150 Vegetable Physiology. 



stems sometimes creep beneath the ground or along its surface, 

 producing buds which become new stems, or branches. Of this 

 kind is the rhizoma, instances of which may be seen in the so- 

 called roots of the Iris, the Solomon's Seal, and many kinds 

 of Ferns, and in the part of the Ginger plant which is eaten 

 as a sweetmeat. The runners of the Strawberry are also stems, 

 which send down roots, and shoot forth buds at intervals. 

 Several kinds of grass, possessing similar creeping stems, ren- 

 der themselves a dreadful nuisance to the cultivator, who finds 

 it utterly impossible to exterminate them, since each node, 

 having buds and roots, becomes a new plant. 



One of the most distorted forms of the stem is that observed 

 in the Potato. The tuber of this plant is evidently a form of 

 the stem, as is shown by its power of producing buds at the 

 points, called the eyes. When, therefore, the tuber is divided 

 into pieces, each one of which has an eye, from which, when 

 placed in the earth, a young plant will spring, the same 

 method of propagation is adopted as that used in regard to 

 the Sugar Cane, whose stem is divided into its internodes, 

 each of which is planted separately. The nature of the 

 potato is also well shown by an accidental case, (an engra- 

 ving representing which is given by Dr. Gray,) in which some 

 of the buds and branches above ground showed a strong ten- 

 dency to develope in the form of tubers. The tubers of the 

 artichoke are of the same nature. There are other subterra- 

 nean modifications of the stem, such as the Cormus, a solid 

 bulb, like that of the Colchicum, and the curious bulblets of some 

 species of Lily and Onion, which grow in the axils of the 

 leaves, or flowers, and spontaneously drop off to the ground, 

 where they take root and form separate plants. 



Buds and roots may spring not only from those parts of the 

 stem which grow beneath or on the ground. Many trees exist 

 whose branches naturally hang downwards, and reaching the 

 ground, give rise to a new set of root, and becomes secondary 

 stems. In this way are formed the celebrated Banyan trees 

 (Ficus indica) of the East Indies, one individual of which some- 

 times forms a small forest. One of these possessed three hun- 

 dred and fifty principal trunks, and more than three thousand 

 smaller ones, each of which was casting out new branches, and 



