118 STOLON.—SUCKER.—RHIZOME. 
less thickened branch, which produces at its apex small roots 
and atuft of leaves, and thus forms an independent plant, which 
is capable of producing other offsets in alike manner. It is well 
seen in the Houseleek. This differs very little from the ordinary 
runner, except in being shorter, somewhat thicker, and its leaves 
distinctly tufted. 
c. The Stolon.—This is a branch given off above the surface 
of the earth, but which curves or proceeds downwards towards 
it, and when it reaches a moist spot it sends rootlets into the 
ground, and a stem upwards into the air, and being thus 
capable of acquiring food independently of its parent, it ulti- 
mately forms a new individual. The Currant, Gooseberry, and 
other plants, multiply in this way. All such plants are said to 
be stoloniferous. Gardeners imitate this natural formation of 
new individuals when they lay down a branch into the earth, 
from which a new plant is ultimately formed; this process is 
technically called layering (fig. 230). 
Mire Heit Hig. 2328 
Figs. 231 and 232. Suckers of species of Mentha. 
d. The Sucker (figs. 231 and 232).—This is a branch which 
arises from the stem below the surface of the earth, and which, 
after proceeding in a horizontal direction for a certain distance, 
and giving off little roots or rootlets in its course, turns upwards 
into the air, and ultimately forms an independent plant. Plants 
thus producing suckers are said to be swrculose. Good examples 
of this kind of stem are seen in the Rose, the Raspberry, and 
the Mint. The sucker can scarcely be said to differ in any 
essential particulars from the stolon, except that it is originally 
subterranean, and ultimately aerial; whereas the stolon is first 
aerial, and then subterranean. 
e. The Rhizome or Rootstock (figs. 233 and 234).— This is a 
prostrate thickened stem or branch running along the surface of 
the ground, or more generally partly beneath it, and giving off 
small roots or rootlets from its lower side, and leaves and buds 
