Invasive Miscanthus; the Challenge of Use and Definition

Miscanthus, landscape solution hero, or villain to natural area eco-systems? Trying to find an answer can help me demonstrate the problems inherent in the invasive species conversation. Just trying to get a handle on exactly how many areas of expertise will be involved in arriving at a knowledgeable position can be an interesting study in frustration.

I thought about presenting a simple dialogue between gardening and natural area preservation. I thought that this would be an elegant solution and would allow me to get a “buy” on understanding economic and development issues, import and export topics, quarantines, insect populations and bird life, non native earth worms and soil structure destruction, and pH consideration and agronomic considerations, as well as taxonomic discussions. Then of course I came across Miscanthus as a bio fuel source, and my plan fell apart.

Here is a tidbit to contemplate for a moment: “Using a computer simulator, Heaton predicted that if just 10 percent of Illinois land mass was devoted to Miscanthus, it could provide 50 percent of Illinois electricity needs. Using Miscanthus for energy would not necessarily reduce energy costs in the short term, Heaton said, but there would be significant savings in carbon dioxide production.” (source Molly McElroy, News Bureau) Other than wondering where the food to eat will come from, I was amazed to find that Europe is hot on Miscanthus production, and not too overly concerned about invasive tendencies.

Part of the problem can be found in trying to determine how, when, and where Miscanthus may be or is a problem and for whom it might or could be. There seems to be reasonable agreement that in sites where the plant is a problem it spreads by seed. Sterile varieties are recommended. Sterility itself, however, is an area of expertise I had failed to list above, and leads one down a new pathway of learning. Deciding which species of Miscanthus may be a problem continues the thinking process, and references to the evil ghost of “the species Miscanthus sinensis” which is the grandfather of all the escapees do nothing to clear up the confusion. Let me quote from the University of Minnesota: “Ornamental plantings of Miscanthus sinensis (the species, not a specific cultivar) are probably the source of the “wild type” Miscanthus sinensis that is now common in western NC; near Valley Forge, PA; and other areas in the Middle Atlantic States.” Of course we can add from HGTV’s site the following:

Given this level of complexity any hope of arriving at a definitive answer is fleeting.
I propose, therefore, if you are still with me, to outline the gardening values at work in making this plant a highly thought of solution for landscape and gardening challenges. Then, tack into the wind and explore a little of the harm the plant is causing in natural areas. If after that you are yet with me, I shall bring in the bio-fuel discussion and finish with a flourish announcing much and answering little.

So, let’s consider some information from a gardener’s perspective and examine the genus Miscanthus. This ornamental grass is comprised of several species all of which bring diversity to a landscape, variety on form, height and texture, and provide almost year around horticultural or visual interest. In addition to these attributes, this ornamental grass grows almost anywhere, especially in the mid Atlantic region. Growing almost anywhere is a significant factor in making a plant selection, and because it needs little help in getting established, minimal effort to maintain, looks good for ten months, and suffers fools gladly, it becomes a workhorse in the garden from a design perspective. Among the species commonly found in the trade are Miscanthus sinensis, transmorrisonensis, sacchariflorus, floridulus.

At Behnke Nurseries, we make an attempt to educate the consumer. Here is the buyer’s (Larry Hurley) abstract for information for the staff and his disclaimer:

(Personal reference notes by Larry Hurley taken from a variety of sources including books by John Greenlee and Rick Darke, various nursery catalogues, a lecture by John Hoffmann, the HGTV website, the Friends of the National Arboretum Newsletter, an article on research by Mary Meyers at the University of Minnesota in American Nurseryman, and so on. Not intended for publication, not proofed for publication....Suspect a lot of quotation marks missing): “Miscanthus and Invasiveness: Guidelines for Behnke Nurseries. Miscanthus is an invasive plant and has become a big problem in North Carolina and western Ohio, for example. According to Rick Darke, it forms dense stands in its native range, so it has great potential to damage wetlands in the US.

He says the keys are early season bloom, which give the seeds enough time to ripen, warm summers (which encourage earlier blooming) and wet locations. When these three aspects occur simultaneously, aggressive seeding can occur. One source also suggests planting only one cultivar to reduce the risk of cross pollination and seedlings reverting to a more aggressive “species form”.

Below is a list of species and cultivars that would seem to be okay, or at least low risk. Following is a list of “do not buys”. These lists comprise about half of what is available. For many, I don’t have enough information to render a decision, or, the cultivar isn’t commonly available at this time from our vendors.

