Involucral bract

Involucral bracts

Bracts that appear in a whorl subtending an inflorescence are collectively called an involucre. An involucre is a common feature beneath the inflorescences of many families, including the Apiaceae (carrot family), Asteraceae (sunflower or the daisy family), Dipsacaceae, and Polygonaceae. Each flower in an inflorescence may have its own whorl of bracts, in this case called an involucel. They can be called chaff, paleas or receptacular bracts and are usually minute scales or bristles. Many asteraceous plants have bracts at the base of each inflorescence.