While going critically through the plant uploaded by Surajit ji, and seeing some older mails I came across this thread with plant uploaded by Raghu ji
It seems this plant is same as one uploaded by Surajit ji and identified as Hibiscus radiatus,
In thread of of Gutter Beaty uploaded although suggested of H. acetosella by Prabhu ji (which we ignored as we could not see the forked tip of epicalyx) most members concluded H. cannabinus.
There are atleast four species in which epicalyx has an appendage on the inner side
In both H. surratensis and H. hispidissimus, besides usually yellow flower with dark center the appendage is almost as long as epicalyx tip so that epicalyx tip appears forked
H. surratensis: tip looks forked and outer branch is ovate, stem strongly prickly with curved prickles, large auriculate stipules and calyx turning red in fruit.
H. hispiidissimus: tip looks forked, outer branch oblong-ovate, stem prickles straight with prominent basal tubercle, stipules lanceolate.
In other two species H. acetosella and H. radiatus the appendage is very small and looks like a small tooth below the tip on the inner side
H. acetosella: Stem and leaves are usually red in colour and tip of epicalyx slightly expanded
H. radiatus: leaves are green, segments narrow and epicalyx tip much narrower, linear. The length of appendage may vary from small tooth to almost as long as the slightly broader tip as can be seen in following photograph
I have cropped and enlarged the photographs from Raghu ji and Surajit ji to show that they are the same and belong to H. radiatus.
I have the feeling that most red flowered photographs of H. cannabinus may actually belong to H. radiatus, as majority of these photographs on even reputed websites of C. cannabinus have toothed appendage.
The members have access to H. cannabinus can help in resolving this confusion
1. locate yellow flowered form of H. cannabinus (as H. radiatus never has yellow flowers), confirm presence of oblong nectary on the under of the leaf near base along the midrib, and similar on calyx lobes, and make sure the toothed appendage of epicalyx (small tooth or long) below the tip inside is missing; also leaves and calyx lobes would have glandular hairs.
2. locate red flowered form of H. cannabinus and look for above features. If glandular hairs are missing, oblong nectary missong from leaf and calyx lobes, epicalyx appendage is present, it should be H. radiatus.
Please do point out if I am wrong somewhere.
Please be warned that there is lot of confusion on the net, with such reputed websites as Wikimedia commons having photograph of H. trionum labelled as H. cannabinus, and many other sites labelling red flowered H. radiatus as H. cannabinus
This exercise will perhaps help us resolve the issue.
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