18(17) Inflorescence subtended by a broad, 2-keeled prophyll; rachilla internodes usually distinct and disarticulating.

花序被包着以一宽分，2龙骨状；小穗间通常清楚。

In the daisy family the numerous bracts which subtend the inflorescence are known as an involucre.

在菊科植物中，苞片数目多而聚生在花序外围，称为总苞。