32 
Applied to Agropyron the inference is clear. The presence or absence 
of pubescence and awn on the lemma cannot be considered of any greater 
taxonomic value in Agropyron than in other genera of Gramineae. 
Whether presence or absence of pubescence and presence or absence 
of awn on the lemma, taking Gramineae as a whole, are of sufficient import- 
ance and inherent quality to justify their employment as so-called essential 
characters in the designation of the major divisions of a genus, or what in 
current terminology are called species, is a question that scarcely needs 
discussion. That the awn character, in particular, is an unimportant one 
becomes obvious from the fact that the length may vary considerably in 
the same spike or even in the same spikelet. 
The use of the above-mentioned characters, as more or less leading 
ones, in keys to the species, or so-called species, of Agropyron , clearly 
demonstrates the over-estimation of their taxonomic value. Their employ- 
ment may bring about the grouping together of forms which clearly are 
widely separated taxonomically, and the placing in different camps, as it 
were, of forms which manifestly are closely related. On the other hand, if 
such characteristics as presence or absence ot pubescence and presence or 
absence of aw T n on the lemma are rated as of minor importance and their 
employment as more or less leading characters consequently is avoided, 
the multitude of existing forms may, in the writer’s opinion, be arranged 
into more natural groups, each consisting of types that obviously are closely 
related morphologically and probably also phylogenetically. 
The species, or so-called species, of Agropyron reported in floras (Gray’s 
Manual, Britton and Brown, 111. FI., and Rydberg, FI. Rocky Mts.) as 
occurring in Canada may be divided into two main groups. 
The first main group includes a number that are characterized by 
having very short (1-2 mm. long) anthers. They belong to Sect. Goularda 
(Husn., Gram. France, p. 93, 1896, pro gen.) emend. Vestergren apud 
Holmberg, Skand. FI., pt. 2, 269, 1926, and include types going under the 
names of A. caninum (L.) Beauv., A. caninoides (Ramaley) Beal, A. 
Richardsoni Schrad., A. tenerum Vasey, A. bijlorum (Brign.) R. & S., 
A. latiglume (Scribn. & Sm.) Rydberg, A. andinum (Scribn. & Sm.) 
Rydb. They arc all tufted grasses without creeping rootstocks 1 . 
The second main group consists of types having anthers 3-7 mm. long. 
These fall into two groups. 
The first group includes species that have creeping rootstocks and 
form open colonies, more or less dense mats, or loose clumps. Three 
natural sub-groups are discernible. 
The first sub-group includes A. Smithii Rydb. and A. ?nolle (Scribn. 
& Sm.) Rydb. These are western forms which may be found in eastern 
Canada as occasional introductions only. They form dense and in many 
cases very extended mats, due to the presence of numerous and rather 
crowded sterile shoots from the rootstocks. The leaves of these shoots are 
erect or ascending and rather crowded, with the upper ones not much 
overtopping the lower. As a result, the sterile shoots have a pronounced 
corymbiform appearance (Plate I, figure 2). The empty glumes are 
faintly nerved, long-attenuate, and more than three-quarters the length 
of the lowest lemmas. In the writer’s opinion A. molle is merely a variety 
of A. Smithii, differing by having pubescent lemmas. 
’For affinity and nomenclature cfr. the chapter following. 
