Poa annua L.

Family: Poaceae, Tribe: Poeae

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)

annual bluegrass

Primary Disseminule Type


Description (diagnostics are in brown)

Spikelets oblong or ovate, not bulbiferous, 3–8(10) mm long, laterally compressed, consisting of 3–10 fertile florets, with sterile florets at apex looking similar to fertile florets. Disarticulation at base of each fertile floret.

Glumes persistent, dissimiliar, shorter than spikelet, membranous, keeled, surface smooth, glabrous. Lower glume lanceolate to ovate, 1.5–2.5 mm long, 1-veined. Upper glume elliptic to oblong, 2–2 mm long, 3-veined.

Floret: rachilla persistent, usually <1.5 mm long, smooth, glabrous, callus typically glabrous but can be pubescent.

Lemma ovate to lanceolate, 2.5–4 mm long, membranous, keeled, 5-veined, veins strongly ribbed, sparsely to densely pubescent below the middle (rarely glabrous), surface smooth, hairy on veins and at base, apex obtuse to acute.

Palea 0.9 length of lemma, keels smooth, hairy or glabrous.

Caryopsis broadly ovate, mildly laterally compressed, ca. 1.5 mm long x 0.5–0.9 mm wide, brown, embryo <0.33 length of caryopsis, hilum round.

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)