30 BULLETIN 1074, V. S. DEPAKTMENT OF AGRICULTURE. 
exceed 5 cm. in length. From a genetic standpoint there probably 
are at least three distinct kinds of awnlessness. For the present 
classification, however, they are all classed as awnless, but in the 
descriptions the average extreme lengths of the apical awns are 
recorded. 
Awned varieties are those that have an awn or beard which termi- 
nates the lemmas on all spikelets. These awns usually increase in 
length from the basal part of the spike upward. In the common 
wheats, awns seldom, if ever, exceed 10 cm. in length. In durum and 
poulard wheats, however, they usually range from 10 to 20 cm. in 
length. 
SHAPE OF THE SPIKE. 
Spikes differ greatly in shape, length, and width. They may be 
flattened parallel to or at right angles to the plane of the face of the 
spikelets. Those flattened parallel to this plane are widest when seen 
in face view and can be said to be dorsoventrally compressed. All 
varieties of common wheat have spikes thus formed, except those 
that are clubbed at the tip, in which case they are only partly so. 
Spikes that are flattened at right angles to the plane of the face of 
the spikelets are narrow when seen in face view and may be described 
as laterally compressed. The club, durum, and poulard wheats are 
separated from the common wheats partly on the basis of having 
such spikes. 
In general, spikes vary in length from 5 to 15 cm., but are usually 
8 to 12 cm. long. They vary in width or thickness from 1 to 3 cm. 
The differences in length and width are not used in themselves but 
are often combined with the spike shape in a compound descriptive 
word. 
Whether dorsoventrally or laterally compressed, whether long or 
short, or narrow or wide, spikes are classified in the keys as having 
the following four general shapes — fusiform, oblong, clavate, and 
elliptical. These shapes are shown in Plate V. For all common 
wheats these shapes are determined from a face view of the spikelets 
and for all club, durum, and poulard wheats from an edge view of 
the spikelets. 
Heuze (112) used several different spike shapes as the leading 
characters in separating varieties within the species. The shapes 
mentioned, however, are here considered only as minor characters, 
though nevertheless very useful in distinguishing varieties. 
Spikes classed as fusiform taper toward the apex or from the 
middle toward both base and apex. The larger number of varieties 
of common wheat have spikes of this shape. 
Spikes described as oblong are usually quite uniform in width 
and thickness throughout the length of the spike, but are always 
several times longer than wide. 
