postgreSQL Traversing tree using WITH RECURSIVE

create table empl (
 name text primary key,
 boss text null
 references name
 on update cascade
 on delete cascade
 default null
);
insert into empl values ('Paul',null);
insert into empl values ('Luke','Paul');
insert into empl values ('Kate','Paul');
insert into empl values ('Marge','Kate');
insert into empl values ('Edith','Kate');
insert into empl values ('Pam','Kate');
insert into empl values ('Carol','Luke');
insert into empl values ('John','Luke');
insert into empl values ('Jack','Carol');
insert into empl values ('Alex','Carol');
with recursive t(level,path,boss,name) as (
 select 0,name,boss,name from empl where boss is null
 union
 select
 level + 1,
 path || ' > ' || empl.name,
 empl.boss,
empl.name
 from
 empl join t
 on empl.boss = t.name
) select * from t order by path;