XX EXPLANATION OF TERMS, 



Ascending Stems are those slightly and obliquely inclined. 



Procumbent Stems are those which lie on the ground. 



Decumbent Stems are the same as procumbent, but which raise them- 

 selves at the ends. 



Creeping Stems run along the ground, and frequently root themselves 

 freely from the nodes. 



A Simple Stem is one that is not branched. 



Leaves, as they are produced, follow three principal forms of arrange- 

 ment. When but two grow at the nodes of the stem and have its semi- 

 circle between them, they are spoken of as being Opposite. (FiG. 7.) 



Alternate Leaves are those which occur singly at the nodes, one above 

 the other and on opposite sides of the stem. (FiG. 8.) 



Verticillate, or Whorled, describes leaves when three or several grow at 

 intervals in a circle about the stem. (FiG. 9.) 



Scattered Leaves are those occurring closely and all about the stem, such 

 as are seen on hemlock branches. 



The THREE PARTS OF A LEAF are its Blade, the broad, expanded net- 

 work of veins and veinlets which support the soft, green, cellular tissue ; the 



FIGS 



Petiole, or individual stalk on which the blade is raised ; and the Stipules, 

 these latter being a pair of small, blade-like bodies at the base of the petiole 

 and often absent or inconspicuous. 



All parts of a leaf are covered by a transparent skin, or epidermis, and 

 according as the surfaces are rough or smooth it is spoken of as being : 



Glabrous : meaning quite smooth, — that is, not provided with a coating or 

 down of hairs. 



Pubescent : when the surfaces are downy, or covered with fine hairs. 



Tomentose : when the hairs which cover the surfaces are matted and 

 woolly. 



Hirsute ; wl^en covered with coarse, rather firm, hairs. 



