php implode multi dimentioanal array key

$array = array(

array( Title => "rose",
 Price => 1.25,
 Number => 15
 ),
 array( Title => "daisy",
 Price => 0.75,
 Number => 25,
 ),
 array( Title => "orchid",
 Price => 1.15,
 Number => 7
 )

 );

$str=implode(',', array_map( function($subarr){return $subarr["Number"];},$array));