THE STEM 101 
a tree. The broadleaf and astelia, as well as the earina 
and dendrobium, common New Zealand orchids, are 
also epiphytes. In the photograph reproduced on the 
preceding page a broadleaf is shown growing on a rata 
and throwing down a root towards the earth, while in 
that on the next page a rata is seen doing the same: 
thing, but on a larger seale. 
A stolon is a branch that roots at the tip. It is 
often seen in the gooseberry, and is the chief means by 
which grasses like fiorin are able to spread. By 
layering, artificially formed stolons are made to pro- 
duce new plants. The branch to be layered is pinned 
to the earth at one of its nodes and there produces 
roots which, when thoroughly established, permit the 
branch to be severed from its parent. 
A runner (Fig. 70) is a long slender branch that 
roots at the tip and there produces a tuft of leaves. The 
strawberry and violet are propagated by runners. 
An offset is a short, stout runner that roots close 
to the parent plant. The echeveria, a common border 
plant, is propagated by this means. 
A sucker is an aérial shoot that rises from an under- 
ground stem or even from a root. In the mint, suckers 
spring from a rhizome, but in the poplar more 
frequently from the root. 
Underground stems have been diverted from the 
work of spreading out the leaves which may be regarded 
as a true stem-function, and have more or less 
confined themselves to the storing of reserve material 
to meet the requirements of the plant or its offspring. 
They may be distinguished from roots by the presence 
of leaf-buds. 
A rhizome (Fig. 71) is a horizontal underground 
stem that gives off leaves above and roots below, 
though in some eases, as in the supplejack and 
Solomon’s Seal, it may produce aérial shoots as well. It 
is well seen in the bracken fern, the New Zealand 
