In
grasses (including
cereals such as
rice,
barley,
oats, and
wheat), the ripe seed is surrounded by thin, dry, scaly
bracts (called
glumes,
lemmas, and
paleas), forming a dry
husk (or hull) around the grain. Once it is removed, it is often referred to as chaff. In wild cereals and in the primitive domesticated
einkorn,
emmer and
spelt wheats, the husks enclose each seed tightly. Before the grain can be used, the husks must be removed. The process of loosening the chaff from the grain so as to remove it is called
threshing before
drying – traditionally done by milling or pounding, making it finer like
flour. Separating remaining loose chaff from the grain is called
winnowing – traditionally done by repeatedly tossing the grain up into a light wind, which gradually blows the lighter chaff away. This method typically uses a broad, plate-shaped basket or similar receptacle to hold and collect the winnowed grain as it falls back down. Domesticated grains such as
durum and
common wheat have been bred to have chaff that is easily removed. These varieties are known as "free-threshing" or "naked". Chaff should not be confused with
bran, which is a finer, scaly material that is part of the grain itself. ==Straw chaff==