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 Compositte are 

 mostly ci'own 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 fron^ frost which 

 this habit affords. By taking up this habit many plants have been 

 able to withstand a climate, which would otherwise i^rove 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 rliizome 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 continue 

 the rhizome from year to year mosWy 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 especial 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 



