The story of Volutaria tubuliflora in Orange County

Ron Vanderhoff

The introduction of this species to southern California is an interesting story.

In 1987 the late Bob DeRuff detected an Asteraceae plant at Upper Newport Bay. He wrote briefly about it (under the name of Centaurea muricata) in his Vascular Plants of Upper Newport Bay.

Bob was the most prolific collector at Upper Newport Bay for many years and did an incredible and thorough job of documenting the floristics of the area. Most of his collections went to the University of California Riverside (UCR) herbarium and were curated by Andy Sanders. In 2003 Bob finally made a collection of his plant.

I'm not sure how the determination was made, but the specimen was labelled Centaurea muricata. It sat quietly in the UCR herbarium for the next 14 years under that name. When Volutaria tubuliflora was finally "discovered" at Upper Newport Bay on 31 March 2015 by Barbara Boethling and confirmed the next day by me, it became a big deal. All the agencies went into motion to try to eradicate it.

In the 12 months or so following the 2015 Volutaria "discovery" at Upper Newport Bay, I uncovered Bob's Centaurea muricata reference and started pursuing it. From his images it was indeed V. tubuliflora. A short while later, in 2017, Chris MacDonald and Andy re-examined the voucher and re-determined it as V. tubuliflora.

Identifying a taxon new to the continent is a pretty dicey thing! Nonetheless, it would appear that Bob's observations and comments about the species at Upper Newport Bay in 1987 represents the earliest record for the U.S. If so, then it would seem reasonable that the Borrego population would have originated from the Newport colony.

The specific morph at Upper Newport Bay, and elsewhere in California, with white flowers, is apparently not common in its native range in Northern Africa. Thus it seems likely that this white morph was introduced in one of the four known sites (Newport Beach, Borrego Springs, Atacama Desert, and Chula Vista), and then spread to the others from that first introduction.

Go to:

• Volutaria tubuliflora, a new invasive knapweed

Copyright © 2022 by Ron Vanderhoff.
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Updated 17 February 2022