The Agaves, also commonly called Century Plants or Maguey, are found in Mexico, Central and South America and in the southern and western United States. They're often incorrectly thought of as a member of the cactus family. Agaves are related to the lily and amaryllis families, and are not related to cacti. They come in many shapes and sizes. They have a rosette of thick fleshy leaves with sharp spines. Agave, in particular the blue agave, is best known for the mezcal, or tequila made from it's sap.
One of my outdoor survival books describes pulling one of the sharp tips off a branch. Usually several long, stringy fibers will stay attached when the tip is removed. The fibers are fairly strong and what remains is nature's original needle and thread.