my @lines = (
  'notmarker <blah> <foo> <bar>',
  'marker <this> <that> <other>',
  'notmarker <blech> <phooey>',
  );

foreach (@lines) {
  chomp;
  if (my @matches = (/(?:^marker\s|\G)<(.*?)>(?: |$)/g)) {
    print join(', ', @matches)."\n";
    }
  }