Phalaris arundinacea (Reed Canary Grass)
|Also known as:||Reed Canarygrass|
|Habitat:||part shade, sun; any moist soil; wetlands, fields, woods|
|Fruiting season:||late spring to early summer|
|Plant height:||2 to 5 feet|
|Wetland Indicator Status:||GP: FACW MW: FACW NCNE: FACW|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Branching cluster at the tip of the stem, taller than wide, 2 to 16 inches long (usually 8 inches or less), narrowly pyramidal in outline at flowering time, the main branches up to 3½ inches long (usually 2 or less), ascending to spreading when flowering, and the branches all becoming erect/appressed at maturity. Spikelets (flower clusters) are single at branchlet tips, 3 or more spikelets per branch, 1/8 to 1/3 inch (3.5 to 7.5mm) long, often tinged with purple, somewhat flattened, narrowly egg-shaped with a pointed tip, each with a single fertile floret flanked by a pair of inconspicuous sterile florets. Branch and spikelet stalks are slender and wiry, green to purple.
At the base of a spikelet is a pair of bracts (glumes) that are thin and papery, rough-textured, elliptic with a pointed tip, keeled, 3-veined, 3.5 to 7.5 mm long, the upper and lower glumes about equal and as long as the spikelet. Surrounding the fertile floret is a pair of bracts (lemma and palea), the lemma egg-shaped, pointed at the tip, 2.7 to 4.5 mm long, keeled, 5-veined, shiny yellowish to dark brown, and hairy; the palea is 2-veined and lacks a keel but is otherwise similar to the lemma. Sterile lemmas are long-hairy, scale-like, and half or less as long as and narrower than the fertile lemma; sterile paleas are lacking or insignificant.
Leaves and stem:
Leaves are alternate, evenly spaced along the stem, ascending to spreading, mostly flat, hairless but rough-textured on surfaces and along the edges, 4 to 12 inches long, ¼ to about ¾ inch (5 to 20mm) wide. Dead leaves turn a bleached tan color and persist through winter.
Stem sheaths are hairless with thin, translucent edging, and the edges overlapping at or near the tip. The ligule (membrane where the leaf joins the sheath) is 4 to 10 mm long, very thin, often folded over and lacks a fringe of hairs. The collar (outer junction between the blade and sheath) is prominent and yellowish. Nodes are smooth. Stems are smooth, unbranched, and form large, dense colonies from long, scaly rhizomes. The entire upper vegetative portion of this species fades to a pale, bleached tan that is diagnostic in the dormant season identification.
The glumes become straw-colored and slightly spreading at maturity, the fertile and sterile florets dropping off as a unit leaving the glumes behind on the stalk. Grains (seeds) are brown, slightly flattened, broadest near the tip with an abrupt taper to a short beak.
This is perhaps the single most destructive, invasive wetland species in Minnesota to date. One of its field identifying characteristics is that it is so everywhere! The stems and leaves eventually collapse into a sprawling mat that is difficult to traverse by humans and wildlife alike and is essentially useless for nesting habitat. At least one DNR ecologist notes that any area taken over by it becomes a biological desert, with little diversity of insects, birds or other wildlife. Its dense stands, voracious root systems and persistent seed bank make it a resource manager's nightmare. Though it has limited commercial seed production in Minnesota it is widely distributed throughout Minnesota, the US and the world. A form with striped leaves, f. varietata a.k.a. Ribbon Grass, is cultivated as an ornamental and is supposedly sterile but has also been known to escape to the wild and spread vegetatively.
Having said all that, a recent study by the University of Minnesota has made an unexpected discovery: most, if not all, Reed Canary Grass populations along the major rivers in the state are native. This was after extensive sampling along 6 major rivers and genetically testing them against populations from the Czech Republic, which is near the same latitude as Minnesota and has a similar river system. The two are genetically distinct, and the Minnesota populations are genetically similar to what has long been considered an extensive native population in Roseau County. Surprise, surprise. The next wave of testing is expected to be along major highway corridors. We'll see how that turns out.
Of note is there are no morphological differences between native and European plants so genetic testing is the only way to distinguish them. And just because it's native doesn't mean it isn't also invasive, at least in areas where it's been introduced. If it forms a monoculture where there was once diversity, consider it grounds for extermination.
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- sprouting Reed Canary Grass
- flowering Reed Canary Grass along a lake shore
- late season panicles folded up
- Reed Canary Grass at a woodland edge
- Reed Canary Grass infesting a wetland restoration area
- choked woodlands affect forest succession
- a monoculture of Reed Canary Grass
- a monoculture of Reed Canary Grass
- a dormant stand of Reed Canary Grass
- more dormant Reed Canary Grass
- winter Reed Canary Grass
- dense mat of Reed Canary Grass in early spring
- Phalaris arundinacea form variegata ©Frank Vincentz
Photos courtesy Peter M. Dziuk and K. Chayka, taken at various locations in MN--it's everywhere! Phalaris arundinacea form variegata By Frank Vincentz (Own work), via Wikimedia Commons, used under CC BY-SA 3.0
Have you seen this plant in Minnesota, or have any other comments about it?