Persicaria Id from BD _SM 609 : 14 posts by 4 authors. Attachments (2)
Habitat : Wild Bush
Location : Saint Martin’s Island, Bangladesh
Flowering: Jan
Photo taken : Jan, 2018

Never seen such leaves for Persicaria !

Yes. Something else. 

Pl. check Meriandra species. 

Pl. check although no distribution is given in Bangladesh, but found in West Bengal. So it is quite probable to be present in Bangladesh.

Also see

Tree or shrub ?

From images appears to be a shrub

Wild guess is Buddleja sp.

If so, I request …, to pl. check species in efi site at Buddleja

To me looks different from comparative images at Buddleja
Why not Salvia dianthera ?

It could be …!