7. Agave × glomeruliflora (Engelmann) A. Berger, Agaven. 95. 1915; as species.
Agave heteracantha Zuccarini forma glomeruliflora Engelmann, Gard. Chron., n. s. 19: 48, fig. 6. 1883; A. chisosensis C. H. Muller
Plants acaulescent, frequently suckering; rosettes cespitose, 4–6 × 5–9 dm. Leaves mostly spreading; blade light to dark green, without bud-prints, linear and 40–55 × 5–6 cm or lanceolate to deltate and 35–50 × (5–)7–10(–12.5) cm, rigid, adaxially concave toward apex, abaxially convex toward base; margins straight, nonfiliferous, conspicuously armed, teeth single, 3–10(–15) mm, 1–3 cm apart; apical spine grayish, conical to subulate, 2.5–4.5 cm. Scape 4–6 m. Inflorescences subspicate to narrowly racemose-paniculate, sparsely flowered; bracts persistent, triangular to narrowly triangular, 1–4 cm; lateral branches 70–90+, comprising distal 1/3–1/2 of inflorescence, 10 cm or shorter. Flowers (6–)10–12 per cluster, erect, 4–4.7 cm; perianth yellow to yellowish lime green, tube funnelform, (3.2–)6–8 × 10–13 mm, limb lobes ascending, subequal, 16–23 mm; stamens long-exserted; filaments inserted on rim of perianth tube, spreading, yellow to lime green or maroon, 4–5.8 cm; anthers yellow, 20–21 mm; ovary 1.3–2(–2.2) cm, neck constricted, 3.5–6 mm. Capsules sessile or short-pedicellate, oblong, 2.5–4 cm, apex beaked. Seeds 5–6 mm.
Flowering mid spring--early fall. Gravelly calcareous slopes in grasslands and oak-juniper woodlands; of conservation concern; 600--1600 m; Tex.; n Mexico.
H. S. Gentry (1982) applied Agave × glomeruliflora to a series of hybrids involving A. lechuguilla (subg. Littaea) and A. gracilipes, A. havardiana, and A. parryi var. neomexicana (subg. Agave), representing “all those cases of the racemose inflorescence seconded by the loose corneous margins of leaves intermediate in width between the wide leaves of the above cited species and A. lechuguilla.” However, A. × glomeruliflora should probably be more appropriately applied only to crosses and back-crosses between A. lechuguilla and A. havardiana.
Unlike species of subg. Littaea, this hybrid (and others that result from intersubgeneric crosses) exhibits the more open inflorescence types of subg. Agave in that the scape is dominated by clusters of flowers on more or less well-defined lateral branches.