34 PHARMACEUTICAL BOTANY 



In the Divided leaf the incisions extend to the mid-rib, but the 

 segments are not stalked. Ex. : Watercress. 



If the venation is pinnate, the preceding forms may be described 

 as pinnately incised, lobed, parted, or divided. If the venation is 

 radiate, then the terms radiately or palmately lobed, incised, etc., 

 are employed. 



The transition from Simple to Compound Leaves is a very gradual 

 one, so that in many instances it is difScult to determine whether a 

 given form is to be regarded as simple or compound. The number 

 and arrangement of. the parts of a compound leaf correspond with the 

 mode of venation, and the same descriptive terms are applied to outline, 

 margin, etc., as in simple leaves. 



Leaves are either pinnately or radiately compounded. They are 

 said to be abruptly pinnate or paripinnate when the leaf is terminated 

 by a pair of leaflets; odd pinnate or imparipinnate when it terminates 

 with a single leaflet. When the leaflets are alternately large and small, 

 the leaf is interruptedly pinnate, as the Potato leaf. When the term- 

 inal leaflet is the largest, and the remaining ones diminish in size toward 

 the base the form is known as lyrate, illustrated in the leaf of the 

 Turnip. 



Radiately or palmately compound leaves have the leaflets attached 

 to the apex of the petiole. When these are two in number the leaf 

 is bifoliate, or binate; if three in number, trifoliate, or ternate; when 

 four in number, quadrifoliate, etc. If each of the leaflets of a palmately 

 compound leaf divides into three, the leaf is called bi-ternate; if this 

 form again divides, a tri-ternate leaf results. Beyond this point the 

 leaf is known as decompound. Example of decompound leaf seen in 

 Cimicifuga. 



Leaf Texture. — Leaves are described as: 



Membranous, when thin and pliable, as Coca. 



Succulent, when thick and fleshy, as Aloes, and Live Forever. 



ScARious, when dry and scaly. 



Coriaceous, when thick and leathery, as Eucalyptus, Uva Ursi and 

 Magnolia. 



Leaf Color. — Petaloid, when of some brilliant color different from 

 the usual green, as the Coleus and Begonia, and other plants which are 

 prized for the beauty of their foliage rather than their blossoms. 



Leaf Surface. — Any plant surface is: 



