FOLIAGE-LEAF 



71 



crenate is used when the edge has small semi-circular prominences. 

 If the indentations are deeper the leaf is then described as lobed 

 {-Jid), parted {-partite), or dissected {-sect) respectively, according 

 as the divisions reach about one half, three quarters, or nearly 

 the whole way down towards the midrib. 



As the indentations follow the direction of the main strands 

 or veins of the leaf we have two types of lobed, parted or dis- 

 sected leaves namely: — {i) pinnatifid {i, Fig. 32) pinnatipartite, 

 pinnatisect and (2) palmatifid (3, Fig. 32), palmatipartite, and 

 palmatisect. 



So long as the divisions of the blade do not quite reach to 

 the main ribs the leaf is said to be simple; in many cases, 

 however, the partitions are such that the leaf appears to have 

 several distinct blades ; it is then compound, and the separate 

 parts are its leaflets (t. Fig. 32). 

 Compound leaves are €\\k\tx pinnate 

 as in pea, vetch, potato, rose and 

 ash ; or palmate as in clover, horse- 

 chestnut, and lupin. 



(d) Surface. — The surface of the 

 blade is smooth ox glabrous, or some- 

 times covered on one or both sides 

 with hairs. 



(«) Apex. — ^The tip of the leaf 

 when it is pointed is acute; when 

 drawn out to a longer point it is 

 acuminate : it may also be obtuse 

 (blunt), emarginate (notched), or 

 mucronate ; in the latter case the 

 midrib appears to project as a sharp 

 point — see leaves of lucerne (Fig. 

 133) and trefoil. 



Ex. 36. — Examine and describe tlie leaves of the cliief farm plants and as 

 many of the common weeds as possible. Observe first if they are simple or 



Fig. 32. — T. Simple pinnatifid leaf , 

 J lobe. 2. Compound pinnate leaf; 

 i leaflet. 3. Simple palmatilid leaf; 

 f lobe. 4. Compound palmate leaf; 

 if leaflet. 



