I think it's just that the tops of stem plants tend to be much more attractive
than the bottoms. The bottom leaves are older (leaves don't live forever),
plus they're shaded by the upper leaves, and are often straggly-looking. The
tops, OTOH, are lush and green. So it just makes sense to save the tops and
discard the bottoms.


Leigh

http://www.fortunecity.com/lavender/halloween/881/