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American agave, American century plant, centuryplant, maguey americano

desert agave, desert century plant

Habit Plants acaulescent or short-stemmed, commonly suckering, trunks less than 2 m; rosettes not cespitose, 10–20 × 20–37 dm. Plants acaulescent or short-stemmed, sparsely or prolifically suckering, trunks 0.2–0.4 m; rosettes solitary or numerous, 3–7 × 4–8 dm, compact to rather open.
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, widest at base, (20–)25–70 × 4.5–10 cm;

blade grayish, gray- or blue-glaucous, yellowish green, or greenish, occasionally cross-zoned, linear-lanceolate to lanceolate, rigid, adaxially concave, abaxially convex;

margins straight or undulate to crenate, armed, teeth single, weakly attached, well defined, of 2 types, 2–3 mm or (5–)6–8 mm, (1–)1.5–3 cm apart;

apical spine light or dark brown to gray, subulate to acicular, 2–4 cm.

Scape

5–9 m.

2–6 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.

paniculate, not bulbiferous, open;

bracts persistent, triangular, 8–15 cm;

lateral branches 6–15, slightly ascending, comprising distal 1/5–1/4 of inflorescence, longer 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.

12–48 per cluster, erect, 3–6 cm;

perianth yellow, tube shallow, campanulate or funnelform, 3–10 × 9–15 mm, limb lobes wilting soon after anthesis, spreading, equal, 13–20 mm;

stamens long-exserted;

filaments inserted unequally above middle or at rim of perianth tube, erect, yellow, 2.5–3.5(–4.2) cm;

anthers yellow, 13–21 mm;

ovary 1.6–4 cm, neck slightly constricted, 4–6 mm.

Capsules

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

short-pedicellate, ovoid to oblong or obovoid, 3.5–5.5 cm, apex beaked.

Seeds

6–8 mm.

5–6 mm.

Agave americana

Agave deserti

Distribution
from USDA
sw United States; Mexico
[WildflowerSearch map]
[BONAP county map]
from USDA
sw United States; nw Mexico
[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.)

Varieties 3 (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. Perianth tube campanulate, 3–5 mm; filaments inserted at top of tube; plants sparsely to prolifically suckering; rosettes numerous.
var. deserti
1. Perianth tube funnelform, (3–)5–10 mm; filaments inserted above middle but well within tube; plants rarely with 1–3 suckers; rosettes usually solitary.
var. simplex
Source FNA vol. 26, p. 452. FNA vol. 26, p. 458.
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. 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
Subordinate taxa
A. americana subsp. americana, A. americana subsp. protamericana
A. deserti var. deserti, A. deserti var. simplex
Name authority Linnaeus: Sp. Pl. 1: 323. (1753) Engelmann: Trans. Acad. Sci. St. Louis 3: 310. (1875)
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