Amaranthus blitoides S. Watson

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)

matweed, prostrate pigweed

Primary Disseminule Type


Description (diagnostics are in brown)

Fruit a dehiscent (circumscissile) utricle, broadly ovoid, 1.7–2.5(3) mm long, mostly smooth (slightly verrucose or rugose in dry plants), with (3)4–5 attached tepals (tepals narrowly ovate to broadly linear, subequal, 1.5–3 mm long), containing 1 seed.

Seed round or elliptic to obovate in outline, somewhat compressed with a distinct (acute) marginal rim, cross-section lens-shaped to fusiform, with a notch along the margin where hilum occurs and an even shallower notch (sometimes flattish, lighter-colored) in the marginal rim near the hilar region, (1)1.2–1.7(2) mm diameter x 0.7–1 mm thick. Surface shiny, ± smooth (under magnification, looking cobblestone-like, as well as pitted or punctate in some spots), dark reddish-black.

Hilar region round to elliptic, consisting of a linear slit between two semi-circular scars (one scar distinctly whitish and sometimes with funicular remnant attached).

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)