26 THE AMERICAN BOTANIST, 



blade it is hastate as in the tear thumb {Polygonum). If 

 the margins of the leaves are without notehes of any kind 

 it is entire ; if notched like the teeth of a saw it is serrate ; 

 if the teeth are rounded it is crenate. There are a large 

 number of terms to indicate other slight variations from 

 the forms above named, but as they are all defined in an\^ 

 good dictionarj^ and in every botanical glossarj^ the be- 

 ginner need not bother his memory with them. It is time 

 enough to hunt them up when he needs them. A few 

 weeks in the work of identifying plants will make him 

 familiar with all the terms in common use. 



The texture of the leaf has a special terminology' 

 scarcely less extensive than that of the outline. If it is 

 perfectly smooth it \s g-Jabrous ; if it is covered with fine 

 soft hairs it is pubescent ; if the hairs are longer and stiffer 

 it is hirsute ; if the hairs are very thick and matted as in 

 the common mullein it is tomentose. Very thick leaves 

 are coriaceous or leathery ; thin ones are membranaceous 

 or membrane-like ; papyraceous leaves are about like 

 ordinary paper. Here again the novice need not borrow 

 trouble b3' learning the many other terms. 



A large number of plants have leaves composed ot 

 many smaller blades called leaflets. Examples may be 

 found in the wistaria, bean, pea, strawberrj^ potentilla, 

 etc. These are called compound leaves. When the leaflets 

 are arranged along the main stalk or rachis the leaf is said 

 to be pinnate as in the locust (Robinia) and the rose. 

 When arranged as in the clover they are ternate or trifoli- 

 ate. In the parsley and ginseng families the leaflets are 

 often again sub-divided. Ranging from the tri-pinnate 

 leaves of Hercule's club {Aralia spinosa) to the entire 

 leaves of the heaths there are all sorts of gradations. If 

 the leaves are very deeph^ divided but not quite pinnate, 

 they are pinnatiHd or if less deeply divided they ma^^ be 

 only lobcd as in the maples. In addition to the pinnately 

 compound leaves, there are others in which the leaflets are 

 all arranged at the top of the common stem, instead of 

 along the side. Such leaves are palmately compound. 



