九層塔

In Taiwan basil is known as 羅勒 or more commonly 九層塔; I prefer the latter name, which means nine level pagoda, from the shape of the leaves. Apparently what we here in the midwest call "basil" is Ocimum basilicum, or Sweet Basil. The leaves are extremely fragrant, more fragrant than what they sell in Taiwan. However, when cooked, the Taiwanese basil is tastier than the American variety. Since it's often used in Thai dishes (with seafood), I'm guessing it's Ocimum basilicum 'Thyrsiflora', or Thyrsiflora Basil, which this site identifies as the one "used in Thai cooking". This site mentions Thai Basil, 'Horapha Rau Que', (Ocimum thyrsiflora), and explains thyrsiflora means flowers arranged in a thyrse (a flower cluster with a central spike that has side branches also clustered with flowers).

Once in the Chinatown grocery in Paris we bought something that we hoped was going to be Thai basil, but was actually 魚腥草 (literally fish-stink grass; Houttuynia cordata). I thought it was mostly a Vietnamese thing, because the Paris Asian community is mostly Southeast Asian (and according to this site, it's known as Vap ca, Fish mint, fishscale mint.

The heart-shaped leaves of this herb have an unusual slightly sour, fishy flavor. Some folks love rau diep ca's tangy qualities and others focus on its unusual fishiness.

No kidding. In fact, it's also found in China, where it's called 摘耳根. This guy tells how when he tasted the fishy and rusty taste, he wanted to spit it out. It's also grown in Taiwan, although it's not widely available commercially. The pic below comes from this site, which calls it pig thigh; it's got a pinkish tinge we didn't see in Paris.