Botanical term for a plant that completes its life cycle within one year. Compare with 一年生植物 (いちねんせいしょくぶつ), a synonym also used in botany.
See also: 一年生植物
この花壇には一年草がたくさん植えてある。
Many annual plants are planted in this flower bed.
Annual plants need to be sown every year.