Ambrosia acanthicarpa  Hook.


Asteraceae (Sunflower Family)




Annual Burweed




Annual Bur-Sage   

                                       September Photo


Plant Characteristics:  Rather strict or corymbosely branched annual 1-7 dm. high, rather densely appressed-canescent and sparingly hispid; lvs. bipinnatifid, the blade ovate in outline, with oblong obtusish divisions, 2-6 cm. long, petiolate; staminate heads very numerous, 2-5 mm. wide; invol. lobes 3-9, tips of longest 3 +/- black-lined along midveins; fr. 1-fld., glabrous or sparsely villous, 5-10 mm. long, the spines 9-18, much flattened, shallowly sulcate, generally +/- golden.


Habitat:  Common weed of sandy plains, stream bottoms, etc., mostly below 2500 ft., occasional to 6500 ft.; V. Grassland, Foothill Wd., Coastal Sage Scrub, etc.; cismontane s. Calif., and desert edge; to Wash., Tex.; Santa Catalina Id.  Aug-Nov.


Name:  Ancient Greek and Latin name of several plants.  (Munz, Flora So. Calif. 109).  Ambrosia is from the Greek meaning "food of the Gods" and is the classical name for various plants.  Its application to these weedy specimens is obscure.  (Dale 51).  Greek, akantha, a thorn, prickle, and Greek, karpos, fruit.  (Jaeger 4, 46).  Referring to the spines on the fruit.


General:  Rare in the study area having been found only along the horse and bike trail in Santa Ana Heights and on the dune behind the Fish & Game trailer at Shellmaker Id.  Several plants have reseeded themselves each year and are still on the dune in 1999.  The fruit of the Shellmaker plants was reddish while the Santa Ana Heights plant had golden fruit per Hickman. (my comments).        Ambrosia species have been known to cause hay fever and asthma.  (Fuller 379).      About. 40 spp., largely of warmer parts of America.  (Munz, Flora So. Calif. 109).       


Text Ref:  Abrams, Vol. IV 149; Hickman, Ed. 193; Munz, Flora So. Calif. 109; Roberts 8.

Photo Ref:  July-Aug 87 # 20, 21; Aug-Sept 87 # 11; Sept 97 # 6A.

Identity: by R. De Ruff.  

First Found:  August 1997.


Computer Ref:  Plant Data 298

Have plant specimen.

Last edit  7/14/05.  


                           August Photo                                                   September Photo