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VIT. On the Anatomy of the Leaves of British Grasses. By L. Lewron-Braty, B.A., 
F.L.S., Hutchinson Student of St. John’s College, Cambridge, and late University 
Demonstrator in Botany. 
(Plates 36-40.) 
Read 18th June, 1903. 
INTRODUCTION. 
DUVAL JOUVE was the earliest investigator who undertook to give a general account 
of the structure of the leaves of grasses. In his first work (1870)* he described the 
general anatomy of the vegetative organs of grasses—root, rhizome, culm, and leaf. 
Later (1875) he published a paper dealing especially with the anatomy of the leaves. 
Güntz (1886) investigated the question of the influence of climate and habitat on 
the development of the mechanical tissue in the leaves of grasses. Schwendener (1889) 
gave an account of the structure of the stomata in the leaves of grasses and sedges, 
and later (1890) a detailed description of the stereome-sheath of the vascular bundles. 
A more complete account of this earlier work will be found in Pée-Laby’s paper (1898). 
Many workers, both botanists and agriculturalists, have recognized the fact that the 
anatomical structure of the leaves is a valuable aid in the identification of many of 
the grasses, especially when, as is the case during a great part of the year, one has 
only the vegetative organs to work with. Thus Stebler (1889), in his work on * The 
Best Forage Plants,’ gives a number of diagrammatic figures of transverse sections of 
the leaves of the grasses he describes. ' 
MacAlpine (1890), too, in his book on grasses, uses certain points in the transverse 
section of the leaf as means of identification. 
Pée-Laby (1898) also has in view the recognition of grasses from the anatomical 
structure of their leaves; thus he says: “I claim that in default of having flowering 
specimens sufficiently developed, this (i. e., the transverse section of the leaf) 
would be the only means of correctly distinguishing very nearly related species.” 
This statement, though to a great extent true, seems to me to be somewhat 
exaggerated, since an examination of the transverse sections of leaves of closely 
allied species of Poa, Bromus, Aira, and other genera will show that in many cases 
the anatomical structure of the leaves of nearly related species is very similar if not 
practically identical. This, as might be expected, is more especially the case 
when the species in question have a very similar habitat: when allied species have 
a dissimilar habitat, they very often have dissimilar leaf-structure; but it must be 
* See Bibliography, infra, p. 357. 
SECOND SERIES.—BOTANY, VOL. VI. EI 
