yerba \yer"ba\, n. sp. bot.
   an herb; a plant.
   1913 webster

   note: this word is much used in compound names of plants in
         spanish; as, yerba buena sp., a good herb, a name
         applied in spain to several kinds of mint mentha
         sativa, mentha viridis, etc., but in california
         universally applied to a common, sweet-scented labiate
         plant micromeria douglasii.
         1913 webster

   yerba dol osa. sp., herb of the she-bear. a kind of
      buckthorn rhamnus californica.

   yerba mansa. sp., a mild herb, soft herb. a plant
      anemopsis californica with a pungent, aromatic
      rootstock, used medicinally by the mexicans and the
      indians.

   yerba reuma. cf. sp. reuma rheum, rheumatism. a low
      california undershrub frankenia grandifolia.
      1913 webster
see also:
mentha sativa mentha viridis micromeria douglasii yerba dol osa rhamnus californica yerba mansa 
anemopsis californica yerba reuma frankenia grandifolia