grass (Deschampsia caespitosa), millet grass (Milium effusum), Hokonechloa macra ‘Albo-aurea’, variegated lily turf (Liriope muscari ‘Variegata’), and ribbon grass (Phalaris arundinacea var. picta). These vary from about 1 to 3 feet tall. Somewhat shorter are Virginia wild rye (Elymus virginicus), Alpine hair grass (Deschampsia alpina), and blue fescue (Festuca ovina glauca). And quite a bit taller are northern sea oats (Chasmanthium latifolium), creeping bluestem (Andropogon stolonifera), bluejoint (Calamagrostis canadensis), and bush grass (Calamagrostis epigejos), which may range from 2 to 6 feet tall.

Well-Behaved Grasses

One of the common complaints about grasses is the invasive nature of many of them. Anything with runners — ribbon grass (phalaris arundinacea), blue lyme grass (Leymus arenarius), and switch grass (Panicum virgatum) are the classic examples — is likely to be a problem. If you’re taken with something that comes without a description, tip it out of the pot and look for signs of runners (underground shoots with upward-pointing tips) before you take it home.

And almost anything with seeds will self-sow, that being what the seeds are for, though some, such as the fountain grasses (Pennisetum spp.), do it more aggressively than others. Be careful of plants described as self-sowing “manageably”; someone has got to do the managing, and that someone will be you. Nurseries are increasingly conscientious about labelling possible invaders, but it’s still best to check with your local extension service before you purchase and plant.

Fragrant Grasses

Several ornamental grasses give off appealing fragrance when their leaves are rubbed or broken. They include lemongrass (Cymbopogon citratus), citronella grass (Cymbopogon nardus), and sweetgrass or vanilla grass (Hierochloe odorata). When dried, sweet vernal grass (Anthoxanthum odoratum) is fragrant as well. Sweet flag (Acorus calamus) is a scented grasslike plant, but not a true member of the grass family.

Grasses for Cold Climates

Many of the most popular ornamental grasses are very hardy, including Miscanthus sinensis cultivars such as ‘Morning Light’ and ‘Purpurascens’; midsize favorites like the feather reed grass Calamagrostis arundinacea ‘Overdam’; yellow foxtail grass (Alopecurus pratensis), which seldom grows taller than a foot; and it’s even shorter cousin, A. alpinus ssp. glaucus, a 4-inch charmer with very blue leaves.

The Minnesota Landscape Arboretum conducted a large study of cold-hardy ornamental grasses and has published the results in North Central Regional Publication No. 573, “Ornamental Grasses for Cold Climates.” Call 952.443.1400 for information about how to obtain the booklet.

 

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Expert’s Tip: Wild Parsnip — What is it and why should we be concerned about it?

by Ken Schroeder, Portage County UW-Extension Agriculture Agent

Wild Parsnip, Pastinaca sativa, is an invasive member of the carrot family that continues to spread into unmanaged areas throughout Wisconsin. It likes to grow in sunny, grassy areas along roadsides, railroads, and field borders but is not limited to these conditions. Primary means of spread is by seed that can be moved long distances while mowing roadsides after the plant has set seed.

What’s the concern?  The biggest concern isn’t the fact that it is invasive and rapidly spreading but that it will cause burns and blistering of the skin if you come in contact with plant sap in the presence of sunlight. This is known as phytophotodermatitis. Blisters and rashes appear 24 to 48 hours after exposure. Blisters do not spread like poison ivy but are uncomfortable and may leave scars lasting for several months to two years.

Pastinaca_sativa_'wild_parsnip'_2007-06-02_(plant)How do we identify wild parsnip?  The plant is a monocarpic (the plant dies after blooming) perennial and has two growth stages. The first year it produces a non-flowering leafy rosette of pinnately compound leaves with 5 to 15 leaflets.  It looks a lot like celery at this stage.  In the second to third year, it produces a flowering stem four to five feet tall. Stems are grooved, hollow, and have alternately arranged compound leaves with 2 – 5 pairs of opposite, sharply toothed leaflets and petioles that wrap around the stems. Flowers are flat-topped clusters (umbels) of yellow flowers 2 – 6” wide blooming in late spring to mid-summer in Wisconsin. Seed begins to form mid to late July changing from yellow-green to tan as they mature.  Along with the seeds maturing the stems and leaves begin to senesce, turning tan to brown in color.

How do we manage wild parsnip?  Early detection when populations are small allow for pulling or digging.  Be sure to wear gloves, long sleeves, long pants, and safety glasses or face shields to avoid skin contact with the sap.  One can simply cut the taproot with a shovel or spade 1 – 2” below the soil surface.  With larger populations mowing is an option if done after emergence of flower heads, but before seeds enlarge.  Additionally, several chemical options exist.  Be sure to read and follow label directions when using chemicals.  For more detailed management options see the UW-Extension wild parsnip management publication A3924-15 at the Learning Store website https://learningstore.uwex.edu/ .

What can I do as a Master Gardener to help?

  • Know how to identify wild parsnip and report locations at the Wisconsin First Detectors Network website http://fyi.uwex.edu/wifdn/get-involved/report-invasive-species/.  Several options are listed including a downloadable smartphone app.
  • Educate others about the existence and danger of wild parsnip.
  • Carry a sharp shovel or spade with you and when you see only one or a few plants consider cutting off the stems below the soil surface.  As long as they haven’t gone to seed the plants can then be left to die.  Check back the next year to see if additional plants emerge and cut those too.  CAUTION do not do this on private property without getting permission from the property owner.

Additional invasive species information

  • The University of Wisconsin Weed Science website http://fyi.uwex.edu/weedsci/ is a great resource for weed id and management info and has several short YouTube videos to help with identification.

The Wisconsin DNR invasive species website http://dnr.wi.gov/topic/Invasives/ has a wealth of information on not only terrestrial invasive species but aquatic and wetland invasives as well.

Another New Weed!

Gesnouinia_arborea_(Tree_Pellitory)_seedlings.Thanks to OCMGA Master Gardener Mary Learman for discovering this information.

Keep an eye on your garden and your lawn. As though we didn’t have enough weeds and invasives to watch, the University of Illinois Extension warns of Pellitory (Parietaria pensylvanica) appearing in the midwest. Funnily, the leaves remind one of peony plants or, perhaps, dianthus before it blooms. Don’t be fooled, however, as it’s aggressive enough to take on your whole garden and flexible enough to grow out of cracks.

For more information, follow this link to the article published by the University of Illinois Extension.

http://hyg.ipm.illinois.edu/article.php?id=914