Bumping down since no one has an answer.

FataMorgana

it's not a north american plant so is likely not readily available

I don't think North American native status has much to do with what is easily available commercially for herbal use. Plenty Asian and European herbs, for example, are very easy to find in the US. I just think it has more to do with it being a commonly used herb or not. Some of the more obscure items are just that, more obscure.

Though if conditions allow and seeds or plants can be obtained of a herb, growing and harvesting yourself is always a possibility.

FataMorgana