30 BULLETIN 1450, U. S. DEPARTMENT OF AGRICULTURE 
has been adopted. 7 The typical haplocorm of timothy, as the mean- 
ing of the term indicates, is composed of a single enlarged inter- 
node. The use of the term has been extended, so that it also applies 
to the swelling on the smaller proportion of timothy shoots com- 
posed of two or occasionally three enlarged basal internodes. 
TIME WHEN THE HAPLOCORM MAKES ITS GROWTH 
In a timothy meadow buds develop into young shoots or innova- 
tions in the largest numbers during the middle to the latter part of 
the summer. It is not until the following spring when the upper 
internodes of these shoots become elongated that the haplocorms are 
formed. The internodes of a timothy shoot develop in the same 
order of succession as the corresponding leaves appear. Since the 
haplocorm is the lowest one of the elongated internodes, it is the first 
one to develop. As it grows in length it also enlarges in diameter. 
To some extent, in different seasons or in different latitudes, cli- 
matic conditions affect the time at which the haplocorms develop. At 
the timothy-breeding field station in northern Ohio a series of obser- 
vations and measurements which were made from May 1 to July 31, 
1916, showed that in that season the haplocorm of timothy snoots 
commenced to grow soon after May 1 and by June 5 their growth, 
both in length and diameter, was practically completed. At Wash- 
ington, D. C., timothy shoots which were examined May 5, 1913, had 
well-formed haplocorms at that time, indicating that their growth 
must have begun some time in April. 
At about the time, in midsummer, when seeds mature on a timothy 
shoot the leaves and upper internodes become dry. The lower part of 
the shoot, and especially the haplocorm, retains its green color for 
several weeks or months longer. In one meadow examined October 
22, 1914, most of the haplocorms which developed in the preceding 
spring were still green in color and turgid in texture, although the 
stubble of most of the shoots had dried as far down as the node above 
the haplocorm. Records made on March 2 and April 3, 1914. of the 
condition of the haplocorms of shoots which developed in 1913 show 
that while most of the haplocorms retained their original form until 
the spring of 1914 their interior parts were more or less brown in 
color, were not turgid, and evidently contained no live tissue. The 
exterior part of the haplocorm is comparatively firm, and it fre- 
quently retains its form for a year or more after the inner tissue of 
the haplocorm has begun to decay. 
CONDITIONS UNDER WHICH THE HAPLOCORM DEVELOPS 
Haplocorms have been found commonly present on practically all 
timothy shoots which become elongated in late spring, whether the 
soil in which the plants have grown is or is not a very productive one. 
It has been observed, however, that the form of the haplocorm is 
sometimes apparently affected to some extent by soil conditions. On 
timothy plants growing in cultivated row plats the ratio of the 
diameter to the length is apparently less than in typical haplocorms 
7 The name " haplocorm " was suggested by the late C. V. Piper. It is composed of the 
word " corm," which is derived from the Greek " kormos," and the prefix " haplo," from 
the Greek word " haplos," meaning single or simple. 
