Tuesday, May 18, 2021

Ya picked the wrong plant to mess with pardner!

Phalaris arundinacea in 2020, with Yellow Flag Iris behind and to the right
Iris pseudacorus (Yellow Flag Iris) is a non-native that is found in semi-aquatic and aquatic habitats throughout North America. It is an attractive plant with yellow flowers that nonetheless can use its rhizomes to form dense monotypic stands that displace other plants in the area.

I was interested in the fact that the species co-existed with Phalaris arundinacea (Reed Canary Grass) along the shores of a nearby pond, and I have been watching the two species grow quickly this Spring.

Yellow Flag Iris surrounded by yellow border, and P. arundinacea to the left
There are large groups of Yellow Flag Iris around the pond, but the one I was interested in sat right next to and behind a big stand of Reed Canary Grass, their respective ramets almost intermingling with one another.

The Iris seemed to have sprouted tall earlier than the grass, but the latter quickly made up the difference and at this time is more than double the height of its erstwhile competitor.

Yellow Flag Iris (foreground), P. arundinacea (back), cattails (tall plants to right)
Both species are weedy invasives, and both have been known to aggressively outcompete and take over wetlands and other semi aquatic and aquatic environments. So I am very much interested in how the meeting between these two plants will resolve itself over time.

One thing I already noticed is that the Yellow Flag Iris clump next to the grass seems to be smaller than the one farther away, and have yet to bloom while their brethren have already pushed out their yellow flowers. But perhaps this is simply because that group is younger, and not because of competition from the Reed Canary Grass.

On first glance, the much larger P. arundinacea seems to be the clear favorite. I can almost see it looking at the Iris and saying "Hmmmmm...ya picked the wrong plant to mess with this time pardner!" 

But there are reports that show allelopathic activity in Yellow Flag Iris, and it is fairly common in the plant world for seemingly innocuous smaller plants to be the more aggressive and successful competitor, so I will definitely be looking with interest on this spot over the summer.

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