CHAPTER II. THE STEM. II 



It often happens, also, that more than one bud is formed in 

 or near the axil of the leaf; extra buds of this kind are called 

 accessory or supernumerary buds. Sometimes they are placed 

 side by side as on the Apple-tree and as is most commonly the 

 case, but sometimes one above the other, as on the Butternut 

 and Walnut. 



Size of Stems. Stems differ widely in this respect. Some, 

 as those of certain mosses, are scarcely the one twenty-fifth of 

 an inch in length, and the diameter does not exceed that of a 

 fine thread, while those of the giant Sequoia of California, and a 

 species of Eucalyptus in Australia attain the remarkable height 

 of more than four hundred and twenty feet. 



Fig. 12. 



Fig. 12a. 



Fig. 12. —Terete or cylindrical stem of Kasswood. 



Fig. 12a. — Flattened stem of Opuntia Cactus. 



Fig. 13. — Triquetrous or triangular stem of a species of Scirpus or Rush. 



Fig. 13a. — Quadrangular stem of Mint. 



Fig. 14. — Jointed stem of Barley. 



Fig. 15. — Fluted stem of Parsnip. 



Shapes of Stems. In this respect they differ no less widely. 

 The ordinary or typical form is that of a cylinder, or rather a 

 very much elongated cone ; such a stem is described as cylin- 

 drical or terete (see Fig. 12); but sometimes it is flattened as in 

 the stems of some species of Cactus, Fig. 12a ; sometimes trian- 

 gular or triquetrous, as in some species of the Rush, Fig. 13 ; 

 sometimes square or quadrangular, as in many Mints and Scro- 

 phularias, Fig. 13a ; sometimes jointed, as in the stems of the 

 Grasses, Fig. 14; and sometimes fluted, as in the stem of Valerian 

 and that of the Parsnip, Fig. 15. In a Palm which is native 

 to the Amazon valley, the Iriartea ventricosa, and in the 



