Plant of the Week
Soapweed Yucca (Yucca glauca)
By Charlie McDonald
Soapweed yucca is one of about 40 yucca species, all of which are native to the New World. It grows in dry rocky soils throughout the Great Plains and is most abundant in short grass prairies and desert grasslands. These plants have a long history of beneficial use. As the name implies, the crushed roots of soapweed yucca produce a lather that makes a good soap or shampoo. The lathering substances called saponins are found in many plants, but are exceptionally concentrated in yucca roots. The dried leaves of soapweed yucca can be woven into baskets, mats, or sandals. The strong coarse leaf fibers can be extracted to make cordage.
Roots labeled “yucca root” are often sold in grocery stores. These roots are actually cassava or manioc (Manihot esculanta). This woody shrub has a starchy tuberous root that is a staple food in the tropical regions where it grows. The roots of true yuccas are generally too fibrous and too full of toxic saponins to be used as food.
Yuccas and yucca moths are the classic example of a plant and animal obligate symbiotic relationship where each organism requires the other to survive. Yucca moths are the only insects that can successfully pollinate yucca flowers and the developing yucca fruits are the only larval food source for yucca moths.