436 BOTANICAL GAZETTE [DECEMBER 
structure exhibited by the remaining species, including Poa alpina 
from Mt. Kelso and Deschampsia caespitosa from Gray’s Peak. 
These culms thus represent five types as to the occurrence of one or 
two bands of mestome bundles, and as to the distribution of the 
stereome as a circular band extending to the epidermis as hypoder- 
mal groups in contact with or separated from some of the mestome 
bundles (the latter case is illustrated in C). 
The fact that two of these types (D and E) have been observed in 
one species (Deschampsia caes pitosa), though from different elevations, 
seems to indicate that the structure may not be constant. The type D 
appears to be the most frequent in the alpine species of Colorado, and 
the most important difference between this and the three preceding 
(A, B, and C) depends upon the presence of two concentric bands 
of mestome bundles, all of which are supported by hypodermal 
stereome. The type E is more complicated on account of the inner 
mestome strands being of different size and lacking the hypodermal 
stereome, and this type, as stated above, was observed in Agropyrum 
violaceum. If this structure be compared with that of the French 
species of Agropyrum described by DuvaL-JouvE, it is observed that 
it does not agree with any of them. The species examined by this 
author were lowland species, and several were maritime. Character- 
istic of these species is the occurrence of hypodermal stereome outside 
the smaller as well as the larger mestome strands; also in some species 
the inner band may be located nearer the center of the culm, a com 
siderable distance from the stereomatic zone. In other words, the 
lowland species of Agropyrum in France represent actually an 
entirely distinct type of structure, which corresponds with the twelfth 
type of SCHWENDENER (J. c.), in which the inner mestome strands 
are in the pith, some distance from the stereomatic cylinder. 
The minor structure of the mestome strands in our alpine spe’ 
agrees in most respects with that of other Gramineae. It has — 
shown that some variation occurs in the outline of cross-section 
some being orbicular (especially the smaller ones), and the large? 
Ones usually oval. The leptome and hadrome differ in no Way suite 
that of other species from lower elevations. A more or less thick- 
*t Duvat-Jouve, Etude anatomique de quelques Graminées et €M particulier 
des Agropyrum de l’Hérault. Mém. Acad. Sci. Montpellier. Paris. 1879- 
