I'm not a star trek nerd but a tea nerd, and if I'm not mistaken Picard drinks earl grey: You generally boil black tea of course that depends on the tea but yeah 80c range is quite low for black. Depending on the green and the time of brew the tempature can be anywhere from room temp to 90c it just depends on many different factors, like freshness or how the tea plant is grown and how those leaves are treated. Generally with Japanese greens you use low temp water, with fresh Chinese green teas you can use near boiling water.