30 
Judging from the descriptions of A. caninum in European floras, 
particularly the very full one given in Holmberg, Skandinaviens Flora, 
1926, there are some other, minor differences which, however, are not- 
absolutely constant. A. caninum of Europe is described as having the 
leaves very scabrous on the upper side, partly with very short scabrescence, 
and partly with hairs about 1 mm. long. In the North American forms 
the leaves are also, as a rule, scabrous on the upper surface, but real hairs 
about 1 mm. long are not generally present. Forms with the leaves pub- 
escent on the upper surface exist, but are apparently rather rare. Such 
forms have been collected by the writer in the provinces of Alberta and 
British Columbia. The European A. caninum is also described as having 
the culm pubescent with retrorse hairs on and below the nodes, rarely 
glabrous. In the North American forms the reverse seems to be the case, 
at least if one is to judge from herbaria, the culm being generally glabrous 
on and below the nodes, rarely retrorse-pubescent. 
The constancy of the characters of the empty glumes, separating the 
European A. caninum from its representatives in North America, might 
alone be sufficient to regard the latter as belonging to a separate species. 
And when thereto are added the pronounced difference in the size of the 
anthers, and the biological difference manifesting itself in the behaviour 
of the spikelets during and after anthesis, there is, it would seem, ample 
justification for doing so. 
SPECIES AND VARIETIES IN AGROPYRON 
In the study of the genus Agropyron, as represented in Canada, the 
writer has come to the conclusion that the manifestly unsatisfactory classi- 
fication of its members, as reflected, for instance, in keys found in floras, is 
in a large measure due to the overestimation of the taxonomic importance 
of certain characters, particularly the presence or absence of pubescence 
and of awn on the lemma. The comparatively small taxonomic import- 
ance of these characters becomes evident when the many forms of Agropyron 
are compared with analogous forms in other genera of Gramineae. Among 
such analogous forms the following may be quoted. 
Lemma glabrous 
Agrostis tenuis Sibth. 
Trisetum spicatum (L.) Richt. 
Phippsia algida (Soland.) R. Br. 
Puccinellia retrojlexa (Curt.) 
Holmb. f. leioneura Holmb. 
Festuca onina L. 
u rubra L. 
Bromus ereclus Huds. 
“ sterilis L. 
“ tedorum L. 
var. nudus Kl. & Richt. 
Bro?nus secalinus L. 
Hordeum nodosum L. 
Elymus virginicus L. 
“ robustus Scribn. & Sm. 
“ striatus Willd. var. arkan- 
sanus (Scribn. & Ball) Hitchc. 
“ australis Scribn. & Ball 
var, glabrijlorus (Vas.) Wieg. 
Asperella Hystrix (L.) Humb. 
Lemma pubescent 
var. setulosa (Murb.) Holmb. 
var. pilosiglume Fern, 
f. vestila Flolmb. 
P. retrojlexa (Curt.) Holmb. 
f. hispidula Hack. 
f. arenaria (Osb.) Fr. and other forma, 
f. villosus (M. & K.) Kunth. 
f. hirtijlorus Borb. 
B. tedorum L. 
/. hirtus (F. Schultz) Asch. & Gr. 
var. marinum Koch 
var. hirsutiglumi8 (Scribn.) Hitchc. 
var. vestitus Wieg. 
E. striatus Willd. 
E. australis Scribn. & Ball. 
var. Bigeloviana Fern. 
