Final answer:
In binomial nomenclature, 'Rhizomes' is the genus name, whereas 'nigricans' is the species epithet. Rhizomes are horizontal underground stems for asexual reproduction.
Step-by-step explanation:
In the name Rhizomes nigricans, Rhizomes is the genus, and nigricans is the species epithet. The genus is the part of the binomial nomenclature (two-part naming system) that refers to a group of closely related species. The species epithet, on the other hand, serves to differentiate individual species within the genus.
Rhizomes are horizontal, underground stems that are specialized for vegetative asexual reproduction. They are important biological structures that enable certain plants to spread and survive in various conditions.