DURATION OF LEAVES 



35 



Glabrous, when perfectly smooth and free from hairs or pro- 

 tuberances. Ex. : Tulip. 



Glaucous, when covered with bloom, as the Cabbage leaf. 



Pellucid-puncate, when dotted with oil glands, as the leaves of 

 the Orange family. 



Scabrous leaves have a rough surface with minute, hard points. 



Pubescent, covered with short, soft hairs. Ex. : Strawberry. 



ViLLOSE, covered with long and shaggy hairs. Ex. Forget-me-not. 



Sericious, silky. Ex.: Silverleaf. 



rage tissue 



Pallaade 

 parenchyma 



rage tissue 



■)i ^3C?oc:3g^g:JOCD 



Fig. 26. Fig. 27. 



Fig. 26. — Cross-section through a portion of rubber leaf, showing the large per- 

 centage of water-storage tissues on both sides of the leaf, and the relation of the 

 palisade and spongy parenchyma to the lateral veins. {From Steiens.) 



Fig. 27. — Surface view of the epidermis of a leaf showing several stomata. The 

 guard cells are dotted. {From Hamaker.) 



Hispid, when covered with short, stiff hairs. Ex. : Borage. 



ToMENTOSE, densely pubescent and felt-like, as the Mullein leaf. 



Spinose, beset with spines, as in the Thistle. 



Rugose, when wrinkled. Ex. : Sage. 



Verrucose, covered with protuberances or warts. 



Duration of Leaves. — Leaves vary as to their period of duration. 

 They are: Persistent, or evergreen, if they remain green on the tree 

 for a year or more. 



Deciduous, if unfolding in spring and falling in autumn. 



Caducous, or fugacious, if falling early in the season. 



