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American agave, American century plant, centuryplant, maguey americano

Mckelvey agave

Habit Plants acaulescent or short-stemmed, commonly suckering, trunks less than 2 m; rosettes not cespitose, 10–20 × 20–37 dm. Plants acaulescent, solitary or sparsely suckering; rosettes 2–4.5 × 3–6 dm, 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.

spreading, broadest at middle, 17.5–40 × 2.8–5 cm;

blade light glaucous green or yellowish green to dark green, usually cross-zoned, linear-lanceolate to lanceolate, rigid, adaxially concave, abaxially convex;

margins straight or undulate to crenate, armed, teeth single, firmly attached, well defined, 4–8 mm, 1–3 cm apart;

apical spine reddish brown to gray, subulate, 1.5–4 cm.

Scape

5–9 m.

2–5 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.

paniculate, not bulbiferous, open;

bracts persistent, triangular, 0.5–2 cm;

lateral branches 10–19, ascending, comprising distal (1/4–)1/3–1/2 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.

6–12 per cluster, erect, 3–4 cm;

perianth light yellow, tube shallow, broadly campanulate, 2–4.5 × 8–10.5(–18) mm, limb lobes wilting soon after anthesis, spreading, equal or subequal, 11–13 mm;

stamens long-exserted;

filaments inserted near or at top of perianth tube, erect, yellow, 2.5–3.3 cm;

anthers yellow, (7–)9–16 mm;

ovary 1.6–2.2 cm, neck slightly constricted, 1–2.5 mm.

Capsules

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

short-pedicellate, narrowly oblong to oblong, 3–4.5 cm, apex beaked.

Seeds

6–8 mm.

5–6.5 mm.

Agave americana

Agave mckelveyana

Phenology Flowering mid spring–mid summer.
Habitat Sandy to gravelly or rocky places with desert scrub, chaparral and pinyon-juniper woodlands
Elevation 800–2200 m (2600–7200 ft)
Distribution
from USDA
sw United States; Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ
[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.)

Agave mckelveyana may hybridize with A. deserti var. simplex and A. utahensis var. utahensis in Arizona.

(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
Source FNA vol. 26, p. 452. FNA vol. 26, p. 459.
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. 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
Name authority Linnaeus: Sp. Pl. 1: 323. (1753) Gentry: Cact. Succ. J. (Los Angeles) 42: 225, figs. 4–6. (1970)
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