use Data::Dumper;
my $sub1 = { 'a' => {'apple' => 1 ,'ape' => 2},
             'b' => {'ball' => 1, 'bell' => 2}
           };

my $sub2 = { 'd' => {'dog' => 1},
             'c' => {'cat' => 1, 'clear'=> 2}
           };
my %hash = (%$sub1 ,%$sub2);
print "\n". Dumper( \%hash);