May a, 1921 
Rooting Stems in Timothy 
175 
why some shoots have their crowns rarther beneath the surface than 
others, even though the buds from which they were produced were 
covered to the same depth with soil. 
Root systems develop from the crown of all timothy shoots having 
underground stems, and each shoot is soon capable of continuing its 
growth independently of the mother plant. On a typical plant, selected 
in November, 1919, from a field in which timothy had been plowed under 
one year previously, the underground stem connecting the new plant with 
the parent plant was partly decayed and disintegrated, showing that the 
plant no longer had any vital connection with the stem from which it 
originated. 
Underground stems of the same type can be induced by placing soil to 
a sufficient depth about the base of a growing timothy plant. An under¬ 
ground stem which has developed in this way is shown in Plate 39, B. 
The plant illustrated originated from a seed sown in the spring of 1919. 
In the following summer soil was placed about the plant to the point 
indicated by x to the right of the figure. The shoot on the left grew from 
a bud at the base of a culm of the parent plant. The underground stem 
that attached the new shoot to the mother plant was 1 inch long and was 
composed of a single elongated intemode. The crown of the shoot was 
% inch below the surface of the soil which surrounded it. 
The second type of underground stem is found where timothy plants 
with growing culms are covered with soil, as by plowing. Buds that 
sometimes form on the culms of these plants frequently develop into shoots 
and ultimately into independent plants, and the culms themselves become 
underground rooting stems. This type is illustrated in Plate 40, A. 
That the stem a had developed as a culm before it was plowed under is 
clearly shown by the lower elongated intemode, which is enlarged in 
diameter and which forms what is commonly, but erroneously, tenned a 
bulb. Further evidence that this stem had already developed as an 
ordinary culm before it was plowed under is found in the dried and partly 
disintegrated leaf at the second node above the enlarged basal intemode. 
This leaf could hardly have grown to a length of several inches beneath 
the surface of the soil. In the plant illustrated in Plate 40, A, it was 
impossible to determine whether the shoot 6, growing at the end of the 
stem, originated from the terminal bud of the culm or from a bud at one 
of the nodes farther back. It will be noted, however, that there is a 
secondary underground stem c arising from the second node above the 
enlarged basal intemode. This is of the type shown in Plate 39. It is 
rarely that secondary shoots develop at nodes between the elongated 
intemodes of timothy culms growing under ordinary conditions, but when 
the culms are covered with soil this frequently occurs. A rooting stem 
such as is shown in Plate 39 and in Plate 40, A, c, might have developed 
in connection with shoot b in Plate 40, A, had the culm a from which it 
arises been covered to a sufficient depth with soil. 
