Jim,
I looked up the monograph on Alliums of Dilys Davis. He states that A
neopolitanum is the valid name and that A. cowanii is an invalid synonym.
The form known here known as A cowanii should probably be considered as
a form or selection of A. neopolitaum. It is widely used here in the cut
flower industry, because it has long rigid upright stem with a good size
umbel of larger flowers, while A neopalitanum has often bend or even
rampant flower stems.
Greeting
Lauw de Jager
http://www.bulbargence.com/
South of France (zone 8 Olivier)
> I've read that much, maybe all, of the material commonly sold as Allium
> neapolitanum is in fact A. subhirsutum or other species.
> Here in zone 7, I've had trouble keeping stock received under the names A.
> cowanii and A. neapolitanum.