efloraindia: 160911 BRS 24:
Pl. find the attached file contain photos for id.

Date/Time-Location- 15.09.2011
Place, Altitude, GPS- Codisia Road, Coimbatore, Near Air Port.
Habitat- Urban
Plant Habit- Herb/climber
Flowers Size/ Colour Yellow

It is Tribulus species, either T. subramanyamii or T. terrestris. We need to see the style and/or fruit to confirm.

Agree with … this is Tribulus sp. of Zygophyllaceae family. Please try get a close up of flower and fruits, if available.

what do you make of the rectangular looking petals… is that normal or just curled up that way?

I think it is just curled up

I have seen the flower of this particular species gets curled/wilt in the afternoon by around 15hr (or even before) when I was doing my MSc in Madurai, Tamil Nadu. Tribulus terrestris was plenty in our campus and in fact this was the species for our practicals for Zygophyllaceae family. Our Taxonomy professor use to say that you must collect the plant with flower in the morning hours otherwise the flower would wilt.

Tribulus terrestris L.