Ambrosia chamissonis  (Less.) E. Greene

=Franseria bipinnatifida

Asteraceae (Sunflower Family)


Beach Bur

                                April Photo


Plant Characteristics:  Perennial monoecious herb with radiating procumbent branching stems from caudex or tap root, forming loose mats 1-3 m. across and 1.5-3 dm. high; herbage silvery canescent with silky hairs, the stems more hirsute; lvs. simple, the blades ovate, rhombic, or oval-oblanceolate, usually obtuse, crenate-serrate to bluntly toothed or lobed or even incised, 2-5 cm. long, tapering to a petiole nearly as long; staminate heads in congested terminal spikes, 7-8 mm. wide; pistillate heads borne in lf.-axils below the male racemes, 1-fld., their invol. +/- turbinate, at maturity armed with several rows of prickles below the 1-4 beaks, bur 7-10 mm. long, its spines flattened or channeled, not hooked.


Growing along with the form above described are plants with lvs. once to thrice pinnatifid into oblong or obovate segms., less silvery; fr. glandular but not hairy, the spines often more slender and less sulcate (longitudinally grooved).  These two forms are said to hybridize freely, yet the two main types persist side by side.  This second form has been treated taxonomically in various ways: as a var. in Franseria as bipinnatisecta Less.; as a ssp. by Wiggins and Stockw., also under the name bipinnatifida, as a sp. in Gaertneria by Kuntze, in Ambrosia by Greene; as a var. dubia under F. bipinnatifida by Eastw.; and as a forma bipinnatisecta in Franseria by Calder and Taylor.  Payne gives no taxonomic recognition.   (Munz, Flora So. Calif. 110).      Munz, Flora So. Calif. and Hickman, Ed. combine the various leaf forms under A. chamissonis.  The local form has bipinnate leaves. (my comments).


Habitat:  Coastal Strand, n. to B.C.; San Clemente, Santa Catalina, San Miguel and Santa Cruz Ids.  July-Nov.


Name:  Ancient Greek, also Latin name of several plants meaning "food of the gods".  Its application to these weedy species is obscure.  The species name honors Adelbert Von Chamisso (1781-1838), the German poet, writer and naturalist who visited Calif. in 1816 with a Russian expedition that also included John Eschscholtz (1793-1831), for whom Chamisso named the Calif. Poppy.  (Dale 51). Latin, bipinnatisecta, refers to the doubly pinnately divided leaves.  (John Johnson).


General:  Uncommon in the study area, the photographed specimen was on North Star Beach.  (my comment).      Ambrosia and Franseria species have been known to cause hay fever and asthma, also dermatitis.  (Fuller 143,371).      About 40 species, largely of warmer parts of America.  (Munz, Flora So. Calif. 109).       Leaf forms intergrade; pls. with compound lvs. have been called A. bipinnatifida.  (Hickman, Ed. 193).


Text Ref:  Abrams, Vol. IV 150; Hickman, Ed. 193; Munz, Calif. Flora 1105; Munz, Flora So. Calif. 110.

Photo Ref:  April 7 83 # 11,12; Feb 2 84 # 6.

Identity: by R. De Ruff, confirmed by F. Roberts.  


First Found:  February 1984.

Computer Ref:  Plant Data 143.

Have plant specimen.

Last edit 7/14/05.


                              April Photo                                                                  February Photo