This is also called as 'khayantharai keerai' in tamil language.
The Tamilnadu Agricultural University portal in this link
http://agritech.tnau.ac.in/horticulture/horticulture_gallery/medicinal_crops/index.html
has picture like this
But in kanyakumari district the below plants are called as Kayantharai by the locals.
The above plants are not kodupai keerai though it looks like that. It is not brahmi also as its flowers does not look like that. It is not karisalankanni as it is identified as below in an image from the web.
Karisalankanni is also called as kayonni.
Kayonni is also botanically called Eclipta alba.
In Wikipedia the page
http://en.wikipedia.org/wiki/Eclipta_alba which says both Eclipta prostrata and Eclipta alba are same,
has pictures of this plant which is more different looking, such as this:
The Tamilnadu Agricultural University portal in this link
http://agritech.tnau.ac.in/horticulture/horticulture_gallery/medicinal_crops/index.html
has picture like this
But in kanyakumari district the below plants are called as Kayantharai by the locals.
The above plants are not kodupai keerai though it looks like that. It is not brahmi also as its flowers does not look like that. It is not karisalankanni as it is identified as below in an image from the web.
Karisalankanni is also called as kayonni.
Kayonni is also botanically called Eclipta alba.
In Wikipedia the page
http://en.wikipedia.org/wiki/Eclipta_alba which says both Eclipta prostrata and Eclipta alba are same,
has pictures of this plant which is more different looking, such as this: