Native or noxious? Distinguishing scentless chamomile from Porter Aster. By Irene Shonle

The petite and charming Porter aster (Aster porteri or Symphotrichum porteri) is out in profusion right now.   This is a lovely, late-blooming native plant.

Porter aster, a late-blooming native plant

There is another less-friendly white daisy that is also  blooming right now that some people confuse with Porter aster – this is the State List B noxious weed called Scentless chamomile (Matricaria perforata or Tripleurospermum inodorum).  This weed  is rapidly increasing in population in our mountain counties, forming monocultures in places like Winter Park, Fraser, Nederland, and many other locations. The reason it can spread so fast is that in a single year, one plant can produce up to 300,000 seeds! http://www.colorado.gov/cs/Satellite/ag_Conservation/CBON/1251621067095.  I swear that it often seems as though each one of those seeds germinates and becomes a plant.  Yikes!  Please remove it from your property if you have it – and the task will be MUCH easier if you do it early in the game, before the exponential explosion occurs.

Scentless chamomile, a noxious weed, will take over every available bit of land

At first glance, the  can look pretty similar, but there are some easy ways to tell the noxious from the native:

1              First, look at the leaves.  

 

Porter aster has small, linear leaves

Scentless chamomile has ferny leaves

                 Next, look at the flowers – scentless chamomile’s flowers are bigger, and have a larger yellow center (disk  flowers).  Porter aster's center is small and frequently turns from yellow to a brown/black.

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      Porter aster is overall a smaller, shorter plant. I often see butterflies and bumblebees land on it for the nectar, and finches eating the seeds.  The only thing I see landing on scentless chamomile is flies.

    

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If you think scentless chamomile is pretty, then supply yourself with free flowers -- Pick a bouquet (make sure to get the roots) and throw it away (after enjoying it in a vase)