The music from the plains comes from a combination of Spanish and native Colombian influences.  The rhythmical structure of the Joropo is a combination of ternary and composite rhythms, but since it's descendant of the Waltz is written in a measure of 3/4.  

The typical ensemble is made by three instruments: El Cuatro, which is a small guitar with four strings, hence the name Cuatro, and which is very similar to the Hawaiian ukulele; the maracas or Capachos, which are of native Colombian origin and the Harp.  The Cuatro is in charge of rhythmic and harmonic support, the Maracas, which are the only percussion instrument in this music, are in charge of rhythmic support and the harp is in charge of the melody and counter melody.  To this three instruments is usually added the electric bass.  In the following sample we can listen a type of music from the plains called Pasaje.