Yerba n. : An herb; a plant.

Example:
Question about Yerba mate: how often should I change the Yerba?

Taxonomy
yerba mate, mate, gourd, infusion, Ilex paraguariensis, in Argentina, plant, maté tea, beverage, flavor, Portuguese, coffee, Argentina, mate cocido, unranked, tea, erva mate, carcinogenic.

Defination from the web:
yerba mate in hot water, rather than in boiling water like black tea. ... However, the Yerba Mate Association of the Americas states that it is always improper to accent the second syllable, since doing so confuses the ...