31 
In the above cases the pubescent form is universally regarded as a 
variety, or even merely as a forma, of the glabrous species, or the glabrous 
form as a variety or forma of the pubescent species, as the case may be, 
except in the genus Elymus in which the various forms by some authors are 
all regarded as distinct species. 
Among grasses, outside of Agropyron, in which awned and awnless 
forms are found, the following may be mentioned: 
Lemma awnless or nearly so 
Ardagrostis latifolia (R. Br.) 
Griseb. 
Agrostis stolonifera L. 
“ tenuis Sibth. 
“ canina L. var. mutica 
Gaud. 
hyemalis (Walt.) BSP. 
Scolochloa feslucaeea (Willd.) 
Link 
Festuca ovina L, var. tenuifolia 
(Sibth.) Dum. 
Festuca rubra L. var. mutica 
Hartm. 
Festuca pratensis Huds. 
Bromus secalinus L. f. submuticus 
Rchb. 
Elymus virginicus L. var. sub- 
muticus Hook. 
Lolium multiflorum L. var, muti- 
cum DC. 
“ remotum Schrank 
Lemma awned 
f. aristata Holmb. 
var. aristata Hartm. 
var. aristata (Hartm.) Holmb. 
A . canina L. 
var. geminata (Trill.) Hitchc. 
f. aristata Hartm. 
F. ovina L. 
F. rubra L. 
f. aristata Holmb. 
B. secalinus L. 
E. virginicus L. 
L. multiflorum L. 
f. aristatum (Doell) Asch. 
In these instances the awned form is universally considered a variety 
or merely a forma of the awnless species, or the awnless form a variety or 
forma of the awned species, except in Agrostis hyemalis and Elymus virgi- 
nicus in which the awned and awnless representatives by some authors are 
held specifically distinct. 
The variations mentioned furnish a rather striking illustration of the 
fact that, in Gramineae, the diversity of many species, belonging not only 
to the same genus but also to different ones, expresses itself along parallel 
lines. This parallelism is by no means confined to the characters of the 
lemma, but is found equally pronounced in others, e.g. in the shape of the 
inflorescence of panicle-bearing grasses, such as Agrostis stolonifera L., 
Dactylis glomerata L., Poa pratensis L., P. palustris L., P. compressa L., 
Bromus inermis Leyss. and other species of Bromus, species of Puccinellia, 
Avena sativa L., and others, as related elsewhere (12, p. 118). 
The similarity in the nature of variation of several characters is, 
indeed, so remarkable that one cannot but agree with Vavilov (17) 
that it expresses not merely simple parallelism but real homology of varia- 
tion, having its basis in the phylogenetic complexion of the whole family. 
In other words, the parallelism is so conspicuous that it most decidedly 
points to a universal law of homologous variation. 
The recognition of such a law gives the systematist a rather definite 
and solid basis to work from w r hen the taxonomic values of the characters 
affected are under consideration. It simply means that, within the family 
of Gramineae, all variations of the same nature ought to be considered as 
equals, i.e. ought to be conceded equal taxonomic rank and value. 
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