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American agave, American century plant, centuryplant, maguey americano

Utah agave

Habit Plants acaulescent or short-stemmed, commonly suckering, trunks less than 2 m; rosettes not cespitose, 10–20 × 20–37 dm. Plants acaulescent, suckering or not; rosettes solitary or sparingly cespitose, 1.5–6 × 1.5–10 dm.
Leaves

erect, spreading to ascending, occasionally reflexed, 80–200 × 15–25 cm;

blade light green to green or glaucous-gray, sometimes variegated or cross-zoned, narrowly to broadly lanceolate, smooth, rigid;

margins nearly straight or undulate to crenate, armed, teeth single, 5–10 mm, 1–4 cm apart;

apical spine dark brown to grayish, conical or subulate, 2–6 cm.

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

5–9 m.

1.7–5 m.

Inflorescences

paniculate, not bulbiferous;

bracts persistent, triangular, 5–15 cm;

lateral branches 15–35, horizontal to slightly ascending, comprising distal 1/3–1/2 of inflorescence, longer than 10 cm.

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

erect, 7–10.5 cm;

perianth yellow, tube funnelform to cylindric, 8–20 × 12–20 mm, limb lobes erect, subequal, 20–35 mm;

stamens long-exserted;

filaments inserted above mid perianth tube, erect, yellow, 6–9 cm;

anthers yellow, 25–35 mm;

ovary 3–4.5 cm, neck constricted, 3–6(–8) mm.

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

short-pedicellate, oblong, 3.5–8 cm, apex beaked.

pedicellate, oblong to ovoid, 1–2.5 cm, apex beaked.

Seeds

6–8 mm.

2–4 mm.

Agave americana

Agave utahensis

Distribution
from USDA
sw United States; Mexico
[WildflowerSearch map]
[BONAP county map]
from USDA
sw United States
[WildflowerSearch map]
[BONAP county map]
Discussion

Subspecies 2 (2 in the flora).

Various chromosome numbers have been reported for Agave americana under a variety of names, typically without regard to the plant’s origin or its precise taxonomic disposition. Nonetheless, the species is most certainly a polyploid complex based on x = 30, with reports of n = 30 and 2n = 60, 120, and 180 documented by S. D. McKelvey and K. Sax (1933), H. Matsuura and T. Sutô (1935), E. B. Granick (1944), A. K. Sharma and U. C. Bhattacharyya (1962), M. S. Cave (1964), S. Banerjee and A. K. Sharma (1987), Huang S. F. et al. (1989) and B. Vijayavalli and P. M. Mathew (1990). Various dysploids have also been reported (A. F. Dyer et al. 1970; J. L. Strother and G. L. Nesom 1997). See H. S. Gentry (1982) for details.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Subspecies 2 (2 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Leaves 80–135 cm, 4–6 times longer than wide; capsules 3.5–4 cm.
subsp. protamericana
1. Leaves 100–200 cm, 6–10 times longer than wide; capsules 4–8 cm.
subsp. americana
1. Leaves 3–5.5 cm wide; rosettes 4–10 dm wide; flowers (2.6–)2.9–4.3 cm.
subsp. kaibabensis
1. Leaves 1–3 cm wide; rosettes 1.5–4 dm wide; flowers 2.3–3.2 cm.
subsp. utahensis
Source FNA vol. 26, p. 452. FNA vol. 26.
Parent taxa Agavaceae > Agave Agavaceae > Agave
Sibling taxa
A. asperrima, A. chrysantha, A. decipiens, A. delamateri, A. deserti, A. desmettiana, A. gracilipes, A. havardiana, A. lechuguilla, A. mckelveyana, A. murpheyi, A. neglecta, A. palmeri, A. parryi, A. parviflora, A. phillipsiana, A. schottii, A. shawii, A. sisalana, A. toumeyana, A. univittata, A. utahensis, A. weberi, A. ×ajoensis, A. ×arizonica, A. ×glomeruliflora
A. americana, A. asperrima, A. chrysantha, A. decipiens, A. delamateri, A. deserti, A. desmettiana, A. gracilipes, A. havardiana, A. lechuguilla, A. mckelveyana, A. murpheyi, A. neglecta, A. palmeri, A. parryi, A. parviflora, A. phillipsiana, A. schottii, A. shawii, A. sisalana, A. toumeyana, A. univittata, A. weberi, A. ×ajoensis, A. ×arizonica, A. ×glomeruliflora
Subordinate taxa
A. americana subsp. americana, A. americana subsp. protamericana
A. utahensis subsp. kaibabensis, A. utahensis subsp. utahensis
Name authority Linnaeus: Sp. Pl. 1: 323. (1753) Engelmann: S. Watson, Botany (Fortieth Parallel), 497
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