Please encourage people to plant substitutes like Panicum, unless they are dead set on Miscanthus. Stick to the “okay to buy” list. Avoid cultivars that bloom in June, July and August. Okay to buy:
Autumn Light
Cabaret
Cosmopolitan
Dixieland
Gold Bar
Gracillimus
Hinjo aka Little Nicky ™
Kirk Alexander
Little Kitten
Little Zebra
Morning Light
Mysterious Maiden
November Sunset
oligstachyus (species)
Positano
Puenktchen (aka ‘Little Dot’)
Purpurescens (X)
Rigoletto
Sarabande
Silberpfeil (Silver Arrow)
Strictus
Super Stripe
Variegatus
Zebrinus
Giganteus
Do Not Buy:
Adagio
Graziella
Grosse Fontaine
Juli
Kaskade
Kleine Fontaine
Kleine Silberspinne (aka ‘Little Silver Spider’)
Malepartus
Nippon
Sacchariflorus (species)
Silberfeder (Silver Feather)
transmorrisonensis (species)

;“Conditions in the southeastern United States most closely approximate ideal conditions for miscanthus, and it is here, especially near moist, sunny bottomlands, that caution is warranted.”

From the longer and earlier, Encyclopedia of Ornamental Grasses by Darke;
“Antique cultivars, including ‘Gracillimus’, ‘Variegatus’ and ‘Zebrinus’ require very long, hot seasons if they are to flowers at all, and their seeds rarely mature in regions where they flower very late in autumn. Many modern cultivars, including some of the most beautiful, such as ‘Graziella’ and ‘Malepartus’ were developed and selected for their ability to flower is short seasons….Unfortunately, these selections bloom early enough to be prolific self-sowers in some warmer zones up into the mid-Atlantic states. They readily naturalize in and out of the garden, and can be a real nuisance in managed meadow gardens….Gardeners should use common sense when selecting miscanthus and considering its use in gardens adjacent to vulnerable native habitats.’; p 222
Moisture and heat are the key things required for spread; not a problem in California, for example (both Darke and Greenlee)

From FONA; in addition to the other data “In addition, the smaller variegated types of miscanthus were found to be “basically sterile”.”

HGTV Website; ”If you live in an area that’s conducive to Miscanthus spreading, avoid planting more than two cultivars. Research shows that cross pollination could mean that any progeny could revert to species.”

Twenty species, Asia to Africa. Clumpers and runners. African species sometimes broken out into a different genus.

Have skipped a few from the Encyclopedias that I, (Larry Hurley) deemed obscure,; e.g., ‘Mt. Washington’ , ‘Roland’, ‘Kleine Silberspinne’, etc.

