Conyza canadensis (L.) Cronquist

Family: Asteraceae, Tribe: Astereae

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

Erigeron canadensis L., C. parva Cronquist

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

horseweed, Canada fleabane

Primary Disseminule Type


Description (diagnostics are in brown)

Fruit a cypsela, narrowly elliptic to oblong, sometimes slightly curved, mildly compressed (1-veined on each edge), cross-section biconvex, 1–1.6 mm long x 0.3–0.5 mm wide x 0.1–0.3 mm thick. Surface sparsely hairy, pale tan to light grayish-brown. Pappus persistent (bristles are easily broken, though not necessarily at their bases), bristles mostly 2–3 mm long, whitish to cream.

Style base inconspicuous, cylindrical, whitish.

Fruit attachment scar basal, cup-like, whitish.

Similar Species

Similar Species Comparison Chart

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)