596 



WEED FLORA OF IOWA 



Serrate, when the teeth point forward, as in the common sun- 

 flower (Helianthus annuus). 



Serrulate, when the margin is finely serrate as in milk purslane 

 (Euphorbia maculata). 



Crenate, when the teeth are broad and rounded as in the common 

 mallow (Malva rotundifolia) . 



Fig. 4511 Fig. 451 II Fig. 451 HI 



Fig. 451. Compound leaves. I. Leaf of Clover with three leaflets. II. 

 Pedately divided leaf of Dragon Root. III. Pinnate leaf of Locust with 

 19 leaflets. 



(After Thome.) 



Lobed, when the leaf is deeply cut, as in the great ragweed. The 

 projecting portions are then called lobes. "When the incisions are 

 sharp the term cleft is often used: the leaf is pinnaiifid when the 

 incision extends almost to the midrib, as in the prickly lettuce 

 (Lactuca scariola) ; it is pinnate when the incisions have extended 

 to the midrib and each separated portion takes the character of a 

 leaf. Each of the smaller portions is a leaflet, and the leaf is now 

 considered compound. The spotted cowbane (Cicuta maculata), 

 spring vetch [Yicia sativa) and cinquefoil (Potentilla monspelien- 

 sis) are good examples. 



