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

my $test="<root><ta>this is <ta>the sample <ta>text</ta> explanation</ta> needded</ta></root>";
my @data;
while ($test =~ m/(<ta>(.*)<\/ta>)/gs) {
        unshift (@data,$1);
        ($test) = $2;
}

foreach (@data) {
        print $_."\n";
}