[romwell]

Never heard "tisane" being used by anyone.

Most of the people in the US don't seem to care much about the distinction between infusions containing tea leaves and infusions that don't (when it's not just tea leaves); those who do, would often ask whether it's a caffeinated "tea" or not (infusions containing tea leaves usually contain caffeine).

Personally, I prefer to use the term "herbal infusion", because it unambiguous and relatively widespread.

However, in common usage people will say "herbal tea", both in English and Russian, even when aware that the tea plant is not in the mix. It seems like the crusade for "tea/chai" meaning something brewed from tea leaves is not only doomed, but has been lost before the West started to drink tea.

[ianleighton]

Tisane probably comes from French, where it is relatively common (at least understood, and a stickler for tea would correct your usage) and perhaps one would use it in English like other French culinary terms like “à la mode”

[klipt]

Wiktionary says it went

English <- French <- Latin <- Greek

https://en.wiktionary.org/wiki/tisane#Etymology

Interesting that in English it starts with the "tea" sound, but has a completely separate origin (I don't think the ancient Greeks were even aware of Chinese tea...)