Miscanthus floridulus is not grown in US, it is generally actually M. saccariflorus or hybrid M. ‘Giganteus’;
M. ‘Giganteus’; hybrid, Blooms very late summer, or not at all in short growing seasons. Generally does not self sow; loses lower leaves by midsummer
‘Little Big Man’; a seedling of ‘Giganteus’; similar in most respects but smaller
Hoffman talk: PPA 2007; leaves break off in winter and blow around, messy
M. oligostachyus: short; August bloom; generally does not self sow; open; smaller flowers.
M. ‘Purpurascens’; hybrid
“Because it rarely if ever self-sows, it is one of the best choices for gardens adjacent to natural areas in the eastern United States.”
‘Good version of Miscanthus”—HGTV Website, from Rick Darke
From John Greenlee: blooms July and August; best in zones 7 and 8
Blooms in July/August in warm climates; Darke; not at all in England; possibly an M. oligostachyus hybrid.
M. purpurascens ‘Autumn Sun’; Emerald Coast: Brilliant red-orange fall color
M. sacchariflorus: Silver Banner Grass; runner; August bloom; self sows. Aggressive in small gardens. A cv named ‘Interstate 95”! Loses lower leaves when dry.
Miscanthus sinensis in general (John Greenlee); clumping, prefers full sun and moist soil and usually tolerates standing or shallow water. Narrow-leaved types seem to better tolerate high heat and humidity
M. sinensis ‘Adagio’; August; Hoffman talk, PPA 2006; does not recommend for Asheville region due to invasive potential, only for the north
M. sinensis ‘Altwelbersommer’ (‘Indian Summer’); Bluemel catalog; blooms September and October.
M. sinensis ‘Andante’; Bluemel catalog says “the best Miscanthus on the market; strong mid-season bloomer; Hoffman talk, PPA: new cultivar, pink , late
M. sinensis ‘Arabesque’; Bluemel catalog says August bloomer; Emerald Coast says September
M.’ Autumn Light’, not in short Darke; zero germ Meyer; green, narrow leaves; blooms in September; Emerald Coast says September
M. sinensis ‘Bluetenwunder’; Emerald Coast; blue-gray foliage.
M. sinensis var condensatus ‘Cabaret’ Not in the short book; from HGTV website, quoting Darke; “The seed is sterile, so self sowing isn’t a problem”. Blooms in late September.
:Good version of Miscanthus”; HGTV website; from Rick Darke
Blooms in late September in warm areas.
Introduced from Japan by Skip March and John Creech.
M. sinensis var condensatus ‘Cosmopolitan’; flowers more freely and earlier than ‘Cabaret’; early September
Greenlee’ improved form of Variegatus
M. “Dixieland’: look at specs; zero germ in Meyer; not in short Darke; “similar to Variegatus but more compact”
Bluemel: dwarf form of Variegatus
Emerald Coast: pink-tinged blooms
M. sinensis ‘Ferner Osten’; Bluemel, September/October bloomer; Darke says mid to late summer; form of Variegatus.
M.sinensis ‘Flamingo’; Darke blooms late summer; Bluemel blooms September, October.
M. sinensis ‘Gold Bar’; Hoffman, PPA 2007; new cultivar; no notes but slide very nice, very heavy gold bar variegation; See Walters catalogue, slow grower, flowers mid-fall.
M. sinensis ‘Gracillimus’
“…is among the last to bloom…in late September or October…”
“Good version of Miscanthus”; HGTV Website; from Rick Darke
Not a clean clone, various variations over the years. Floppy
M. sinensis ‘Graziella’; a bad one, see Darke intro above; August or Early September
Bluemel blooms in August; “one of the best”
M. sinensis ‘Grosse Fontaine’; mid-summer flowers (Bluemel; early August)
M. sinensis ‘Hinjo’ aka “Little Nicky”, TM ; Compact Zebra Grass
Superb, much of character of Zebrinus; best choice of banded leaved Miscanthus for smaller gardens. Photo in mid-August in PA not yet in bloom.
“Good version of Miscanthus”; HGTV Website; from Rick Darke
Not floppy; Hines introduction
M. sinensis ‘Huron Blush’; Walters; flowers late summer
M. sinensis ‘Huron Sentinel; Walters; flowers late summer.
M. sinensis ‘Huron Sunrise’; Walters; “The most profusely blooming miscanthus.” Flowers late summer.
M. sinensis ‘Juli’: early summer flowering, probably a hybrid; Bluemel blooms in August, strong grower.
M. sinensis ‘Kascade’; midsummer blooms
M. sinensis ‘Kirk Alexander’; not in short Darke; zero germ Meyer
Better than Zebrinus, not as good as Hinjo (same banding form)
M. sinensis ‘Kleine Fontaine’; similar to Grosse Fontaine but smaller; assume mid-summer flowering
M. sinenis ‘Kleine Silberspinne’; Walters; green foliage; mid-summer blooms. The call it ‘Little Silver Spider’
M. sinensis ‘Little Dot’; Walters; see ‘Puenktchen’.
M. sinensis ‘Little Kitten’
Seedling of Yaku Jima; flowers sparsely; Low germ Meyer
Bluemel blooms late summer into fall.
M. Little Nicky TM, see ‘ Hinjo’
M. sinensis ‘Little Zebra’
“Good version of Miscanthus”; HGTV website; from Rick Dark; not in short book
Flowers late summer; Walters.
M. sinensis ‘Malepartus’: a bad one; see Darke intro above; blooms early September
M. sinensis ‘Minuett’; Bluemel; small, graceful, blooms in September
M. sinensis ‘Morning Light’
“Blooms late…and is not inclined to self-sowing, although it may do so in the warm, moist parts of the southeastern United States.” Blooms late.
“Good Version of Miscanthus”; HGTV Website, from Rick Darke
From John Geenlee: blooms mid-October; essentially a variegated Gracillimus
Darke: “Arguably the best all-around garden plant of the Miscanthus species and cultivars.”
Skip March and John Creech brought from Japan. Upright, doesn’t flop.

