Soaptree Yucca (Yucca elata) - ON YOUR RIGHT. The soaptree yucca is a widely distributed plant that can be found throughout the northern Chihuahuan and Sonoran deserts. Soaptree yucca is the tallest yucca in Big Bend: some individuals may tower 30 feet above the desert floor. Most yuccas grow very slowly, so large soaptrees may be 250 to 300 years old. Yuccas have been harvested by people for many years. The flowers are edible, and when properly prepared taste like brussel sprouts. Within the shaggy trunk and spreading roots is a slippery fluid that the early Americans extracted and used as soap and shampoo. The leaves also have medicinal uses: a dry powdered leaf blade mixed with goat kidney tallow is a traditional Mexican folk remedy for treating wounds.