Intertidal Organisms EZ-ID GUIDES

 

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Ambrosia chamissonia (Silver beachweed)

photo of silver beach weed
Copyright © 2006 Mary Jo Adams

 

Ambrosia chamissonis is very common along Island County beaches.  It is a native species and belongs to the sunflower family.   This species forms large sprawling mats up to 10 feet across.  The flowering stems are present from June through August.  A close look at them will reveal small button-like aggregations of tiny flowers.   After the flowering season has ended, the flowers will be replaced by spiny burs.  Silver beachweed is commonly seen along our beaches in association with the dunegrass Leymus mollis.   In California this species often has a dense coating of fine silvery-white hair.  Further north, it may lack much of the hairy coating giving it more of a gray-green appearance.  Due to this variation, some scientists have assigned the less hairy plant the subspecies name A. chamissonis bipinnatisecta.  This species has also been known under the scientific name Franseria chamissonis.  Other common names include silver bur, beach bur, sand bur, silver bur weed, beach bursage, silver bursage, and silver bur ragweed.       

 

 

 

 

This page was created by Mary Jo Adams on 8/21/06.

 

 

photo of silver beach weed

photo of silver beach weed

photo of silver beachweed

 

closeup photo of silver beachweed

 

photo of silver beachweed bur