botany, phytology - the branch of biology that studies plants

sepal - one of the green parts that form the calyx of a flower

hull - persistent enlarged calyx at base of e.g. a strawberry or raspberry

chlamys, floral envelope, perianth, perigone, perigonium - collective term for the outer parts of a flower consisting of the calyx and corolla and enclosing the stamens and pistils

pappus - calyx composed of scales or bristles or featherlike hairs in plants of the Compositae such as thistles and dandelions

curl, curlicue, gyre, ringlet, scroll, whorl, coil, roll - a round shape formed by a series of concentric circles