Rotala verticillaris

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Rotala verticillaris is endemic to southern India and Sri Lanka. In India, this species is confined to Andhra Pradesh, Madhya Pradesh and Tamil Nadu (Cook 1996), Karnataka (Sharma et al. 1984) and Maharashtra (Singh et al. 2001).
It is annual or perhaps also sometimes perennial. It is found in pools and along the marshy margins of ponds. It flowers as the water recedes (Cook 1996).

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Is it Myriophyllum?: These were herbaceous plants growing near the shores of a lake at Bannerghatta. These plants were growing wild and they were attached to the soil. They are very minute with red stems and the flowers seem to be whorled around the stem. I did use Cook’s flora and probably thought maybe it might belong to Myriophyllum. Please do let me know your take on it.

It looks like Rotala to me

Any chance for Pogostemon erectus?

Looks like Pogostemon erectus; synonym: Rotala verticillaris

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References: IUCN Red List (LC)  The Plant List Ver.1.1 (Unresolved)  India Biodiversity Portal  IBIS Flora  An Excursion Flora of Central Tamilnadu, India By K. M. Matthew (1995- Details with keys)