Yucca filamentosa is often cultivated and has become naturalized in some areas beyond its native range. Varieties that have been described are rarely recognized in recent literature. Yucca filamentosa and Y. flaccida are very closely related and perhaps are not distinct species.
Shrub to 1.5 m tall Stem: usually growing just below soil surface, to 30 or 40 cm long. Leaves: evergreen, 30 cm - 0.8 m long, 2 - 7 cm wide, linear-elliptic, narrowing abruptly a into spine-like tip, non-toothed but with curly thread-like filaments separating from margin. Inflorescence: borne above the leaves on a 1 - 3 m long stalk, loosely branched (panicle), 0.75 - 1.5 m long, erect, cone-shaped, many-flowered. Flowers: yellowish white, 5 - 7 cm across, 2 - 3 cm wide, drooping, with six fleshy tepals, six stamens, and a pistil 1.5 - 3.8 cm long. Fruit: capsule-like, 2 - 5 cm long, 2 cm wide, cylindrical to oblong, erect, thick, breaking open from inner partitions (septicidal), containing many dull black and thin seeds 6 mm across.
Similar species: Yucca filamentosa can easily be identified in the Chicago Region by its evergreen, linear-elliptic leaves with spine-like tips and thread-like filaments along the margins.
Flowering: late June to early July
Habitat and ecology: Introduced from the southern United States, this species occasionally escapes from cultivation and is most often found along railroads or roadsides in sandy soil.
Occurence in the Chicago region: non-native
Notes: Yucca moths have a mutual relationship with members of this genus. The fragrance of the flowers draws the female moth to the flower's nectar at night. After feeding on the nectar, she rolls the flower's pollen into a ball and transports it to another flower. She then lays her eggs in the ovary of this flower and drops the pollen ball onto the stigma, making certain seeds will develop to feed her young. However, the larvae will only consume 20 to 40 percent of the seeds, leaving plenty of seeds to mature and disperse.
Etymology: Yucca is the Carribean name for manihot or cassava. Filamentosa means "having filaments or threads," referring to the stringy leaf edges.
Caudex short, to 3 or 4 dm; lvs numerous, stiff, linear- elliptic to linear-spatulate, to 8 dm, 2-7 cm wide, fibrous along the margins, abruptly prolonged into a short stout spine, ±scabrous; infl paniculate, many-fld, rising to 1-3 m, its base elevated well above the lvs; tep 5-7 נ2-3 cm, rounded above, short-acuminate; style nearly 1 cm; stigmas slender; fr thick- cylindric, 2-4 cm; seeds 6 mm. Sand-dunes and dry sandy soil, especially near the coast; Md. to Fla. and La.; often escaped from cult. farther n. June-Sept. (Y. concava; Y. smalliana)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
This yucca has been reported as an escape several times and remarks have been made as to its persistence and its ability to spread. It is frequently planted in cemeteries from which it has most often escaped. I recall having seen it covering a hillside near a cemetery in Crawford County near the Blue River Church. I also saw it in a woods as an escape from a cemetery in Fulton County. It is so massive that I have never collected it. In the original Coblentz edition of "Travels in the Interior of North America" published in 1839-41, Prince Maximilian writes of his travels from Owensville, Gibson County to Vincennes, on June 10, 1834, as follows: "The region on the other side [north side of the White River, which he crossed in the vicinity of what is now known as Hazelton] changes considerably; and here appears in a now again sandy soil nearly the same plants as are found in the sandy soil and the prairies of St. Louis, with the addition of a few new ones, a fire-colored lily (Lilium catesbaei), the great-flowered lady slipper (Cypripedium spectabile), a species of Yucca, and many others." It is not known what species Maximilian saw. It may have been this one or Yucca glauca Nutt. both of which may have at that time extended up the Mississippi Valley into Indiana.
Indiana Coefficient of Conservatism: C = null, non-native