Source : Webster's Revised Unabridged Dictionary (1913)

Sagittate \Sag"it*tate\, a. [NL. sagittatus, fr. L. sagitta an
   arrow.]
   Shaped like an arrowhead; triangular, with the two basal
   angles prolonged downward.

Source : WordNet®

sagittate
     adj : of a leaf shape; like an arrow head without flaring base
           lobes [syn: {sagittiform}, {arrow-shaped}]