GLOSSARY OF BOTANICAL TERMS 157 



(B) ; by twisting leaf -stems, (c) ; or by aerial 

 rootlets, (D). (8) 



Twining, when they twist themselves round 

 a support, sometimes the stem of a stronger 

 plant. (9) 



LEAVES. 



Leaves digest the nourishment carried to 

 them by the stems, absorb carbonic acid gas, 

 breathe out oxygen, and give back the assimi- 

 lated sap to the stems. 



The Blade is the main part of a leaf. 



The Base is the end by which it is attached 

 to the stem. 



The Apex is the opposite end. 



The Margin is the edge. 



The Mid-rib is the principal vein which runs 

 from stem to apex. 



The Petiole is the leaf -stalk by which a leaf 

 is attached to the stem. (10) 



LEAF ATTACHMENT 

 Leaves are said to be 

 Sessile, when the blade sits directly on the 

 stem and has no leaf -stem (petiole) of its own. 



(ID 



