Firstly, I'd like to point out that while this root is often called California ginseng it has no relation to anything correctly called ginseng
Spikenard is a mild stimulant and is eaten by Native Americans and Russians (where it also grows) for that reason. Except that stimulants are generally useful to the student of aphrodisia, this herb is not an aphrodisiac.
Spikenard is also classed with the aromatic plants and has been used in India for millenia to that end. Solomon, great importer of exotics that he was, knew of spikenard and listed it in a passage of The Song of Solomon along with other perfumed spices such as cypress, calamus
and saffron. Muslim men still sprinkle essence of spikenard (among other perfumes) on themselves to incite their women to desire.