Kolkata, December 2021 :: Cactus for ID :: ARK2022-025: 1 very high res. image.
This was clicked at the Indian Botanic Garden (AJBC Garden) at Shibpur, Howrah, WB in December 2021.
Requested to please ID.
Just a guess- some Echinocereus like Echinocereus pencilis ? (as per comparative images at Cactaceae)
Could not not find a match as per Euphorbia.
I have never seen it blooming. Difficult to say.