S. americanum Miller, The Gardeners Dictionary, Ed. 8, art. Solanum no. 5, 1768
syn: Solanum nigrum L.; S. humile Lam.
For a long time S. americanum and S. nigrum were treated at distinct species, former characterised by smaller flowers (less than 5 mm across), smaller anthers (1-1.5 mm long) smaller (6-7 mm) shining black berries, and latter by larger flowers (6-9 mm across), longer anthers (2-3 mm) and larger (7-9 mm) dull black, purple or yellowish-green berries. Both species are distinct from S. villosum in inflorescence with usually more than 6 flowers, longer peduncles (1.5-3 cm in fruit).
According to the latest update of Kew Plant list the two species are conspecific and accepted name for the species is S. americanum Mill. and S. nigrum is to be treated as its synonym. I am, however, not able to find justification for this choice, as S. nigrum happens to be the earlier published name.
I am uploading the specimens of the species from Kashmir, photographed in June, 2010 (S. nigrum s. str.). The photographs of S. americanum s. str. were uploaded by Satish Phadke ji having distinctly shining black berries.
Dr. Gurcharan Singh
Retired Associate Professor
SGTB Khalsa College, University of Delhi, Delhi-110007
Res: 932 Anand Kunj, Vikas Puri, New Delhi-110018.
Phone: 011-25518297 Mob: 9810359089