title: How to plot the world without the countries’ boundaries?
body: <p>I would like to plot the world map and I found this interesting Package. But this plots also the countries’ boundaries.</p>
  
  <pre><code>         require(maptools)
           data(wrld_simpl)
           plot(wrld_simpl)
  </code></pre>
  
  <p>Is there a way to get rid of the countries’ boundaries?</p>