Sorry Surajit ji and Ushadi
I said yes to the plant being T. grandiflora without reading your first line about KEW The Plant List listing.
Having gone through the Plant List, with so many missing names, unresolved names, and many wrong synonymy records, I have become increasingly unsure about The Plant List. I prefer to follow GRIN for records which are dealt there and periodically updated by its scientists. GRIN as well as several recent treatments recognise T. grandiflora. as distinct species.
Yes Ushadi is right, T. alata is a sufficiently distinct from T. grandiflora, and to call T. grandiflora its synonym at least I find hard to digest.
If there is any species closest and can be combined with is T. laurifolia. The two are very close.
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