22 
0. S. U. Naturalist. 
[Vol. 1, No. 2 
Many geophilous plants of the rhizome type were doubtless once 
crown formers and here again we find a transition stage which con- 
tains every gradation between the two groups. The Composite are 
mostly crown formers, but some are true rhizome plants and some 
are transitional. 
The advantages of a rhizome habit are very apparent. The first 
and most important advantage is the protection from frost which 
this habit affords. By taking up this habit many plants have been 
able to withstand a climate, which would otherwise prove fatal. 
The Alpine Willow is an example. Rhizomes are often storehouses 
for food and become swollen and distorted in consequence. Vege- 
tative propagation is usually combined with the geophilous habit 
and with great advantage to the plant. In most cases a rhizome 
dies off at the back as fast as it grows in front so that any part of it 
lives a definite number of years. The individual segments of the 
Solomon’s Seal, for instance, live from three to five years. In this 
way a branch soon becomes a separate plant. In some cases, how- 
ever, the rhizome may live for many years and thus hundreds of 
seemingly independent plants may be connected beneath the surface 
of the ground. The Brake Fern (Pteris aquilina L.) is of this class 
and an entire hillside may be covered with a much branched speci- 
men of this plant. 
A plant which has no means of migration when it has exhausted 
the nearby food supply is manifestly at a disadvantage when com- 
pared with a progressive rhizome plant which moves every year 
into a new and fresh location. To be sure, the distance it travels 
may not be far but it is enough to remove the plant from an ex- 
hausted position and from its wornout and useless tissue. Thus this 
group of plants may be said to have found the secret of potential 
immortality, for, unless some catastrophe overtakes them, they may 
live indefinitely and remain young. It is interesting in this con- 
nection, to note how far some of these plants travel in a century. 
This may be calculated in a general way by measuring the annual 
growth in length of the rhizome. Solomon’s Seal travels from 
twelve to twenty feet in this length of time, Uvularia perfoliata L- 
from eight to ten feet, Onoclea sensibilis L. from three hundred to 
five hundred feet, and others still farther. 
The Iris group) are exceptions, in that they travel in a circle- 
The reason seems to be that the lateral branches which contiuue 
the rhizome from year to year mostly arise on the same side 
of the terminal bud, so that each branch goes off at a slight angle to 
the former branch. The degree of angle determines the size of the 
resulting circle. One class of rhizome plants is very distinct and 
requires espiecial mention. This class may be termed upright or 
retrogressive rhizome plants. The upright rhizome may originate 
from a progressive rhizome, or from a crown former or in some other 
