Looking at my plants list, I noticed that Rose of Sharon is now listed as Hibiscus sinosyriacus instead of H. syriacus. The only H. syriacus I see in the database are cultivars. Can anyone explain what prompted the change? I see that CoL still list H. syriacus as and accepted name.

Rose of Sharon is the common name of both species (H. syriacus and H. sinosyriacus). Both species are included in the Roses of Sharon Database.

Roses of Sharon (Hibiscus syriacus)

I'm not sure why preference is given to H. sinosyriacus in the name of the main plant entry. Perhaps the choice is made by alphabetical order?

The alphabetical order is probably the case. When there are multiple accepted names the system just grabs whichever one comes out of the storage DB and that would usually be alphabetical.

Too bad it couldn't default to the shortest name instead.