CLASSIFICATION OF AMERICAN WHEAT VARIETIES, 49 
back, and the other including Sitopyrus, in which the glumes are 
sharply keeled and in which are found all cultivated forms. This 
bulletin is concerned only with the latter section of the genus 
Triticum. 
There are many forms of einkorn, spelt, and emmer (including the 
so-called “ wild wheat” of Palestine) which are not cultivated in the 
United States and, therefore, are not considered in these pages. 
Wheat is characterized asa midtall annual grass with flat blades and 
a terminal spike. The spikelets are solitary,1 to 5 flowered, sessile, 
arranged alternately on the nodes of a zigzag, channeled, articulate 
rachis; the rachilla of the spikelets disarticulating above the glumes 
and between the florets, or continuous; the glumes keeled, rigid, and 
3 to several nerved, abruptly acute or acuminate; the lemmas keeled 
or rounded on the back, many nerved, ending in a single tooth or 
awn. 
The following eight divisions of wheat varieties were used by 
Hackel (101, p. 180-187), and have been recognized by others: 
vulgare Vill. . . ....Common wheat. 
pial e compactum Host. ..Club wheat. 
A ao). Qoraemneaany “eis turgidum L........ Poulard wheat. 
ee Sag durum Desf......-. Durum wheat 
Triticum. ... . y 
dicoceunm Sehr ieee fal oo Emmer. 
f speltaih sie wags, eolsaliqg yu Spelt. 
polonietimmilae! Sees NN eNe es o a 8 Polish wheat. 
IMONGCOCCUMM Lc. ou Wee sre ceh dower sae ene OS Einkorn. 
Only three of these divisions were considered by Hackel as valid 
and distinct species, namely, sativum, polonicum, and monococcum. 
The other divisions he called races and subraces. The term race is 
now more properly used for a pure line within a variety, and these 
ranks probably would be better designated as subspecies and varieties. 
As previously pointed out, other authors have considered these divi- 
sions as distinct species or subspecies. The present writers have not 
yet given sufficient study to the question of their botanical relation- 
ships to express a positive opinion. 
In the present work it seems best to maintain these well-estab- 
lished divisions, but at the same time to rearrange their order. The 
writers make no attempt to assign definite rank to the different divi- 
sions, as they have not made a cytologic study of them or a genetic 
_ study of crosses between the different divisions nor have they 
\ made an exhaustive morphological study of existing varieties or 
strains which are of a type intermediate between any of the eight di- 
visions. Such studies were not projected as a part of these investi- 
gations. The divisions which have been established or recognized 
as species or subspecies by different authors, however, may be dis- 
tinguished by the accompanying key. 
95539°—22—Bull. 1074-4. 
