Síriëna (Av. "Water-gift"?) was a short, fine, dark green grass, related to Pasámar, native to semiarid to temperate shortgrass prairies, which grew in tight clumps.When properly cleaned and brewed, síriëna broth preserved organic material (up to body size) for one week.
If ingested, this broth was a strong reduction poison which attacked the gastrointestinal system.