43 
North America: Newfoundland to British Columbia and Yukon terri- 
tory; south to Tennessee, Iowa, and Colorado; also in southern Greenland. 
Agropyron trachycaulum, thus amended, constitutes a unit composed 
of a very large number of biotypes, most of which, judging from observa- 
tions so far, are homozygous and thus breed true to type. To describe and 
classify the multitude of the biotypes is at present out of the question, as to 
do so properly it would be necessary to study them in the field much more 
extensively than has been done so far, and also to follow up the field study 
with investigations in gardens or other experimental grounds where they 
could be grown together under identical conditions. It is feasible, how- 
ever, and seems desirable, to arrange the biotypes into certain groups 
according to the most conspicuous morphological characters. These 
characters are presence or absence of pubescence on the lemma, presence or 
absence of awn on the lemma, presence or absence of pubescence on the 
leaf-sheaths, and presence or absence of glaucescence on the culm and 
foliage. The groups thus segregated are here termed varieties. These 
varieties, it should be emphasized, are by no means mono-typic. Within 
some of them at least may be found a large number of biotypes, differing 
from each other, for instance, in the relative length of awn, the relative 
degree of pubescence on the leaf-sheaths, the relative degree of scabrousness 
on the lemma, the relative width, rigidity, and roughness of the leaves, the 
colour of the foliage, in presence or absence of pubescence on the upper 
surface of the leaves, in presence or absence of pubescence on the nodes, 
in earliness and lateness of flowering and ripening, etc. 
Key to the Varieties of A. trachycaulum 1 
1. Lemma glabrous or more or less scabrous 
2. Awn wanting or at most about half as long as the lemma 
3. Sheaths glabrous 
4. Plant green var. lenerum 
4. Plant glaucous. . var. glaucescens 
3. Some or all of the sheaths pubescent 
4. Plant green. var. trichocoleum 
4. Plant glaucous var. Fernaldii 
2. Awn longer than the body of the lemma 
3. Sheaths glabrous 
4. Plant green var. unilaterale 
4. Plant glaucous. var. caerulescens 
3. Some or all of the sheaths pubescent 
4. Plant green var. ciliatum 
4. Plant glaucous var. glaucum 
1. Lemma pubescent 
2. Sheaths glabrous var. pilosiglume 
2. Lower sheaths pubescent var. hirsutum 
l RecentIy, Hitchcock (2, p. 159) has transferred Elymus vulpinus Rydb. to Agropyron under the name of A. 
richardsonii vulpinus. Rydberg (15, pp. 540-541 ), when describing Elymus vulpinus, says: “This is one of the species 
connecting the genera Elymus and Agropyron. The type was originally named Agropyron caninum unilaterale 
(Cassidy) Vasey, which is the same as A. Riehardsanii. J. G. Smith in his revision referred it to A. Gmelini It 
resembles both a great deal in habit, but is distinguished by the hispidulous floral glumes and by the empty 
glumes, which are attached more or less obliquely, a character which would place the species in Elymus rather than 
in Agropyron.” 
Through the courtesy of Dr. Rydberg the writer has had the opportunity to examine the type of Elymus vul- 
pinus. Superficially it resembles A. Richardsoni (A. trachycaulum var. unilaterale of the key), but differs in having 
the anthers about 2-4 mm. long, whereas in the latter they are at most 2 mm. The anthers of Elymus vulpinus are 
furthermore conspicuously narrow and shrunken, and the pollen is practically to 100 per cent sterile, with the grains 
very irregular in size, malformed, transparent, and void of normal, granular protoplasm. This is the kind of pollen 
that, according to Vestergren (18, p. 270), is found in Agropyron hybrids. Furthermore, as Elymus vulpinus 
morphologically appears to connect Agropyron and Elymus, it may very well be a hybrid between two species of the 
two genera. 
