Stomatal Pattern in Four Species of Monocotyledons

Abstract

The distribution of stomata has been investigated in the leaf epidermis of Chlorophytum comosum, Galanthus nivalis, Schizostylis coccinea and Scilla lancifolia. The epidermis was considered to consist of units of construction of two kinds: type A, a long epidermal cell with a stoma at its distal end, and type B, a long epidermal cell without an associated stoma. Except in Scilla, the probability of an epidermal unit being type A increases approximately with its length. Considering the epidermis as rows of units, alternating sequences of type A and type B do not occur randomly along the rows. In Chlorophytum, Galanthus and Schizostylis, both type A and B units tend to be aggregated into longer sequences than would be expected on a random basis. It is suggested that homoeogenetic induction (i.e. of like by like) may be occurring during development. No case can be made for homoeogenetic induction of units in Scilla. There is a slight tendency to periodicity of distribution of type A units in Galanthus, Schizostylis and Scilla, but this does not seem to represent a primary element of pattern. There is interaction between rows in the sense that unit ends (transverse walls) tend to avoid those in neighbour rows; this affects the relative distribution of stomata, but there is no evidence of any direct interaction between stomata in different rows.