The story
Perhaps related to Ewe súsruba and/or sū́sùmɛ, sū́sumɛ (an aromatic soup-plant, sometimes identified as Solanum torvum or another Solanum) or Twi Akan nsúsŭaa (a kind of pot-herb; related to ǹsú (“water”)?) + mma, mbá (“offspring, young (plants, etc)”).
Etymology from Wiktionary, CC BY-SA 4.0.