You can accomplish this by determining the contents of the directory (opendir, readdir, closedir) combined with the -d file test (-X). If you run into difficulties, post some code and we'll help you debug.

Lightly modified from readdir:

opendir(my $dh, $some_dir) or die "can't opendir $some_dir: $!";
my @subdir = grep { /^[^.]/ && -d "$some_dir/$_" } readdir($dh);
closedir $dh;
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Update:As JavaFan points out below, note the above code excludes any directory starting with a '.'. Seems reasonable to me since those are 'invisible' under most operations and your intent/spec is not explicit, but removing the regular expression from the grep test will remove the condition.