LEAVES 159 



the palmately lobed leaf of sassafras; it is cleft when its divi- 

 sions extend about half way to the midrib, as in the pinnately 

 cleft leaf of wood betony, or about half way to the petiole, 

 as in the palmately cleft leaf of motherwort; it is parted when 

 its divisions extend more than half way to the midrib, as in 

 the pinnately parted leaf of wild lettuce, or more than half way 

 to the petiole, as in the palmately parted leaf of wild geranium; 

 it is divided when the divisions extend to the midrib, as in 

 the pinnately divided leaf of celandine, or to the petiole, as in 

 the palmately divided leaf of birdfoot Violet. 



Forms of the Apex. The apex is attenuate when it tapers 

 gradually to a point, as in wild sunflower; it is acute when 

 the apex tapers to form an acute angle, as in beech and dog- 

 wood; it is mucronate when the apex ends in an abrupt 

 flexible or non-fibrous tip, as in apocynum ; the apex is cuspi- 

 date when it ends in a sharp fibrous point which readily 

 penetrates the skin, as in low juniper and Canada thistle; it 

 is truncate when the apex appears as if cut at right angles 

 to the petiole, as in tulip tree; it is obtuse when the apex is 

 rounded, as in wintergreen; it is retuse when the rounded apex 

 has a shallow notch, as in the leaflet of black locust; it is 

 emarginate when the apex is decidedly indented, as in small 

 leaved pilocarpus. 



Outline of Simple Leaves. The outline is acerose when it 

 is very narrow and long and of an angled outline, as in white 

 pine; it is subulate when the leaf is narrow and short and 

 ends in a sharp point, as in low juniper; it is linear when it is 

 long and narrow and of nearly uniform width, as in ever- 

 lasting; it is oblong when the leaf is broad and long and of 

 nearly uniform width, as in milkweed; it is lanceolate when 

 it is several times longer than broad and tapers gradually 

 to a point, as in smartweed; it is falcate when several times 

 longer than broad, tapering to a point, and curved to one side, 



