Division of initials can be either solely anticlinal (orthogonal to the axis of growth) resulting in a single file of cells or first anticlinal then periclinal (parallel to the axis of
growth) resulting in two or more cell layers. The columella initials generally divide only analytically and their progeny undergo rapid cell expansion and then differentiate, producing starch-containing amyloplasts that play a role in gravity sensing. The other three types of initials generally undergo both anticlinal and periclinal divisions, resulting in cell lineages that acquire different identities