98-105 Days to maturity. Nassella tenuissima (syn. Stipa tenuissima). Pony Tails Grass Stipa Seeds. Non-GMO, Annual or Perennial. Open Pollinated. Ornamental. Pony Tails Stipa seeds grow one of the most versatile ornamental plants available. Stipa can just as easily be grown indoors as it can be out in the garden. Pony Tails seeds deliver 36 inches tall feathered mounds of grass with a dense spread, ideal for large planters or garden boxes. Stipa (Nassella) is native to the hottest and arid regions throughout North and South America. 100 Seed Packet.