Plants solitary or forming small to large colonies of rosettes, acaulescent or rarely caulescent, to 3 m diam.; rosettes usually small. Stems procumbent, 0.1-0.4 m, or erect, 1-2 m. Leaf blade rigidly spreading, including distal leaves, linear, lanceolate, concavo-convex, or plano-keeled, widest near middle, 20-80(-150) × 0.4-2 cm, rigid or flexible, not glaucous, margins entire, becoming filiferous, white, becoming brownish, gray, or green, apex long-acuminate, spinose, spine acicular, short, 3-7 mm. Inflorescences racemose, occasionally paniculate proximally, arising well beyond rosettes, (4-)8-20 dm, glabrous or finely pubescent; branches, when present, 0.5-1 dm; bracts erect, linear, proximal 10-20 × 1-2 cm, distal 3-8 × 1-2 cm; peduncle scapelike, 0.3-2.5 m, 1-2 cm diam. Flowers pendent, 3-5.5(-6.5) cm; perianth campanulate to globose; tepals distinct, white to cream or greenish white, often tinged pink or brown, broad to narrowly elliptic to lanceolate-elliptic or orbiculate, 3-6.5 × 1.3-2.5 cm; filaments 0.7-2.8 cm; anthers 3.2-6 mm; pistil 1.5-3.5 cm; style white to pale green, 3-10(-13) mm; stigmas lobed. Fruits erect, capsular, dehiscent, moderately to deeply constricted, 3.5-7.5 × 2-3 cm, dehiscence septicidal. Seeds dull black, thin, 7-9 × 5-7 mm.

Our treatment of Yucca angustissima reflects the concepts of J. L. Reveal (1977c). Each variety is well isolated geographically, but they overlap with one another morphologically. S. L. Welsh et al. (1993) treated the taxa in this complex at species level, with the exception of Y. angustissima var. aria, considered a high-altitude extreme of the typical variety. K. H. Clary (1997) presented DNA evidence that supports Welsh et al.´s treatment of this complex, in that Y. angustissima, Y. kanabensis, and Y. toftiae sort out distinctly from one another in her consensus tree. However, Welsh et al. indicated significant intergradation among these taxa, which makes their recognition at varietal rank seem most appropriate.

Springer et al. 2011

Common Name: palmilla Duration: Perennial Nativity: Native Lifeform: Shrub Wetland Status: None General: Plants acaulescent or rarely caulescent; solitary or in colonies up to 3 m in diameter. Leaves: Basal, forming a rosette, linear to lanceolate, plano- keeled or concavo-convex, 20-150 cm long, 0.4-2 cm wide, widest near the middle, rigid or flexible, pale yellow to bluish green, margins entire, white, forming threadlike fibers and becoming brownish, gray, or green with age, apex long-tapered, spine-tipped, the spine 3-7 mm long. Flowers: Inflorescence a panicle, 40-120 cm long; flowering stalk 30-150 cm tall; flowers small, whitish to yellow-white; tepals 6, oblanceolate to obovate, 1-3 mm long, distinct; stamens 6. Fruits: Septicidal capsule, oblong-cylindric, 3.5-7.5 cm long, usually with a deep constriction, opening at maturity; seeds 7-9 mm long, dull black. Ecology: Desert flats, mesas, often in sandy habitats or sandstone outcrops from 3,000-7,500 ft (914-2286 m), flowers May-June. Notes: This species is our most common narrow leaved yucca. Yucca elata has similar narrow leaves, but can be identified by its distinctive trunk, as opposed to ground-hugging habit. The very similar species Y. baileyi (Navajo yucca) is mostly found at lower elevations, but has been collected at the lower edges of our range near Sunset Crater in Coconino County, and in the Lukachukai Mountains in Apache County. Yucca baileyi has short inflorescences that arise within or just beyond the rosettes, and capsules with thick, tough walls with few or no constrictions; Y. angustissima has taller inflorescences that extend well beyond the rosettes, and capsules with thin, fragile walls and definite constrictions. Narrowleaf yucca is pollinated by the yucca moth, whose larvae feed on the seeds. It is also a host plant for Strecker-s giant skipper butterfly. The plant is used by the Apache to treat snake and insect bites. The crushed root is also used for soap and shampoo, and the leaves are used to make string, baskets, and brushes. Etymology: Yucca comes from Haitian for uuca, or manihot, because young inflorescences are sometimes roasted for food, while angustissima means narrow leaved Editor: Springer et al. 2011