Ligusticum is part of the Apiaceae (Carrot) family. According the the Jepson Manual of Higher Plants of California the genus has approximately 25 species, however the electronic version of the Flora of China says the genus has approximately 60 species with 35 endemic to China. Further research will need to be done to see if I can figure out a more accurate number.
This genus has quite a number of medicinal species. Of the 12 species in North America, the most notable is Ligusticum porterii and to a lesser extent Ligusticum grayi, which I wrote about in my first book. For a very good paper on L. porterii go here. These two plants are very close in medicinal properties and many herbalists consider them to be interchangeable, including myself. They grow in different regions and L. porterii has a larger root, but other than that there is little difference. Some of the other species such as L. californicum and L. apiifolium are of interest to me. They are quite different from this two species, being less aromatic and acrid and more sweet, leading me to wonder about the possibility of them being used as supplementing herbs. They are, however, less common and smaller.
In China there are three main species used, L. chuanxiong (chuan xiong 川芎) and L. sinense and L. jeholense (these are both used as gao ben 藁本, but the later is specifically known as liao gao ben 辽藁本. Photos of both can be found here.) However, there are several other species used in Chinese medicine. L. pteridophyllum (hei gao ben 黑藁本), which unlike the previous two “gao bens” grow in the mountains of Southwestern China but are generally used in the same way. It has the functions of dissipates cold and stopping pain, mostly used for headaches and muscle aches associated with the common cold. L. tenuissimum (xi ye gao ben 细叶藁本), which like the first two “gao bens” grows in the mountains of the Northeast and has the functions of expelling wind-dampness, dissipating cold and stopping pain.
I would like to invite you to view the newly established Sylvan Institute of Botanical Medicine at www.sylvanbotanical.com for upcoming classes and much more.