Amaranthus hybridus L.

Family: Amaranthaceae

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


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

smooth pigweed

Primary Disseminule Type


Description (diagnostics are in brown)

Fruit a dehiscent (circumscissile) utricle, obovoid, 1.5–2.5 mm long, smooth proximally, rugose or verrucose distally, with 5 attached tepals (tepals lanceolate to linear, subequal or unequal, 1.5–3 mm long, apex acute to acuminate narrowing into an aristate tip), with subtending sharply-pointed bracts 2–4 mm long, containing 1 seed.

Seed round to elliptic in outline, compressed with an obtuse marginal rim, cross-section lens-shaped to barely fusiform, with a protruding notch along the margin where hilum occurs and from which a shallow depression runs inward for a short distance, 1–1.5 mm diameter x 0.4–0.6 mm thick. Surface shiny, ± smooth (under magnification, looking cobblestone-like, as well as pitted and punctate in some spots), dark reddish-brown to black.

Hilar region round to elliptic, consisting of a round to linear opening between two semi-circular scars.

Embryo annular, surrounding copious perisperm.

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)