Guard cells first, then epidermis

Stomata in the moss Funaria are regularly spaced at the base of the capsule.

Funaria. Photo: Jayesh Patil / Flickr

Merced and Renzaglia describe the patterning and distribution of stomata and how they are coordinated with the formation of substomatal cavities and spaces in the sporophyte. Unlike Arabidopsis, stomata in moss do not develop from a meristem-like cell that continuously divides. Instead guard mother cells differentiate into guard cells from non-contiguous protodermal cells arranged in files. The surrounding epidermal cells divide after stomata are formed in synchrony with capsule expansion. Differentiation of guard cells before the rest of the epidermis ensures that stomata are spaced apart from each other.