LIFE HISTORY OF TIMOTHY 45 
ELONGATION OF THE RACHILLA 
Early in November, 1920, a number of timothy heads were observed 
on which there were one or more spikelets with the floret borne on 
an elongated axis, which apparently represented the rachilla. This 
elongation of the rachilla may be regarded as one form of prolifera- 
tion, which is much less common than the enlargement of bracts to 
form leaves. A similar, if not an identical, form of proliferation 
has been observed in Agropyron cristatum (30, p. I$3). 
Three timothy spikelets, photographed November 10, 1920, each 
bearing a floret on an elongated rachilla, are shown in Plate 8, D. 
The bracts of the florets were somewhat thickened but in other ways 
resembled the lemmas and paleas of florets growing in the usual 
position. The floret at the right had recently bloomed, as is indi- 
cated by the three anthers attached to it by their filaments. 
A rare form of proliferation is illustrated in Plate 8, E. On each 
of the three spikelets shown the floret was borne on an elongated 
axis, which probably was the rachilla. On each one of the three 
florets the lemma resembled a small leaf. 
HEADS WITH BRANCHES 
Timothy heads with branches develop rarely. They have been 
observed to be associated with the development of proliferous florets. 
On November 9, 1920, a timothy head, shown in Plate 10, 6', was 
collected on which there were six small branches, each bearing a 
number of spikelets, the bracts of which were relatively small. 
There were also a number of proliferating florets on the same head. 
This one and a second head with branches less well developed were 
the only ones observed during the investigations made of prolifera- 
tion of timothy in the fall of 1920. 
EFFECT OF LENGTH OF DAY ON GROWTH OF TIMOTHY 
In any timothy meadow, during the spring and early summer, 
the stems of the plants grow in length, heads appear, florets bloom, 
and seeds mature. Each phase of growth occurs at approximately 
the same time on all the plants in the meadow. The process is 
repeated annualty, with but relatively slight deviations in the dates 
when the same stages of growth are attained in different j^ears. 
Evidently there is some very close relationship between climatic 
conditions at certain times in the season and the phases of growth 
which normally occur when these particular conditions exist. It is 
true that the stems may become elongated and that heads with 
florets in bloom can be found in smaller numbers in timothy meadows 
in the fall, several months after the usual time, but, as has already 
been stated, these late shoots do not usually grow in a normal 
manner. 
GROWTH THROUGH THE WINTER WITH NORMAL PERIOD OF LIGHT 
Plants of many kinds bloom and produce seed only at certain 
times in the season when the length of day is right for these processes 
