Stipa spartea is a grass

Grass

Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...

 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 in the genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Stipa

Stipa

This article is about a type of grass.For Speech Transmission Index for Public Address Systems, see Speech transmission index.For the Italian aircraft designer, see Luigi Stipa...

and is often called porcupine grass.

The seed

Seed

A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

s 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 sheeps' hair while they are feeding, and once entangled it often works its way into the animal's skin.