POPULAR BOTANY. 457 
not reach the lower regions with the rapidity of the wild goat, but it 
will reach them just as well and surely with much less trouble and dan- 
ger. Some other plants resemble those just described, but throw out 
their runners under ground instead of over the surface ; for instance, 
our quackgrass, thistle, convolvulus, and others. These plants embrace 
some of the most troublesome weeds ; as the smallest piece of root will 
become a new plant, if not carefully taken up alter digging or ploughing. 
The power of reproduction in many plants is so strong that small 
twigs or even dropped leaves, if placed in the least favourable position 
will take root and form a new individual. 
Of many perennial plants the old root will decay every season, but 
not until it has produced a number of young roots, each of which will be- 
come a new plant at the next succeeding season. 
The so-called bulbous roots, for instance :— hyacinths, tulips, crocus, 
and others, yield a brood of small bulbs every year. Some others, as 
Lilium bulbiferum and Dentaria bulbifera, bear besides those of the root, 
small bulbs between the leaf axil ; and others again, as Allium viviparum 
the so-called grape onion, bear, entirely developed, small onions instead 
of flowers, and each of these little onions also often drive out another 
stem, each of which is crowded with still another crop of onions. 
For their full development plants in general need a full share of 
light ; without this they will pale, droop and die. The effect of this 
is nowhere more forcibly manifested than in very dense forests. As 
the light in such places can fall only from above, every tree endeavours 
to receive as much of light as can possibly be obtained, and for this end 
a strife as for life and death will ensue. Accordingly, the trees grow 
with an almost incredible rapidity to an enormous height ; such are 
generally quite straight, but often not thicker at the bootom of the trunk 
than at the top. And should any one of them fail to keep up the con- 
test he is lost ! His neighbour trees will overgrow and then spread 
their branches over such a weary one ; shut out from the necessary light 
the tree will suffer death, while the remains of his decomposition will 
serve as food for the more successful rivals. 
Plants are generally organised in a way to live in soil of very different 
composition ; the quality of the latter, however, bears still a great in- 
fluence upon their habits. So, for instance, may a plant in poor barren 
soil grow to the height of ten inches which would reach the size of 
twelve feet in rich or more convenient soil. For this reason it is often 
very difficult to recognize these two so unequal individuals really as 
sisters. 
Many other plants, however, are so dependent on a certain admix- 
ture of soil, that their appearance can serve as a true hint to geologists 
for the discovery of certain strata of earth. As, for instance, we can 
surely depend on finding a layer of zinc, where Viola calaritinaris, Statice 
Armeria and Spergula muscosa grow naturally on the surface. 
