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American agave, American century plant, centuryplant, maguey americano

Palmer agave, Palmer's 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, rarely suckering; rosettes usually solitary, not cespitose, 4–13 × 7–13 dm, 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 to spreading, 35–92 × 3.5–19 cm;

blade pale to glaucous-green or green, sometimes tinged reddish, not cross-zoned, linear-lanceolate to lanceolate, rigid, adaxially concave toward apex, abaxially convex toward base;

margins straight or somewhat undulate, armed, teeth single, well defined, firmly attached, 3–6 mm, (0.5–)1–2 cm apart, interstitial teeth 4–6, mostly along distal 2/3 of margins;

apex not conspicuously incurved, spine reddish brown to brown, acicular, 3–6 cm.

Scape

5–9 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.

(1.7–)4–6.5(–7.2) m. Inflorescences broadly paniculate, not bulbiferous, open;

bracts persistent, triangular, 1–5 cm;

lateral branches 8–26(–32), slightly ascending, comprising distal 1/3 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.

8–16 per cluster, erect, 4.5–7.5 cm;

perianth cream to pale yellow or light green, tube not shallow, urceolate, 10–18 × 10–16 mm, limb lobes persistent and often leathery during and after anthesis, erect, strongly unequal, (6–)9–18 mm, apex often flushed with maroon;

stamens long-exserted;

filaments inserted at 2 levels, above mid perianth tube and near rim, erect, pale yellow or reddish, 4–5.5(–5.8) cm, apex often flushed with maroon;

anthers yellow, 11–25 mm;

ovary 1.8–3.6 cm, neck slightly constricted, (0.5–)4–6 mm.

Capsules

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

short-pedicellate, narrowly oblong to oblong, 3.5–6 cm, apex short- to long-beaked.

Seeds

6–8 mm.

5–7 mm.

2n

= 60.

Agave americana

Agave palmeri

Phenology Flowering late spring–summer.
Habitat Sandy to gravelly places on limestone in oak woodlands and grassy plains
Elevation 900–2000 m (3000–6600 ft)
Distribution
from USDA
sw United States; Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; NM; 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.)

Agave palmeri hybridizes with A. chrysantha 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. 460.
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. 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) Engelmann: Trans. Acad. Sci. St. Louis 3: 319. (1875)
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