Ambrosia psilostachya DC.
Family: Asteraceae, Tribe: Heliantheae

Pertinent Synonyms & Notes (particularly those used in California; go to GRIN for other synonyms)

none

Pertinent Common Names (particularly those used in California; go to GRIN for other common names)

western ragweed

Primary Disseminule Type

spiny bur

Description (diagnostics are in brown)

Disseminule a spiny bur consisting of hardened phyllaries tightly enclosing a single cypsela.

Bur obpyramidal to obovoid, various shades of brown, puberulent, 2–4.5 mm long, with 0–7 spines near the apex. Spines (0.1)0.5–1 mm long, conic (looking like tubercles), ± straight.

Risk Assessment (codes in yellow or red indicate cause for concern; assessments are current as of mid-2011; click AUQP, NZBORIC, or NZBPI for access to the most recent versions of these databases and possible assessment changes)

AUQP, NZBORIC, NZBPI