#!/usr/bin/perl -w
use strict;

my $data = {
	Colour  => 'blue',
	Entries => {
		Flowers => {
			Dahlia => {
				Smell => 'nice'
			},
			Rose   => {
				Colour => 'red'
			}
		}
	}
};

my $ref_flowers = $data->{Entries}->{Flowers};

my $colour = sub {
   my $flw=shift;
   $ref_flowers->{$flw}->{Colour} || $data->{Colour}
};

print "Rose's color is ",$colour->('Rose'),"\n";
print "Dahlia's color is  ", $colour->('Dahlia'),"\n";

__output__
Rose's color is Red.
Dahlia's color is Blue.