Stipa spartea

Stipa spartea
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
(unranked):	Commelinids
Order:	Poales
Family:	Poaceae
Genus:	Stipa
Species:	S. spartea
Binomial name
Stipa spartea Trin.

Stipa spartea is a grass species in the genus Stipa and is often called porcupine grass.

The seeds are needle-like with sharp tips and long tails. The tails are composed of two different strands that dry at different rates and twist around each other, causing the sharp head of the seed to be driven into the soil. Just behind the sharp, needle-like tip, is a collar of long thick hairs that face backward, preventing the seeds from working their way back out of the soil. This species of grass can have its seeds entangled in sheep's hair while they are feeding, and once entangled it often works its way into the animal's skin.

Note the two differently colored strands wrapping around the tails: they twist at different rates depending on the humidity of the air.