M. sinensis ‘Mysterious Maiden’; Emerald Coast; new plant forum PPA 2006; Blooms of Bressingham; September; thin, gold banded, upright
M. sinensis ‘Nippon’; mid-summer bloom. Bluemel blooms late June to fall.
Flowers mid-summer; Walters.
M. sinensis ‘November Sunset’; late summer bloom. Bluemel blooms in November.
M. sinensis ‘Positano’; Bluemel blooms September October.
M. sinensis ‘Puenktchen’; Emerald Coast; small version of M. strictus. Walters; flowers in late August.
M. sinensis ‘Rigoletto’; not in short Darke; low germ Meyer
Bluemel, compact Variegatus
M. sinensis ‘Sarabande’; blooms in August
Emerald Coast: “An excellent alternative to ‘Gracillimus’ for the Appalacian region, as it produces sterile seed.”
M. sinensis ‘Silberfeder’ (John Greenlee); older selection, flowers in August
Flowers freely; even in England (Darke) Flowers mid-summer; Walters.
M. sinensis ‘Silberpfeil’; not in short Darke; 0% germ Meyer
Darke encyclopedia says nearly impossible to distinguish from Variegata
Bluemel blooms August September
M. sinensis ‘Strictus’
…blooms in September…”; low germ Meyer
From Greenlee; very stiffly upright, vs Zebrinus, which is floppy; September bloom
Blooms early fall; Walters.
M. sinensis ‘Super Stripe’: Emerald Coast; Blooms of Bressingham; gold banded; small clumper
M. sinensis ‘Variegatus’
“…blooms in mid-September…”; low germ Meyer
Best variegation but usually needs staking
Flowers early fall; Walters.
M. sinensis ‘Yaku Jima’; not a true clone; several similar selections; very low germ Meyer
Bluemel blooms August September, ‘Adagio’ improved form
M. sinensis ‘Zebrinus’
“Flowers copper tinted in mid-September…; ‘Hinjo’ is better.
Usually requires staking.
M. transmorrisonensis; Evergreen Miscanthus; from Greenlee and Bluemel; green until heavy frost. Almost continual bloom from June to November. Flowers shed in fall and are ineffective in winter.”

As one can see, the varieties, forms, bloom times and textures available, make this landscape ornamental important in current design solutions, But it follows that there are many opportune pathways for introduction to natural areas, most of which will occur because of limited or absent information at the point of purchase. The end user even the professional is confronted by a bewildering array of choices and information.

And in due course the definition challenge of invasiveness raises its head as in this posting from the Takoma Gardener Weblog site: “Wikipedia tells us that witch-hunting is the persecution of a perceived enemy with extreme prejudice and disregard of actual guilt or innocence; it's a type of "moral panic." Okay, I think I have the right term, but you be the judge.

My second example is from a talk I heard recently by a plant expert from the University of Maryland. When asked if ornamental grasses are invasive she declared that Miscanthus sinensis is, yesiree. At which point I jumped into the fray to ask, "Isn't it just the species, not varieties like 'Morning Light'"? And to my surprise she responded that yes, in our area it's just the species that's a problem. So why the hell didn't she say that in the first place? “

As the reader might note, understanding requires far more investigation and time than most people are willing to invest.. Checking reference sites, we read: “Chinese Silver Grass Miscanthus sinensis Chinese silver grass was introduced from Asia about a century ago for use as an ornamental plant. It is a showy grass that readily spreads in areas where the soil is disturbed, such as roadsides, forest edges and clearings, and can create a thicket that prevents the growth of other plants. Because it is highly flammable, Chinese silver grass can be a fire hazard. It spreads by wind-dispersed seed and locally through growth of rhizomes.” This would lend credence to the Takoma Gardener’s position, it would seem. As I look at several information sites on invasive characteristics, I see a tendency to gloss over species differentiations as well as limited information on cultivar habits. A few more minutes of searching and I find: “In the United States there are two species, Miscanthus sinensis and Miscanthus sacchariflorus, that are of concern in being weedy or invading natural areas. Their differences are described below. Click on the illustrations for enlarged images” (© 2003 Regents of the University of Minnesota)

This should be a signal that there needs be a deeper investigation of the characteristics of this genus before claiming absolute knowledge one way or another. It is worth keeping in mind the resulting potential cost of a wrong choice. “According to the National Invasive Species Council, invasive plants cover more than 100 million acres in the United States and are spreading across an additional 3 million acres each year. The estimated cost of invasive species to the U.S. economy is approximately $137 billion per year.”(Kathy Reshetiloff)

I remind the reader of the idea to use Miscanthus as a bio-fuel, and one begins to see the reach of conflicting goals based on complete knowledge and science. And the always changing nature of information gathered by scientific research means that we need to make educated choices based on a continues flow of new information without the hammer of absolute scientific position. One needs to accept the current preponderance of evidence when making a gardening choice.