6. Agave lechuguilla Torrey in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 213. 1859.
Plants acaulescent, frequently suckering; rosettes openly cespitose, 3–4 × 5–6 dm. Leaves mostly ascending to erect, (25–) 30–50 × 2–4(–5.2) cm; blade light green to yellowish green, sometimes checkmarked but without bud-prints, linear-lanceolate, stiff, adaxially concave toward apex, abaxially convex toward base; margins straight, easily detached, nonfiliferous, conspicuously armed, teeth single 2–6 mm, mostly (1–)2–4 cm apart, rarely absent; apical spine grayish, conical to subulate, 1.5–4.5 cm. Scape (2–)2.5–3.5 m. Inflorescences spicate, densely flowered on distal 1/2; bracts caducous, linear, 1–3 cm; peduncle 2–5 mm, rarely 20–150 mm. Flowers 2–3 per cluster, erect to slightly recurved, (2.4–)3–4.5 cm; perianth yellow, frequently tinged with red or purple, tube campanulate, 1.5–4 × 6–12 mm, limb lobes ascending, subequal, 11–20 mm; stamens long-exserted; filaments inserted on rim of perianth tube, spreading, yellow to reddish, 2.5–4.2 cm; anthers pale yellow, (11–)15–20 mm; ovary (0.8–)1.5–2.2 cm, neck constricted (2–)4–8.5 mm. Capsules sessile or short-pedicellate, oblong, 1.8–2.5(–3) cm, apex beaked. Seeds 4.5–6 mm. 2n = 110–120.
Flowering mid spring--late summer. Gravelly to rocky calcareous places in desert scrub; 500--1400 m; N.Mex., Tex.; n, e Mexico.
Agave lechuguilla is the principal source of “istle” or “ixtle,” a hard fiber used for rope and known by the trade name “Tampico fibre.” The plant is poisonous to cattle, goats, and sheep. This species is the dominant agave on the Chihuahuan Desert. It hybridizes with A. havardiana, A. neomexicana, A. gracilipes, and A. × glomeruliflora.