Edit Page
Print Page

Ambrosia chamissonis - Silver Burweed





General Herb.[E-flora] Sprawling clumps [WildPNW] "whole plant silky or the stems woolly" [HNW] Somewhat succulent. 20-100 cm tall. [PCBC2004]
Lifecycle Perennial[IFBC-E-flora]
Flowers Rayless and greenish.[WildPNW] Male (sterile) heads nearly unstalked or short-stalked. Female (fruiting) heads egg-shaped, 1-flowered.[IFBC-E-flora] involucral bracts that have several rows of prickles. [PCBC 2004]

Fruits "Achenes enclosed within the involucral bracts; pappus lacking."[IFBC-E-flora] "...the whole forming 6-11 mm long burs with 2-4 series of somewhat flattened prickles".[PCBC 2004]
Leaves Finely whitish- or silvery-haired. [IFBC-E-flora] 2-7 cm long. [PCBC 2004] Mostly alternate.[PWOBC] "Coarsely toothed or the lower dissected, or the leaves once or twice dissected in var. bipinnatisecta" [HNW]
Stem "Decumbent stems much branched".[WildPNW] Forming mats.[PWOBC] More or less prostrate. [HNW] "Stems leafy, spreading-hairy, stout, branched just below the surface."[IFBC-E-flora]
Root Long, creeping rhizomes.[IFBC-E-flora]
Habitat "Moist to mesic coastal sandy or gravelly upper beaches and shorelines in the lowland zone". [IFBC-E-flora] Coastal beaches.[HNW] "limited to backshores of sandy beaches, sandy edges of salt marshes, and other maritime situations."[PWOBC]
Range "Common in coastal BC; S to CA." [IFBC-E-flora]
Status Native [E-flora]
Similar Species "Ambrosia chamissonis var. chamissonis is more common in Calif. and Oreg. than farther N. Where it and var. bipinnatisecta occur together, they intergrade freely and some specimens are intermediate." [PWOBC]



Medicinal Uses




Family: Asteraceae (Compositae)
Habit: Annual to small tree; monoecious. Leaf: simple, opposite or alternate, generally petioled, entire to 1--4-pinnately lobed or divided, distal-most often reduced, bract-like. Inflorescence: staminate heads and pistillate heads together in distal leaf axils or in terminal, spike-like clusters, or staminate heads in spike- or raceme-like clusters distal to pistillate heads; staminate involucre +- cup-shaped, phyllaries in 1 series, +- fused, receptacle flat or rounded, paleate; pistillate phyllaries 0 or few, in 1 series, free, +- thin, receptacle paleate, palea bases fused, becoming a hard bur with each pistillate flower in a separate chamber, tips (occasionally not evident in flower heads) becoming hard knobs, spines, or scarious wings. Staminate Flower: 3--many; corolla translucent to yellow or red-purple; filaments fused, anthers free; style unbranched, ovary vestigial, pappus 0. Pistillate Flower: 1--5; corolla 0; style branches elongated. Fruit: inside bur with beak(s) surrounding style(s); pappus 0.
Species In Genus: 45--50 species: native to America, especially southwestern United States, northern Mexico.
Etymology: (Greek: early name for aromatic plants; mythic food of the gods) Note: Wind-blown pollen often allergenic.
Unabridged Note: Spines of bur derived from paleas, not phyllaries. [Jepson]


1. Involucres with 2-4 series of short, sharp spines; leaves mostly alternate................Ambrosia chamissonis
1. Involucres with a single series of short spines or tubercles above the middle; leaves, or at least the lower ones, opposite.

2. Plants annual from fibrous roots; leaves mostly stalked, mostly twice pinnatifid; involucres with short spines..................Ambrosia artemisiifolia?
2. Plants perennial from creeping roots; leaves short-stalked or nearly unstalked, only once-pinnatifid; involucres with tubercles...................... A. psilostachys
Dry roadsides and waste areas in the lowland and montane zones; rare in S BC east of the Coast-Cascades Mountains; introduced from SW U.S. -- 2 records near Vancouver, on the mainland.[IFBC-E-flora]

Local Species

Generic Uses

  • Ambrosia spp.; "Chew the root of the ragweed at night to drive away all fear."[EMH Cunningham]
  • Ambrosia Sp.; Antidote(Sumach), Diarrhea, Dyspepsia, Fever, Gonorrhea, Intestine, Vermifuge. [DukePhyto]
  • "Ambrosia peruviana WILLDENOW has similar properties to Ambrosia cumanensis and is used in a similar way. Leaves, stems, flowers and roots are used as medicinal drugs. The healing properties are similar." [Roth SAMP]
  • "Some species of the genus Artemisia are used as spices. Ambrosia is the cause of hay-fever and many species act as agricultural pests." [BEOC, Sousa](Ambrosia artemisiifolia and A. trifida) are stimulants, tonic and astringents.[MPP2]
  • "A. tenuifolia Spreng and A. elatior L. are known in Argentina by the names of Altamisa and Ajenjo del Campo. Both plants are used by the natives in medicinal beverages since several pharmacological effects have been attributed to them."[Bajaj MAP5]


  • "Wang and Zhu (1996a, b) identified the allelopathic potentials, through water leaching, of ragweed (Ambrosia artemisiifolia) and A. trifida...Aqueous extracts of Artemisia ordosica strongly inhibited seedling growth of Amaranthus tricolor, Orychopragmus violaceus, Raphanus sativus and Triticum aestivum (Ma et al. 1999)."[Zeng ASA]
  • "Root and leaf aqueous leachates of Ambrosia cumanensis did indeed produce a strong inhibition on the growth of weed species." [Waller Alleochemicals]
  • "Rice (1964) reported inhibition of growth of Rhizobium strains by numerous plant species, with most inhibitory being ..., Ambrosia elatior,..." [Reigosa Alleleopathy]
  • "higher plants (such as Ambrosia plisostachya, ...Helianthus annuus) were found to be very inhibitory to the nitrogen-fixing bacteria, and also to inhibit nodulation and nitrogen fixation of several legumes (Rice, 1974, and relevant references therein included)."[Reigosa Alleleopathy]
  • "Putnam et al. (1983) demonstrated that several cover crops like rye, wheat, sorghum, and barley suppress weed species such as redroot pigweed, common purslane (Portulaca oleracea L.), and common ragweed (Ambrosia artemisiifolia L.) up to 95% within 30 to 60 days when their residues (either frozen or desiccated with herbicides) are placed on the soil. "[Singh2003]


The information presented on this site is provided for educational purposes. Self diagnosis and treatment, without due diligence, could be harmful and is not encouraged. Some information & images may be copyright. Every effort has been made to present the information in the spirit with which it was originally presented. Some data has been omitted for legal and/or practical consideration. There is some data not covered in the scope of this project, including, but not limited to, cell culture and large-dose animal studies. I have made comparisons and links between related species which may later prove erroneous. I have not verified the information for accuracy and I accept no responsibility for its authenticity. Many of the plants presented are poisonous, have poisonous properties, or could cause illness through misuse, allergic reaction, drug interactions and environmental contaminants. Please use caution and mindfulness when harvesting plants for any use.

Page last modified on 05-02-2017