St. Patrick's Day Challenge!
Mathematica - 106 bytes

c=RegionPlot[x^2+y^2&lt;Abs@Sin[#x~ArcTan~y/2]||x&gt;0&amp;&amp;y^2&lt;.001,{x,-1,1},{y,-1,1},Frame-&gt;0&gt;1,PlotStyle-&gt;Green]&amp;


Ungolfed version:

c[leaves_] := (
    angle = ArcTan[x,y];
    RegionPlot[
        x^2 + y^2 &lt; Abs[Sin[leaves*angle/2]]
        || x &gt; 0 &amp;&amp; y^2 &lt; .001
      , {x,-1,1}
      , {y,-1,1}
      , Frame -&gt; False, PlotStyle -&gt; Green
    ]);


Here are the outputs for c[3] through c[6].



At the cost of another 7 bytes you can improve the colour (using PlotStyle-&gt;Darker@Green or PlotStyle-&gt;Hue[.3,1,.7] instead), and for another 15 bytes you can remove some of the sampling artifacts (using an additional option ,PlotPoints-&gt;90), giving a total of 128 bytes for these beauties:



The braces and commes in those pictures are not produced by c, but just by how I output them to fit them all in one row.

Lastly, here is an attempt at somewhat neater shading. I didn't even bother golfing this down further, the option names are just too long. I'm not even sure I'm too pleased with the result, but I thought I'd post it anyway. This is 188 bytes as it stands:

c=RegionPlot[x^2+y^2&lt;Abs@Sin[(l=#)x~(a=ArcTan)~y/2]||x&gt;0&amp;&amp;y^2&lt;.001,{x,-1,1},{y,-1,1},Frame-&gt;0&gt;1,PlotPoints-&gt;90,ColorFunction-&gt;(Hue[.3,1,.5+.2Sin[.5l#~a~#2]^8]&amp;),ColorFunctionScaling-&gt;0&gt;1]&amp;