a genus of annual herbaceous plants of the family Gramineae. The inflorescence is a panicle consisting of numerous single-flowered, terete spikelets. The glumes are papery and unequal; the lemma is more slender and has a long, sinuous awn. There are three species, found in Europe and western Asia (including the USSR). The most common species is silky apera (Apera spicaventi), which grows as a weed in rye, barley, wheat, potato, and clover fields. It also grows in sandy floodplains and weed patches. The Apera ripen before the edible grains do, and their seed fall easily and infest the soil. The plants can be used to dye wool green.