Silver beach bur is one of the most common plants found growing along the coastal sand dunes of Southern California.  It is a matted, many-stemmed perennial herb with brown to gray-canescent procumbent branches up to 5' long covered with ± silky hairs.  The leaves are variable, simple, long-petioled, and in outline ovate, rhombic to oblanceolate or widely triangular, and toothed to 3-pinnately lobed.  This is a mono-
ecious species with staminate and pistillate flowers in separate heads on the same plant, the staminate flowers in dense terminal spikes and the pistillate flowers crowded below.  The staminate heads are 25-50-flowered and each pistillate head contains a single flower.  The fruit is an ovoid, ± reddish-brown bur with 10-20+ awl-shaped spines with wide bases.  Silver beach bur blooms from July to November on coastal strand beaches and dunes to about 75' from Baja north to British Columbia, and on San Clemente, Santa Catalina, San Miguel and Santa Cruz Islands.  These pictures were taken at Bolsa Chica.

Click here for Latin name derivations: 1) Ambrosia 2) chamissonis.
Pronunciation: am-BRO-zee-a sham-i-SEW-nis.
Click here for Botanical Term Meanings.