INSERTION. 



123 



some Erect ; some obliquely Ascending ; some Hori- 

 zontal ; and some Relining downwards ; but these 

 are distinctions which are rarely observed. 



2. INSERTION. 



A Petiolate leaf has a footstalk inserted into its base, 

 as in the Maple, Poplar and Vine, Figs. 31, 32 and 48. 



When the Petiole is inserted into the inferior sur- 

 face of a leaf, at a greater or less distance from its mar- 

 gin, it is said to be Peltate, as in Nasturtion and Water 

 shield, Fig. 27. 



A Sessile leaf arises immediately from a stem, branch 

 or root, without the intervention of a footstalk, as in 

 the clustered and two leaved Solomon's seal. 



Clasping leaves embrace the stem with their base. 

 as in the New England Aster, and Clasping Bell-flower, 



When two opposite leaves are united at their base, 

 as in Fever-root and Bone-set, they are said to be Con- 

 nate; and Perfoliate when a stem passes through a 

 solitary leaf, as in most of the Bell-worts. Fig. 26. 



Sometimes we find examples which appear interme 

 diate between the two preceding, but all necessary pre- 

 cision is obtained in these cases, by using the term 

 Connate-perfoliate. To the leaves of the Bone-set 

 and Chlora perfoliata :•, Fig. 16, such a term is strictly 

 applicable. 



When leaves form a sheath for each other or for the 

 stem, as in the Iris, and some of the Grasses, they are 

 said to be Sheathing. In the latter, however, the 

 sheath is usually an expanded petiole, and not according 

 to the common acceptation of the term, a portion of the 

 leaf itself. 



When the base of a leaf is extended down the side of 



