S. Watson, Botany (Fortieth Parallel), 497.
Plants acaulescent, suckering or not; rosettes solitary or sparingly cespitose, 1.5–6 × 1.5–10 dm. Leaves ascending, 12–50 × 1–5.5 cm; blade grayish green to yellowish green or green, without bud-prints, linear-lanceolate or lanceolate, stiff, adaxially plane or concave toward apex, abaxially convex toward base; margins straight or undulate, nonfiliferous, conspicuously armed, horny from distalmost teeth to apical spine, teeth single, 2–12(–15) mm, 1–4 cm apart, rarely absent; apical spine light gray to ivory white, acicular or subulate, 2–20 cm. Scape 1.7–5 m. Inflorescences spicate, racemose or narrowly paniculate, open to densely flowered; bracts caducous, narrowly triangular, 4–8 cm; lateral branches 50+, horizontal to slightly ascending, comprising distal 1/2–2/3 of inflorescence, shorter than 10 cm. Flowers 2–12 per cluster, erect, urceolate, 2.3–4.3 cm; perianth yellow, tube campanulate, 1–4 × 6.5–11.5 mm, limb lobes connivent, erect, subequal, 7–12 mm; stamens slightly exserted; filaments inserted at or 1–3 mm above base of perianth tube, erect, white, 1.3–2.4 cm; anthers pale yellow, 5–12 mm; ovary 1.2–2.9 cm, neck constricted, 3.5–8.5(–10) mm. Capsules pedicellate, oblong to ovoid, 1–2.5 cm, apex beaked. Seeds 2–4 mm.
sw United States.
Subspecies 2 (2 in the flora).