THE RUNNER.—THE OFFSET. bh 4 
forms occasionally pass from one into the other, thus being both 
subterranean and aerial at different points, or at different 
periods of their course. 
1. Aerial Modifications of the Stem and Branches.—Of these 
the more important are the runner, the offset, the stvlon, the 
sucker, and the rhizome. 
a. The Runner or Flagellum (fig. 228).—This is an elon- 
Fic, 228, ~ } 
Fic. 229, 
Fig.228, A portion of the common Strawberry plant. a’. An axis producing 
a tuft of leaves atits extremity, the upper of which, 7, are well developed 
and green, and the lower rudimentary. From the axil of one of the latter 
a second axis or runner, «”, arises, bearing a rudimentary leaf, 7’, near the 
middle, and a cluster of leayes, 7, at Its end, a”, A third axis produced 
in a similar manner to the former. 7,7. Roots or rootlets, Fig. 229. 
Offset of Sempervivum. Fig, 230. Plant showing the process of layering. 
gated, slender, prostrate branch, a’, sent off from the base of 
the stem, and giving off at its extremity leaves, 7, and roots, f, 
and thus producing a new plant, which extends itself in a similar 
manner. This is well seen in the common Strawberry. 
b. The Offset (fig. 229).—This is a short, prostrate, more or 
