ID Characteristics
This plant is in the Asparagaceae - the asparagus family.
Soaptree yucca is a large plant that typically grows to 10-15 feet. As a young plant the leaves form a dense radial head. Eventually a trunk begins to grow, 6-12 inches wide. A mature plant can have as many as 10 trunks, some branching near the top.
The leaves are thin and flexible with a sharp tip but otherwise unarmed. They are 2-3 feet long but less than 1/2 inch wide. The leaf edges are white, composed of compressed fibers that eventually shred and curl, especially at the base of the leaves. Older leaves brown and hang down, forming a natural, protective thatch.
Soaptree yucca does not flower every year but it does flower often. In late spring, late April into May, a tall flower stalk grows from the center a leaf cluster. Branches near the top of the stalk hold many pendant, creamy-white, bell shaped flowers (some flowers may be tinged with pink or pale green). Sometimes this cluster is so heavy that tall plants will be bent over by its weight.
About 2 inches long, these flowers have parts in 3s, a structure common to monocotyledonous plants. There are 3 sepals and 3 petals (so similar they are usually grouped together as 6 tepals) forming the bell. Inside the bell are 6 stamens and a single pistol with 3 lobes.
If the flower is pollinated by a yucca moth, a 3-part capsule forms. When the black, flat seeds are mature, the capsule splits open.