Stomatal ontogeny and phylogeny. I. Monocotyledons

The study of the cuticle in living and fossil gymnosperms has made it abundantly clear that stomatal and other epidermal characters are often of great value not only in the delimitation of genera but also in distinguishing the fragmentary fossil remains of allied species (see Florin 1931, 1933, 1958). In the early thirties of the present century, two comprehensive works appeared dealing with the systematic value of these characters in the living and fossil angiosperms. The first by Odell (1932) describes the cuticle in 84 genera of the living angiosperms and the conclusion is reached that none of the epidermal features of the vegetative parts of the living or fossil angiosperms is really satisfactory for diagnostic work. Contrary to this Edwards (1935) stated that the structural differences in the leaf epidermis do provide a means of distinguishing some closely related taxonomic groups. He, however, argued that as with other features in classification a sum total of the epidermal characters must be taken into account. Since the appearance of these two publications, a considerable body of data has accumulated regarding the cuticle. However, in the absence of any comprehensive account, it was thought worthwhile to bring together the available information on this aspect. I propose to complete it under two separate articles, the first one will deal with the monocotyledons and the second with the dicotyledons.