Yucca filamentosa – L. is an excellent survival plants with numerous uses!

ROOT- Eat once boiled (*slightly controversial) Use raw with water for soap. Can be used as a fish toxin in smaller pool of water to extract in a survival situation (cook the fish).
Flowers – Edible raw; High in Vitamin A & C
Leaves – Used for cordage and weaving
Stalk – Used as friction fire device
Yucca wood — actually the dry flower stalk — has the one of the lowest flashing temperature of any wood, desirable for fire starting, in particular while using with primitive methods such as the bow and drill. Use the yucca stalk for the drill. The roots and leaves can be rubbed in water to get a natural soap . With some of the yuccas you can crush the root, and shampoo with the juice. Also the leaves can be made into extremely strong cordage. Many yucca come with a needle built in at the end of the leaf, and others like the filamentosa pictured and discussed here, shed threads
• The reason for the controversy is the roots contain saponins. While saponins are quite toxic to people, they are poorly absorbed by the body and so tend to pass straight through. They are also destroyed by prolonged heat, such as slow baking in an oven. Saponins are found in many common foods such as beans. Saponins are much more toxic to some creatures, such as fish, and hunting tribes have traditionally put large quantities of them in streams, lakes etc in order to stupefy or kill the fish.