Foliage Friday: Centaurea

Today’s foliage friday is this alien-looking flower that was familiar to me, but I couldn’t think of the name:

Centauria!

I get centaurea and centranthus mixed up for some reason. Very different flowers.

Centranthus ruber (Red Valerian)
Centranthus not Centaurea! (Image from gardenia.net)

Centaureas are a genus of plants in the Asteracea family (which includes daisies, zinnias, and many other classic flowers). They can be perennials, biennials, or annuals. What I didn’t know about Centaurea is that they can be invasive weeds!

In Oregon and Washington, some species of Centaurea are considered noxious, class B, weeds! From what I understand, Centaurea originated in Europe or the Meditterranean and was brought over the the US as seeds. The plant produces hundreds of seeds each year, and they spread easily. The species that are considered invasive in Oregon and Washington are Centaurea diffusa and Centaurea maculosa, more commonly known as knapweed. Another common name for some of the invasive Centaurea species is starthistle.  

On the other hand, Centaureas provide lots of nectar for beneficial insects and pollinators.

According to a GardenSmart Oregon pamphlet (link), non-invasive alternatives to C. maculosa or C. diffusa include Centaurea moschata and Scabiosa columbaria (which just so happens to have been a recent foliage friday).

Amberboa moschata1UME.jpg
Centaurea moschata
Scabiosa (not columbaria)

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