32 INTRODUCTION TO BOTANY 
31. Reproduction by means of roots. Roots are often capable 
of producing buds which may develop into new individuals 
and thus propagate the plant. The sweet 
potato is a good instance of this, each root, 
if buried in moist sand, being capable of 
giving rise to several new plants (fig. 24). 
Roses are propagated by root cuttings, and 
some trees, such as the silver-leaved poplar 
(Populus) and the black locust (Robinia), 
are very troublesome because of the readi. 
ness with which young sprouts (sometimes 
called suckers) spring up from the roots. 
A considerable colony of these young 
sprouts may often be seen quite surround. 
ing the parent tree and extending many 
feet away from it. Many bad weeds, such 
as the field sorrel (Rume,) and the Canada 
thistle (Cirstum), are reproduced by roots. 
Fig. 24, Vegetative In case of desirable plants that can be 
pe leer = propagated either by pieces of root or by 
Hiilc ietaté aa eased seeds, it is generally better to use root 
in moist sand and began cuttings, as they will grow much faster. 
to sprout, thatis,tosend = A mong plants that you know, are there 
out shoots from adven- : te 
titious buds at various More instances of useful or of injurious 
points. Each shoot may }inds that are usually propagated by the 
grow into a new plant. 
About half natural size root? Give ex amples. 
PROBLEMS 
1. When actively growing stems are cut off, do they “ bleed ” on both 
the upper and the lower cut surfaces? Why? 
2. How could an experiment be made to show the exact amount of 
upward pull and of lateral pull which the anchorage of a plant will 
resist ? 
3. What practical advantage is taken of the powerful anchorage of 
shade trees ? 
4. Why must swamps be drained before most crops can be grown in 
them ? 
