4 NODES AND INTERNODES [CH. 



and the leaves therefore crowded into a rosette, as in the 

 Dandelion, Plantain, Strawberry, many Grasses and Ferns, 

 &c, where the main stem is so short that the tuft of 

 leaves seems to spring from the root in the ground 

 whence such leaves are termed radical ; or in the Palms, 

 Screw Pines, Agave, Yucca, Larches, Cedars, Daphne Lau- 

 reola, and many others where the rosette or tuft of leaves 

 is elevated on a stem or borne on branches. 



In a still larger number of common plants, however, 

 the leaf-insertions are separated by more or less evidently 

 elongated portions of the stem, termed internodes, in contra- 

 distinction to the nodes or parts of the stem bearing the 

 leaf-insertions. Examples showing evident internodes 

 are afforded by most of our ordinary trees, such as the 

 Elm, Beech, Ash, and shrubs such as the Lilac, Rose, &c. 



The difference between the two classes of cases ob- 

 viously depends on the relative growth in length of these 

 internodes ; for every gradation can be found between the 

 scattered and distant leaves of the Passion-flower, Aristo- 

 lochia, Vine, &c, which, like most climbers, have long inter- 

 nodes, and the rosulate or closely crowded leaves of the 

 Spurge Laurel, Primrose, Cypress, Larch, Cedar, &c, 

 where the internodes remain so short as to be practically 

 obsolete. 



In addition to their distance apart, moreover, the ar- 

 rangement of leaves on the shoot {Phyllotaxy) is governed 

 by the relations of the leaf-insertions to the stem in 

 another way. 



The leaves of the Ivy, Elm, Beech, Bramble, Fig, and 

 Vine, for instance, are inserted singly, and in such a way 

 that if a line is drawn from the insertion of any particular 

 leaf so as to join the insertions of all those leaves situated 

 higher up or lower down on the same shoot, the course 

 traced will be of the nature of a spiral ; this spiral insertion 



