9. Yucca rostrata Engelmann ex Trelease, Rep. (Annual) Missouri Bot. Gard. 13: 68, plates 40–42, plate 84, fig. 3, plate 93, fig. 2. 1902.
Yucca rostrata var. linearis Trelease
Plants solitary or forming colonies of rosettes, caulescent, arborescent, 2.5–3.6 m, not including inflorescence, 1.8–3.2 dm diam; rosettes each with more than 100 leaves. Stems 1–several, erect, mostly simple, occasionally 1–3-branched. Leaf blade linear, often twisted, flat to concavo-convex, widest considerably beyond middle, 25–60 × 1.2–1.7 cm, glaucous, smooth, margins minutely denticulate, lemon yellow, hyaline, apex spinose, spine tipped. Inflorescences paniculate, arising just within or beyond rosettes, ovoid, 3–10 dm; branches up to 3.8 dm; bracts erect; peduncle sometimes scapelike, 0.3–1 m, less than 2.5 cm diam., glabrous or glabrescent. Flowers pendent; perianth globose to campanulate; tepals distinct, white, narrowly ovate, 4.2–5.2 × 1.1–2 cm, apex sharply acuminate; filaments 1.7–2 cm; pistil 2.5–3.5 cm; style white, 6–14 mm; stigmas lobed. Fruits erect, capsular, dehiscent, ovoid to ellipsoid, rarely constricted, 4–7 × 1.8–2.5 cm, dehiscence septicidal.
Flowering spring. Rocky mountain slopes, canyon bottoms; 700 m; Tex.; n Mexico (Coahuila).
In the United States, Yucca rostrata is restricted to Brewster County, Texas. It is closely related to Y. thompsoniana (K. H. Clary 1997), which is perhaps just a northern variant of this species.