Prat (1932) of France published an exhaustive study of the epidermis of leaf blades, sheaths and glumes of species of the genus Agropyron. He studied many species, in addition, in the tribes outside the Hordeae, his findings confirming, for the most part, the already existing grouping of the grasses in keys based on morphology and anatomy. His work has some value in the identification of grasses in their vegetative stage, although primarily intended for use with mature plants.
Burr and Turner (1933) published a work on the identification of British economic grasses in which they present two keys, one based on morphological characters and the other on anatomical characters. The illustrations include camera lucida drawings of cross-sections of grass blades made from free-hand sections.
Vickery (1935) issued the first in a series of papers on the vegetative features, and anatomical characters of the leaves, of grasses indigenous to New South Wales. A discussion of the general vegetative and anatomical characters of the grasses is followed by details of these characters in species of the tribes Andropogoneae, Zoysieae, and Tristegineae. The author plans to conclude her series of papers with an artificial key to the native grasses of New South Wales in their vegetative state.
Hitchcock (1936) prepared a compact key to the almost two hundred species of grasses of Montana. Certain of the species within a genus differed so imperceptibly in their vegetative characters that they were grouped, and the reader was referred to short descriptions, or advised to compare them with authentic herbarium material for certain identification. Each distinctive species was illustrated by drawings grouped on eight plates at the end of the key, and the whole was bound in handy form for use in the field.
Pechanec (1936) studied eighteen grasses belonging to eleven different genera in the semi-arid area of the upper Snake River Plains, Idaho, where, in unusually dry seasons, few or no flowers are produced. This study formed the basis of a key to the vegetative stages of the grasses as well as detailed descriptions of each species. Only two of these species occur in eastern Canada.
Theron (1936) described in detail the leaf anatomy of thirty-eight species and six varieties of the genus Aristida indigenous to South Africa. His work, based on herbarium material in the Botanical Museum of Berlin-Dahlem, includes an anatomical key to these African grasses as well as drawings of the lower epidermis and cross-sections of the blades of seventeen species.
3. COMMON GRASS-LIKE PLANTS
There are many common plants occurring in meadows and pastures which might easily be confused with the true grasses (Gramineae) on account of similarities in vegetative structures. These, however, are confined mainly to two families, also monocotyledonous, the Sedge Family