CHAPTER II. THE STEM. 



13. As has been noted above, Nodes, 

 the stem of a plant bears the structures which we call 



T i J.T_ A j-x. 



leaves. If we examine an ordinary stem we rind tnat tne Le ave s and 

 leaves are situated at certain definite positions on it, which Buds, 

 are separated by a more or less considerable length of stem 

 which bears no leaves. The places where the leaves are 

 borne are called the nodes, the piece of stem lying between two 

 successive nodes is called an internode. The nodes are often 

 swollen and are sometimes marked by a distinct line or joint, 

 as in Gnetum. The youngest leaves are found to be nearest the 

 growing apex of the stem, i.e. they are developed in acropetal 

 succession. If only two leaves occur on one node they are on 

 opposite sides of the stem and are said to be opposite, if there 

 is only one leaf at each node, the leaves are said to be alternate, or 

 scattered. If more than two leaves occur at a node, they are 

 situated at equal distances apart and are then said to be in 

 whorls (or in verticils) or whorled (or verticillate). If at each 

 node there are two leaves which are nearly, but not quite, 

 opposite, they are said to be sub-opposite. When more than two 

 leaves occur at a node which are nearly, but not quite, at the 

 same level, they are said to be in false whorls (or verticils). In 

 practical . descriptive botany, however, the difference between 

 true and false whorls (or verticils) is often not insisted on, 

 both being merely called whorls (or verticils). When pairs of 

 opposite leaves are arranged on the stem in such a way that 

 the longitudinal axis of each pair is at right angles to the axis 

 of the pair above and below it, the leaves are said to be 

 decussate, and are then in four vertical ranks. When leaves 

 are arranged in two vertical ranks they are distichous, or bifa- 

 rious. When two or more leaves are inserted very close together 

 so that they appear to be in tufts, the leaves are said to be 

 fascicled, or in fascicles, as in the Deodar. The upper angle 

 between a leaf and the stem is called the axil. On the stem, 

 in addition to leaves, we find the structures which we call buds 

 and which are capable of growing out into new stems, or 

 branches. These buds are normally found in the axils of the 

 leaves when they are called axillary, or at the apex of the stem 

 when they are said to be terminal. The leaf, in the axil of 

 which a bud appears, is called the subtending leaf, while the bud, 

 having a leaf close below it, is said to be subtended by the leaf. 



